• Volume 36,Issue 3,2014 Table of Contents
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    • A Pseudo dynamic Relationship for Describing the Cyclic Stress strainResponse of Soft Clays in Undrained Conditions

      2014, 36(3):421-428.

      Abstract (1296) HTML (0) PDF 557.50 K (1103) Comment (0) Favorites

      Abstract:In this study,we develop a pseudo-dynamic relationship describing undrained cyclic stress-strain responses of soft clay elements under general stress conditions,based on equivalent visco-elastic and creep theories.This relationship includes three basic parameters:the cyclic shear modulus,the damp ratio and the cyclic accumulative strain increment.The variation of the cyclic shear modulus and the damp ratio with the octahedral shear strain are used to describe undrained cyclic strain.The cyclic accumulative strain increment is determined based on the Mises creep potential and the associated flow rule.We determine these by unconsolidated and undrained cyclic triaxial compression tests of soft soils.We made cyclic triaxial extension and torsion test predictions using the parameters determined.Predicted variations of the cyclic shear modulus and the damping ratio with the octahedral shear strain are basically in agreement with the test results from the cyclic triaxial extension tests.Predicted variations of the cyclic accumulative strain with respect to the number of cycles is also basically in agreement with the test results for the cyclic torsion tests wherein the static and cyclic deviatoric stresses have the same direction.The predicted variations of the cyclic accumulative strain are less than those of the test results when the direction of the static deviatoric stress is different from the direction of the cyclic deviatoric stress in the cyclic torsion tests.

    • Vibration Test and Analysis at the People’s Square of Shanghai,Metro Line 1

      2014, 36(3):429-433.

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      Abstract:A field test was performed in the subway tunnel of metro Line 1 at Shanghai People’s Square Station. According to the data of the track acceleration test and the equation of the vehicle system vibration,a simulated deterministic expression of the metro load was obtained.The ground vibration due to the moving metro was simulated by applying the load to an FLAC3D numerical model. Through comparison of the numerical analysis results of different working conditions, the wave propagation, and attenuation at the ground surface, the dependence of the ground vibration on the tunnel depth and the frequency of the simple harmonic excitation load are analyzed.

    • A Nonlinear Seismic Response Analysis Model for UndergroundTunnels Based on the Viscous spring Boundary

      2014, 36(3):434-440.

      Abstract (1255) HTML (0) PDF 1.76 M (945) Comment (0) Favorites

      Abstract:This paper presents a model for the nonlinear seismic response analysis of tunnels,in which the viscous-spring boundary method and the earthquake equivalent node force input method are combined for half-space seismic excitation and the general finite element software ANSYS is utilized for analysis.The model uses the equivalent linear method to model soil nonlinearity and combines Rayleigh damping and material damping to model soil damping.Concrete and reinforcement nonlinearity are considered separately,and soil-liner contact is taken into account. The model is validated through comparisons with the results in the existing literature.The nonlinear seismic response of the metro twin tunnels in Tianjin City with thick soil layers is implemented,and it is shown that when two tunnels are close, the tunnel tunnel interaction is significant and nonlinear seismic stresses of the two tunnels become larger.This model can be used for the nonlinear seismic analysis of underground structures.

    • Effects of Soft and Hard Interlayers on Ground Motion Characteristics

      2014, 36(3):441-445.

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      Abstract:The program for one-dimensional equivalent linear soil seismic response is verified using the underground and surface seismic records of the KiK network in Japan.The results show that,in the range of small soil deformations,the calculated ground motions are consistent with the actual motions for the sites where the stiffness of soil layers increase with depth,but not for the sites with soft or hard interlayers.Accordingly,this paper presents a method to study the effects of soft and hard interlayers on ground motions.As a reference,the interlayer is replaced by a normal soil layer to meet the condition of increasing stiffness.Then,the surface seismic response excited by the actual underground motions is computed using the program.Comparing the computed motions and the actual motions on the surface,conclusions can be drawn.Some representative sites are studied in this paper.The results show that the effects of soft and hard interlayers on ground motions are consistent;there is an amplification of high-frequency motions if the interlayer is shallow,but there is an action of seismic isolation to high-frequency motions if the interlayer is deep.

    • D-S Theory-Based Parameter Estimation and its Application in Loess Landslides

      2014, 36(3):446-451.

      Abstract (1341) HTML (0) PDF 743.93 K (686) Comment (0) Favorites

      Abstract:Parameters of rock and soil materials are the key factors in the calculation of landslide stability,but these parameters necessarily exist with some uncertainty.This reduces the reliability of stability evaluations and has an important influence on engineering safety,engineering design optimization,and other aspects of engineering.The Dempster-Shafer (D-S) evidence theory is the most efficient method of solving the uncertainty of multiple parameters.It is a kind of expansion of probability theory that is able to not only distinguish between uncertainty and what is unknown but also deal with the uncertainty caused by unknowns.The D-S theory can provide consistent results by means of combining independent pieces of evidence and dealing with synthesis problems of fuzzy and uncertain information.It has been adapted to and achieved sound results for problems in artificial intelligence,system decision-making,diagnoses,assessment,and other practical problems in various fields.In this study,the D-S evidence theory was introduced to select and estimate slip soil mechanics parameters.The parameter selection and the revised counter-calculation of the selected parameters of a typical loess-red layer interface landslide in the Gansu province were conducted on the basis of the D-S combination rule.First,combined with the huge actual mechanical parameters of slip soil of the loess landslide by tests,the D-S evidence theory was adopted to D-S evidence analysis of huge mechanical parameters of slip soil of the loess landslide.Thus,the discernment frame and basic probability assignments of the mechanical parameters of slip soil were established from the subjective and objective aspects.Secondly, the D-S combination rule was applied to combine the reliability of multiple test parameters to achieve the optimal mechanical parameters of sliding zone reliability estimates.Finally,a revised counter-calculation of the slip soil mechanics parameters was applied for the demonstration of the obtained parameters.The results show that the D-S evidence theory is an effective approach to estimate and select the slip soil mechanics parameters.The parameters obtained from the D-S evidence theory coincide with the revised counter-calculation analysis of the slip soil mechanics parameters;such results show that the theory is applicable to dealing with the uncertainty of the above parameters.Furthermore,the slip soil mechanics parameters obtained from the D-S evidence theory can help to better reflect the actual conditions of the landslide,providing a reliable basis for the stability evaluation of loess landslides.In addition,the mechanical parameter estimation of loses landslides based on D-S theory are valid and reliable;moreover,it plays an important role in geotechnical engineering laboratory test data processing and stability calculation of mechanical parameter selections and is significant in the stability evaluation of the loess landslide.

    • Consolidation of the Softening of Soft Soil under Wave Loading

      2014, 36(3):452-456.

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      Abstract:A breakwater was constructed near Shanghai Port,China,in order to deepen the navigation channel along the Yangtze Estuary.In some sections of the breakwater a thick layer of soft soils was installed prior to construction.The breakwaters,designed as gravity-retaining structures,are made of prefabricated,semicircular concrete caissons.During construction,the caissons in one section failed during a heavy storm.In this study,the causes of the failure were investigated by running dynamic triaxial tests on undisturbed soil samples taken from the construction site.We found that the dike failure was induced by the weakening of the soft soil layer below the foundation.This paper describes the design of a guide dike and related soil improvement projects.We adopted surcharge preloading and prefabricated vertical drains to improve the soft soils below the caissons.These soil improvement measures were proven to be effective in maintaining the stability of the breakwater in subsequent heavy storms.

    • Calculation of Soil Pressure Considering the Softeningof Soft Soil during Earthquakes

      2014, 36(3):457-461.

      Abstract (1283) HTML (0) PDF 685.22 K (695) Comment (0) Favorites

      Abstract:To calculate the soil pressure of a retaining wall during earthquakes,previous methods have added only the dynamic load applied to the retaining wall or made an appropriate reduction in the internal friction angle of the soil,before calculations based on the pressure at rest.This paper,through experimental study,determines the dynamic triaxial strength variation of soft soil under dynamic loading,and then provides a method for determining the strength of the softened soil.We develop a method for calculating soil pressure that considers the softening of soft soil during an earthquake.We compare the soil pressure results in example cases that consider the softening effect with those that do not consider the softening effect.Our research results provide a strong basis for calculating the influence of soil pressure under earthquake loads and other dynamic loads.

    • Influence of Pile Sinking on Pile Capacity during Pile Driving on Offshore Platforms

      2014, 36(3):462-467.

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      Abstract:Pile sinking during pile driving is common.A sudden drop of a pile after a strike from the hammer may cause a serious accident,such as the pile falling out of the drive cap or damage to the pile from high tension stress.Pile sinking also often causes a large deviation between the drivability prediction and the measured blow count.Therefore, an accurate assessment of pile capacity after pile sinking becomes an important problem to address in practice.In this paper,two projects in the East China Sea are chosen to analyze.Based on the results of dynamic load tests in the field and pile driving records,the influence of pile sinking on pile capacity at the end of driving (EOD)is studied.The analysis results show that pile sinking will lead to a significant decrease in the total energy used in pile driving.The results from CAPWAP show that the unit friction of a soil layer where piles run off is close to zero,while the pile end resistance shows no obvious abnormalities.This indicates that the decrease in pile capacity caused by pile sinking is mainly from friction reduction.In this instance,the pile capacity reduction resulting from pile sinking can reach a maximum of 17% of the designed value.

    • Experimental Study of Horizontal Dynamic Response andP-Y Curves of Piles during Earthquakes

      2014, 36(3):468-475.

      Abstract (1231) HTML (0) PDF 1.90 M (1072) Comment (0) Favorites

      Abstract:The horizontal dynamic response of pile foundations in liquefiable soil has always been an important research question in the geotechnical field and the field of earthquake engineering.Based on the shaking table test with different input waveforms,the horizontal dynamic interaction responses of the soil-pile-slab system and the variation of the P-Y curve were analyzed using the FBG system.The P-Y curves of each pile in the pile group and single piles were compared with the API specification method.The research results showed that magnification of cap acceleration and displacement was small in general for non-liquefied tests.The cap acceleration and displacement of single piles were 2 to 3 times greater than for piles in the pile group,while the cap acceleration and displacement of piles in the pile group were 2 to 3 times greater than for non-liquefied cases.The slope of the P-Y curve for non-liquefied tests agreed well with the API specification method; however,the P-Y curves for both single piles and piles in the group were needed to reduce the API method appropriately in saturated soil.

    • Comparison of Measures for Eliminating High-frequency Instability of a Multi-transmitting Boundary in Scattering Problems

      2014, 36(3):476-481.

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      Abstract:The multi-transmitting boundary is a local artificial boundary widely used in the numerical simulation of near-field wave motions in infinite media. But,like other artificial boundaries,the multi-transmitting boundary is unstable in numerical simulations.In this paper,we analyze the cause of this high-frequency instability and discuss the applicability of previous stability measures by performing numerical scattering problem experiments.We found that(1)for the perfect elasticity problem,the filtering method is more suitable for eliminating high-frequency instability,but it must be used carefully because of the need to consider the empirical value of the parameters;and (2)for the viscoelastic problem,the explicit difference scheme with a suitable damping value is more suitable for eliminating high-frequency instability due to the energy dissipation of the difference scheme.This scheme is also more convenient for application because no empirical parameters must be considered.

    • Seismic Stability Analysis of Highway Subgrade Based on the Pseudo-static Method

      2014, 36(3):482-488.

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      Abstract:China is an earthquake-prone country,especially in its central and western regions.Earthquake is an unexpected event,and while its occurrence is not frequent,it can be catastrophic,and its effect on high grade highways is no exception.Previous research has rarely addressed the dynamic characteristics of subgrade filing and the stability of subgrade structures under earthquake loads.The effect on the seismic dynamic load,as documented by the current“Code for the Design of Highway Engineering,” typically uses the region of earthquake intensity as its only reference.This code does not consider seismic vibration frequency,the duration of an earthquake,or other characteristics.Therefore it cannot accurately reflect the characteristics of a subgrade structure during an earthquake. In this paper,we carry out research on the dynamic stability of the roadbed structure using the pseudo-static method.We have improved upon the quasi-static method with respect to its formula for the dynamic stability of the roadbed structure.The retaining wall acceleration,as affected by the seismic load,is considered in the calculation of the earth pressure on the retaining wall,as is the influence of the seismic acceleration distribution coefficient.With respect to the roadbed,we also improved the seismic inertia force by introducing the acceleration distribution coefficient.From these pseudo-static method modifications,the stability calculation formula for subgrade slopes was thereby improved.

    • Study on Difference of Ground Motions in Faulted Basin of Xichang

      2014, 36(3):489-494.

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      Abstract:In this study, by analyzing the peak ground acceleration (PGA) and spectral characteristics of the earthquake acceleration records from the main shock of the Wenchuan earthquake, the difference of the ground motion at both sides of the Anninghe fault zone is discussed. By analyzing the local site conditions at the observation stations, such as local site soil, topography, and tectonics, a preliminary explanation of the discrepancy is obtained, and the numerical solution of 2D model of this site derived by the explicit finite element combined with the local multi transmitting artificial boundary method is used to interpret the mechanism causing the difference in the ground motion. The results of numerical calculations indicate that in spite of its simplicity, such an idealized model is also successful in reproducing many of the essential characteristics of ground motion and the mechanism causing the difference in ground motion within the fault zones of Anninghe. The characteristics of the faulted basin under control of the Anninghe fault zone may be used to interpret observed seismic data obtained during the Wenchuan main shock and theoretical calculations of nearby fault responses in Xichang.

    • Buckling Restraint Conditions for Innovative Aluminum Alloy Energy Dissipation Braces

      2014, 36(3):495-503.

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      Abstract:The concept of structural damage control,introduced in the seismic retrofitting area in the late 1980s,has become popular in its applications for engineering bridges and buildings.Under strong or severe earthquake excitations,plans are made such that damage is expected to take place in energy dissipation devices and the primary structure can be kept away from the damage.Among many types of damping devices,increasing attention is being paid to hysteretic dampers,because the inelastic deformation capacity of metallic substances presents an effective approach in transferring seismic energy to other forms of energy at a low cost.Buckling-restrained braces (BRBs),as an axial-type hysteretic damper,are widely studied through their component behavior and system applications in civil engineering.Aluminum has drawn our attention for improving the durability of high-performance BRBs.Usually,aluminum and its alloys need no protection against atmospheric or chemical corrosive agents,because aluminum oxide,which is naturally generated on the surface of the metal,protects the body of the metal against corrosion.Because of the advantages of aluminum and its alloys,such as its light weight,corrosion resistance,ease of production,and economic and environmental benefits,aluminum alloy is selected for the manufacture of BRBs in this paper.Further numerical analysis of the mechanical behaviors of the aluminum alloy BRB (ALBRBs) was conducted based on aluminum alloy material tests and corresponding BRB tests,which were performed abroad.The objective of the analysis is to conduct a parametric study of BRBs with different gap widths(between the core and the restraining member)and initial imperfections to investigate the buckling behavior of the brace.The core plate and BRM were modeled using 8-node C3D8R linear brick elements with reduced integration.Large displacement static cyclic analysis was performed using the ABAQUS 6.10 general purpose finite element program.The results showed the conventional BRB design method does not consider the effect of initial imperfections and eccentricities,but the safety factor method can solve this problem.In order to enhance the aseismic ability of space structures,a new type of ALBRB was developed.The characteristics of the new ALBRB showed more reliable performance and simple construction,as well as decreased mass.Analysis of the buckling restraint conditions of the new ALBRB was completed.Results show that the stability of the ALBRB was good under monotonic loading and that it completed the full hysteresis loop and had preferable ductility and dissipative capacity under cyclic loading. The new ALBRB performs well and can be used in the aseismic design of space structures.One of the underlying requirements of BRBs is avoiding both overall and local buckling until the brace member reaches the target displacement and ductility.This required performance becomes important as the weight of the BRB and the strength and rigidity of the restraining member are reduced.Further experimental and analytical investigation is necessary to examine the overall buckling prevention conditions of ALBRBs,taking into consideration different gap sizes,BRM types,and frictional response effects in ALBRBs.

    • Prediction Model Framework for Assessing Liquefaction induced Lateral Deformation Based on Seismic Damage Investigation Data

      2014, 36(3):504-509.

      Abstract (1139) HTML (0) PDF 510.62 K (1159) Comment (0) Favorites

      Abstract:This paper presents a framework for assessing the probability that a specified liquefaction-induced lateral deformation will be exceeded based on seismic damage investigation data.This framework overcomes the defect in traditional empirical formulas and regression models in how the terms of uncertainty are described.It deals not only with the effect of liquefaction but also with the probabilistic characterization of all possible region ground motions at a given site with a known earthquake history (in terms of the joint distribution of PGA and MW).In the case analysis,we obtain a liquefaction-induced lateral deformation hazard curve by applying the framework to the calculation in order to demonstrate the annual rate of deformation exceedance at a given site for a given exposure time.Thus,this framework has the potential to be a very useful tool in the field of geotechnical earthquake engineering.It can also facilitate further research efforts to describe the uncertainties associated with liquefaction induced lateral deformation.While the proposed framework is simple and effective,more work is necessary,especially on other factors that may be influencing the deformation,before it may be considered to be complete.

    • Numerical Analysis of Screening Efficiency of DrivenPiles in Different Layouts

      2014, 36(3):510-515.

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      Abstract:While rapid development of high-speed railways brings convenience,it also causes vibration impacts on the surrounding ground that need to be mitigated.The study of using driven piles as a vibration isolation method is almost in the stage of theoretical analysis.In this article,the train load is represented by the Fourier expression form that can be used in finite element calculation,and the three-dimensional piles vibration isolation model is created with ABAQUS finite element software.The different factors of the vibration isolation effect are analyzed using the control variable method,and these factors include the pile length,spacing,material,double row distance,and arrangement.The results can provide the basis for a construction design.

    • Cyclic Elastoplastic Constitutive Model of Clayey Sand and its Dynamic Numerical Analysis

      2014, 36(3):516-524.

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      Abstract:The definitions of overconsolidation state parameter R and structural property state parameter R* are perfected, and a new derivation of the super/subloading yield surface model is offered based on these definitions. The numerical implementation based on this unified constitutive model is compiled, and the simulation is carried out. The mechanical characteristics of clay and sand and the differences between their state parameters are analyzed. The numerical implementation of clayey sand is then simulated based on the theoretical analysis. To find the correspondence between the numerical parameters and the clay content, simulations of clayey sand with varying parameters are carried out.

    • Improvement of Spring Constant Calculation in ResponseDisplacement Method

      2014, 36(3):525-531.

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      Abstract:When the response displacement method is adopted for the seismic calculations of underground structures,the key is to determine the soil spring constant, as spring constant values directly affect the calculation results.Based on the existing static finite element method of calculating the spring constant,six variations of this method are designed through different applications of force,and their calculation results are compared. The calculation results of the whole solution and the whole simultaneous solution of the radial and tangential spring constant methods should be dangerous,the single solution and the single simultaneous solution of the horizontal and vertical spring constant methods possess high computational precision,and the calculation results of the whole solution and the whole simultaneous solution of the horizontal and vertical spring constant methods show be safe.

    • A Comparison of the Seismic Responses at Different Sites byTwo Analysis Programs under Weakly Nonlinear Conditions

      2014, 36(3):532-539.

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      Abstract:The one-dimensional equivalent linear method for soil layer seismic response analysis is widely used in engineering practices and academic fields. LSSRLI-1 and SHAKE2 000 are typical codes.LSSRLI-1,which represents the 1980s skill level,is recommended in Chinese manuals on seismic safety evaluation practices.SHAKE2 000 represents a more internationally advanced level.Improvements to LSSRLI-1 must be made with respect to the drawbacks of the equivalent linear method it uses.To reveal the differences between LSSRLI-1 and SHAKE2000,we established a horizontal layered model for class-Ⅰ to class-Ⅳ sites.Then we ran the two programs on the same working cases.A comparison and statistical analysis of the results shows the difference between the two programs and we therefore propose a variation of the relative deviation rule.Results indicate that peak ground acceleration (PGA),the spectrum,and the shear strain results do not obviously coincide in class-Ⅲ and class-Ⅳ site conditions. But in class-Ⅰ and class-Ⅱ sites conditions,there is little difference between the results of the two programs.After preliminary analysis,we conclude that the shear strain calculation method can be improved by modifying the shear modulus method to narrow the gap between LSSRLI-1 and SHAKE2000 results.We make this conclusion on the basis of the relative relationships between the shear strain,the PGA,the spectrum,and the shear modulus relative deviation.

    • Analysis of Numerical Simulation of Liquefiable Silty Soil Reinforced by Gravel Pile

      2014, 36(3):540-543,554.

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      Abstract:The gravel pile technique is currently one of the most effective,economical, and widely used methods for dealing with saturated silt soil foundations.Many scholars have conducted research on the gravel pile mechanism with respect to saturated silt or sand foundations,and they have found some useful conclusions.However,further analysis is required on the seismic liquefaction characteristics of gravel piles in saturated silty soils.In this paper, we investigate the seismic liquefaction characteristics of gravel pile in the silt foundations of a number of Anhui expressway roadbed engineering projects.We performed numerical analysis using the three-dimensional finite difference program FLAC3D.By studying the pore pressure increase and the law of dissipation at different distances from the gravel pile center,we determined the reasonable pile space and the reasonable depth of gravel pile strengthening in a saturated silty soil foundation during high-intensity earthquake conditions.These results can provide reference data for similar engineering projects.

    • Experimental Study on Liquefaction Depth of Saturated Silty Soil Ground under Seismic Loading

      2014, 36(3):544-548.

      Abstract (1081) HTML (0) PDF 1.23 M (998) Comment (0) Favorites

      Abstract:To obtain the corresponding maximum liquefaction depth of saturated silty soil ground under different seismic shock conditions,we studied the liquefaction behavior of saturated silty soil under various seismic loading conditions at different depths.We conducted a series of GDS dynamic triaxial tests to consider different dynamic loads which were set in advance,and determined the degree of silt soil liquefaction at different depths and different seismic shock conditions.We also obtained the relationship between the dynamic shear stress ratio and the number of soil cycles.We established liquefaction depth according to the discriminate formula.The results can be used to predict soil liquefaction depths for high seismic intensity area projects.

    • Stress Characteristics of Soil around the Pile of a MonopileFoundation in Offshore Wind Turbines

      2014, 36(3):549-554.

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      Abstract:The mechanical behavior of soil plays a significant role in the deformation and stability of the pile foundations of offshore wind turbines.The soil’s stress path around the pile foundation is complex under the wind and wave loadings.This paper conducts a numerical simulation for a simplified pile foundation using the finite element method (FEM),and studies the deformation,stress path,and rotation mode of the principal stress axes under cyclic loadings.We found that the soil’s stress components around a pile foundation show periodical variation with an increasing number of cycles.The stress path in the first cycle is significantly different from that in subsequent cycles. We observed a marked repetitive rotation of the principal stress axes in the shallow region of the soil foundation and the rotation amplitude that it can reach.

    • Determination and Hazard Evaluation of Seismic Liquefaction

      2014, 36(3):555-561.

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      Abstract:Earthquake liquefaction of saturated sandy soils may induce severe damage,and this issue has become an important research topic in the field of soil dynamics.To judge the potential for earthquake liquefaction and to evaluate liquefaction hazards can lead to better control and prediction of liquefaction.Liquefaction discrimination may be considered first by making a preliminary judgment.Preliminary judgment,according to available survey data or a simple testing method,may provide a determination of the initial level of soil liquefaction.Further discrimination is necessary for soil layers where earthquake liquefaction may occur,as determined by the preliminary judgment.Since there are many factors affecting soil liquefaction,we recommend an empirical method that includes the standard penetration test,the static cone penetration (static sounding)test,and the shear wave velocity method.The single discrimination method has limitations in its scope of application;therefore,a combination of various methods is more reliable.Liquefaction hazard evaluation adopts a harmfulness index to analyze the degree of harm caused to buildings by liquefaction.Evaluation methods mainly include the liquefaction index method,the seismic settlement value method,the spectrum intensity ratio method,and the synthetic method.Based on the evaluation index,a comprehensive liquefaction ranking can fully reflect the potential and extent of the liquefaction hazard.

    • Study on Tensile Properties of Remolded Loess in Jiuzhou Development District,Lanzhou,China

      2014, 36(3):562-568.

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      Abstract:Loess is a typical water sensitive structural material with relatively low tensile strength. Under most circumstances in engineering practice,the tensile strength of loess and most geomaterials is negligible.However,there are many earth structures(slopes,subgrades,and tunnels)damaged due to tensile stresses.So the tensile properties of loess become very significant for practical engineering.The shear,unconfined compressive,and tensile properties of remolded loess taken from Jiuzhou Development District in Lanzhou,China, are thoroughly investigated in this study using the undrained triaxial shear test,unconfined compressive test,and unconfined penetration tensile test.The relationships among the tensile strength,shear strength,and unconfined compressive strength of the remolded loess are comparatively analyzed.The test phenomena show that the shear test specimen under low confining pressures fails in a brittle pattern,while under high confining pressures,it fails in a plastic pattern,and that the plasticity seems to grow with the increasing of the water content of the loess.The specimen in the unconfined penetration test fails in a brittle pattern,splitting into two or three petals with peak tensile stresses.The axial tensile stress first increases to a maximum value with the increasing of penetration depth and then has a steep decreasing process with the continued increasing of penetration depth.The test results indicate that the tensile strength of remolded loess decreases in a quadratic polynomial pattern with the increasing of water content,and the degree of correlation is satisfactory.By comparison and analysis,it is shown that the tensile strength of remolded loess is much smaller than the unconfined compressive strength,and the unconfined compressive strength tends to increase with the tensile strength in a linear pattern.The ratio of tensile strength to compressive strength first decreases,then increases,and finally decreases again as the water content increases;however,it increases,then decreases,and finally increases with the increasing of dry density.The maximum ratio of tensile strength to compressive strength occurs around the optimum water content and maximum dry density,while the minimum ratio of tensile strength to compressive strength appears to be at the maximum water content and minimum dry density.Cohesion and internal friction angle are the two indicators of the shear strength of soils,and they are affected by the structural and strength characteristics of soils.Regression analysis on the shear strength,unconfined compressive strength,and tensile strength suggests that the cohesion of the remolded loess decreases with little amplitude at first and then increases approximately in a monotonic linear pattern with the unconfined compressive strength and tensile strength.Both the unconfined compressive strength and tensile strength increase exponentially with the product of cohesion and tangent of internal friction angle.Similar to the water content,the degree of saturation of loess also has something to do with the strength characteristics of loess.The test results indicate that both the unconfined compressive and tensile strength decrease with the increasing of the degree of saturation in a polynomial pattern.

    • Discussion of the Selection of Initial Values for Rock Spectrum Parameter Inversion Based on the Least Squares Method

      2014, 36(3):569-574.

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      Abstract:Spectral induced polarization (SIP) is an effective means to explore an induced polarization target and deep minerals in geophysical prospecting. Induced polarization (IP) is a geophysical imaging technique used to identify subsurface materials, such as ore. The method of IP is similar to electrical resistivity tomography, in that an electric current is induced into the subsurface through two electrodes and voltage is monitored through two other electrodes. IP is a measure of a delayed voltage response in earth materials. The IP effect is caused by a current-induced electron transfer reaction between electrolyte ions and metallic luster minerals and is a measurement of the electrical energy storage capacity of the earth. The IP effect can be determined by passing an induced current into the ground and measuring the change in voltage with respect to time (TDIP), or by measuring changes in phase at a given frequency with respect to a reference phase (FDIP). To produce an IP effect, fluid-filled pores must be present, since the rock is essentially an insulator. The IP effect becomes evident when these pore spaces are in contact with metallic luster minerals, graphite, clays, or other alteration products. IP effects make the apparent resistivity of the host rock change with frequency. Generally, the rock resistivity decreases as the measurement frequency increases. Understanding the rock spectrum parameters, which are obtained through resistivity and phase inversion, is the most important step. There are many methods applied in rock spectrum inversion. Generally, when using the least squares algorithm, the inversion result is primarily determined by the initial value of each parameter. In this paper, the authors will show that the initial value based on the least squares algorithm can be selected randomly from the scope of various parameters. In order to demonstrate the practicality of this method, the theoretical data determined by Luo Yan-zhong is compared to shale measurement data (complex resistivity and phase) measured by an SI-1260A Impedance Analyzer. The shale was saturated before starting the experiment and the measuring conditions were room temperature and standard pressure. During the measurement, the frequency was applied at a total of 61 points, varying from 0.01 Hz to 10 kHz and the measuring mode was a symmetric quadrupole. In order to prevent the partial saturation fluid to evaporate and alter the electrical characteristics of the rock samples, both of the shale core's ends were soaked in the saturation fluid. In order to reduce the electrode polarization effects, the annular high-purity platinum network was used as unpolarized electrodes. In order to reduce noise disturbance, each core was measured a minimum of three times until the error of two adjacent measurements was within the permissible range. The experiment was automatically controlled by a computer during the entire process. Impedance and phase parameters were obtained from the experiment. Complex resistivity could be calculated through the impedance according to the geometric parameters of the shale cores. The single and double Cole-Cole models are selected to study the complex resistivity properties of shale. The inversion results show that the complex resistivity and phase curves can be described well and the spectrum parameters also can be obtained precisely. Simultaneously, relative to blindly selecting the initial value, this method has the advantages of avoiding local minima and performing at a high speed, and it overcomes the previous detrimental impact on the results.

    • Finite Element Analysis of Reducing the High speed RailwayVibration Effect on the Environment Using Open Trenches

      2014, 36(3):575-579.

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      Abstract:The high-speed railway vibration effect on the environment has become more and more widespread in recent years,and technical measurements are needed to minimize the damage to the environment caused by this new transportation vehicle. It has been shown that open trenches can be used for this purpose because of their easy construction and relatively good isolation effects. The finite-element software ABAQUS was adopted to analyze the open trench isolation effects.In order to adequately absorb the shock wave and reduce the impact of border-reflected waves on the results, the infinite element and visco-elastic boundary is used in this model.The parameter ARF is introduced in the calculation procedure so as to evaluate the isolation effects.The reduction effect of different factors that influence the resulting vibration reduction,such as the different sizes of an open trench and the frequency of the vibration load,are also discussed.The obtained approaches can be applied by designers in this area.

    • Dynamic Properties of Soil in Intertidal Zone under Cyclic Lifting Loads

      2014, 36(3):580-584.

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      Abstract:A series of dynamic triaxial tests of soil samples from intertidal zone were performed under strain-controlled and stress-controlled conditions respectively.The relationships among stress,strain and pore pressure of soil samples under cyclic lifting loads were obtained,and the dynamic properties and liquefaction potential of the foundation soil were analyzed.Finally,some suggestions about construction methods in site were proposed.

    • Research on Slope Stability Safety Factors of a High Earth rock Dam under Seismic Conditions

      2014, 36(3):585-591.

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      Abstract:The current design code for earth-rock dams (DL/T5395-2007)specifies that it applies only to earth-rock dams up to 200 m in height. With new developments in dam design and construction technology,design safety standards must be established for slopes of earth-rock dams more than 200 m high. Based on the theory of relative safety, the reliability index and safety factors associated with mapping should have the same platform.The permissible slope stability reliability indicator for a rolled earth-rock dam less than 200 m high, as specified by the current design code,is 4.2.Based on risk management principles,an allowable slope stability reliability indicator for a 200~250 m high earth-rock dam is 4.45,and that for a 250~300 m high earth-rock dam is 4.7.The corresponding slope stability safety factors for high earth-rock dams under seismic condition are 1.35 and 1.4,respectively.Slope stability safety factors for high earth rock dams under various seismic conditions were shown to meet safety standards.

    • Research on the Influence Factors of Vibration dueto Metro Shield Construction

      2014, 36(3):592-598.

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      Abstract:This study focusess on the shield construction of Beijing subway line 8 under typical working conditions,using the field monitoring system at the shield construction work face,to obtain the amplitude and frequency characteristics of the vibration source.Based on these characteristics,we conducted a sensitivity analysis of the factors influencing the vibration source. We first used the grey relation entropy method,and then performed multiple regression analysis on the vibration induced by the metro shield construction.The research results are as follows:(1) we propose that the main controlling factor of the shield construction vibration source-the stratum condition and its quantization characteristic parameter-is the weighted dynamic elastic modulus of the tunnel face stratum,and the main construction parameters influencing the vibration are the cutter head torque and the gross propulsion;(2)we establish a regression model of the shield construction vibration source which shows remarkable correlations.These research results may be used as a basis for analysis,forecast,and construction with respect to controlling of the environmental vibration response caused by shield construction,which fills a void in this area of research.

    • Focal Mechanism of Small and Moderate Earthquakes and Tectonic Stress Field in Sichuan-Yunan Areas

      2014, 36(3):599-607.

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      Abstract:Seismic activity is the direct reflection of tectonic stress fields.Under a regional stress field,the cumulative strain reaches a certain level before the crustal rock fractures and is dislocated,resulting in an earthquake.The accumulation of tectonic stress follows the temporal variation and spatial migration of the stress field.The study of stress field trends in wide regions may determine the epicenters of future large earthquakes to provide a scientific foundation for the physical meaning of earthquake prediction.Current research methods of tectonic stress fields mainly include geological structure analysis,seismic analysis,in-situ stress measurement,numerical simulation,and experimental simulation.The most direct method for reflecting the stress state of the crust is to examine the focal mechanism of earthquakes in the deep crust.Compared with strong earthquakes of lesser quantity and concentrated distribution,small and moderate earthquakes are numerous and widespread;these conditions provide the possibility of detecting the stress state of the crust in the study area.Some of the most intense seismic activities in China have occurred in Sichuan-Yunnan,located in the southeastern region of the Tibetan Plateau.Several large earthquakes have occurred in this area during the past 30 years,and its unique tectonic environment has a specific meaning in the dynamics of the continent. In this paper,we calculate the focal mechanism of 1893 M≥3.0 small to moderate earthquakes that occurred from 2003 to 2012 by using the Hash method on the basis of P-wave first motion and S-wave amplitude ratios,and we analyze their characteristics.Moreover,we investigate the focal mechanisms of moderate and strong shocks occurring from 1976 to 2012.The regional stress field is inverted by using the spatial and temporal stress inversion (SATSI) method for damping regional stress with 1651 reliable focal mechanism solutions, and its space characteristics are analyzed.Our research shows that the focal mechanism solutions of small and moderate M≥3.0 earthquakes were dominated by strike slip from 2003 to 2012 in the Sichuan-Yunnan region,with some reverse and normal faulting M≥4.0 earthquakes were dominated by strike slip,which is consistent with the regional background.The fault type is indicative of 3.0 ≤M≤3.9 random earthquakes.The Sichuan-Yunnan area is divided into five zones of A,B,C,D,and E according to geological and seismic activity and other characteristics to examine the characteristics of the focal mechanism in detail.The results show that characteristics differ among zones.The stress action is mainly horizontal,and strike-slip faulting is dominant in the study area.The maximum horizontal principal stress orientation of the tow side of the Hong-he fault tail is NW-SE.In the Sichuan-Yunnan area,the rhombic block stress is divided into two different states by the Lijiang-Xiaojinhe fault;the stress orientation of the south region is NW-SE,and that of the north region is N-S.The stress orientation has a rotating clockwise tendency from inner the Tibetan Plateau to the east border of the Sichuan-Yunnan rhombic block.In the eastern boundary area,there is a gradual transition from NE to SW in the north to NW-SE in south.The maximum horizontal principal stress orientation is parallel to the fault orientation in western and southwestern Yunnan.We compared our results with the Harvard Centroid Moment Tensor (CMT) database and determined that our results are comparatively accurate.

    • Study of Attenuation Characteristics, Site Response and Seismic Source Parameters of the Pubugou Reservoir Region

      2014, 36(3):608-615.

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      Abstract:On the basis of digital seismograms recorded by the Pubugou reservoir digital seismic network, we obtained the nonelastic coefficient of Pubugou reservoir area by using the method proposed by Atkinson. The site response of each station was obtained by using the Moya method. The frequency-dependent Q(f) at the reservoir area is estimated as Q(f)=47.1*f0.92; the site response of each station is approximately 1.0, showing little amplification. On the basis of the Q(f) and the site responses, we detected approximately 67 tectonic earthquakes and 208 source parameters of blasting shocks by using the Atkinson inversion method. The results show obvious differences in the source parameters of the tectonic earthquakes and blast shocks. The parameters near the reservoir dam area and Hanyuan County were lower because of the blasting vibration.

    • Effects of Potential Earthquakes on Construction and Development in South China Sea Region

      2014, 36(3):616-621.

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      Abstract:The South China Sea (SCS)region is rich in oil,gas,and fishery resources,as well as potential tourism sites.With the establishment of the city of Sansha,traffic engineering,civil engineering,and infrastructure construction in the SCS have become the core of the economy.The SCS is located at the intersection of the Eurasia,Pacific,and Indian Plates and has a very complex geological structure.Considering the impact of potential earthquakes on the development of the SCS region,steps need to be taken to mitigate their dangerous effects.China currently has established relatively complete seismic design codes for structures on land,but studies on offshore earthquake engineering are still rare,and attenuation strategies for offshore engineering are incomplete.This paper will analyze the seismotectonics of the SCS and its adjacent areas through analysis of historical seismic data.The results show:(1) Earthquakes greater than magnitude 7 have occurred in the northern part of the SCS.Thus,offshore engineering in the region should consider the impact of earthquakes related to the Honghe and Qiongyue offshore fault zones. (2) In the central region of the SCS,the impact of the subduction zone from south Tainan to the west side of the Luzon Island in the Philippines should be taken into account. (3)The characteristics of subduction earthquakes and shallow crustal earthquakes are different,and it is necessary to study the specific features of interface and intraslab earthquakes in a subduction zone.

    • Fault Parameters and Slip Properties of the 1954 Northern Tengger Desert M7.0 Earthquake

      2014, 36(3):622-627.

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      Abstract:The northern Tengger Desert M7.0 great earthquake that occurred in 1954 resulted in varying degrees of damage in many areas of Neimenggu and its adjacent regions.Thus far,research results of the cause of this earthquake are few and inconsistent.Because it occurred in the Gobi Desert,the aeolian effect of was intense.These facts cause difficulties in studying the earthquake through geological prospecting methods.It is known that clustered small earthquakes often occur in the fault plane vicinities of large earthquakes.We used precisely relocated earthquakes that occurred near the earthquake rupture zone between 1985 and 2012 and selected a strip-shaped zone according to clustered small earthquakes and long-axis morphology in the meizoseismal area.On the basis of simulated annealing and Gauss-Newtonian nonlinear inversion algorithms,we obtained fault plane parameters of earthquakes such as strike,dip,and location by using data of densely populated small events.On this condition,rake angles of the fault plane are further inferred from regional tectonic stress parameters.Finally,we determine that the inverted results and known results are similar and that the former are in the cycle of the highest seismic intensity.These findings indicate that the inverted results are reliable.

    • Preliminary Analysis of Coseismic Response of Tiltmeters with High Sampling Rate Used at Huzhou Seismostation

      2014, 36(3):628-633.

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      Abstract:By comparing the response characteristics and seismic phase parameters recorded by VP, SSQ second sampling tiltmeter and JCZ-1T seismometer in the same period of the earthquake, this paper presents that the three instruments can all record clear P wave, S wave and surface wave, and S wave recorded by VP and JCZ-1T is clearer than that recorded by SSQ. Bandwidth of seismic waves recorded by VP is more consistent with that of JCZ-1T records. Before the Iran and Pakistan boundary M7.7 earthquake on April 16, 2013, JCZ-1T seismometer and SSQ tiltmeter simultaneously record a slowly moving event at intervals of 15~30 s.

    • Characteristics of Horizontal Deformation Field of the Shanxi Seismic Zone before and after the Wenchuan M8.0 Earthquake

      2014, 36(3):634-638.

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      Abstract:We obtain the horizontal velocity field and tectonic strain rate field of the Shanxi seismic zone derived from Global Positioning System(GPS) data before and after the Wenchuan M8.0 earthquake.The results indicate that after the Wenchuan M8.0 earthquake,the velocity of each region in the Shanxi seismic zone deflected westward in varying degrees.The north area including Taiyuan Basin shifted to SWW from SW and SSW directions in 1999-2007,and the velocity developed from an average of approximately 2 mm/a to 4 mm/a. In addition,the area south of Taiyuan Basin shifted to SW from a SSE direction.The strain rate field in the Shanxi seismic zone was significantly enhanced after this earthquake and formed three compressive strain concentration areas in Datong Basin,north Taiyuan Basin,and southwest Linfen Basin.In these respective areas, the Datong M4.5,Yangqu M4.6,and Hejin M4.8 earthquakes occurred in 2010.These earthquakes may have occurred because a regional stress field environment with compressive strain accumulation is beneficial to the formation and occurrence of a moderate earthquake in the Shanxi seismic zone.Moreover,because of the Japan M9.0 earthquake,the westward velocity of the Shanxi seismic zone was weakened,and the strain rate field expanded obviously during 2009 to 2011.In addition, the velocity in the north area including Taiyuan Basin decreased to approximately 2~3 mm/a,and the area south of Taiyuan Basin moved toward the south from the SW direction.This area may return to the background velocity of that during 1999 to 2007 in the future.

    • Characteristics of Gravitational Field Anomalies prior tothe Yuanping M4.2 Earthquake in Shanxi

      2014, 36(3):639-644.

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      Abstract:On March 28,2009,an earthquake of M4.2 occurred in Yuanping in Shanxi Province that affected people’s residences 200 km the epicenter area.The epicenter was at middle part of Yiding Basin,which is a horseshoe-shaped extensional basin,and the edge faults of the basin include the northern Wutaishan,northern Xizhoushan,eastern Yizhongshan,and southern Henshan faults.In this study,we collect the gravity data of the Portable Gravity Observation Network from 100 observed points distributed in the Shaxi-Inner Mongolia region during 2007—2009.The values of gravity field variation with time are calculated in terms of six months and one year at every observed point,and values at every network point are obtained by interpolation with kriging and trend extrapolation methods in that region. Analysis of gravity variation characteristics prior to the M4.2 Yuanping earthquake shows that the gravity field data in the epicenter area exhibited negative banded anomalies in the E-W direction before the M4.2 earthquake and those positive anomalies appeared both north and south of the epicenter zone.The observed gravity field values show characteristics of ascent-descent-restitution at most observation stations near the epicenter.The Yuanping earthquake occurred during the restitution period.The varied characteristics of the gravity field described above did not appear in gravity observation points in the Inner Mongolia region far from the Yuanping epicenter zone.The Yuanping epicenter is located in a negative anomaly zone of the Bouguer gravity gradient and in a negative gradient anomaly zone of variation of Bouguer gravity,which corresponds with the northern Wutaishan Fault.This phenomenon implies that a corresponding relationship existed between gravity changes and tectonics in the study area Due to media inhomogeneity of the earth,earthquakes cause different areas to exhibit varied values of media density,which is generally more obvious near the faults.It is widely accepted that variation in the gravity field can be deduced from changes in media density and can be observed at the surface.Seismogenic body impending is a basic physical process of seismogenic theory.During the process of seismogenic body impending,media density in the focal zone is reduced;therefore,the gravity field value would decrease at the Yuanping epicenter.This reduction in media density may have caused the gravity field values observed at Yuanping epicenter prior to the earthquake occurrence.In addition, the epicenter is generally near the largest gravity change zone between ascending and descending variations.Moreover,the epicenter does not coincide with the largest position change of gravity field variation.These results support that the shape of the Bouguer gravity field gradient varied with time before the earthquake occurrence according to the seismogenic body impending theory.

    • Seismic Hazard Assessment for Active Faults of Longnan City

      2014, 36(3):645-655.

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      Abstract:Based on active fault mapping in Longnan City,Gansu Province,we determine in this study parameters used in seismic hazard assessment for active faults.Five main fault zones are identified.The first is the Diebu-Bailongjiang fault zone,which ruptured during the M7 earthquake in 186 BC.The second is the Guanggaishan-Dieshan fault zone,which is separated into three main strands.The north strand had been found to cause a paleo earthquake,although the Pingding-Huama strand had a significantly faster slip rate.The Hanan-Qingshanwan-Daoxizi fault zone is the third.A surface rupture of approximately 3.5 km long was found in the Zhuyuanba strand.The fourth is the Lianddang-Jiangluo fault zone,which had strong activity in the Holocene.The fifth is the Wudu-Kangxian fault zone,in which four paleo-earthquakes have occurred since the Late Pleistocene.We estimated potential maximum earthquake magnitude and repeat interval time with magnitude rupture length and magnitude-frequency relationships for every fault or fault sub-area.The probability of destructive earthquake occurrence in the future 50,100,and 200 years was computed with a time-dependent seismic potential probability model and a Poisson distribution model.The methods for estimating potential maximum earthquake magnitude include four principles:(1)maximum magnitude can be an upper limit magnitude in the same seismic zone and (2)should not be smaller than the largest historical earthquake.(3)It can also be estimated by a relationship,such as M-L and G-R.Moreover,(4) it may have a reference to the maximum magnitude in a seismic zone with intensity of VIII degrees during the 200 years since last big earthquake because the lapsed time is longer than the interval time.The article gives mean maximum magnitudes,which are 7.5,7,7,7,and 6 for the Diebu-Bailongjiang,Guanggaishan-Dieshan,Liangdang-Jiangluo,Wudu-Kangxian,and Hanan-Qingshanwan-Daoxizi fault zones,respectively,with a combination of the four principles.We also used the method of b value spatial mapping to reveal high stress or high seismic hazard zones.On the basis of the seismic gaps identified,we used the relationship between magnitude and number or frequency to compute the b value of the study area with small earthquakes of the most recent 40 years.The small earthquakes were relocated with seismological methods.If the area had a lower b value,lower strain was accumulated in the area.We determined higher strain areas from the b value map;such areas are future high seismic hazard zones.We used the maximum curvature method to determine minimum magnitudes of completeness,which are minimum magnitudes of earthquakes for computing the b value.We used a 1° × 1° grid for the study area.Every node had a b value that was calculated with at least 50 selected small events.The events for computing the b value were selected by a circle with a particular radius and a node center point.The results indicate that the west Guanggaishan-Dieshan fault zone has a higher potential for seismic hazards in the future; therefore,more attention should be paid to this area.Although many methods were used to prevent error in the results,many unknown parameters remained,which caused our results to have uncertainties.

    • Probability Seismic Hazard Analysis Considering the Near-fault Directivity Effect and Nonlinear Site Response

      2014, 36(3):656-662.

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      Abstract:This paper presents seismic response analyses,based on the equivalent linear method,of a sandy site subjected to near-fault ground motions.We investigate the effects of soil nonlinearity on the pulse characteristics of input ground motions,and explore the amplification factors for the spectral acceleration from near-fault pulse like and non-pulse-like motions. We found that input non-pulse motions can be transformed into pulse-like motions by attenuating the high-frequency component as it propagates through the soil.The input pulse motion probably remains as a pulse characteristic,and tends to have multiple pulses when the input motion includes other potential pulses.The attenuation of the amplification factor, along with the spectral acceleration of the bedrock motion,has a more significant effect on pulse-like motions than non-pulse motions.We expect that this finding is related to the strong nonlinear response of the soil caused by the pulse excitation.However,the amplification factor for a long period(e.g., 3 s),when the pulse motion is greater than 0.1 g,is larger than that of a non-pulse motion.Finally,a probabilistic seismic hazard analysis (PSHA)procedure is proposed to incorporate the coupled effects of the near-fault pulse characteristic and the nonlinearity site response.

    • Supplement Textual Research on Historical Data of the 1884 Ninger Earthquake in Yunnan Province and Discussion on its Seismogenic Structure

      2014, 36(3):663-673.

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      Abstract:Based on the historical earthquake reports of the Ninger earthquake in the Yunnan province on November 14,1884,and a site inspection,new information has been obtained about this historical earthquake,providing credible evidence for the improvement of the isoseismal line.This paper thus reevaluates the Ninger earthquake parameters.The historical earthquake material is primarily from Guangxu Memoir and the memorial to the throne of the Palace,as well as the historical material of local chronicles.The results show that the epicenter was located near Puer mansion (presently Ninger), which is 23.1°N,101.0°E.The accuracy is class 1,with an average error less than or equal to 10 km;the earthquake magnitude was 6.75;the epicentral intensity was Ⅷ.The most damaged area in this earthquake was Puer mansion.The damage scope was limited,and the epicenter zone can be delineated within 30 km from Puer mansion.The aftershocks were frequent and lasted for almost one month.It was a typical mainshock-aftershock earthquake.The early frequent seismic activity and continued aftershocks,as well as the relief activity of the local government and the Qing court,reveal that the magnitude of this earthquake was high and the damage was severe.The isoseismal line damage area of this earthquake pointed northwest,and the long axis of the earthquake-sensitive area pointed northeast.There is a marked difference between those two areas. Yunnan is located on the east edge of the continental border of the Indian and Eurasian plates.There are two force components acting on the Yunnan region.One is the strong lateral pressing of the Indian plate,and the other is the SSE squeezing force related to the plate activity.The east fault activity of the Yunnan region is closely related to the squeezing force.Analysis of seismogenic structures shows that the Puer fault is a seismogenic structure of this Ninger earthquake.The geometric position of the Ninger earthquake in year 1884 overlaps with the position of the Puer fault,and it is located among the checkerboard made of the NNW-trending Puer fault and a series of NEE-trending faults.Because the lateral offset of the Puer fault and the left offset of the NEE-trending faults,the earthquake of MS6.75 happened in 1884 in Ninger.The Puer fault belongs to the Simao secondary block,which is located between the Longling-Lancang River fault and the Red River fault.The trend of the long axis of the meizoseismal damage area runs parallel to that of the causative fault.Between the NNW-trending Puer fault and the Mohei fault,there exist multiple NEE-trending parallel fracture belts,which are small-scale,have poor continuity,and form in groups with a left-lateral dislocation.These grouped parallel faults formed a checkerboard fault block.An MS6.4 earthquake occurred approximately 3 km south of Ninger on June 3,2007. Studies of this earthquake showed that main characteristics of the northwest nodal plane were a right-lateral thrusting slide and those of the northeast nodal plane were left slip. Thus, the right-lateral slide of the NNW-trending Puer fault and the left-lateral dislocation led to this earthquake.Because of the fragmentized crustal structure,the region is MS6.2~6.8 earthquake-prone,and this is why there are no bigger earthquakes in this region.Due to the complicated fault structure and fragmentation,as well as the landscape and geomorphic influences,there are still uncertainties.A further detail study of the Puer fault and seismogenic structures should be carried out so as to obtain more reliable results.

    • Textual Researches for 1477 Yinchuan Strong Earthquake

      2014, 36(3):674-681.

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      Abstract:A strong earthquake occurred in the region of Yinchuan on the May 13,1477.Due to the earthquake happened at the edge of Tenggeli desert,which is a desolate and uninhabited place,historical records about this earthquake is limited.On the basis of historic documents,the magnitude of this strong earthquake was examined to be M=6 1/2,the epicenter of the west of Yinchuan(38.5°N),106.3°E, the epicentral intensity of Yinchuan was Ⅷ in all previous publication of the catalogues of earthquake in China.However,some experts have questioned the identification results,we also have problems with the magnitude and epicenter.In the paper,based on the same historical earthquake data,we use the empirical formula for estimation of seismic magnitude and elliptical attenuation of seismic intensity and some interrelated modern earthquake data;by the methods of estimating and comparing,we reanalyze the magnitude,it’s epicenter and the seismic intensity of several region of the 1477 strong earthquake. In our opinion,we recommend that the magnitude of the earthquake should be identified as M=7 1/4 ,the epicenter should be located in the east of Minqin(38.40°N,104.36°E).In addition,the epicentral intensity of Yinchuan is advised to be Ⅶ,and Zhangye is Ⅵ. Finally,combining with the proposal epicenter location,we simply discuss the seismogenic tectonic background of 1477 earthquake.

    • Preliminary Study on the OLR Anomalies Based on the Cycle Process of Celestial Tide Forces: A Case Study on the Xinyuan MS6.6 Earthquake

      2014, 36(3):682-687,704.

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      Abstract:Earthquakes are definitely a mechanical phenomenon in which stress plays an important role.Many researchers have conducted statistical studies on the relationship between celestial tide forces (CTF) and earthquakes that prove that CTF may trigger earthquakes when the tectonic stress of the focal zone is at a critical stage.However,a method for identifying the critical stage point has not been determined thus far.Outgoing long-wave radiation (OLR) signals have been observed prior to strong earthquakes in recent years.OLR data describe the radiation information from the top of the atmosphere,which is believed to reflect energy changes in the earth-atmosphere system that occurs prior to earthquakes.OLR has characteristics of a large coverage range.Because earthquake-related anomaly information of OLR is extracted and applied to earthquake prediction,OLR anomalies are highly useful for areas that are out of the monitoring range of the current precursory seismic networks.Moreover, these anomalies are helpful for monitoring the stress stage of tectonics.In this study,we use National Oceanic and Atmospheric Administration (NOAA)satellite data to observe OLR data provided by the National Centers for Environmental Prediction (NCEP)with 1° × 1° resolution and attempt to analyze the OLR anomalies before and after the Xinyuan MS6.6 earthquake through the periodic variation effect of CTF.The earthquake occurred at a relativity high value of CTF,which it indicates that the CTF had a trigger effect on the earthquake. These results show that one month before the earthquake,no OLR anomalies were noted near the Xinyuan area.With the passage of time,the figures of spatio-temporal evolution of OLR increase were noted as initial rising on June 25 → continued rising on June 26 → reaching the peak on June 27 → weakening from June 28 to 29 → earthquake occurring on June 30.This evolution reflects the following activities of the seismic fault under tectonic stress:micro breaking-rupture strengthening → accumulating energy (the decrease of stress) → releasing energy → shaking. These abnormal areas moved and expanded,and the earthquake occurred at northeast edge of the anomaly;the epicenter of this earthquake was not at the area of maximum abnormality.This result may be related to the geological structure and underground environment of the epicenter.These characteristics can provide some clues for determining future seismogenetic times and for tracking the locations of the epicenters. It is necessary to combine the study of CTF with that of OLR anomalies to explore the catastrophic events of seismic faults under tectonic stress and to reveal the complex processes of the energy accumulated and released during an earthquake.We should emphasize that only considering the factors of CTF and OLR anomalies according to relative statistical analysis is insufficient for launching a theoretical model to predict the time and magnitude of future earthquakes in a particular region.The current understanding of the genetic mechanism of the anomalies for earthquakes is not complete; therefore,additional case studies are needed.

    • Analysis of Underground Fluid Anomalies Prior to the Wenchuan MS8.0 Earthquake

      2014, 36(3):688-696.

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      Abstract:The Wenchuan MS8.0 earthquake caused widespread attention. To determine whether earthquakes can be predicted and whether anomalies are present before earthquakes, several scholars have previously studied a summary of the precursory data of the Wenchuan earthquake. On the basis of such previous research, the present study analyzes the anomalies of underground fluid present before the earthquake. By using the methods of medium-term anomaly, short term and imminent abnormalities, co-seismic variation, and the adjustment after the earthquake, this study analyzes the data of water radon, water level, water temperature, and flow. Using the subordinate function extraction for recognition and extraction of the medium term anomaly proved to be effective. The Wenchuan MS8.0 earthquake, with intensity up to XI, caused inestimable human and economic losses in the affected areas involving 125,500 km2 in 247 counties, cities, and districts. 69,180 people died, 374,008 were injured, and 17,406 were reported missing. More than 10 million people were affected. 785.88 million houses collapsed, and 2,421.54 million were severely damaged. The direct economic damage could substantially exceed RMB 845.1 billion. This disaster occurred for four main reasons. First, the earthquake had a large magnitude, high energy, and shallow focus. Fracturing lasted up to 90 s, and the earthquake excitation was more powerful in the fracture zones. Second, because the fracture surface continued for several hundred kilometers through the town, the earthquake wreaked havoc on the buildings. Third, the earthquake occurred in the mountains. Fourth, secondary effects aggravated the disaster. Field investigation and the precursory data research by previous scholars revealed that the Wenchuan earthquake included macro-precursor abnormalities and seismic effects. This earthquake had the largest magnitude of those occurring in north-south seismic belt in recent years. Therefore, it is necessary to summarize the Wenchuan earthquake precursor anomaly.In recent years, China’s seismic monitoring network has become denser, and the observation scale has become greater. Data have been accumulated for moderate earthquakes. In addition, many achievements have been in fundamental theories, earthquake prediction methods, and the precursory mechanism. In the history of more than 40 years of earthquake monitoring and forecasting, 20 destructive events have been predicted with varying degrees of success. Despite some progress in the method of forecasting, it is quite difficult to predict earthquakes. Therefore, earthquake prediction is still in the primary stage. Although the Wenchuan earthquake was not predicted, some abnormal fluid phenomena appeared before the earthquake. By summarizing and analyzing data after the earthquake, some scholars detected 28 credible underground fluid anomalies within 1000 km in addition to 11 suspected abnormalities and 194 coseismic abnormalities. A month after the Wenchuan earthquake, the China Earthquake Administration subsurface fluid disciplinary technical coordination group found 39 suspected underground fluid abnormalities within 1,000 km from the epicenter. According to the Sichuan Seismological Bureau of Statistics, nine underground fluid anomalies may be related to the Wenchuan earthquake. Despite an exception, it is certain that subsurface fluid exists before the earthquake anomalies. The following exception is divided into short-term, short-Pro, and coseismic anomalies, which are discussed in this paper.

    • Evaluation of Seismic Intensity Influence Field in Gansu Province and its Relationship with Terrain Factors

      2014, 36(3):697-704.

      Abstract (1205) HTML (0) PDF 4.09 M (875) Comment (0) Favorites

      Abstract:The Gansu earthquake emergency command system was founded during the Tenth Five-year Plan by the Earthquake Administration of Gansu province.It was reviewed and accepted by the China Earthquake Administration and was enacted in 2007.With this system,we can first obtain the seismic intensity distribution and influence region according to the local intensity attenuation relationship and then quickly estimate earthquake casualty loss according to the seismic intensity distribution.We can then propose emergency measures and rescue plans and assist in decision-making for earthquake relief headquarters.Damage degrees of construction and lifeline engineering,including water supply, power supply,heat supply,air supply,transportation,and communication systems,differ among affected areas.Moreover,secondary disaster influences also differ,as well as casualties and financial loss.The seismic influence field examines the influence areas by different damage intensities.After an earthquake,designing and presentation of the influence field according to the earthquake parameters and formulating a relatively reasonable seismic intensity distribution range is very important for government investigation of the situation and damage distribution.The feasibility of the earthquake influence field will directly affect the rationality and accuracy of the assessment results.The calculation results of the existing evaluation system differ significantly from the actual results;therefore,the influence of the relief results also differs.The attenuation relationship model makes use of the large scale nationwide western attenuation relationship,the Gansu attenuation relationship of seismic intensity,and modified seismic intensity affecting the field model of the Gansu area in the Gansu earthquake emergency command technology system module to make fast judgment of the seismic influence field and heavy disaster area.However,differences occur in the actual attenuation relationship among areas and magnitudes due to different source characteristics,propagation media,and site conditions.In this paper,isoseismal line maps of actual earthquakes in the Gansu region were collected and compared with theoretical intensity generated by the attenuation relationship.In addition,the influence of terrain factors on the intensity influence field in study area was analyzed by using the digital elevation model(DEM).Conclusions show that the actual and theoretical seismic intensity distribution at each magnitude level differed. In general,the theoretical epicentral area is relatively small at the 5.0~5.2 level and shows subarea characteristics at the 5.3~5.9 level,whereas the theoretical intensity distribution is close to actual results at the 6.8~7.5 level.The subarea study shows that the outer major and minor axes and area of theoretical seismic influence field are greater than those of the actual values in the Qilian Mountains-Hexi Corridor region.However,except for the meizoseismal area,performance in the southeast region of Gansu is opposite.The impact of terrain factors on the intensity influence field is obvious.Higher altitude relates to higher intensity,and the intensity at the summit point is higher than that in the surrounding region.A greater slope to the epicenter relates to faster attenuation of the intensity and vice versa.There are obvious differences between actual and theoretical seismic influence fields,which should be considered in practical application.We should adjust the distribution of theoretical intensity by considering local terrain,landform,and site type to obtain a more reliable post earthquake assessment outcome.Furthermore, quantification of the site influence would better serve earthquake emergency response and rescue.

    • The Design of a Transient Filter and its Application in Local Seismic Observation

      2014, 36(3):705-712.

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      Abstract:At present,the phase of the last two stages of the digital filter in the earthquake data acquisition system can be divided into two types: minimum phase and linear phase.Phase characteristics directly affect the quality of recorded seismic waveforms. Important nonlinear characteristics of the minimum phase will lead to wave distortion,and the linear phase filter will result in an extra wave in front of the original wave.Based on the analysis of the two types of filter,a new transient filter is designed with the characteristics of both minimum and linear phases.The transient filter belongs to a finite impulse response filter (FIR),which consists of two cascaded stages,FIR1 and FIR2.The FIR1 filter stage has a decimation ratio of four.It compensates for previous filter droop and flattens the magnitude response of the pass band.The FIR2 filter stage has a decimation ratio of two. It creates a low pass brick wall filter to block aliased components of the input signal. In this paper,we introduce the detailed design method using Filter Design Toolbox and Signal Processing Toolbox in MATLAB and the characteristics of the filters,and we compare the testing data are introduced in this paper.The testing results of the seismic wave recorded in a number of local earthquakes show that the extra wave is eliminated and the first half period is not broadened.Thus,wave distortion can be minimized.The smooth interaction angle between the pass band and transition band and the slow roll off rate in the transition band are the common features of all transient filters.As a consequence, the sampling rate of the earthquake data acquisition system using the new transient filter must be increased to maintain the same frequency as that of the pass band edge.

    • The Effect of Initial Principal Stress Orientation on the Cyclic Shear Behavior of Saturated Siltehavior of Saturated Silt

      2014, 36(3):713-717,726.

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      Abstract:By using a soil static and dynamic universal triaxial and torsional shear apparatus,stress-controlled undrained cyclic torsional tests were performed on remolded saturated silt prepared by tamping methods with initial sampling water contents of 0% and 10%.The initial anisotropic consolidation conditions included an initial mean principal stress of 100 kPa,an initial intermediate principal stress coefficient of 0.5,an initial deviator stress ratio of 0.433,and principal stress initial orientation angles of 0°,30°,and 45°,respectively.During the undrained cyclic shearing process,the mean principal stress and the intermediate principal stress coefficient were fixed.We studied the effects of the initial orientation of the principal stress and the initial sampling water content on the silt’s dynamic shearing deformation,its strength,and its pore water pressure development.The test results show that the extent of the initial principal stress orientation’s effect on the remolded silt’s deformation and strength behaviors varied,and that the initial sampling water content has considerable influence on the cyclic behavior of saturated remolded silt.

    • A Comparison of Dynamic Response and Failure Simulations in Geotechnical Dynamic Centrifugal Model Tests and the Key Issues

      2014, 36(3):718-726.

      Abstract (1179) HTML (0) PDF 1.48 M (1526) Comment (0) Favorites

      Abstract:Focusing on two similar levels of the simulation of dynamic response and dynamic failure in the model and the prototype for geotechnical dynamic centrifuge model tests,this paper analyzes and summarizes the research and development status of the simulation of dynamic response and failure in the centrifugal model test.The implementation requirements and differences of a similar scale were analyzed in simulations of the dynamic response and failure.According to the anti-slide pile and tunnel models,the specific model-theoretical scale relationships were deduced, and the key problems of the simulation of dynamic response and failure in the dynamic centrifuge model are discussed in the paper.The existing problems and development direction of the geotechnical dynamic centrifuge model test are described.The results show that for a similar scale relationship between the model and the prototype,there is a stricter similar scale requirement for the dynamic failure model than for the dynamic response model,which is the fundamental reason that the dynamic failure simulation model can reveal the prototype failure of geotechnical structure.

    • Influence of Clay Content on Post liquefaction Characteristics of Silt

      2014, 36(3):727-733.

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      Abstract:Silt is one of the most common soils encountered in the field,and it is prone to liquefaction when earthquakes occur.In China,silt is widely located in the zones of the Qiantang River,the Yellow River,the cities of Kunming and Tangshan,and numerous other regions.The topic of silt liquefaction has been one of the hottest issues since the 1976 Tangshan earthquake.This paper presents the post-liquefaction stress-strain characteristics of silt samples with different clay contents induced by strong earthquakes.Large deformations occur during the post-liquefaction stage,which may trigger a large amount of horizontal ground movement or destroy the structure built there.It is of great importance to take precautions when confronting post-liquefaction deformation induced by earthquakes,especially on horizontal ground.Silt samples with clay contents of 3%,6%,8%,9%,12%,and 15% were used in this research.The original silt,sand,and clay samples were mixed in different mass proportions in order to obtain silt samples with different clay contents.The influence of the clay content on the degree of post-liquefaction deformation was studied by a series of monotonic tests.The test was based on liquefied silt samples by using a specially made triaxial apparatus.Large deformations can be recorded using the adequately large displacement sensors in this apparatus.These samples with different clay contents were isotropically consolidated to the specified pressure.Then cyclic loading was performed to trigger the initial liquefaction and was maintained until the specified severity of liquefaction was reached.Finally,monotonic loading was conducted to simulate the post-liquefaction stage based on the liquefied silt samples.Undrained shear tests were performed during the cyclic and monotonic loading stages.The post-liquefaction shear stress and shear strain were recorded automatically for these test results.From the stress-strain relationship of different clay contents,the 3% and 15% clay content samples showed less strain at the same stress level,and the 8% clay content sample showed the largest strain.This phenomenon can be explained as resulting from the clay content in the silt.Clay particles acted as both the lubricant and the adherent in the silt samples.As the clay content increased,the lubrication decreased and the glutinousness increased.There exists a critical clay content level,where the post-liquefaction strain reaches a maximum at a constant stress level.This explanation is consistent with the effect of clay particles in silt on the cyclic shear stress ratio.The silt sample with 8% clay content produced the minimum shear stress ratio during the cyclic loading stage and thus the maximum strain during the monotonic loading stage.The effect of the clay content on post-liquefaction characteristics can be quantifiably evaluated from our test results. As is known,the strain at nearly zero effective stress was the key strain component of post-liquefaction deformation.The relationship between deformation and the cyclic maximum strain was linear for silt samples with different clay contents.The slopes of these lines reflect the effect of clay content on post-liquefaction stress-strain.Therefore,the effect of the clay content on post-liquefaction characteristics was calculated.It was confirmed that the silt post-liquefaction stress-strain formula compared well with data collected from other tests.

    • Strong Motion Observation and Records of the Gaoyou BaoyingMS4.9 Earthquake in Jiangsu Province

      2014, 36(3):734-740.

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      Abstract:The strong motion of the Gaoyou-Baoying MS4.9 earthquake occurring on July 20,2012,was recorded by 43 of 50 strong motion stations in Jiangsu Province.The observation system of every strong earthquake station includes the Etna strong motion recorder produced by the KMI Company in addition to a domestic force balance accelerometer(FBA) sensor.These instruments effectively recorded the earthquake ground motion that occurred in Jiangsu Province by setting the appropriate threshold and transmitting the strong motion events through PSTN or CDMA wireless networks to the digital strong motion network center of Jiangsu Province.During this earthquake,the recorded maximum acceleration was 33.76 cm/s2.The earthquake epicenter was located at 33.04°N,119.57°E,and the focal depth was approximately 6 km.The microcosmic-epicenter was located in Shuanggou Village,Gaoyou City,where strong earthquake motion was felt.Tremors were felt throughout Jiangsu Province,as well parts of Anhui Province at its junction with Jiangsu Province. Fourier spectral analysis was used to determine that the seismic acceleration included abundant frequency components mainly between 2 Hz and 4 Hz. The acceleration time history and Fourier spectrum records from several strong ground motion stations are also given in this paper.Moreover, this study gives a brief introduction of the American ShakeMap system,which is the primary method used to calculate instrument intensity,and a recommended intensity scale provided.We collected recent strong earthquake records of Jiangsu Province and fit the instrumental intensity calculation formula (below intensity of VI)with these strong earthquake records.Due to the limited earthquake records in this region, however,we were unable to give a complete intensity calculation formula.Finally,two methods of producing an intensity contour map are given in addition to comparisons between approaches and conclusions.The characteristics of the seismic intensity contour are intuitive and vivid,which makes it easier to more accurately describe the distribution characteristics of earthquake damage.The results from the analysis of spectral characteristics with the strong motion records show that the peak acceleration of the horizontal component is larger than the vertical component.Moreover,the site covering of soil has an obvious amplification effect.On the basis of the strong motion records and influence of the field contour map,we obtained the peak acceleration distribution of the Jiangsu area.These result conform those of the actual investigation.The result of using the strong motion data to quickly assess the spatial distribution of seismic intensity has important significance for the earthquake emergency rescue work.Therefore,the method used in this study has a certain degree of feasibility. It is difficult to calculate instrument intensity values that are consistent with macroscopic intensity values because of objective factors such as subjectivity,and vagueness that exist in the evaluation of seismic intensity.Therefore,by selecting a suitable method for intensity evaluation of ground motion parameters and examining the seismic ground motion attenuation relationship,in addition to researching methods of field calibration for future work,the instrument intensity calculation method is proven to be scientific and reasonable.

    • Centrifugal Model Test of an Offshore Wind Turbine Foundationon Saturated Sand Ground

      2014, 36(3):741-745.

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      Abstract:With its low cost and simple structure, the bucket foundation has great application potential for the offshore wind turbine foundation. The main load of the foundation suffers horizontal cyclic loading, which we simulate in this study by an eccentric wheel and cylinder. We conduct centrifugal model tests on a saturated sand foundation in which we simulate and measure the stress, deformation, and pore pressure. We then analyze the deformation and stress characteristics of the bucket foundation according to the measurement results, which show that dumping destruction obviously occurred under monotonic and cyclic horizontal loads, and deformation appeared mainly around the bucket foundation.

    • Research on the Residual Deformation of Sandy Soil of Land Reclamation in Airport Industrial Park in Dalian

      2014, 36(3):746-752.

      Abstract (1277) HTML (0) PDF 3.23 M (920) Comment (0) Favorites

      Abstract:We conducted dynamic characteristic tests on sandy soil samples collected from Dalian Airport Industrial Park,adopting the DSZ-1-type electromagnetic vibration triaxial apparatus developed by Engineering Mechanics,China Earthquake Administration.Sandy soils are characterized by strong permeability,high shear strength,small deformation,and subsidence.This test investigated the dynamic residual deformation characteristics of two types of sand(i.e.,shallow and deep sand)under a complex stress state.Increasing the dynamic stress ratio and confining pressure improved the residual volumetric strain and residual shear strain,and the influences of both quantities on both strains could be described by the same law.However,the consolidation ratio was reduced by increasing the residual volumetric strain,and increased by increasing the residual shear strain.While the consolidation ratio of residual volumetric strain significantly affected the fitting results,that of the residual shear strain exerted small impact.The influences of consolidation ratio on the residual volumetric strain and residual shear strain were significantly different.The Cvr was linearly related to the dynamic strain amplitude of residual volumetric strain as well as residual shear strain,and the discreteness was very small.In contrast,the relationship between Cdr/S21 and the dynamic strain amplitude had a relatively large discreteness.From the test results,we derived the fundamental Shen Zhujiang model parameters for analyzing seismic subsidence.The results may provide a foundation for the deformation analysis of subsidence at Dalian Airport.They may also guide industrial park land reclamation engineering and seismic design on earthquake prone ground,and are applicable to similar engineering designs.

    • Mechanism of Changes in Microstructure of CompactedLoess Based on Triaxial Test

      2014, 36(3):753-758.

      Abstract (2239) HTML (0) PDF 2.39 M (1244) Comment (0) Favorites

      Abstract:Loess is widely distributed in China, and it’s an example of regional soil with uncommon characteristics.Because of its special formation process and environmental conditions,loess has unique structural characteristics,which are closely related to its physical and mechanical properties.Studying the microstructure of loess can speak to its possible uses in macroscopic engineering and explain the essential factors of its deformation and strength.At present,the study of the quantitative parameters of the microscopic structure of soils has achieved many results.These results provide a convenient method for the quantitative analysis of how the microstructure of loess changes under triaxial shear tests, which can provide a more reliable basis for the interpretation and validation of macroscopic test results.The macroscopic tests are unconsolidated and undrained triaxial shear tests.The confining pressures for the samples are 100,200, and 300 kPa,and the shear rate of all samples is 0.8 mm/min. Performing macroscopic tests to simulate the actual projected path of building loads allows shear strength parameters to be obtained.The samples for the microstructure test are taken after macroscopic triaxial shear test,with a sample size of 3.91 cm (diameter) × 8 cm (height).All samples are sliced from the major principal stress direction,which is the vertical plane, as well as the horizontal plane,and the cut positions are in the center of the specimens.A JSM-6610LV scanning electron microscope (SEM) from Qinghai University was used to observe samples.During the scanning,2~3 areas of each sample were selected to take photographs.The magnification of all samples was 150 times.Quantitative analysis of the changes in the microstructure of loess was then made by reviewing the SEM images.The SEM was used to observe the microstructure of the compacted loess in the horizontal and vertical planes before and after shearing under triaxial shear tests,and the observed planes are 8.This paper analyzes the microscopic nature of soil strength in three respects:the changing characteristics of pore arrangement,pore patterns, and pore scale.Test results reveal that the probable entropy is near 1 before and after shearing and the pore arrangement is disordered at different confining pressures after shearing,which minimally influences the macroscopic strength.The average shape factor and fractal dimension of the pore morphology at different confining pressures show a decreasing trend after shearing,and the changing characteristics of the pore pattern contribute significantly to the strength of the compacted loess.The aggregate level of soil particles is positively related to the strength of the soil samples.Increases or decreases in the void ratio result in the opposite changes in strength,and the changes in pore scale are the control factor of strength.Changes in the microstructure before and after shearing could be explained by macroscopic experimental phenomena.

    • Visualization System of Immersed Tube Tunnel Construction Basedon Remote Real-time Monitoring

      2014, 36(3):759-764.

      Abstract (1133) HTML (0) PDF 3.44 M (933) Comment (0) Favorites

      Abstract:In the process of immersed tube tunnel construction,floating and sinking are among the main priorities carried out underwater.The current construction technology cannot adequately or accurately control the floating and sinking processes,because the construction is carried out underwater.The result of this is the work must be done by hand.The visualization system of immersed tube tunnel construction based on remote real time monitoring is helpful in assisting with the measurements in construction sites and checking the results of diving operations for the distance of abutting points.This makes this visualization system greatly significant and useful in maintaining the safety and management of the construction in the immersed tube tunnel.The construction is unique because of its floating and sinking processes.In this paper,a series of key technologies are employed and integrated,including the establishment of the measuring point coordinate system making use of GPS and accurately converting coordinates,the use of the PSM configuration,visualization technology based on VTK,Autodesk 3DS Studio MAX,model driven data,Microsoft SQL Server Express,and others.A three dimensional visualization system of immersed tube tunnel construction based on remote real time monitoring is designed and developed by combining these key technologies.The system includes a GPS testing system in the pipe section and a dip angle system in the construction site for the processes of floating and sinking.The database of Microsoft SQL Server Express is included in the control center,along with the SOAP Web Service protocol communication.More specifically, the system can display the real time situation of a section of pipe on the construction site, inquire about a great deal of information concerning the pipe section,and play back any time sequence of the construction process.The presented visualization system realizes the function of remote real time monitoring for the tube’s floating and sinking,and it is successfully applied to the construction of the Haihe River immersed tube tunnel engineering in Tianjin.Its results closely match the information from the construction technical personnel and can reflect the pipe section’s real time situation and tendency in the toleration of the engineering error range. In addition,the system provides a guarantee for the safety and efficiency of the construction and can be further applied to related engineering projects.

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