• Volume 34,Issue 4,2012 Table of Contents
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    • Spectral Inversion Based on Very Fast Simulated Annealing Algorithm

      2012, 34(4):313-318,323.

      Abstract (902) HTML (0) PDF 739.97 K (1277) Comment (0) Favorites

      Abstract:The description of thin bed in seismic prospecting is very important for obtaining high frequency.Spectral inversion is a method based on the spectral resolution and time-frequency analysis,which can effectively determine the layer thickness below the seismic tuning thickness.In this paper,a global search method——Very Fast Simulated Annealing(VFSA) is used to spectral inversion in high SNR post-stack seismic data.As the presence of noise,in experiment,band spectrum is used in spectral inversion.The result is Quiasi-reflection coefficient.The method expands the bandwidth of the original data,and enhances the data resolution.It is an important role to explain the subtle characteristics in seismic prospecting.

    • Seismic Response Analysis on Multistage Series Non-proportion Damping Isolated Structure

      2012, 34(4):319-323.

      Abstract (768) HTML (0) PDF 277.04 K (1148) Comment (0) Favorites

      Abstract:The dynamic analysis model of multistage series non-proportion damping isolated structure is established.Citing partition of Rayleigh damping model,the non-proportional damping matrix of isolated structure is decomposed into the Rayleigh damping matrix and the surplus damping matrix reflecting non-proportional damping,and the damping matrix of multistage series non-proportion damping isolated structure is derived.Using the MATLAB software,the seismic respone analysis for a real structure is done.The results show that structure layer shear ration of the overall structure and peak displacement of isolation layer tend to correspond to value of base isolation as the lower structural mass and stiffness increased,when substructure has one layer and stiffness greater than 4 to 6 times of the upper structure stiffness of ground floor,it can approximately analyze as base isolation structure.

    • Scattering of Transient Elastic Wave by Cylindrical Cavity with Lining in Saturated Soil

      2012, 34(4):324-330.

      Abstract (817) HTML (0) PDF 400.61 K (989) Comment (0) Favorites

      Abstract:Based on the Biot's dynamic theory,the expressions of displacements,stresses and pore pressures in saturated soil,and those of displacements and stresses on cylindrical lining in transient elastic wave condition are obtained by using the method of Laplace transform and wave function expansion.Employing the inner boundary stress free condition of the lining and the continuity conditions between the soil and the lining,the unknown coefficients in the expressions are determined.With the inverse Laplace transform,the numerical solution of the problem is presented.The wave pattern properties of dynamic stress concentration factor on the lining and influence of different shear modulus of material and thickness of lining on the dynamic stress concention factor are studied.The results show that the wave type demonstrates damping with the increase of the order n.The value of dynamic stress concentration factor is lower with the increase of the lining thickness and larger when the shear modulus of the lining is larger than that of the soil.

    • The Nonlinear Improvement of Nishihara Rheological Model in Petrology and Its Analysis

      2012, 34(4):331-334.

      Abstract (749) HTML (0) PDF 250.31 K (1189) Comment (0) Favorites

      Abstract:The classic Nishihara rheological model can better describe the former two stages of creep process of rock,but can't describe the accelerated creep stage.The most of predecessors made yield strength threshold to define the accelerated creep stage in the rheological model improvement and combination,but the researches on using time threshold to define the accelerated creep stage were relatively few.In this paper a time element which can reflect the accelerated creep loading time and a nonlinear clay pot which can describe the accelerated creep curve are introduced.Their parallel connection called TN combined with traditional Nishihara model,formed a nonlinear viscoelastic-plasticity rheological model that can describe the attenuation creep,steady creep and accelerated creep.Finally,fitting the new model and the actual experimental data,the similarity coefficient is higher than 0.99.The model is more suitable to describe the rock rheological phenomenon.

    • Time-frequency Analysis and Energy Calculation for Acceleration Records of Luhuo M_S5.3 Earthquake in Sichuan Province in 2011

      2012, 34(4):335-341,358.

      Abstract (752) HTML (0) PDF 510.52 K (1051) Comment (0) Favorites

      Abstract:Luhuo MS5.3 earthquake occurred in Sichuan on April 10,2011.In this paper three components of acceleration time history records acquired by different stations with different epicenter distances are selected.Aimed at the problem in HHT method in the decomposition of EMD which is present common way for extracting the signal time-frequcncy characteristics,a EEMD method is used and the energy calculation and time-frequency analysis on acceleration records are made.The method can not only effectively restrain the problem occurred in EMD decomposition process,but also can extract record's time-frequency characteristics and the energy concentration distribution bands.Comparative study among this method and Fourier transform and wavelet analysis is made.The validity and practicability of the method are proved in dealing with the unsmooth,nonlinear strong signal,and has a good prospect in earthquake data processing area.

    • Research on Real-time Evolutionary Earthquake Epicentral Location

      2012, 34(4):342-349.

      Abstract (826) HTML (0) PDF 1.06 M (1126) Comment (0) Favorites

      Abstract:In a earthquake early warning system,the ability to quickly locate devastating earthquake is very important.In this paper a new method to estimate earthquake epicentral region,hyperbolic curve range and epicenter point from only the three earliest P-wave arrival times in a seismic network is developed.In the method the constraint conditions that some stations record P arrivals the others do not record P arrivals,and seismic wave travelling characteristics are considered fully to improve earthquake epicentral location accuracy.The method is applied to P-wave seismic data from the Virtual Seismic Network of Shandong province with 79 stations for 425 earthquakes in 2009-2010,the results show agreement with actual earthquake epicentral locations.The method can satisfy the real-time and accurate need in the earthquake early warning system.

    • Seismic Isolation of Combined System of Continuous Girder-arch Railway Bridge Using Friction Pendulum Bearing

      2012, 34(4):350-354.

      Abstract (750) HTML (0) PDF 297.52 K (1066) Comment (0) Favorites

      Abstract:The seismic isolation of combined system of continuous girder-arch railway bridge is studied with friction pendulum bearing(FPB).Based on the characteristics of the system,the design principles and methods for seismic isolation of combined system using FPB is proposed.The nonlinear time history analysis method is used for the analysis of isolation effect.The results show the maximum seismic moment and deformation of the vault can be significantly reduced by using FPB in longitudinal direction.The reduction of isolation is greatly influenced by input ground motion in transverse direction.

    • The Research Significance and Model Analysis of Vertical Strain

      2012, 34(4):355-358.

      Abstract (850) HTML (0) PDF 301.36 K (1014) Comment (0) Favorites

      Abstract:In nearly 20 years,the vertical strain field has been neglected in China.The vertical strain can promote the strain observation caused by earth tide from plane strain to the three dimensional space.In this paper the research necessity of vertical strain observation is explained,and the initial model of vertical strain observation system is built.The research difficulties and its theoretic solution are put forward also.

    • Application of Higher-order Statistics on Extracting the Tidal Deformation Anomalies

      2012, 34(4):359-364.

      Abstract (752) HTML (0) PDF 683.45 K (918) Comment (0) Favorites

      Abstract:The higher-order statistics method is applied to processing the earthquake tidal deformation observation data.The tidal deformation observation data of Tai′an seismic station before the ML4.6 earthquake in the boundary region of Puyang and Xinxian counties on April 9,2006,are processed and analyzed.In the period of time before the earthquake,intervention of abnormal signal is found.On low point of the results has guiding significance to seismic anomaly information extraction.This method can extract some short-impending anomalies of seismic tidal.

    • Study on Earthquake Casualty Forecasting Model Based on Principal Component Analysis and BP Neural Network Analysis

      2012, 34(4):365-368.

      Abstract (764) HTML (0) PDF 217.93 K (1338) Comment (0) Favorites

      Abstract:There are many factors that influence the casualty in a earthquake,and the factors always relate each other.In this paper,some factors are selected as the evaluation indicators,such as time of earthquake、 population density、 earthquake forecast、 rate of building damage、 resistance level、earthquake magnitude、earthquake intensity.First using the method of principal component analysis to calculate the principal components,then using the method of BP neural network analysis to construct the prediction model.Test for true cases prove the model has good prediction result.

    • Comparative Analysis on Dynamic Responses of Deep-seated Highway Tunnel under Bidirectional Seismic Actions

      2012, 34(4):369-374,382.

      Abstract (814) HTML (0) PDF 520.27 K (1024) Comment (0) Favorites

      Abstract:The effect of earthquake actions on deep highway tunnel lining is investigated by numerical simulation using the finite element method(FEM) code MIDAS/GTS with the emphasis on the ground motions in unidirection,bidirections and on the gravity load.The acceleration time history obtained from the tunnel site with exceedance probability of 10% in 50 years is corrected with baseline before as input into simulation.The simulated results indicate that the response of tunnel lining under bidirectional seismic actions is bigger than those under unidirectional seismic action,where the arch springing and crown are the most dangerous positions under seismic forces.The combined actions of longitudinal and vertical directions will produce the biggest responses in tunnel lining.The impact of earthquake for deep tunnel can not be ignored.

    • Tomography of High Resolution Seismic Refraction Traveltimes in Tianjin-Beijing Profile

      2012, 34(4):375-382.

      Abstract (742) HTML (0) PDF 2.13 M (905) Comment (0) Favorites

      Abstract:The traveltimes tomography of first arrive waves along Tianjin-Beijing profile with high resolution is done using regularization inversion method.The impacts on the inversion results from very different starting models and inversion parameters are analyzed,the resolution of the final model is assessed by the checkboard method,and the upper crust fine structure with blind faults in the study area is obtained finally.The results show that the resolution of the final model is up to 5 km×1 km with some are more fine.The study region is alternate by depressed areas with upheaval areas,and small sags are within big ones.The depths of crystalline basement change in the range of 2-8 km and its fluctuant pattern complies with the geological tectonic characteristics.The fault activity and crustal moment since Tertiary have greater impact on the velocity structure of this region.

    • Matched-filter Analysis of Geomagnetic Profile Anomaly in Eastern Dabie Orogenic Belt and Research on Seismic Activity

      2012, 34(4):383-387.

      Abstract (762) HTML (0) PDF 632.45 K (841) Comment (0) Favorites

      Abstract:Using matched-filter method,the geomagnetic anomaly data from profiles of Luan-Yingshan(Ⅰ),Baitafan-Wuwei(Ⅱ) and Jinzhaiqingshan-Wanfuhu(Ⅲ) in Eastern Dabie Orogenic belt are processed,the local anomalous field is extracted from regional field.Based on regional anomalous field,the buried depth of Curie surface along profiles are calculated using the approximate linear invertion method.Combined with the geological results and earthquakes distribution in this area,the relations between seismic activity and Curie surfaces,and the seismogenesis mechanism are researched preliminarily.The results show that the curves of geomagnetic anomaly exhibit the various characteristics and differences of structural basements of different profiles,existing apparent mirror image relationship with the depth of Curie surfaces.Fluctuation of Curie surface in the area is about 14 km,the lowest position is at Huoshan,where is the intersection part of profile Ⅰ and Ⅲ.The corresponding relation between earthquakes distribution and Curie surface is apparent,most earthquakes occur on gradient zone of Curie surface.Thermal stress generated from temperature difference of gradient zone might be direct dynamic sources of Houshan area.The invertion result of Curie surface provide proof for offset on Moho along Xiaotian-Muzitan Fault.

    • Cross-Fault Deformation Anomaly and Confirm Each Other with the Fixed-point Precursors Observation before Yumen and Minle Earthquakes

      2012, 34(4):388-392.

      Abstract (775) HTML (0) PDF 352.89 K (1128) Comment (0) Favorites

      Abstract:A certain number and significant across-fault short leveling deformation anomaly were observed in the source region around a dozen hundred km range before Yumen MS5.9 earthquake in 2002,Minle MS6.1 and MS5.8 earthquakes in 2003 and Minxian MS5.2 earthquake in 2003.The main abnormal morphology were acceleration,sudden jump or sharp point sudden jump,with mid-term background or short-term precursors significant.Anomalies reflect that the fault first enhanced inverse then changed to relaxation,earthquakes usually happened when the fault change relaxation.The spatial distribution and occurrence time of anomaly have added and confirmed significance to precursor anomalies of fixed-points.

    • Analysis of Tectonic Deformation on Zhuanglang River Terraces in Lanzhou Based on the Differential GPS Surveying

      2012, 34(4):393-397,404.

      Abstract (745) HTML (0) PDF 933.55 K (1073) Comment (0) Favorites

      Abstract:Based on the general analyzing the characteristics of distribution and development of the terraces along Zhuanglang river,in Lanzhou,the longitudinal and latitudinal profiles of Ⅰ-Ⅲ terraces are given by virtual of high-resolution differential GPS carried through detail surveying.According to the dating result of different terraces,their tectonic deformation characters are studied and the quantificational parameters of terrace deformation in fault area such as deformation characters,breadth of deformation zone,extent of deformation and velocity etc are gotten.The result indicates that fault-propagation fold plays most important role in the tectonic deformation of the terraces.The terrace deformation rates have been accelerated since the late Quaternary.

    • Exploration on Lintong-Chang′an Fault for Its Activities since Quaternary Period

      2012, 34(4):398-404.

      Abstract (1131) HTML (0) PDF 1.20 M (902) Comment (0) Favorites

      Abstract:Lintong-Chang'an fault is an important active fault near Xi′an city.It may affects the development expansion region of Xi′an.In this paper the activity of the fault is discussed by using high-resolution shallow seismic reflection,composite drilling and dating methods.The result of seismic reflection shows that some layers in Quaternary were offseted and the dislocated distances decrease from deep layer to upper one,means a continual longtime active of the fault.The geological sections of composite drilling shows that sand and clay layers of middle Plaistocene were cut and the displacements are in 8.7-2.5 m.All of this prove that active rate of the fault decreased from early to late Pleistocene Epoch.

    • Application of Matlab Software on Intensity Rapid Report of Tianjin Strong Motion Network

      2012, 34(4):405-412.

      Abstract (857) HTML (0) PDF 1.05 M (1471) Comment (0) Favorites

      Abstract:In the intensity rapid report work of Tianjin strong motion network,utilizing the Matlab software,a series of relative procedures are developed,which can effectively execute the decode EXE file provided by different equipment producers and make best use of the excellent function of Matlab GUI-operation and imaging.These procedures overcome some basic technical difficulties including the interruption of data decoding,bulk of imaging,selecting of data,extracting of the max values and transferring them to equipment intensities,intensity rapid report etc.The time of rapid equipment intensity in the Tianjin network reduces apparently to a few minutes in comparison with some hours before.Some skills of overcoming the above difficulties and the application that can support the feasibility of using Matlab to deal with intensity rapid report in Tianjin are introduced.

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