• Volume 42,Issue 1,2020 Table of Contents
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    • >结构抗震
    • Seismic Absorption Performance of Fabricated ShearWall Structures under Prestressed Constraint

      2020, 42(1):1-6. DOI: 10.3969/j.issn.1000-0844.2020.01.001

      Abstract (556) HTML (0) PDF 3.51 M (686) Comment (0) Favorites

      Abstract:To contend with the construction policy of "economy, application, green, and beauty" introduced by contemporary China, the fabricated structure has gradually become the focus of attention in recent years. Compared with the traditional cast-in-place structure, the assembled structure is more in line with the requirements of energy-saving, material-saving, environmental protection, etc. Therefore, it is extremely important to further study the seismic performance of fabricated structures. Owing to the existence of wet operation in the joints of existing fabricated shear wall structures, construction is very difficult as strong members and weak joints often appear. Hence, we propose a new type of fabricated shear wall structure under prestressed constraint. The shear wall of the proposed structure was constructed by prestressed reinforcement. Due to no wet work at the construction site, the construction quality was improved. When an earthquake occurs, the natural period of the structure was increased by changing its stiffness, so as to reduce earthquake stress. At the same time, steel waste was avoided. Based on the time history analysis of the cast-in-place shear wall structure model and the prestressed shear wall structure model, the findings revealed that compared with the cast-in-place shear wall structure, the prestressed shear wall structure can reduce seismic response by approximately 90% and effectively reduce the earthquake effect.

    • Active Vibration Isolation Effect of the Pile-PlankStructures under Rail Traffic Loads

      2020, 42(1):7-14. DOI: 10.3969/j.issn.1000-0844.2020.01.007

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      Abstract:In this study, a pile-plank structure model was set on the roadbed using the finite element analysis method, which combines the boundaries of the infinite element method and the finite element method, to study the effect of the active vibration isolation measures of the pile-plank structures under rail traffic load. Subsequently, the model test was conducted by setting a concrete pile-plank structure in a sandy soil foundation. Further, the finite element numerical simulation results were verified based on the model test, and the effects of the pile length, burial depth, and filling rate on vibration isolation were studied. The model test results verify the reliability of the finite element method. (1) The amplitude reduction ratio decreases and the effect of vibration isolation becomes obvious with increasing pile length. (2) The burial depth is the main factor that influences the active vibration isolation measures of a pile-plank structure; with increasing burial depth, the amplitude reduction ratio obviously decreases and the effect of vibration isolation becomes more obvious. (3) The effect of filling rate is more obvious during the finite element calculation process when compared with that in the model test.

    • Dynamic Sensitivity Analysis of Pier-heightParameters of Curved Bridges

      2020, 42(1):15-21. DOI: 10.3969/j.issn.1000-0844.2020.01.015

      Abstract (448) HTML (0) PDF 1.72 M (777) Comment (0) Favorites

      Abstract:To study the sensitivity of the pier-height parameters of curved bridges to the seismic response, we used Midas Civil finite-element-analysis software to establish two finite-element-analysis models for high and middle-range piers. We then used the Newmark-β method to perform a dynamic time history analysis of a curved bridge structure with a multi-degrees-of-freedom system. Combined with the basic input of the seismic excitation of a curved bridge structure, we calculated the changes in the basic period, displacement at the top of the pier, and the internal forces of the main beam and pier bottom of a two-span continuous bridge under two different pier-height arrangements. Based on our calculation results, we discuss the influences of the pier height and pier-height ratio on the seismic response of the curved bridge structure. The results show that under the same conditions, the overall stiffness of bridge II is less than that of bridge I, and the sensitivities of the radial displacements at the top of each pier to the pier height and pier-height ratio differ. We found the internal force of a high pier to be closely related to the type of bridge pier arrangement. These results can be used to guide the seismic analysis and design of curved bridge structures in mountainous areas.

    • Effect of Wedge Block on the Transverse Seismic Performanceof Small- and Medium-Span Girder Bridges

      2020, 42(1):22-31. DOI: 10.3969/j.issn.1000-0844.2020.01.022

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      Abstract:The phenomena of beam falling and broken piers are likely to happen to small and mid-span bridges under the action of an earthquake. To prevent such earthquake damage to these bridges, a wedge-shaped block was used as the limiter to enhance the transverse seismic performance of a bridge. Taking a 3 m×20 m continuous concrete bridge as an example, a finite element model was established by OpenSees. Dynamic time-history analysis was carried out after considering the friction-sliding effect of laminated rubber bearings and the nonlinear effect of the reinforced concrete pier. Displacement response of the main beam and the maximum displacement response of the pier top were introduced as indicators. Two working conditions, i.e., the flexible shear key and the rigid shear key, were used to compare and analyze the influence of different angles of the wedge block on the displacement response. Results showed that the wedge block can restrain the displacement response of the girder effectively when the wedge block angle is set properly, but does not significantly improve the displacement response of the pier top.

    • Instability Behavior of the Steel Frame Rib-StiffenedPanel Structures

      2020, 42(1):32-37. DOI: 10.3969/j.issn.1000-0844.2020.01.032

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      Abstract:The mechanical properties of the panel structure must be improved because the steel frame panel contributes to the stress of the whole building structure and bears some part of the external load of the steel frame members. The rib-stiffened panel can achieve a good connection with the outer frame and improve the mechanical performance of the whole structure. Therefore, the mechanical instability performance of the steel frame rib-stiffened panel structures is investigated in this study. Here, the dynamic analysis method is used to calculate the displacement of the panel structure. The stability of the panel structure can be judged according to the displacement value; thus, the stability of the panel structure can be ensured. The example test results denote that the hysteretic curve shape exhibits the characteristics of the shuttle hysteretic curve, and the whole structure exhibits plastic deformation performance and aseismic performance after being subjected to tension; the skeleton curve denotes that the bearing capacity of the test specimens can satisfy the requirement of elastic design with respect to the wall panel structure in the first stage and achieve the elastic-plastic seismic design and ductility requirements in the second stage. The proposed detection model can judge the instability of the steel panel structures.

    • Seismic Response Analysis of LRB Isolation BuildingsConsidering the Effects of Temperature

      2020, 42(1):38-43. DOI: 10.3969/j.issn.1000-0844.2020.01.038

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      Abstract:A pseudo-static experiment was carried out to study the effect of temperature on the performance of a lead rubber bearing (LRB). Results showed that the hysteretic curves of the specimen was clearly different under different temperatures, and the stiffness and yield shear force of the bearing decreased with increasing temperature. At low temperatures, mechanical properties of the bearing varied greatly, but tended to be stable when the temperature was >20℃. Taking a five-story base isolation building as an example, a nonlinear time history analysis program NBIS for base isolated structures was compiled to calculate the seismic response of the building after considering the effect of temperature. Results showed that the restoring force of the bearing decreased with increasing temperature under frequent earthquakes, which was contrary to the changing trend under rare earthquakes. The seismic decrease coefficient of base-isolated structure increased with decreasing ambient temperature considering the effects of temperature, and maximum displacement of the bearing increased with increasing temperature.

    • Seismic Isolation Design of Mega-sub ControlledStructures under Bidirectional Seismic Wave

      2020, 42(1):44-51. DOI: 10.3969/j.issn.1000-0844.2020.01.044

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      Abstract:To strengthen the dynamic characteristics and stability of mega-sub controlled structure buildings, an individual controlled structure building under the action of bidirectional seismic wave is designed by using three kinds of magneto-rheological dampers (MRDs) and sliding base isolation. A dynamic analysis model of the controlled structure is then established. On the basis of the input of horizontal and vertical earthquakes to the dynamic analysis model, the differential equations of motion in the vertical and horizontal sliding states of the model are obtained. In accordance with the two equations, the adaptive fuzzy neural network is used to optimize the dynamic analysis model, and an optimization model is constructed. Experimental analysis of an example indicated that installing one MRD between the layers and one MRD in the isolation layer of the superstructure can ensure the best seismic response control effect for the controlled structure under different bidirectional seismic wave conditions. The time history curves of acceleration and displacement at the first floor, the middle three floors, and the top floor of the controlled structure have the same trend under condition 2, with a small difference. The lateral displacement response of the top floor of the megastructure increases with the increase in the stiffness of the substructure, and the dynamic characteristics do not change obviously. With the increase in its own stiffness, the lateral displacement response of the top floor of the substructure is stable and the dynamic characteristics of the substructure are enhanced.

    • Anti-collapse Reliability Evaluation with Respect to the High-RiseBuilding Frame Structures Based on Incremental Dynamic Analysis

      2020, 42(1):52-56. DOI: 10.3969/j.issn.1000-0844.2020.01.052

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      Abstract:The traditional methods used to evaluate the anti-collapse reliability of the high-rise building frame structures simply analyze the structures from the overall point of view, resulting in inaccurate results and inaccurate reflection of the collapse resistance of high-rise building frame structures. In this study, a method is proposed to evaluate the anti-collapse reliability of the high-rise building frame structures based on incremental dynamic analysis (IDA). Further, the safety reserve of a high-rise building frame structure is subjected to detailed analysis, and the collapse reserve coefficient of the building frame structure is obtained. The IDA method is used to set the collapse resistance capacity ratio of the high-rise building frame structure, and the anti-collapse reliability of the structure is evaluated according to the coefficient. The test results denote that the evaluation results obtained using the proposed method exhibits considerable reliability and that the collapse resistance of the high-rise building frame structures can be accurately evaluated.

    • Seismic Behavior of the Textile Reinforced ConcreteColumns under Earthquake

      2020, 42(1):57-62,72. DOI: 10.3969/j.issn.1000-0844.2020.01.057

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      Abstract:Reinforced concrete and textile are used to cast reinforced concrete columns using carbon and glass fiber bundles as the main materials to understand the seismic performance of the textile reinforced concrete columns under earthquake. An electro-hydraulic servo loading system is used to load the seismic monitoring data for the specimens. Some specimens are placed in the sodium chloride solution for multiple dry-wet cycles. The experimental results obtained under different environments denote that the bearing capacity of the reinforced concrete columns is strengthened and the seismic performance of the reinforced concrete columns is improved with increasing number of textile layers. The seismic performance of the textile reinforced concrete columns is only poor in the late stage of seismic action when the hoop spacing is large. The larger the number of dry and wet cycles, the weaker will be the bearing capacity of the textile reinforced concrete columns and the seismic performance of the reinforced concrete columns. In a chloride environment, the corrosion resistance of the textile reinforced concrete columns can be increased to improve the seismic performance. Appropriately increasing the number of textile layers and reducing the hoop spacing can improve the seismic performance of the textile reinforced concrete columns.

    • Seismic Performance of Multi-story Steel-ConcreteStructure for Civil High-rise Buildings

      2020, 42(1):63-72. DOI: 10.3969/j.issn.1000-0844.2020.01.063

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      Abstract:In this paper, based on the fiber model theory and the finite element model established by PERFROM-3D software, we perform an elastic dynamic time-history analysis, provide a damping calculation equation for large hybrid structures, and present an example of a 17-story civil building.For the composite structure in the example, we used El Centro ground motion as input to simulate the actual situation and explore the influence of different earthquake conditions on this kind of structure.We also analyze the seismic performance of the structure and present related methods, which have strong practical significance.

    • Seismic Performance of Buckling Restrained BraceConcrete Frame Based on OpenSees

      2020, 42(1):73-79. DOI: 10.3969/j.issn.1000-0844.2020.01.073

      Abstract (583) HTML (0) PDF 11.41 M (980) Comment (0) Favorites

      Abstract:OpenSees software was used to simulate a two-story three-span buckling restrained brace concrete frame (BRBCF) that adopts an anchoring connection joint with a T-stub, and the simulated results were compared with the test results to verify the accuracy of the model. The seismic behavior of the original BRBCF of the test frame was then analyzed. Good agreement between the numerical and experimental results was obtained, and OpenSees could accurately simulate the seismic performance of BRBCFs. The BRBCF showed good energy dissipation and horizontal bearing capacity, and the buckling restrained braced frame system revealed favorable seismic performance by increasing the lateral stiffness of the structural system and effectively controlling the deformation of the structure.

    • Seismic Performance of Precast Concrete Energy-dissipationFrame Structures with Sector Lead Viscoelastic Damper

      2020, 42(1):80-89. DOI: 10.3969/j.issn.1000-0844.2020.01.080

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      Abstract:To further study the effect of the sector lead viscoelastic damper (SLVD) and the influence of its design parameters on the seismic performance of the energy-dissipation frame of precast concrete (PC), a refined Abaqus finite element model was established. The Abaqus model was validated by comparison with the experimental results. The differences in seismic performances between the PC energy-dissipation frame with SLVD and ordinary reinforced concrete frame were studied. Then, the influences of the key design parameters of SLVD-i.e., the lead diameter, rubber hardness, and fan radius-on the seismic performance of the PC energy-dissipation frame were analyzed. The results show that the SLVD plays a role of energy-dissipation haunch brace in the PC energy-dissipation frame. The bearing capacity, structural stiffness, and the energy-dissipation capacity will increase with the increase of the lead diameter, and this has a great influence on the seismic performance of PC energy-dissipation frames. The rubber hardness has little effect on the seismic performance of the structure. Moreover, with the increase of the fan radius, the bearing capacity and stiffness of the overall structure will be enhanced; however, the yield area of the lead will decrease.

    • >地震科学研究
    • Paleoearthquake Characteristics along theBaiyanghe Fault in Jiuxi Basin

      2020, 42(1):90-97. DOI: 10.3969/j.issn.1000-0844.2020.01.090

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      Abstract:The Jiuxi basin, located at the westernmost part of the Hexi Corridor, is a Cenozoic depression basin bounded by multiple groups of active faults. Many Holocene active faults have been developed in the basin. These faults played an important role in the coordinated absorption of the eastward expansion of the Qilian Mountains and the left lateral slip rate of the Altyn Tagh fault. The basin has a complex structure, and there is a tectonic setting for the occurrence of moderate-strong earthquakes. In recent years, many Holocene activities have been found in the inner and surrounding areas of the Jiuxi basin. Therefore, its seismic risk cannot be ignored. The Baiyanghe fault, with a length of 25 km and almost E-W trending, is located in the middle part of the Jiuxi Basin. The fault dips to the north with a dip angle about 25°. In a former research, the fault was deemed as a buried fault. Its continuous activity resulted in the deformation of the overlying terrace and the formation of the Baiyanghe anticline. According to the satellite image interpretation and field geological investigation, we found a continuous development of a low fault scarp in the west and middle segments of the fault, indicating that the fault is not entirely a buried fault, and some parts of the fault have reached the surface and become a broken surface fault. Two trenches excavated across the fault scarp revealed that at least two paleoearthquake events, aged about (8.7±0.6) ka and (3.9±0.5) ka, respectively, have occurred along the Baiyanghe fault since the Holocene. The vertical dislocation of the events was about 0.6 m. Using an empirical formula, we inferred that the magnitude of the earthquake was about 6.8.

    • Co-seismic Response Characteristics of Near-field Water Level andWater Temperature and Associated Prediction of Earthquakes

      2020, 42(1):98-106. DOI: 10.3969/j.issn.1000-0844.2020.01.098

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      Abstract:To understand the co-seismic response characteristics of near-field water level and water temperature in strong earthquakes with magnitude less than 7, the Minxian-Zhangxian MS6.6 earthquake was studied. The co-seismic response characteristics of digital water level and water temperature within 300 km of the epicenter were analyzed, and their associated relationship with the region where MS4.0 earthquakes may occur was studied. Main analytical conclusions were as follows:co-seismic relative changes in amplitude in water level and water temperature induced by MS<7.0 earthquakes were not large, and were of short duration during the last event, with sudden-jump being the main effect. Relative amplitudes of the co-seismic changes were not clearly different in different regions. Initial directions of the co-seismic changes were distributed in a four-quadrant form. The station concentration region where the initial direction was up was related to the region where MS4.0 earthquakes may occur. Because the frequency of 6 < MS < 6.9 earthquakes was relatively higher than that of MS ≥ 7.0 earthquakes, and the scope of the near-field study was relatively small, the near-field earthquakes were found to be more advantageous than the far-field ones in predicting future earthquakes.

    • Discrimination Method and Characteristic Analysis of Geoelectric Storms

      2020, 42(1):107-115. DOI: 10.3969/j.issn.1000-0844.2020.01.107

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      Abstract:In this study, we consider the geoelectric storm events that occurred from 2015 to 2018 in China and identify the bases for quickly and accurately judging such phenomena by summarizing and analyzing the variation characteristics of screened data:(1) When a geoelectric storm occurs, the observation data of a geoelectric field are suppressed and the variation amplitude becomes more than twice the normal diurnal variation value. (2) Geoelectric storm events have a wide-area synchronicity, which can be judged by comparing the observation data of several stations. (3) A geomagnetic storm and geoelectric storm have homology, and the former can be judged by geomagnetic observations. (4) After the initial judgment, the influence of the observation system, natural environment, human interference, and environmental events should also be excluded before a geoelectric storm event is affirmed. The analysis results of the waveform characteristics of a geoelectric storm show that its amplitude is generally proportional to the K index, but the amplitude of a geoelectric storm at the same station greatly varies under the same K index. Under the same geoelectric storm, different stations have different amplitude responses, and the latitude effect is unclear, so it has regional characteristics. These characteristics may be related to the geological conditions of a station, the electrode distribution of a geoelectric field, and other factors.

    • Mathematical Modeling Analysis of Non-StationaryFeature Extraction of the Seismic Wave Intensity

      2020, 42(1):116-122. DOI: 10.3969/j.issn.1000-0844.2020.01.116

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      Abstract:An earthquake considerably threatens the safety of human life and obviously impacts the building structure. Studying the non-stationary characteristics of the earthquake wave intensity can provide a reference for earthquake prevention. Herein, the non-stationary feature extraction model of the seismic wave intensity is studied, and the deterministic and random parameters are set. Further, the non-stationary characteristics of the seismic wave intensity are analyzed based on the Fourier transform. Subsequently, a mathematical model is selected according to the analysis results, and the model parameters are set. The seismic amplitude spectra corresponding to the recorded seismic wave intensity are decomposed into a set of components on different scales, and continuous components can be obtained by reorganizing them; subsequently, the seismic wave amplitude spectrum is extracted. The relation between the amplitude and phase spectra of a seismic wave is used to extract the non-stationary characteristics of the seismic wave intensity. The simulation results denote that the proposed method is more accurate in extracting the non-stationary features of the seismic wave intensity when compared with the remaining methods; therefore, the proposed method is of considerable significance for analyzing high-resolution seismic data.

    • Information Extraction and Data Updating Method for an EarthquakePrecursor Database Based on Spatial Correlation

      2020, 42(1):123-128. DOI: 10.3969/j.issn.1000-0844.2020.01.123

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      Abstract:Seismic precursor data are easily interfered by noise and the data updating speed in a database is slow. To solve this problem, an information extraction and data updating method of a seismic precursor database based on spatial correlation is proposed in this paper. Using a fast Myriad filter, a sliding window is introduced, and window data are selected to participate in the calculation. The calculated results are regarded as the output value of the current window filter, and the data filtering and denoizing of information extraction is realized. In accordance with the preliminary filtering results, the current data are taken as the center, a spatial window is determined, and then related data statistics are horizontally conducted. A sliding time window is selected for each data in the spatial window, and filling repair parameters of the missing data are obtained. A surface weighting function is introduced to smooth the filling repair parameters, and S-transform data are updated according to the smoothed filling repair parameters. Then, the data updating of the earthquake precursor database is realized based on spatial correlation. The experimental results show that the signal-to-noise ratio of the proposed method is high, and the data update time is short. Thus, the method can preliminarily realize the information extraction and data updating of the earthquake precursor database.

    • Observation Difference Analysis of Three Typesof Cave Strain Meters

      2020, 42(1):129-135. DOI: 10.3969/j.issn.1000-0844.2020.01.129

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      Abstract:On the basis of the strain observation data of three types of baselines (quartz tube, indium steel bar, and indium steel tube) of seven stations in Hubei Province, the variation characteristics of the tidal parameters of the baselines were summarized, and the influence of natural environmental factors on the observation was quantitatively analyzed. The clustering method and principal component analysis method in SPSS were used. Results showed the following. (1) Among the three baselines, the tidal factor and mean error of the M2 wave and the relative noise of the M1 wave of the indium steel tube were the lowest; the average annual drift of the indium steel bar was the smallest. (2) The natural environmental factors of air pressure, precipitation, thunderstorm, and temperature exerted a significant influence on the cave strain observation in the Hubei area. The indium steel tube had the lowest strain under equal pressure, and the indium steel bar had the lowest strain under equal temperature.

    • Quantitative Analysis and Mechanism of the Relation betweenDeformation Observation and Rainfall ParametersBased on Data from Wuhan Station

      2020, 42(1):136-142. DOI: 10.3969/j.issn.1000-0844.2020.01.136

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      Abstract:The deformation observation data at Wuhan station were systematically analyzed on the basis of the "Analysis Platform of the Precursor Network (Station) Observation Data Tracking." Three sets of digital deformation observation instruments, namely, the DSQ water tube tiltmeter (NS component, EW component), SSY indium rod extensometer (NS component, EW component), and VS vertical pendulum tiltmeter (NS component, EW component), were installed at Wuhan station. All three sets of instruments operated stably, and the recorded data were continuous and reliable. The observation curves of the events affected by rainfall disturbance were extracted. Moreover, the influential rainfall events were analyzed in terms of rainfall parameters, including the amount of rainfall, initial driving rainfall, and maximum value of instantaneous rainfall. Results showed that the DSQ water tube tiltmeter was subjected to rainfall disturbance when the total rainfall amount was 40 mm, the initial driving rainfall reached 0.3 mm, or the maximum value of instantaneous rainfall was 0.6 mm. The SSY indium rod extensometer was susceptible to rainfall when the total rainfall amount was 60 mm or the maximum value of instantaneous rainfall was more than 0.5 mm; no significant correlation was observed between the rainfall interference of the VS vertical pendulum tiltmeter and the rainfall parameters. The influence of rainfall amount on the observed physical quantities of the instruments was linear. However, no significant correlation was noted between the observed physical quantities of the instruments and the initial driving rainfall and maximum value of instantaneous rainfall. The influence of rainfall on the deformation observation at Wuhan station was attributed to rainfall infiltration and surrounding water load changes.

    • Relationship between Long-Time Trend Change of Earth Resistivityat Nanjing Station and Regional Stress Adjustment

      2020, 42(1):143-149,214. DOI: 10.3969/j.issn.1000-0844.2020.01.143

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      Abstract:From 2013 to the beginning of 2016, the earth resistivity in the north-south (NS) channel at Nanjing station showed a long-time trend change of rising synchronization with the adjacent Jiangning station. In mid-2016, it showed a synchronous downward trend with Jiangning, Gaoyou, and Xinyi stations. In this study, the long-range observation data of earth resistivity at Nanjing station, combined with the rainfall in the study area, were analyzed using data processing methods. The cause of the trend change of earth resistivity was discussed based on the constitutive relationship of the apparent resistivity change with parameters ρ°, ρf, and ν. Results show that the rising trend of earth resistivity in the NS channel at Nanjing station is due to the stress adjustment process of the regional underground media in the station and its surrounding area, and the dynamic source may be the local tectonic movements of the crust in this area.

    • Anomalies of b-value Changes prior to theHutubi MS6.2 Earthquake in 2016

      2020, 42(1):150-156. DOI: 10.3969/j.issn.1000-0844.2020.01.150

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      Abstract:Based on the Gutenberg-Richer relation between earthquake magnitude and frequency, along with seismic data from the China Earthquake Networks Center since 2009, in this study, we analyzed the abnormal distribution of b-values prior to the Hutubi MS6.2 earthquake in 2016. We used the maximum likelihood method to calculate the b-values for the epicentral and surrounding region prior to the Hutubi earthquake and obtained spatial images of the b-value in the study area. The results showed that there is a large area of low b-value anomalies prior to the Hutubi MS6.2 earthquake, with the b-values ranging between 0.6-2.2, which indicates that this region is accumulating a high degree of horizontal stress. This anomaly may reflect the stress accumulation process in advance of an earthquake and prove the physical significance of the b-value.

    • Characteristics of Late Quaternary Activities along theDaluo Fault in Southwest Yunnan Province

      2020, 42(1):157-167. DOI: 10.3969/j.issn.1000-0844.2020.01.157

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      Abstract:The Daluo fault is located in southwestern Yunnan Province at the front of SE-oriented material extruded from the Tibetan Plateau, and it is responsible for the latest tectonic activity recorded in the southeastern margin of the Tibetan Plateau. Through satellite image analysis, a field investigation, trench excavation, dating sample testing, and high-precision mapping of dislocated micro-geomorphology, the characteristics of the late Quaternary activities of the Daluo fault are studied in detail. The results show that the Daluo fault is a Holocene active left-lateral strike-slip fault. The upper limit value of the horizontal slip rate of the fault in the late Quaternary is (2.5±0.1) mm/a, the lower limit value is (0.8±0.1) mm/a, and the average is about (1.7±0.9) mm/a. According to the maximum dislocation along the fault[about (11.2±0.5) km], it is estimated that if the slip rate of the fault has remained constant, the time of strike-slip structural transformation activity occurred in 4.4-14.9 Ma B. P, and the latest paleoseismicity of the fault occurred between 360±30 and 850±30 B. P.

    • >岩土抗震
    • Cyclic Degradation of Saturated Clay Based ona Bounding Surface Model

      2020, 42(1):168-174. DOI: 10.3969/j.issn.1000-0844.2020.01.168

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      Abstract:An incremental stress-strain relationship was developed based on the incremental elastoplastic bounding surface theory. This relationship could describe the degradation of saturated clay subjected to cyclic loads. In the relationship, a rotational hardening rule based on a rigorous theory was used to describe the change in size and location of the bounding surface during the action of vibrational stress. The plastic accumulative deviatoric strain length was used as a state parameter to reflect the effect of vibration stress history on the stress-strain response of saturated clay. An interpolated relationship of plastic modulus associated with the state parameter was formulated to describe the cyclic degradation of soft clay subjected to cyclic loads. Finally, the incremental stress-strain relationship was established using the associative flow rule. The relationship included nine parameters, five of which were modified Cambridge model parameters, while four had relatively clear physical meanings. Monotonic and cyclic undrained triaxial test results of two kinds of saturated clay were predicted using the relationship to verify its validity. Comparison of predicted and test results showed that the relationship can skillfully describe the cyclic degradation behavior of saturated soft clay subjected to cyclic loading.

    • Design of a Transverse Shaking Table Test for Utility Tunnels

      2020, 42(1):175-181. DOI: 10.3969/j.issn.1000-0844.2020.01.175

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      Abstract:Based on an investigation of the literature and a comprehensive consideration of test purposes, test conditions, and test funds, a transverse shaking table test for utility tunnels was designed in detail. First, test facilities such as shaking table, model box, and testing element are introduced. Second, the two main aspects of the experiment, model similarity ratio and model reinforcement, were studied. In designing the similarity ratio, the four parameters of acceleration, density, elastic modulus, and length, were taken as basic quantities. Then, according to the Bockingham π theorem and the gravity neglected model, other similarity ratios were derived. Reinforcement of the prototype structure was simple, thus, the equal area reinforcement ratio principle was adopted in the design of the model for this test, accounting for the rationality of the force. Third, based on the seismic response of the underground structure, El Centro, Kobe, and Taft waves were selected, and a detailed loading system is given. Finally, based on the numerical simulation in a previous two-dimensional model, the layout of test elements for the utility tunnel is present.

    • Anti-seismic Measures for a Cross Structure between a RailwayTunnel and a Cross Passage under Strong Earthquakes

      2020, 42(1):182-193. DOI: 10.3969/j.issn.1000-0844.2020.01.182

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      Abstract:With the orthogonal structure between the main tunnel and a cross passage as the analytic target, a finite element analysis model was established by ABAQUS based on the engineering of the Yuelongmen railway tunnel in Maoxian county, Sichuan Province, China. Selecting El-Centro seismic wave data and applying the extended finite element theory, crack damage of the cross structure between the cross passage and main tunnel under the most severe earthquake conditions was studied. Seismic resistant measures of the shock absorption layer combined with a flexible joint are presented. Research and analytical results showed that the combination of a shock absorption layer and flexible connectors reduced and restrained the crack range of the cross structure tunnel under a strong earthquake. Installation of flexible connectors prevented the extension of longitudinal cracks. A circular flexible connector in the middle of the intersection completely prevented the formation of cracks in the arch of the intersection. Installation of a shock absorption layer between the initial support and secondary lining gave more deformation space to the lining. Also, the secondary lining was not readily affected by the initial support deformation and cracking.

    • Anti-dislocation Technology for Fiber-reinforced Concrete Liningsof Tunnels Crossing Stick-Slip Faults

      2020, 42(1):194-198. DOI: 10.3969/j.issn.1000-0844.2020.01.194

      Abstract (482) HTML (0) PDF 1.09 M (529) Comment (0) Favorites

      Abstract:To improve the safety and stability of tunnels crossing stick-slip faults, we used fiber-reinforced concrete lining to research the technology of fault dislocation resistance for tunnels crossing stick-slip faults, based on the stick-slip fault F1 crossing the Youyi tunnel of the Duwen highway. Results showed that, under the same volume of fiber content, the compressive strength of SBFRC cube was slightly lower than that of SFRC, although the flexural strength of SBFRC was slightly higher than that of SFRC. The effect of stick-slip fault dislocation on hanging wall was larger than that on footwall. The effect of fiber-reinforced concrete lining on the dislocation resistance of the tunnel structure of footwall was better than that on hanging wall. Average dislocation resistance effect of the SFRC secondary lining was 12.22%, and 15.81% for the SBFRC secondary lining. These results can provide a reference for the structural design and construction of tunnels crossing stick-slip faults.

    • Experimental Study of Dynamic Elastic Modulus andDamping Ratio of Deep Clay under Strain Control

      2020, 42(1):199-204. DOI: 10.3969/j.issn.1000-0844.2020.01.199

      Abstract (481) HTML (0) PDF 4.41 M (966) Comment (0) Favorites

      Abstract:To research the dynamic properties of the deep clay in the Binhai new area, Tianjin, changes in the dynamic elastic modulus and damping ratios of the deep clay under strain control were studied using GDS dynamic triaxial apparatus. In every group of tests, the pressure of the overlaying soil at corresponding depth was set as the confining pressure, with the controlled strain as the only variable. Test results showed that the dynamic elastic modulus and the damping ratio of the soil were affected by the confining pressure in a fixed scope, while out of the scope (about three times referenced confining pressure), the influence of the confining pressure could be neglected. However, the influence of the dynamic strain of the soil on the dynamic elastic modulus and damping ratios was significant.

    • Dynamic Characteristics of Clay-Rock Mixtures underDifferent Gravel Contents and Confining Pressures

      2020, 42(1):205-214. DOI: 10.3969/j.issn.1000-0844.2020.01.205

      Abstract (457) HTML (0) PDF 12.95 M (1205) Comment (0) Favorites

      Abstract:Clay-rock mixtures are widely used as subgrade filler in projects, but there are few studies about their dynamic response under the influence of traffic loading. For this reason, according to different gravel contents and confining pressures, the dynamic shear modulus and damping ratio of the clay-rock mixture at small strain (10-6-10-4) were studied with the free vibration column instrument. In this paper, the soil/rock threshold was set as 0.05 Lc(Lc is diameter of the traxial sample). Results showed that the maximum dynamic shear modulus increases with increasing gravel content in the mixture, has a greater increase in amplitude when the content of the gravel is 20%-40%, and increases with increasing confining pressure. Under the same strain amplitude, the decay in dynamic shear modulus decreases with increasing gravel content, decreases greatly in the content range of 20%-40%, and decreases with increasing confining pressure. Minimum and maximum damping ratios both decrease with increasing gravel content and confining pressure. Based on the test results, the influence mechanism of gravel content and confining pressure on the dynamic shear modulus and damping ratio of the clay-rock mixture is put forward. Finally, the estimation formula among gravel content, confining pressure, and dynamic behavior parameters of the clay-rock mixture are established with the modified Hardin-Drnevich model, with the aim of providing theoretical guidance for the design and construction of soil-rock mixed subgrade.

    • A Numerical Simulation Study of the Surrounding Rock Deformationof Deep-buried Tunnels Under Earthquake

      2020, 42(1):215-220. DOI: 10.3969/j.issn.1000-0844.2020.01.215

      Abstract (513) HTML (0) PDF 3.56 M (759) Comment (0) Favorites

      Abstract:To improve the safety and stability of tunnels, a numerical simulation study was conducted on the deformation of the surrounding rock of deep-buried tunnels under earthquake. Taking a tunnel in a city as the object, we used FLAC software to build a three-dimensional dynamic model. Based on the physical and mechanical parameters and seismic load conditions, we used the relative displacement method to study the surrounding rock deformation characteristics, energy accumulation characteristics, and safety performance of a deep-buried tunnel under earthquake. The results show that the surrounding rock of the deep-buried tunnel is affected by the earthquake load, which results in the tendency for squeezing and elliptical deformation. When the deformation reaches maximum value, areas with a strain energy density higher than 2 350 J/m3 are concentrated in the tunnel wall on the left side of the surrounding rock and middle rock pillar; The safety factor of each monitoring point is asymmetric, and that of the lower corner area on the right side of the tunnel is lower than the value specified in the relevant national code. The calculated results are in good agreement with the actual measurement results.

    • Time Domain Analysis of Effects of Water Depth on theDynamic Responses of Underwater Site

      2020, 42(1):221-229. DOI: 10.3969/j.issn.1000-0844.2020.01.221

      Abstract (417) HTML (0) PDF 8.62 M (727) Comment (0) Favorites

      Abstract:Based on the 1D time domain method for dynamic response analysis of underwater site subjected to obliquely incident seismic waves, the expressions of displacement, acceleration, and stress of underwater site under the incidence of plane P-waves were derived. The effects of water depth on the peak displacement, peak acceleration, peak shear stress, and peak pore water pressure along the vertical depth of soil layer were explored. The numerical results showed that at the same depth of soil layer, when the water depth is less than 1 time the soil thickness, the peak vertical displacement increases with the increase in water depth; when the water depth is greater than 1 time the soil thickness, the peak vertical displacement decreases with the increase in water depth. The relation between peak horizontal displacement and water depth is basically the opposite of the peak vertical displacement. Under the same water depth, the peak vertical displacement and peak vertical acceleration continuously decrease with the increase in soil depth, and the peak horizontal displacement decreases first and then increases. Beyond the range from 0.75 times the soil thickness to the bedrock, the water depth has little effect on the peak shear stress. First, the peak pore water pressure generally decreases and then it increases and decreases gradually.

    • >震灾防御及其他
    • Improvement of the Deformation Monitoring Precision forHigh-rise Buildings after Strong Earthquakes

      2020, 42(1):230-235. DOI: 10.3969/j.issn.1000-0844.2020.01.230

      Abstract (410) HTML (0) PDF 1.86 M (499) Comment (0) Favorites

      Abstract:A high-precision monitoring method of structural deformation of inclined high-rise buildings after strong earthquake is proposed to solve the problems of real-time monitoring of inclined high-rise buildings after strong earthquakes; such problems include low precision and long time consumption. The structural deformation of the building under a strong earthquake is determined by defining the normal inclination value, inclination angle, and tilt direction of the inclined high-rise building after a strong earthquake in a regression plane. Then, deformation monitoring of the inclined high-rise building after a strong earthquake is completed. The deformation simulation experiment of the building is conducted by using BXJC 1.0 software. Four reference points are set near the building, and 16 deformation monitoring points are set on each column at the bottom of the building. The proposed method has the advantages of small error (the maximum monitoring error is 0.05%), high precision, and short monitoring time. Thus, the method can be used for real-time monitoring.

    • Planning of Urban and Rural Emergency SheltersBased on Particle Swarm Algorithm

      2020, 42(1):236-241. DOI: 10.3969/j.issn.1000-0844.2020.01.236

      Abstract (493) HTML (0) PDF 3.92 M (606) Comment (0) Favorites

      Abstract:Earthquakes are devastating natural disasters that necessitate the design of reasonable emergency shelters for areas likely to be severely damaged by earthquake. In this paper, we describe our use of a particle swarm optimization algorithm to study urban and rural emergency shelter planning. We combined the particle swarm optimization theory of the annealing algorithm with the planning of emergency shelters in urban and rural residential areas. In the case of many constraints, the emergency shelter is regarded as a particle, and the objective function is to plan emergency shelters, i.e., the scale planning and design of emergency shelters in urban and rural residential areas. Next, we designed a model of the content and location of the emergency sites, and identified the factors influencing the layout of urban and rural demand points. We then built different emergency shelter facility points. On this basis, we achieved the overall planning of emergency shelters that provided coverage of all the demand points. The simulation results show that the proposed particle swarm algorithm has a good planning efficiency and can ensure that after urban and rural residential areas are damaged by earthquake, victims will have access to immediate shelter.

    • Comparison of the Effects of Mountainous Regionsand Sedimentary Plains on Ground Motion

      2020, 42(1):242-249. DOI: 10.3969/j.issn.1000-0844.2020.01.242

      Abstract (794) HTML (0) PDF 11.56 M (1015) Comment (0) Favorites

      Abstract:Mountainous regions and sedimentary plains have different amplification effects on the strong ground motions and damage arising from destructive earthquakes. To obtain the influence rules of these two terrains, based on the strong-motion records from the ML6.6 aftershock of the Chi-Chi earthquake, we processed and analyzed records from four strong-motion stations located in different terrains and along the same line with the epicenter. Then, we compared and analyzed the calculation results from many aspects and obtained the distribution of the long-period response spectra of ground motion. The results show that the high-frequency components of the input earthquake motion are amplified by a mountainous region, and the long-period components of the input earthquake motion are amplified by a sedimentary plain. We found the peak value of the long-period response spectrum located in the middle of the sedimentary plain. The long-period amplification coefficient spectra of the strong-motion records on the sedimentary plain are beyond the range of the seismic design code. Consequently, more attention should be paid to the seismic fortification of high-rise buildings on sedimentary plains.

    • Spatial Distribution Pattern of Landslides and Its InfluencingFactors in the Baxie River Basin Based on Fractal Theory

      2020, 42(1):250-258. DOI: 10.3969/j.issn.1000-0844.2020.01.250

      Abstract (704) HTML (0) PDF 7.34 M (2068) Comment (0) Favorites

      Abstract:Quantitative study of the spatial distribution and revelation of the distribution patterns of different types of landslides are of great significance in predicting and evaluating their risk. Based on the spatial analysis function of ArcGIS and the correlation and box dimensions of fractal theory, spatial distribution patterns and influencing factors in landslides of different types were analyzed. The research showed that:(1) landslides in the Baxie River basin can be divided into 164 loess types with an area of 3.21×106 m2, and 85 loess-mud types with an area of 6.05×106 m2. (2) Individual associations of regional landslides have multi-scale fractals. Loess landslides and loess-mud landslides have thresholds on scales of 8 km and 12 km, respectively. Individual landslides have different degrees of spatial correlation at any scale smaller or larger than the threshold scale, and the degree of spatial correlation and aggregation of loess landslides are always higher than those of loess-mud landslides. Area distribution box dimensions of loess-mud landslides are greater than those of loess landslides, indicating that loess-mud landslides have a wider distribution area and more complex distribution characteristics. (3) Analysis of influencing factors showed that the formation lithology and slope angle exert the biggest influence on the distribution patterns of regional landslides, followed by ravine density. Formation lithology and its combination directly determine landslide type and the complexity of the distribution of the landslide area. Distribution gradients of different types of landslides are not the same. Although the degree of undulation has an important impact on the development of landslides, it has less influence on the quantity and area distribution of both types of landslides.

    • Rationality Evaluation of Spatial Layout of Urban EmergencyShelters Based on Improved Gravity Model

      2020, 42(1):259-269. DOI: 10.3969/j.issn.1000-0844.2020.01.259

      Abstract (621) HTML (0) PDF 24.24 M (804) Comment (0) Favorites

      Abstract:Emergency shelters are important for the evacuation, rescue, and resettlement of citizens, and their spatial layout directly affects the ability of a city to resist disasters. Accessibility and the degree of potential crowding are two key indicators relating to the interaction between the size of the residential area and the emergency shelter; therefore, establishing a reasonable method of evaluating these factors is important to provide a reference value for the design and balanced layout of such shelters. In this paper, three parameters are introduced to improve the gravity model:the population-scale influence factor, the service capacity of emergency shelter, and the travel limit distance. The Chengguan district of Lanzhou City is used as an example for evaluating the spatial layout rationality of urban emergency shelters with respect to accessibility and the potential degree of crowding under different travel limit distances. The results show that there is an unbalanced spatial distribution of emergency shelters in the study area, which would not fully meet the evacuation needs of the current population. With short travel limit distances (500 m and 1 000 m), the accessibility for people in most areas is low, and there are significantly different degrees of potential crowding between the southwest and northeast. With a travel limit distance of 2 000 m, accessibility shows an attenuating trend from northeast to southwest, and the degree of potential crowding is reversed, the crowded degree of each emergency shelter is less than 0.4 person/m2. The improved gravity model comprehensively considers the attenuation of distance, the service capacity of emergency shelters, and the population of the residential area, and it can effectively measure the accessibility of emergency shelters and the potential crowding degree; it can thus be used to reliably evaluate the rationality of their spatial layout.

    • Design of a Real-Time Detection System for False Post-EarthquakeInformation Intrusion Based on the Internet

      2020, 42(1):270-275. DOI: 10.3969/j.issn.1000-0844.2020.01.270

      Abstract (436) HTML (0) PDF 3.28 M (506) Comment (0) Favorites

      Abstract:False post-earthquake information intrusion seriously interferes with earthquake relief and postdisaster reconstruction. To prevent the spread of false post-earthquake information on the Internet, this study designs a real-time detection system. Web servers are used as carriers to transmit information on the Internet. Thus, the WinPcap technology is used herein to capture valid data packets. The transmission control protocol/internet protocol, control message protocol, and user datagram protocol are decoded in the protocol analysis module. The decoded data are used inputs in the false post-earthquake information detection model based on support vector machine. The model seeks the optimal hyperplane to divide the post-earthquake information into false and true. Results indicate the completion of the real-time detection of false post-earthquake information intrusion. The false alarm rate of this system is less than 3%. Different from related systems, the proposed system can receive data with high efficiency and is of great importance in accurately detecting false post-earthquake information.

    • A Magnetic Flux Leakage Detection Method for High-voltage PowerTransmission Splicing Sleeves after Strong Earthquakes

      2020, 42(1):276-282. DOI: 10.3969/j.issn.1000-0844.2020.01.276

      Abstract (457) HTML (0) PDF 5.20 M (720) Comment (0) Favorites

      Abstract:To maintain the safe operation of a power system during a strong earthquake and improve the efficiency and quality of high-voltage transmission (HVT), in this paper, we propose a magnetic leakage detection method for HVT splicing sleeve under the influence of a strong earthquake. The magnetic flux leakage signal is obtained using a magnetic sensor, and the characteristic quantities of the signal in the splicing sleeve are extracted by calculation. Based on these characteristics, detection of the magnetic flux leakage from the HVT splicing sleeve is realized. We performed a simulation analysis of the HVT splicing sleeve by constructing a three-dimensional finite element geometric model. The experimental simulation results show that under the influence of a Beijing wave with a 9-magnitude, the characteristic quantities of the magnetic flux leakage signal in the splicing sleeve can be used to determine the depth of the defect and detect magnetic flux leakage. By detecting the peak value of the magnetic flux leakage signal on both ends of the upper and lower surfaces of the splicing sleeve of the DL/T1192-2012 standard transmission line, we proved that the proposed method is effective for detecting magnetic flux leakages from the splicing sleeve of a HVT line under the influence of a strong earthquake.

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