Superintend by：China Earthquake Adiministration
Sponsored by：Lanzhou Institute of Seismology, CEA
Tsinghua University
China Civil Engineering Society Seismological Society of China
Edited by：Editorial Board of China Earthquake Engineering Journal
Editor-in-Chief：SHI Yucheng
Address：450 Donggang West Road, Lanzhou, Gansu, China
Post Code：730000
Tel：0931-8275892
Email：dzgcxb2021@163.com
dzgcxb@gsdzj.gov.cn
dzgcxbtg@163.com
ISSN 1000-0844
CN 62-1048/P
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Seismic response and damage analysis of simply supported beam bridges under near-fault pulse-type ground motions
HAN Jianping, CHAI Wenyang, SHI Yan, LIU Yunshuai
2025,47(2):251-262, DOI: 10.20000/j.1000-0844.20231021001
Abstract:
In this study, a single analytical model was employed to simulate the low-frequency impulsive components in near-fault ground motions, facilitating the investigation of the seismic response characteristics and damage of simply supported beam bridges under near-fault pulse-type ground motions. These components were superimposed with the high-frequency components obtained from the actual near-fault ground motion data after filtering, resulting in a synthesized near-fault pulse-type ground motion as the input. Then, a finite element numerical model was established using a four-span simply supported beam bridge as a prototype. Nonlinear seismic response time-history analysis was conducted to systematically study the effects of factors, including fault distance, number of impulsive pulses, moment magnitude, and the high-frequency components of the synthesized ground motion on the top displacement and damage state of bridge piers, along with the displacement and collision forces on the main beams. The results revealed that the low-frequency components of the ground motion served as the primary influencing factors on the impulsive peak values. Furthermore, the low-frequency impulsive components in the ground motion were used to determine the intensity of the simply supported beam bridge. When the moment magnitude of the ground motion was relatively small, the seismic response of the simply supported beam bridge was greater due to the larger peak value of a single impulsive pulse compared to multiple repeated pulses. Conversely, for ground motions with larger moment magnitudes, the seismic response of the bridge was greater under the action of multiple repeated pulses. The high-frequency components in the ground motion had a relatively minor impact on the structural seismic response; however, they affected the peak and residual displacements of the bridge. The study's findings underscore the fact that the influence of high-frequency components on structural response should not be overlooked during damage analysis.
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Seismic response of the main pier pylon of a multispan extradosed cable-stayed bridge with a single cable plane under traveling wave excitation
2025,47(2):263-269, DOI: 10.20000/j.1000-0844.20230711001
Abstract:
A six-span extradosed cable-stayed bridge with a single cable plane was investigated in this study to assess the influence of wave traveling effect on the earthquake response of multispan extradosed cable-stayed bridges. A finite element model of the full bridge was established using the software MIDAS/Civil, and the multi-point excitation behavior was simulated based on the theory of relative motion. The internal force or displacement response of three key positions, namely pier bottom, tower bottom, and tower top, under multipoint ground motion excitation were analyzed. Furthermore, the variation law of structural internal force and displacement under different apparent wave velocities was also explored. The research results reveal that the traveling wave excitation has a significant effect on the earthquake response of the multispan extradosed cable-stayed bridge. At an apparent wave velocity of 500 m/s, the internal forces or displacements at the most unfavorable key position are approximately 1.2 times those under uniform excitation. Furthermore, traveling wave excitation has adverse effects on the bending moment and shear force at the bottom of the middle pier and side tower, as well as on the displacement at the top of the side tower. As the apparent wave velocity increases, the influence of traveling wave excitation gradually weakens. When the apparent wave velocity exceeds 7000 m/s, the internal forces and displacements at key positions are basically the same as those under uniform excitation. This finding indicates that the influence of traveling wave excitation on the internal force at key positions of the structure can thus be ignored.
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Experimental study on the effect of aggregate size on the dynamic characteristics of saturated red clay
CHEN Bo, YANG Tianchen, JIN Pan
2025,47(2):270-280, DOI: 10.20000/j.1000-0844.20230731001
Abstract:
The use of red clay, a widely-used material for subgrade-filling, easily results in the formation of an aggregate structure with different sizes, which means it has an important influence on the dynamic characteristics of soil. With the goal of investigating the effect of aggregate size on the dynamic characteristics of saturated red clay, a series of consolidation-undrained dynamic triaxial tests under different cyclic stress ratios were conducted in this study on compacted specimens prepared with different aggregate sizes (Dmax =5.0, 2.0 and 0.5 mm) using the dynamic triaxial apparatus GDS. The evolution of dynamic axial strain, dynamic elastic modulus, and damping ratio with aggregate size was analyzed. Several key findings are obtained. (1) The obvious increase in cumulative dynamic axial strain with increasing cyclic number is concentrated within the first 200 cycles, and such axial strain exhibits exponential growth as the cyclic stress ratio increases. (2) The more cumulative dynamic axial strain is observed from specimens prepared with larger aggregate sizes before the allowable cyclic stress ratio. In comparison, more cumulative dynamic axial strain is observed from specimens prepared with smaller aggregate sizes after the allowable cyclic stress ratio. (3) Under the same cyclic stress ratio, the dynamic elastic modulus and damping ratio of specimens with different aggregate sizes, almost align with the same growth tendency as the vibration times increased, thus indicating that the influence of aggregate size on dynamic elastic modulus and damping ratio is only obvious in the initial stage of cyclic loading.
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Fundamental frequency calculation method and parameter analysis of monopile offshore wind turbines
YU Yunyan, HOU Haosheng, KONG Jiale
2025,47(2):281-288, DOI: 10.20000/j.1000-0844.20230720003
Abstract:
As a dynamic-sensitive structure, the changes in the offshore wind turbine structure are easy to affect the fundamental frequency of the system. The fundamental frequency of the system is key to the structure and foundation design of offshore wind turbines; hence, it is of great engineering significance to accurately calculate the fundamental frequency of the system. Based on the Euler-Bernoulli beam theory, considering the pile-soil interaction, added water mass, and the variable section characteristics of the tower, a calculation method of the transverse fundamental frequency of the single-pile offshore wind turbine system was established using the reverberation-ray matrix method. The accuracy and effectiveness of the proposed method were verified by a practical project, and the fundamental frequency excursion factors of the system were comprehensively analyzed. The analysis results showed that the pile-soil interaction, the added water mass, and the variable section characteristics of the tower all have a significant effect on the fundamental frequency of the system. The sensitivity of the system's fundamental frequency to different parameters is as follows: buried depth of pile foundation ＞ pile diameter ＞ modulus of foundation soil ＞ upper mass ＞ seawater depth ＞ wall thickness of pile foundation. When the buried depth of the pile foundation, the pile diameter, the foundation soil modulus, and the wall thickness of the pile foundation exceed the critical value, the change of parameters has little effect on the fundamental frequency of the system. To a certain extent, this paper revealed the influence law of fundamental frequency excursion factors of the system, thus providing a reference for the structure design of offshore wind turbines.
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Integrated design and performance analysis of seismic isolation structures for a special fortification building in Kunming
ZHANG Longfei, LIU Xiangyu, DONG Yiqiao, LIU Bang, LIU Zhiqiang
2025,47(2):289-299, DOI: 10.20000/j.1000-0844.20230718002
Abstract:
This study presents an integrated seismic isolation design methodology tailored for special fortification buildings in compliance with the Standard for Seismic Isolation Design of Buildings.The approach was applied to a design project for a special fortification building situated in Kunming City. The structural design process was executed using the YJK software. Subsequently, seven seismic-motion time histories that meet the specified criteria were selected, and a dynamic elastic-plastic time-history analysis of the structure was conducted under seismic fortification, rare, and extremely rare earthquake scenarios using the ETABS analysis platform. The inter-story displacement angle and the floor horizontal acceleration under seismic fortification align with regulatory standards. During rare seismic events, the structure's inter-story displacement angle, floor horizontal acceleration, tensile and compressive stresses, and horizontal displacement of the isolated rubber bearings also conform to specifications. In the event of extremely rare earthquakes, the inter-story displacement angle and horizontal displacement of the isolated rubber bearings meet the prescribed requirements.The tensile and compressive stress limits of the isolated rubber bearings are maintained at 1 MPa and 20 MPa, respectively, indicative of a safety-focused approach. Results from the dynamic elastic-plastic time-history analysis confirmed that the isolation structure has effectively met the seismic fortification objectives by remaining intact during earthquakes, being repairable in rare seismic events, and averting collapse in extremely rare seismic circumstances.
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Experimental study on the seismic performance of precast segmental CFST piers considering the strength of external links
TAN Xingfeng, YIN Chongli, WANG Chengquan, WANG Xinquan, CHEN Bin, WU Xi, LIU Rongyang
2025,47(2):300-308, DOI: 10.20000/j.1000-0844.20230809003
Abstract:
To reduce the damage and loss of bridge substructure during earthquakes, avoid casualties, and achieve rapid repairs after earthquakes, this study proposes an external replaceable energy dissipating links (EREDL)-precast segmental concrete-filled steel tubular pier based on the structural design concept of resilience. EREDLs with different levels of strengths were set at the joints of two groups of piers, and quasi-static tests were conducted on the piers under horizontal low cyclic loadings. Upon comparing the deformation of the two groups of piers, the results show that EREDL with Q355 strength is more resistant to deformation. Furthermore, a comparative analysis of the hysteretic curves, energy dissipation capacity, residual displacement, and degradation stiffness of two groups of piers reveals that the increase of EREDL strength within the range of 5% offset rate reduces the bearing capacity and increases the residual displacement of the pier. Overall, the research results can provide an important reference for the design and seismic performance optimization of precast segmental bridge piers.
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Dynamic response of oil well casings during earthquakes
LIU Yang, LIU Hanchen, HE Jintao, FAN Linlin, CHU Feng
2025,47(2):309-318, DOI: 10.20000/j.1000-0844.20231123004
Abstract:
The dynamic response of oil well casings during earthquakes is crucial for the safety of oil well production and operation. In this work, a mechanical model for the transverse vibration of oil well casings was established based on the theory of elastic foundation beam and soil-structure interaction. Moreover, the numerical models for site soils without oil well casing and oil well casing-soil were established using the finite element and time-history analysis methods. The dynamic response characteristics of oil well casings subjected to El-Centro waves with varying peak accelerations were also investigated. The results indicate that, with increased burial depth, the displacement and acceleration responses of the casing and soil decrease, while the reduction amplitude increases. The seismic dynamic response of site soil is decreased due to the casing, while the reduction amplitude is small. The casing's seismic dynamic response is most pronounced at the surface (0 m), highlighting the nonlinear characteristics of soil. The casing produces stress concentration near the surface (0 m), representing the most critical position. The sudden change of stress occurs at the position where the soil stiffness changes considerably, with peak stress values fluctuating continuously in 2-6 and 9-12 s, resulting in severe deformation and damage to the casing. Furthermore, the acceleration time-history curve of the casing lags behind the input seismic wave time-history curve by 0.08 s. Soil deformation near the surface (0 m) is more severe than that in deep soil, and the acceleration time-history curve exhibits distinct multipeak characteristics. The research findings serve as a theoretical foundation and provide technical support for seismic design, safe production, operation, and maintenance of oil wells.
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Susceptibility assessment of geological hazards in Changjiang County,Hainan Island, based on IV, CF, LRIV, and LRCF models
LI Xin, XUE Guicheng, LIU Changzhu, MA Bo, YANG Yongpeng, YANG Feng, WANG Xiaolin, LI Jieyu
2025,47(2):319-330, DOI: 10.20000/j.1000-0844.20230512003
Abstract:
In Changjiang County, located in the southwest mountainous area of Hainan Province, geological hazards have occurred frequently in recent years owing to the complex geological conditions and frequent engineering activities in the area. Therefore, studying the susceptibility of geological hazards in this region for the prevention, monitoring, and early warning of geological hazards has great practical significance. To evaluate the susceptibility of geological hazards in Changjiang County, the rock-soil mass, elevation variation coefficient, slope, fracture, undulation, river, road, and rainfall were selected as assessment indicators. The evaluation was conducted using four models: information value, certainty factor, logistic regression of information value (LRIV), and logistic regression of certainty factor. The results indicate that the high-susceptibility areas of geological hazards in Changjiang County are mainly distributed along roads and rivers in the mountainous areas, while the extremely low-susceptibility areas are located in the plains. The AUC values of the four models, 0.755, 0.749, 0.766, and 0.764, respectively, indicate that the prediction accuracy meets the requirement of susceptibility assessment and that the LRIV model is more reliable and accurate than the three other models. The findings of this research can provide a scientific basis for the prevention, monitoring, and early warning of geological hazards in the southwest mountainous areas of Hainan Island.
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Experimental research on the seismic performance of embedded perforated steel plate-reinforced concrete composite shear walls
XIA Zhiyuan, LI Yiran, FANG Youzhen, YAO Gangfeng, CAI Yimin, XU Dong
2025,47(2):331-341, DOI: 10.20000/j.1000-0844.20230725004
Abstract:
The seismic behaviors of embedded perforated steel plate-reinforced concrete composite shear walls (EPSP-RCCSWs) are investigated in this study. In particular, two perforated steel plate shear walls and one EPSP-RCCSW were designed and fabricated based on the boundary condition and out-of-plane buckling constraint, after which the quasi-static test was carried out on these specimens. Then, the hysteretic behavior, lateral stiffness degradation, and energy dissipation capacity of shear walls were compared and analyzed through the experimental phenomena and data. The analysis results reveal that the EPSP-RCCSW realizes the two-stage design concept, which states that the embedded steel plate and the encased concrete provide lateral stiffness together under small earthquakes, and the encased concrete collapses to consume energy while providing out-of-plane restraint for the steel plate under large earthquakes. Furthermore, the reinforced concrete composite shear wall has high lateral stiffness, strong energy dissipation capacity, and good seismic performance. The force transmission mechanism of the tension band can be adjusted artificially, and the local bending and tearing caused by the buckling of nonperforated steel plates can be avoided by weakening the perforation of the steel plate. The results also indicate that the perforated steel plate specimen connected on four sides has better integrity and more sufficient tension band development. Moreover, the ultimate bearing capacity and lateral stiffness of the EPSP-RCCSW are significantly higher than those of perforated steel plate shear walls. The corresponding story drift also exceeds the limit of the elastic-plastic drift ratio of frame shear-wall structure (1.0%) with ultimate bearing capacity. Meanwhile, the bearing capacity and lateral stiffness tend to be the same as those of the perforated steel plate shear wall when the drift displacement reaches 4.0%. The viscous damping coefficient and energy dissipation capacity of the EPSP-RCCSW are significantly higher than those of the perforated steel plate shear wall. Moreover, the bearing capacity of the composite shear wall is approximately the sum of the bearing capacities of the perforated steel plate and the reinforced concrete walls. While the ductility of the composite wall is not as good as that of the perforated steel plate shear wall, the internal steel plate continues to bear the load and dissipate energy due to the constraint of the encased concrete plate.
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Model testing of protective grilles for debris flow erosion on bridge piers
2025,47(2):342-350, DOI: 10.20000/j.1000-0844.20230506001
Abstract:
The impact and destructive capacity of debris flow on bridge piers are influenced by factors such as debris flow velocity, solid matter content, and solid particle composition. On this basis, a novel protective grille designed to shield bridge piers from debris flow erosion is proposed. The protective grille works by continuously regulating the solid particles in the debris flow, reducing the bulk density, the solid particle size, and impact force, thereby effectively protecting the bridge piers. A series of laboratory model tests were carried out to investigate the impact of structural parameters on the protection effect. Results indicate that: (1) As the drainage angle increases, the reduction rates of bulk density and coarse particle content in the debris flow within the grille initially increase and then decrease, following a quadratic function relationship; (2) As the grille span increases, the reduction rates of bulk density and coarse particle content consistently increase, displaying a linear relationship; (3) The scour height of the debris flow at the grille decreases as the relative opening spacing of the grille increases, showing an exponential function relationship. By contrast, the scour height gradually increases with the drainage angle, exhibiting a linear relationship. Meanwhile, through theoretical analysis, a method was developed to determine the structural parameters of the novel grille, including the drainage angle, span, height, and spacing. This approach provides a foundation for engineering design.
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Implementation of the Davidenkov constitutive model based on finite state machine
DONG Zhengfang, LI Haojie, WANG Yongfeng, JIN Deyin
2025,47(2):351-360, DOI: 10.20000/j.1000-0844.20230802002
Abstract:
Two methods based on finite state machine (FSM), namely state model-driven and table-driven, were investigated in this study to solve the problems of poor maintainability and difficult secondary development in the implementation of nonlinear constitutive models using traditional programming methods. Through comparison, the results reveal that the table-driven method can efficiently describe nonlinear constitutive models. Then, the stress-strain hysteretic curve of the Davidenkov constitutive model was modified, from which two construction forms of the hysteretic curve were proposed: failure point and correction point type. The results reveal that the modified Davidenkov model can correct the shortcoming of the “n-fold method” model, in which the shear strain reversely reaches the upper limit shear strain and is unable to enter the failure state, so it is more reasonable to be used in simulating the dynamic stress-strain relationship of soil, especially using the failure point model to simulate the shear stiffness of soil under cyclic loading and unloading. Based on the programming method of FSMs and the table-driven method, the constitutive programs of the Davidenkov model and its modified models were compiled, thereby verifying the effectiveness and correctness of the proposed method.
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Model tests and stability analysis of loess-mudstoneinterface landslides under heavy rainfall
WANG Haiming, ZHU Dianzhi, DING Yutao, YANG Xiaohui, ZHAO Zhizhong
2025,47(2):361-369, DOI: 10.20000/j.1000-0844.20231121005
Abstract:
In this study, the failure characteristics of loess-mudstone interface landslides under heavy rainfall were investigated, and their stability was evaluated. In particular, physical model tests, finite element numerical simulation, and theoretical analysis were conducted to reveal the deformation and failure characteristics of loess-mudstone interface landslides and improve the theoretical analysis and calculation methods, taking a landslide incident that occurred in Hui County, Longnan City, Gansu Province, as a case study. Several results were obtained. (1) Under the action of continuous heavy rainfall, the soil near the loess-mudstone interface is always in a saturated state. The main deformation process of loess-mudstone interface landslide is sliding-crack, with a composite failure mode of traction-push. (2) Landslide stability gradually decreases with the increase in rainfall intensity. After conducting multiple sets of landslide model tests to determine the landslide initiation times under different rainfall intensities, the results reveal that rainfall intensity and the landslide initiation time are logarithmically related. (3) Upon simulating the displacement changes of loess-mudstone interface landslide, it is revealed that the pore water pressure at the interface between loess and mudstone is the highest and gradually diffuses and decreases. This result is consistent with the actual infiltration characteristics of loess-mudstone interface landslides, thus verifying the accuracy of the conclusions obtained from the landslide model test. (4) Based on the traditional unbalanced thrust force method, the stability calculation method is improved, and the landslide stability is evaluated considering the influence of the seepage force generated by rainfall infiltration. The results indicate that the landslide stability coefficient is significantly lower than that required by the code, indicating that the time from the beginning of rainfall to slope instability is shorter than the conventional prediction value. The research conclusions provide an important basis for the research and prevention of landslide disasters.
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Seismic response of column-and-tie timber structures under long-period ground motions
GUO Rui, XUE Jianyang, DENG Lei, QI Liangjie
2025,47(2):370-382, DOI: 10.20000/j.1000-0844.20230722001
Abstract:
A finite element (FE) analysis model was established in this paper to analyze the dynamic responses of column-and-tie timber structures with flexible mechanisms under long-period ground motions. The OpenSees was applied to verify the rationality of the FE model, after which the dynamic damage evolution mechanism of column-and-tie timber structures under long-period ground motions was explored. The results indicate that the errors between the first natural frequencies from the FE results and the corresponding shaking table test results are 6.5% and 11.3% in the x and y directions, respectively. The variation trend of the acceleration amplification factor along the structure's height direction based on the FE results is similar to that based on experiment results. Moreover, the Fourier spectral amplitudes of long-period ground motions TCU054, TCU102, ILA048, and ILA056 are mainly concentrated in low-frequency bands, while the long-period components of their acceleration response spectra are richer than Taft waves. Furthermore, the acceleration amplification factor, displacement response, and interlayer shear force of the structure under long-period ground motions are greater than those under the Taft wave with the same peak ground acceleration (PGA). Under the long-period ground motion with a PGA of 0.22g, the maximum relative displacement of the roof in the x and y directions are 2.09-9.76 times and 2.68-8.71 times of those under the Taft wave, respectively. Moreover, the corresponding shear forces in the x and y directions are 1.30-1.71 and 1.46-2.09 times those under the Taft wave.-
Quantitative analysis of subway interference on borehole tiltmeter in the Qingdao area
LI Xiao, YUE Long, XU Qingfeng, ZANG Yibo, HAN Bangjie, WANG Zhe, LI Wei
2025,47(2):383-392, DOI: 10.20000/j.1000-0844.20231106001
Abstract:
Due to the subway's operations, high-frequency interference occurs on the tiltmeters in the Qingdao area. Furthermore, the daily interference occurs simultaneously with the subway's operation time. After conducting a qualitative analysis of data obtained from five sets of borehole tiltmeters in the Qingdao area, the results reveal that the tiltmeters within 2 km of the subway are disturbed by the subway's operations. However, when the distance exceeds 15 km, the tiltmeters are no longer affected by subway interference. At the same time, to quantitatively analyze the interference characteristics of the subway, the variational mode decomposition (VMD) method was used in this study to decompose the data of tiltmeters affected by the Qingdao subway interference. The accuracy of the K value of the VMD decomposition layer and the effectiveness of denoising were also verified using the generalized S transform. The findings indicate that the borehole tiltmeters undergoing interference from different subway lines in Qingdao have five interference mode components. Upon removing these components and reconstructing the data, the signal-to-noise ratio of the data is improved, effectively improving data availability.
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Dynamic response characteristics and failure modes of medium-steep bedding rock slopes subjected to earthquake forces
DOU Yanghao, ZHAO Qihua, ZHENG Xiuhong
2025,47(2):393-403, DOI: 10.20000/j.1000-0844.20240415002
Abstract:
The deformation and failure mechanism of medium-steep bedding rock slopes under earthquake action is relatively complex. A medium-steep bedding rock slope with a rock dip angle greater than the slope angle was designed and fabricated using shaking table tests. The dynamic response characteristics and failure modes of the slope were examined under unidirectional and coupled seismic wave actions. The experimental results reveal a distinct nonlinear elevation amplification effect on the horizontal dynamic acceleration of the model slope. Remarkable nonlinear amplification and surface effect were observed within a depth range of 20 cm from the slope surface. Moreover, the dynamic response of the slope is more pronounced under coupled seismic waves. Under low amplitude and low frequency conditions, the slope exhibits a stronger dynamic response to natural waves than to sine waves. The peak horizontal acceleration (PHA) amplification factor of the slope increases with the amplitude. As the frequency increases and approaches the natural frequency of the slope, the PHA amplification factor experiences a significant increase. Coupled seismic waves further enhance the PHA amplification factor across various waveform, amplitude, and frequency conditions. Compared with other seismic waves, coupled seismic waves exert a more destructive impact on the slope. The failure process of medium-steep bedding rock slopes under earthquake action can be categorized into three stages: crack generation at the upper part of the slope, crack expansion and penetration, and sliding in the upper slope region, leading to slope instability.
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Dynamic evolution of “8·14” debris flow in Nichang Gully,Caoke Township, Shimian County
XIA Zhe, CHANG Ming, ZHANG Yuanming, LI Hongjie, LI Linze, XU Hengzhi
2025,47(2):404-414, DOI: 10.20000/j.1000-0844.20230905001
Abstract:
After the “9·5” Luding earthquake in 2022, a series of coseismic landslides and collapses occurred in the earthquake area, leading to the extensive accumulation and formation of loose solid debris. Under the action of heavy rainfall, the possibility of debris flow outbreak in the mountainous areas after the earthquake was greatly improved. On September 20, 2022, a once-in-a-decade heavy rainfall occurred in Nichang Gully, Caoke Township, Shimian County, resulting in a debris flow outbreak. During this event, massive amounts of debris flow rushed out of the gully and accumulated in the river, causing the river to be blocked. On August 14, 2023, another debris flow broke out in Nichang Gully again, leading to the silting-up of a new check dam downstream. In this study, FLO-2D was used to analyze the dynamic evolution processes of the Nichang Gully debris flow with and without a dam when the rainfall frequency reached 10%. Furthermore, the model accuracy was verified using the method of evaluation coefficient Ω . The results indicate that the modulus evaluation coefficient Ω of the dynamic evolution of Nichang Gully debris flow using this simulation method is 1.59, indicating the model's reliability. Meanwhile, the prediction of debris flow under three rainfall frequencies of 5%, 2%, and 1% was carried out. The simulation results of debris flow with prevention and control engineering under a rainfall frequency of 10% were coupled with the actual movement results of the “8·14” debris flow in Nichang Gully. The results indicate a preliminary judgment wherein the outbreak frequency of the “8·14” debris flow is once every 10 years. At the same time, the simulation results of debris flows under rainfall frequencies of 2% and 1% indicate that both lead to the failure of the control effect of the check dam. As the debris flow materials rush out of the gully, this incident causes the blockage of the river. With the change in rainfall frequency from 5% to 1%, the scope of debris flow threat also increases gradually. Overall, the threat of debris flow in Nichang Gully can be effectively reduced by adding retaining measures for the debris flow, building and maintaining the drainage channel project, and inspecting and dredging the check dam before the start of the rainy season each year.
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Seismic behavior of pile-soil interaction of simply supported beam bridges in a typical loess site
YE Chenyang, WANG Ping, ZHOU Tingru, WANG Huijuan, WANG Yali, YU Haoran, ZHANG Xingfu
2025,47(2):415-425, DOI: 10.20000/j.1000-0844.20240228001
Abstract:
The amplification effect of ground motion on infrastructure found in loess sites was investigated in this study. Taking a simply supported beam bridge as the research object, a pile-soil-bridge model considering the horizontal coupling effect of the El-Centro wave was established based on finite element theory. The analysis focused on acceleration response, spectral characteristics, and displacement response, clarifying the pile-soil interaction characteristics in loess areas. The results reveal that the relative pile-soil displacement and the peak acceleration of pile foundation show an apparent increasing trend with the increase in peak ground accelerations (PGA). Furthermore, as the elevation rises, the PGA amplification factor and Fourier amplitude increase gradually, while the predominant frequency of structure gradually shifts to the low-frequency direction. Compared with the far-field soil, the peak acceleration of loess soil around the pile in the range of 0-20 m increases by 30.87%. With the increase in pile length, the relative pile-soil displacement and the acceleration response of the pile foundation also show an obvious increase. Furthermore, the increase in pile diameter can effectively reduce the relative displacement of pile and soil and a structure's acceleration response.
Earthquake Research
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Preliminary study on the Quaternary activity characteristics of the Hefei Basin section of Jiashan—Lujiang fault
YANG Yuanyuan, LI Fei, LI Pengfei, PENG Liuya, SHU Peng, PAN Haobo, CAO Junfeng, ZHAN Meihuang, LI Yong
2025,47(2):426-436, DOI: 10.20000/j.1000-0844.20230821001
Abstract:
The Jiashan—Lujiang fault is a major fault of the eastern branch of the Anhui section of the Tan—Lu fault zone, yet the Quaternary activity characteristics of the Hefei Basin section remain understudied. This paper presents an initial investigation into the geometric distribution characteristics and Quaternary activity of the Hefei Basin section. The study used shallow seismic exploration (high-density electrical exploration and ground-penetrating radar detection) in key concealed areas along the fault, as well as remote sensing interpretation and outcrop profiling in the bedrock outcrop areas. The results indicate that: (1) The Jiashan—Lujiang fault mainly extends northward from the interior of Guhe Basin, located east of Fucha Mountain, through the Zhangbaling Uplift. It should not be confused with the Outang—Qingshuijian fault, which is situated at the eastern foot of Fucha Mountain and the western foot of Zhangbaling Uplift; (2) The Hefei Basin section of the Jiashan—Lujiang fault exhibits distinct linear features, influencing the distribution of linear valleys, ridges, and some rivers, indicating recent activity; (3) The latest activity of the Hefei Basin section of the Jiashan—Lujiang fault is characterized by thrusting, with the most recent movement occurring during the middle-late period of Mid-Pleistocene.
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Directionality of Newmark displacement during the Lushan MW6.8 earthquake in 2013
LIU Ping, LIU Chuan, CHEN Xingzhou, WANG Hai, WEI Changgang, FAN Yiren, CHEN Fan, WU Yuxin
2025,47(2):437-447, DOI: 10.20000/j.1000-0844.20231008002
Abstract:
Using the strong motion records from 22 near-field stations in the focal area, the directionality of Newmark displacement during the 2013 Lushan MW6.8 earthquake was investigated. The ground motions were projected using the modified Boore method to analyze the characteristics of Newmark displacement, including changes in directionality, the predominant direction (θmax), and the ratio of maximum to minimum displacement values (Dnmax/Dnmin). Results show the following: (1) Newmark displacement exhibits distinct peaks and valleys as it changes with direction, and in most cases, the angle between the maximum and minimum directions is generally vertical. (2)Dnmax/Dnmin increases with critical acceleration (ac); when ac is large, Dnmax/Dnmin gradually increases with fault distance. In addition, the site type has a certain influence on Dnmax/Dnmin (3) A strong correlation exists between θmax and the direction of coseismic displacement on both sides of the fault, but a weak correlation is observed on both ends of the fault. The correlation between θmax and the vertical direction of the fault strike is weak, and θmax does not notably change with ac (4) The empirical model of Newmark displacement, which considers Arias intensity and earthquake magnitude, yields the best prediction effect of Newmark displacement when considering directionality.
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Design and implementation of Gansu Province earthquakedisaster defense service platform
SUN Yanpin, CHEN Wenkai, LI Dagui, MA Yupeng, LU Songting, ZHU Wujun
2025,47(2):448-457, DOI: 10.20000/j.1000-0844.20230530004
Abstract:
Gansu Province, one of China's provinces with high seismic intensity, has made notable progress in the informatization of earthquake disaster defense in recent years. However, technical systems for earthquake disaster defense at the municipal and county levels remain underdeveloped, resulting in issues such as ineffective resource integration across the province and limited data information services. Based on the earthquake disaster risk survey in Gansu Province, this study aims to develop a comprehensive earthquake disaster defense service platform at the provincial, city, and county levels. The platform integrates the display, query, and service of data related to earthquake hazards, disaster-bearing bodies, and earthquake disaster risk assessments. It also facilitates the unified aggregation and delivery of risk survey results across the three levels. Through various formats such as web pages, maps, and statistical charts, the platform provides informatization services for earthquake disaster risk prevention and control across Gansu Province. It aims to fully satisfy the operational requirements of earthquake departments at all levels and comprehensively enhance the seismic damage prevention and control capabilities across the entire province.
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Three-dimensional S-wave velocity structure of the crust in Northwest Yunnan using the surface wave direct inversion method
CHA Wenjian, WANG Weijun, ZHANG Yuanyuan, HEI Hetang
2025(2):458-467, DOI: 10.20000/j.1000-0844.20231121004
Abstract:
The northwestern region of Yunnan Province (25°—27°N, 99°—101°E) lies along the western boundary of the Sichuan—Yunnan rhomboid block, a zone marked by active tectonic movements. This region is among the most seismically hazardous in China, requiring a comprehensive understanding of its seismogenic structures. In 2020, we analyzed continuous waveforms from 69 short-period stations in the area. We extracted Rayleigh surface-wave phase-velocity dispersion curves using cross-correlation of ambient noise and time-frequency analysis. We derived the Dl S-wave velocity structure beneath the study area using the direct inversion method of surface-wave dispersion based on ray tracing. The results reveal significant variations in the crustal velocity structure, particularly in segmented features along major fault zones. For example, at a depth of 5 km beneath the Weixi—Qiaohou fault zone, high velocities are observed in the northwestern section, whereas low velocities dominate the southeastern section. Similarly, the Chenghai fault zone exhibits high velocities in its northern segment and low velocities in the southern segment. In the Binchuan Basin, a low-velocity anomaly of approximately 5 km suggests the presence of a substantial sedimentary layer. Shallow crustal wave velocity correlates closely with terrain relief, with low velocities observed in basin areas and high velocities in mountainous regions. The 2021 Yangbi M6.4 earthquake occurred in a transition zone between high and low S-wave velocities. In addition, low-velocity zones of varying extents are identified in the middle and lower crust, potentially providing a seismogenic environment for the earthquake.
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Seismic damage assessment of reticulated shell structures using a modified Park-Ang model with consideration of failure characteristics
HUANG Jianming, LIU Xiang, WANG Xiangru, LIU Tao
2025,47(2):468-479, DOI: 10.20000/j.1000-0844.20231125001
Abstract:
To evaluate the damage degree of reticulated shell structures under 3D seismic action, two typical failure characteristics of these structures were analyzed using the incremental dynamic analysis method. By modifying relevant parameters in the formula of the Park-Ang seismic damage model, a damage assessment criterion was developed, incorporating two dynamic response indexes: structural deformation and energy. Moreover, damage performance levels corresponding to various failure states of reticulated shell structures were proposed. Results indicate that the failures of reticulated shell structures can be classified into dynamic strength failure and dynamic instability failure. The modified Park-Ang seismic damage model effectively evaluates the damage degree for these failure modes, with the damage value converging to 1.00 and exhibiting minimal dispersion. The damage degree of reticulated shell structures can be categorized into five levels: basically intact, slight damage, moderate damage, severe damage, and collapse, with corresponding damage limits of 0, 0.15, 0.65, and 1.00, respectively. Finally, by verifying the model with four different types of seismic waves that satisfy the specification, the modified Park-Ang seismic damage model effectively accounts for the coupling effect of displacement and energy consumption, providing a more accurate assessment of the overall damage to reticulated shell structures.
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Discussion on the controversies of seismogenic fault dipping direction for 2023 Jishishan MS6.2 earthquake and seismic hazard assessment of its adjacent faults
PING Zifei, GE Weipeng, ZHANG Bo, ZHU Junwen, CAO Xiyu
2025,47(2):480-491, DOI: 10.20000/j.1000-0844.20240520001
Abstract:
On December 18, 2023, an MS6.2 earthquake occurred in Jishishan County, Gansu Province. The ascending and descending Sentinel-1A SAR satellite images were selected and the differential interferometric synthetic aperture radar (D-InSAR) technology was used to obtain the co-seismic deformation field of the earthquake. The results show that the long axis direction of co-seismic deformation field in the line of sight (LOS) direction is NW-SE, and the deformation is positive, indicating an approach towards the satellite and revealing surface uplift. The maximum deformation in the LOS direction of ascending and descending tracks is 12 and 9 cm, respectively. Subsequently, the co-seismic slip distribution was inverted using the steepest descent method with ascending and descending deformation data as constraints. The inversion results show that both the SW-dipping and NE-dipping fault models fit the observed values of InSAR co-seismic deformation field well, indicating that the MS6.2 earthquake is a combined thrust/strike-slip faulting type. The tectonic background and aftershock distribution in the study area were discussed to solve the controversies on the seismogenic fault and its dipping direction of the event. It is inferred that the seismogenic fault of the Jishishan MS6.2 earthquake is a hidden fault striking NW-SE and dipping SW, with a strike of approximately 148.4°, a dip angle of 52°, and a slip angle of approximately 130°, possibly a branch fault of the Jishishan east margin fault. Additionally, the co-seismic Coulomb stress model shows that the eastern section of Lintan-Tanchang fault, the eastern section of Lenglongling fault, the western section of Haiyuan fault, the western section of Lajishan southern margin fault, and the Guide fault are located at the positive-negative transition zone of co-seismic Coulomb failure stress change (ΔCFS), which should be given attention.
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Influencing factors and characteristics of residential housing damage in typical earthquake-stricken areas of the Sichuan Basin
PENG Qiaoqiao, MENG Xiangrui, DI Baofeng, ZENG Yajie, LUO Xiaolong, HU Shunzhong
Abstract:
An MS6.0 earthquake occurred on September 16th, 2021, and affected 18 towns in Luxian County, Sichuan Province, with varying degrees. The seismic damage of residential houses in these areas is quantitatively analyzed through an onsite survey, and the relationship among house structures, epicentral distance, and degree of residential damage is assessed. A matrix of residential housing vulnerability in typical earthquake-stricken areas of the Sichuan Basin with different intensities is then established. Considering this matrix, the difference in average earthquake damage indexes between the affected areas and other regions that previously experienced earthquakes of the same magnitude is compared. Furthermore, the characteristics and factors that contribute to the residential housing damage in the study area are discussed, and the following conclusions are drawn: (1) The vulnerability of houses from high to low is brick-concrete structures, brick-wood and other structures (civil, wood, and stone structures), and steel-concrete structures; (2) 90% of the housing damage during the Luxian earthquake occurred in the area within 6 600 m from the epicenter; (3) Under two earthquakes with the same magnitude, the damage to residential houses in the basin is 1-2 times lower than that in the mountains. The results of this study can be used as a scientific reference for the rapid assessment of damages, planning, and reconstruction of residential housing after earthquakes in the Sichuan Basin and other earthquake-prone areas.
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Fault locking and seismic risk analysis of Lintan-Tanchang fault
ZHAO Ningyuan, LIU Lei, ZHUANG Wenquan, LI Ning, JIANG Fengyun
DOI: 10.20000/j.1000-0844.20240131001
Abstract:
Based on the GNSS data from 2009-2013 and 2015-2019, the fault locking and fault slip deficit of the Lintan-Tanchang fault before the Minxian-Zhangxian MS6.6 earthquake and Xiahe MS5.7 earthquake were inverted by using Tdefnode negative dislocation method. Combined with the spatial distribution of small earthquakes and GNSS velocity profile results, the characteristics of small earthquake activity and horizontal crustal movement before the earthquake occurred are analyzed, and the future seismic risk of the fault is discussed. The results show that the locations of the two earthquakes were strongly locked before the two earthquakes, the depth of the fault locking was consistent with the hypocenter depth of the two earthquakes, and the fault slip deficit rate was relatively low. Combined with the results of the spatial distribution of small earthquakes, it is found that there was a seismically quiet period before the two earthquakes, and the length of the seismically quiet period is consistent with the length of aftershocks. Based on the GNSS velocity profile, it is shown that the Lintan-Tanchang fault is dominated by thrust compression and sinistral strike-slip movement. The fault slip rate is enhanced after the earthquake compared with before the earthquake. Based on the above anomaly characteristics, it is found that there are strong locked and high slip deficit rate in the eastern part of the Lintan segment to the Minxian-Tanchang segment and the eastern Hezuo segment, and the strong locked fault segments also correspond to a seismically quiet period, future attention should be focused on these two regions.
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Study on Correlations between Surface/Borehole Spectral Acceleration Ratios and Microtremor HVSR
WANG Yushi, ZHANG Yaqiong, LI Xiaojun, LI Min, DUAN Jianbin
DOI: 10.20000/j.1000-0844.20231202001
Abstract:
While the fundamental theory behind the horizontal/vertical spectral ratio (HVSR) of microtremor Fourier amplitudes remains elusive, its application in estimating site condition parameters as well as in investigating seismic site effects is widely recognized. The microtremor HVSR was refined, and a novel empirical method for estimating the surface/borehole spectral acceleration ratio (SBSRa) of ground motion was developed. This methodology enabled the estimation of ground motion amplification factors by in-situ microtremor measurements, consequently enhancing foundational data for the seismic site effects researches. Utilizing a dataset comprising over 300,000 sets of strong motion acceleration records from 589 stations within Japan’s KiK-net network, the stable microtremor HVSR was derived from microtremor data recorded during the pre-event of the time history. The correlation between microtremor HVSR and ground motion SBSRa was calculated at each station under weak seismic motion. Interestingly, it was observed that microtremor HVSR and ground motion SBSRa exhibited analogous curves and approximate dominant frequencies. Building on this finding, empirical correction coefficients for each type of microtremor HVSR were determined using a frequency normalization approach. Subsequently, a methodology for predicting ground motion SBSRa based on microtremor HVSR was proposed. Reliability analyses demonstrated that the predicted SBSRa using this methodology achieved engineering acceptable accuracy. Furthermore, the Jaccard similarity coefficients between the predicted values and the measured values of ground motion SBSRa at 75% of stations exceeded 0.58, affirming the validity of the approximate estimation for ground motion SBSRa under weak seismic motion predicted by microtremor HVSR.
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Application and Test of Bayesian Probabilistic Statistical Prediction Model in the Seismic Trend of the Key Monitoring Area of the Three Gorges Reservoir Seismic
lingjiangzhu, Liaoxin, yaoyunsheng, shiyun, qianjianxiu, qinweibing
DOI: 10.20000/j.1000-0844.20231223001
Abstract:
The reservoir earthquake is an earthquake activity caused by human engineering activities. It has the characteristics of group occurrence, high frequency and high intensity. The prediction and research on it is helpful to evaluate the risk of reservoir earthquake disaster. In this study, the earthquake monitoring area of the Three Gorges Project reservoir is divided into several prediction units of 1 km × 1 km. The Bayesian probability statistical prediction model is used to predict the probability of induced magnitude based on eight induced factors : reservoir water depth, rock mass type, regional tectonic stress state, fault activity, karst development degree, reservoir water permeable depth, communication relationship with reservoir water, and seismic activity background. The results show that in the key monitoring area, the probability of induced earthquakes is higher in the area near the reservoir bank dominated by carbonate rocks. There is a possibility of inducing medium-strong earthquakes ( 6.0 > M3 ≥ 4.5 ) in the northern part of Fairy mount fault and the near reservoir bank section of Gaoqiao-Niukou fault. The probability of non-earthquake or induced micro-earthquake in the Three Gorges dam site area and far away from the reservoir bank area is higher. In addition, in order to verify the accuracy of the prediction model, this study also uses the actual earthquake situation since the 175 m impoundment of the Three Gorges Reservoir to test the prediction model. The test results show that the location and magnitude of the actual earthquake are obviously consistent with the prediction results. It shows that the Bayesian probability statistical prediction method with fine and reasonable division method has a good effect in the risk assessment of reservoir induced earthquake. The probability prediction results of this study have important reference significance for determining the earthquake risk area, formulating earthquake early warning and prevention strategies, and ensuring the safe operation of reservoir projects.
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Using Unmanned Aerial Vehicle Image to Research New Active Behavior and Integrity of Paleoseismic Events on the Linze Fault
YU Jinchao, WANG Youlin, YUAN Daoyang, LI Shuwu, WEN Yameng, ZHANG Lijun
DOI: 10.20000/j.1000-0844.20240614001
Abstract:
The integrity of paleoseismic events on active fault is an important basis for recognizing activity behavior and evaluating its future strong earthquake risk. Interpreting the microtopographic features of active faults based on high-resolution imagery can complement with paleoseismic trenching methods, jointly constructing a complete earthquake recurrence model. This paper takes the Linze Fault on the northern margin of Yumushan in the middle of the Hexi Corridor as the research object, generate high-precision topographic and geomorphological data based on unmanned aerial vehicles and photogrammetric methods, through detailed interpretation of the offset geomorphology of active faults, then measure 90 set of single or multiple cumulative vertical offset on linear fault scarps saved on alluvial-proluvial fan along the fault zone, and get the curve of cumulative offset probability density(COPD) to obtain its vertical offset clustering characteristics. A total of 6 peak accumulated offset were identified along the fault, which were 0.5、0.9、1.5、2.1、2.7、3.3 meters, respectively, revealing that the Linze fault may have experienced at least six palaeoseismic events with magnitude ranging from Ms6.6 to 7.0 since Late Pleistocene. Thus, we compared and analyzed the integrity of paleoseismic events revealed by previous studies using paleoseismic trenching methods. Referring to the dating results of paleoseismic events determined by trenching, the latest seismic event occurred 2.1-2.5 ka ago. Based on the above analysis, the Linze fault conform to the characteristic seismic recurrence pattern, and its tectonic activity continuously compresses and expands towards both sides of the fault and interior of the basin. Comprehensive analysis of recurrence pattern and elapsed time, the latest seismic event of the Linze fault is close to its recurrence interval, indicating a high risk of strong earthquakes.
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Deformation damage mechanisms and failure modes of the creep-slip bedding rock landslides controlled by faults
GUO Shuangfeng, FU Jinyu, ZHANG Peng, LI Ning
DOI: 10.20000/j.1000-0844.20231008003
Abstract:
The stability of bedding rock slopes with weak interlayers is controlled by both weak interlayers and rock mass. Due to the poor physical and mechanical properties of the weak interlayer, it is prone to triggering landslide disasters along the bedding plane. The instability mechanism and failure mode of bedding rock slopes containing controlled faults have always been highly concerned in the field of geotechnical engineering. Based on the field investigation, taking the bedding rock slope on the right bank of a large hydropower project dam site in the upper reaches of the Yellow River as an example, a model is established using the finite element direct solution for slope stability. The interface elements are adopted to simulate the frictional sliding, opening, and closing of the structural surface. These conditions are applied to study the developmental characteristics, cause mechanism, and stability state of the deformation body under different working conditions when creep-sliding deformation and failure occur on the slope controlled by the F27 fault. It has been shown that the potential sliding surfaces composed of bedding joints as well as fault F27 are key factors in controlling slope stability. Under natural and heavy rain conditions, the overall slope is basically stable to less stable. Under earthquakes and extreme conditions, the bedding joints and the fault F27 have successively extended, expanded, and connected to form a creep slip bottom boundary, as well the trailing edge was damaged by tensile deformation. As a result, the creep-sliding destabilization occurred on the slope along medium-gentle dipping controlled structural surfaces. The engineering hazards are serious after slope instability, which requires key engineering treatments and slope reinforcement measures.
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Measurement of seismic isolation bearing displacements in complex environments by integrating improved Camshift and Kalman filters
DU Yongfeng, XIONG Xiaoqiao, FAN Ning, HAN Bo, LI Hu
DOI: 10.20000/j.1000-0844.20240222001
Abstract:
In order to solve the problem that the traditional Camshift algorithm overly relies on color information and is susceptible to the interference of the surrounding environment in the application of seismic isolation engineering, a vision-based displacement measurement method for seismic isolation bearings is proposed. First, the captured video is subjected to image preprocessing, after which the fusion information histogram is generated by adjusting the weights of the target edge information obtained by the Canny operator and the color information obtained by the Camshift algorithm, thus enhancing the stability of the algorithm during target tracking. When the target is not occluded, the improved Camshift algorithm is directly used to obtain the position of the target; when the target is occluded, the degree of occlusion is judged by the occluded area of the target, the kalman gain is introduced to predict the position of the target, and the prediction and observation results are fused to obtain the new positional state estimate of the target. Subsequently, the real displacement information is obtained by coordinate transformation. The accuracy of the method was verified by shaking table tests on a model of a three-story steel frame structure, which showed that the maximum displacement errors obtained from the results of the visual method and the tensile wire displacement meter measurements were less than 6.84%, and the correlation between the two was above 0.91. Finally, the visual method was applied to a real project, and by comparing the data of visual displacement measurement and wire-displacement meter at one monitoring point, it was found that the error value of the two was only 0.15mm, with an accuracy of 98.56%, which further demonstrated that the method was able to adapt to the complex environment of seismic isolation layer such as light change, dust and obstruction, and had good accuracy and robustness.
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Global Overview of Earthquake Disasters in 2024
LiMeiyi, FengWei, WangWuxing, QianGeng
DOI: 10.20000/j.1000-0844.20250121002
Abstract:
This study compiles data from multiple sources to analyze global seismic activity and earthquake-induced disasters in 2024. A distribution map of disaster-related earthquakes is presented, and the seismic magnitude characteristics contributing to major disaster years are examined. The study provides a comprehensive summary of earthquake events that resulted in casualties and economic losses, along with an in-depth analysis of major disasters. Compared to previous years, global seismic activity in 2024 was relatively low, with no earthquakes exceeding magnitude 8.0 and a decline in the frequency of events above magnitude 7.0. Earthquake disasters in 2024 were characterized by low casualty rates, with most destructive events concentrated along the Pacific Ring of Fire. The major disasters were geographically clustered, with well-defined causes of casualties. Based on an analysis of 2024 earthquake disasters and seismic activity trends since the 21st century, this study proposes targeted preventive measures and highlights key areas for future earthquake risk mitigation.
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Research on the method of determining the yield point in the design of self-centering braced structures
Wang Tao, Kong Tao, Meng Li-yan, Pan Rui, Pan Yu-tong
DOI: 10.20000/j.1000-0844.20231026003
Abstract:
Determining the yield point of structural design is the key problem to establish the equal ductility elastic-plastic displacement response spectrum. A method for determining the design yield point of self-centering braced structures is proposed in this paper. Three-story and five-story steel frame structures with self-centering buckling-restrained braces are designed by using the direct displacement-based design method, and the influence of the design yield point on the accuracy and design results of the direct displacement-based design method is analyzed. The research results show that for low-rise and multi-story structures, when the yield point determination method proposed by the author is used for direct displacement-based seismic design, the ductility capacity of the structure can meet the requirements of ductility design; Compared with the traditional design yield point determination method, the maximum interstory displacement angle of the structure under 8-degree earthquake is closer to the design goal of 2%, and the first stiffness design value of self-reset anti-buckling brace is reduced. the designed structure not only meets the safety, but also has better economy.
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Study on 3D seismic response characteristics of valley site based on real terrain
p>ZHANG Chao, ZHANG Shenghai, YIN Ke, GAO Zhiyong, ZENG Shichao
DOI: 10.20000/j.1000-0844.20230906003
Abstract:
In order to explore the seismic response characteristics of typical valley sites, a three-dimensional finite element numerical model was established based on the real geomorphology of a typical valley site in the North Tien Shan region as a background, and the response characteristics of the site displacements, accelerations, and spectral accelerations were analyzed under impulsive and non-pulsive seismic effects. The study shows that: the dynamic response of the site is significantly affected by the topographic features, the surface displacement and acceleration are amplified with the rise of the ground level, and the displacement response of the narrow valley area is stronger than that of the wide valley area, but the acceleration response is weaker than that of the wide valley area; the topography of the local protruding nozzle causes the amplification of the local displacement, and the phenomenon of local acceleration amplification is remarkable under the non-pulsed seismic effect, while the phenomenon of local amplification under the pulsed seismic effect is not obvious. With the decrease of depth, the displacement and acceleration are amplified, and the amplification effect of shallow rock body on displacement is weakened, but the amplification effect on acceleration is strengthened; the difference of surface displacement and acceleration under the two types of earthquakes is significant, but the difference of acceleration is relatively small, and the displacement and acceleration increase nearly linearly with the increase of PGA; the short-period spectral acceleration in the high relief area of mountain peaks and other high terrain areas is significantly higher than that in the low relief area of valleys, while the long-period spectral acceleration in the low relief area of valleys is significantly higher than that in the low relief area of valleys. The short-period spectral acceleration of high relief areas such as mountain peaks is obviously higher than that of low relief areas in valleys, while the long-period spectral acceleration of low relief areas in valleys is higher than that of mountain peaks, and the long-period spectral acceleration of narrow valleys is obviously higher than that of broad valleys.
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Analysis of the causes of earthquake damage to residential buildings in the Ms 6.8 Dingri earthquake, Xizang
Wangyanqiao, Lixiangxiu, Wangning, Wuqing, Luchenhu, Liuaiwen
DOI: 10.20000/j.1000-0844.20250113001
Abstract:
On January 7, 2025, a magnitude 6.8 earthquake occurred in Cuoguo Township, Dingri County, Shigatse City, Xizang Autonomous Region, with a focal depth of 10 km. The meizoseismal area is located in a high-altitude and extremely cold area, with an epicenter intensity of IX. The epicenter of this earthquake is located in the Shenzha-Dingjie Rift Valley within the Lhasa terrane of the Qinghai Xizang Plateau. The seismogenic fault is the Dengmo Fault, which is mainly a normal fault with a maximum coseismic displacement of nearly 3 meters. Based on the survey of residential building styles in the earthquake-prone regions of Xizang prior to the earthquake, this paper provides a summary of significant destructive earthquakes that have occurred in Xizang from 1980 to 2024. The seismogenic structure of the Dingri 6.8 earthquake and the seismic damage to local residential buildings is analyzed. The research results indicate that the Dingri 6.8 earthquake is one of the most powerful, intense, and devastating seismic events in Xizang in recent years, causing significant casualties. Local residential buildings predominantly feature wall-lifted beam structures. The primary earthquake-induced damages include the peeling or complete collapse of self-supporting walls, external wall cracking, and house collapses due to heavy roofing. Additionally, wooden columns were fractured, beam-column connections were damaged, and non-structural components fell. Finally, a comprehensive analysis was conducted to identify the factors contributing to the severe casualties in this earthquake.
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Experimental study on seismic behavior of cross-slanted corrugated steel plate shear wall
ZHANG Zhen, YANG Taochun, LI Yiwei, LIN Mingqiang, XIE Qun
DOI: 10.20000/j.1000-0844.20230508001
Abstract:
In order to address the problem that flat steel plate shear walls are prone to out-of-face buckling, a new type of cross-slanted corrugated steel plate shear wall (CCSPW) with self-protection against out-of-face buckling is proposed. In order to study the influence of corrugation angle on its seismic performance, three 1/3 scaled CCSPW specimens were designed and manufactured, and the experimental study was conducted through the MTS loading system. Meanwhile, the seismic performance indicators, such as initial stiffness, bearing capacity, failure process and damage form, energy consumption capacity, and ductility, were analyzed under the low cycle of repeated loads. The study shows that under the action of low cycle repeated loading, CCSPW can effectively prevent the phenomenon of outward bulging and has excellent lateral bearing capacity; cross-slanted corrugated steel plate with one tensile and one compressive joint force effectively improves the initial stiffness of the specimen. Among them, the CCSPW specimen with an oblique angle of 60° has the greatest initial stiffness. The CCSPW specimen with an oblique angle of 45° has a bearing capacity that is 5.5% and 10% higher than that of the other two specimens, and has the largest ductility coefficient and the best ductility. The CCSPW specimen with an oblique angle of 60° has the largest equivalent viscous damping coefficient, which is 2-5% higher than that of the other two specimens, and has a more excellent energy dissipation capacity is excellent.
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Multi-factor constrained downsampling method for adaptive quadtree InSAR data
Mo Xinyu, Jia Zhige, Huang yu, Deng debeier, Liu Juntao, Ruan Qiaozhe, Liu Xiaoli
DOI: 10.20000/j.1000-0844.20231128002
Abstract:
Down-sampling of InSAR displacement fields helps to remarkably improve inversion efficiency of inversion of coseismic slip distribution and fault geometry. However, how to keep balance between removing noise and redundant information and retaining more global and local key displacement information is a challenge to traditional down-sampling methods. For this reason, we here proposed a downsampling method constrained by multiple thresholds of variance, deformation gradient and coherence for coseismic deformation fields, which was verified with three strong events associated with complex fault systems. The result suggests that this method can effectively eliminate low coherence points, preserve critical deformation details, and has lower sampling rate, better robustness and stronger constraints on the linear distribution of deformation.
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STUDY ON THE ATTENUATION RELATIONSHIP OF EARTHQUAKE INTENSITY IN LOESS PLATEAU REGIONWAN Wei1,2,3, BO Jingshan1,2,3, PENG Da1,LI Xiaobo1
wan wei, bo jing shan, peng da, li xiao bo
DOI: 10.20000/j.1000-0844.20230819003
Abstract:
This study systematically collected and organized seismic intensity isopleth maps and relevant damage investigation data for 44 seismic events in the Loess Plateau region.We employed a constrained model of seismic intensity ellipses and applied two-step regression with double weighting to establish seismic intensity attenuation relationships for both the western and eastern regions of the Loess Plateau. By imposing additional fitting constraints, we achieved the requirement of approximately equal intensity values for the major and minor axes at epicentral and far-field distances. Comparative analysis with seismic intensity attenuation relationships in other regions revealed distinct regional characteristics in the Loess Plateau area. In most cases, at equivalent distances, the intensity values in the western region of the Loess Plateau are higher than those in the Qinghai-Tibetan Plateau, with a maximum difference of 0.8 degrees. For short epicentral distances, both major and minor axis intensity values in the eastern region of the Loess Plateau are lower than those in the eastern strong earthquake zone. Due to the slower attenuation rate of intensity in the Loess Plateau"s eastern region, as the distance increases, the intensity values in the eastern region gradually surpass those in the eastern strong earthquake zone.
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Construction and Application of Vs30 Data in Sichuan Province - Taking the 8.0 magnitude Wenchuan Earthquake in Sichuan Province as an Example
ZHANG Can, GUO Hongmei, ZHAO Zhen, LU Changjiang, ZHANG Ying, HE Zonghang
DOI: 10.20000/j.1000-0844.20231201001
Abstract:
The average shear wave velocity at a depth of 30 meters (Vs30) is an important parameter for site classification used extensively in both domestic and international seismic design codes for buildings and structures, as well as for correcting local site effects. However, the applicability of the widely used Vs30 data provided by the USGS for the China region still requires further verification. In this study, the correlation between the terrain slope in Sichuan Province and the shallow average wave velocity, as well as the relationship between the Vs30 and shallow average shear wave velocity, were used to produce a Vs30 dataset for Sichuan Province. This dataset was then applied to the seismic intensity assessment of the magnitude 8.0 Wenchuan earthquake in Sichuan. The results show that the Vs30 results for Sichuan Province obtained from this study are closer to the actual situation compared to the widely used USGS Vs30 data. The rapid assessment of seismic intensity for the Wenchuan earthquake using the Vs30 data from this study yielded more accurate determinations of the heavily and severely damaged areas. The findings of this study can enhance the accuracy of seismic emergency outputs for Sichuan Province in the future, providing primary reference materials for post-earthquake emergency command decisions and emergency rescue efforts.
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Typical seismic damage characteristics of school buildings in Ms6.2 Jishishan earthquake and implications for evacuation
Pan Yi, Chen Zifeng, Guo Xin, Lin Xuchuan
DOI: 10.20000/j.1000-0844.20240811001
Abstract:
On December 18th ,2023, a Ms6.2 earthquake struck Jishishan County, Gansu Province. Field investigation was conducted immediately by part of authors to evaluate the damage of 15 frame structures and 24 masonry structures from 9 schools and 4 teaching points located in varying seismic intensity zones. The investigation showed that the 12 severely damaged buildings were single-story masonry structures with wood-and-steel composite trusses. Most of frames exhibited minor damage, except that a few frame structures suffered moderate damage. Additionally, despite the relative integrity of structural components in some school buildings, non-structural components and ancillary structures exhibited significant seismic damage, threatening the safety and smooth evacuation of students and teachers. The study identified seismic damage patterns within educational facilities, and summarized the potential safety hazards in evacuation routes, including "rooms," "corridors," "staircases," and "outdoor" spaces. Consequently, reinforced measures are recommended for the non-structural components, equipment, and ancillary structures in campus to achieve improved safety and faster evacuation of students and teachers.
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