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 damage mechanism of slopes reinforced by anchor sheet-pile wall
QU Honglue, ZHU Mengjia, DONG Wangwang, LUO Hao
2024,46(5):1001-1008, DOI: 10.20000/j.1000G0844.20221019004
Abstract:
The anchor sheet-pile wall is known for its excellent anti-seismic properties. Previous research has focused on the slope displacement, anchor stress, and deformation of anti-slide piles, often neglecting the monitoring of seismic waves within the slope. This gap makes it difficult to clearly characterize the damage characteristics inside the slope in the time-frequency domain. To address this, a large-scale shaking table test with a geometric similarity ratio of 1∶10 was designed and conducted. Using the Hilbert-Huang Transform (HHT) method, this paper analyzes the seismic damage diagnosis and mechanism of slopes reinforced by an anchor pile-sheet wall. The results reveal that the slope failure starts from the sliding surface. As the peak ground acceleration increases, surface failure of the slope occurs earlier than internal failure and gradually develops to lower elevations. The anchor sheet-pile wall effectively transmits seismic forces through the anchor cable and dissipates these forces via the anti-slide pile. The slope failure near the side of the anchor cable anti-slide pile lags behind that farther from the anti-slide pile, and the soil integrity near the side of the anchor sheet-pile wall is obviously better. The characteristic frequency and amplitude of the marginal spectrum using the HHT method can clearly characterize the slope damage process. A dynamic response discontinuity exists between the bedrock and the slope, marking the design sliding surface's position. This study provides a theoretical basis for further understanding the propagation mechanism of seismic waves in the slope and studying the failure process of the slope.
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Experimental study on the strength of loess solidified by soybeanurease-induced calcium carbonate precipitation
DONG Xuguang, FANG Lixin, MA Yuanbo, HU Qianqian, LI Ruirui
2024,46(5):1009-1020, DOI: 10.20000/j.1000-0844.20231125002
Abstract:
Soybean urease-induced carbonate precipitation (SICP) is a technology for microbial mineralization of plant enzymes. The unconsolidated undrained triaxial test was conducted on the solidified loess at a cementation solution concentration of 0-4.5 mol/L to explore the prospect of its application in loess engineering. The strength and stress-strain relationship of loess before and after solidification were analyzed, and the microstructure changes and mineral composition of loess before and after solidification were also tested via SEM and XRD. The results show that the strength of loess first increases and then decreases with the rise in the cementation solution concentration, revealing the maximum value when the concentration of cementation solution is 2.5 mol/L. The strength of loess is substantially increased by the solidification of SICP, revealing a maximum value of 2 066.63 kPa, which is at least 1.31 times larger than that of unconsolidated soil. The SEM test results show that the calcium carbonate crystals generated by SICP can fill the pores of soil and cement some soil particles, thus improving the strength of the soil. The XRD test results reveal that the main mineral composition of loess remains unchanged before and after solidification, while the number and height of diffraction peaks of calcium carbonate crystals drastically increase after solidification. Overall, these results can provide new ideas for the application of SICP technology for loess solidification.
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Dynamic characteristics and seismic response of base-isolated structures with negative stiffness devices
HUANG Xiao, LIU Fangling, HU Zhixiang, WANG Donghua
2024,46(5):1021-1031, DOI: 10.20000/j.1000-0844.20230408002
Abstract:
Setting a negative stiffness device in the isolation layer can adjust the dynamic characteristics and seismic performance of base-isolated structures. The force-displacement relationship was linearly approximated by Taylor series expansion to address the nonlinearity problem caused by the preloaded spring in the isolation layer and the frequency response characteristics of base-isolated structures with a pure negative stiffness (PNS) element and a damping negative stiffness device (NSD) were compared and studied. Furthermore, the wavelet analysis was used to perform the time-frequency analysis on actual near-fault earthquakes, and the analytical mode decomposition method was used to decompose the ground motion into highand low-frequency components. The effects of PNS and NSD on the seismic response of base-isolated structures under highand low-frequency seismic waves were then compared. Compared with the base-isolated structure without NSD, results show that setting PNS can reduce the displacement and acceleration responses under high-frequency excitation but increase the displacement and acceleration responses under low-frequency excitation. Setting NSD not only markedly reduces the peak values of displacement and acceleration frequency response functions of base-isolated structures but also minimizes the displacement response of base-isolated structures in a wide frequency range.
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Dynamic characteristics of silt-solidified soil and its application in seismic analysis of vertical bank revetment
ZHAO Jie, XIANG Tianyi, WANG Hao
2024,46(5):1032-1042, DOI: 10.20000/j.1000-0844.20230202001
Abstract:
This paper investigates the dynamic characteristics of silt-solidified soil based on the land reclamation project at Dalian Linkong Industrial Park. The finite element software FLAC3D was used to simulate the dynamic response of vertical caisson revetment structures with different foundation treatment schemes under earthquake action. The seismic safety of these revetment structures was quantitatively evaluated by analyzing factors such as acceleration response, pore pressure, effective stress, and residual deformation. The test results for the dynamic characteristics show that the damping ratio of silt-solidified soil increases with shear strain and the content of the curing agent. Additionally, higher confining pressures result in lower damping ratios. Numerical analysis results show that under earthquake action, the acceleration amplification coefficient shows a different peak value under different foundation conditions. The sand layer below the caisson does not experience liquefaction. Further findings reveal that the residual deformation of a caisson placed on a silt-solidified soil foundation is significantly smaller compared to one on an undisturbed silt foundation. Moreover, high water levels contribute to reducing residual deformation and improving the caisson safety. These insights can provide valuable references for the seismic design of similar port projects.
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Damage identification and load transfer capacity evaluation for transverse connection of beam bridges based on modal tests
LIANG Jinping, QI Sheng, QI Xingjun, GUO Dongmei
2024,46(5):1043-1051, DOI: 10.20000/j.1000-0844.20230629001
Abstract:
The advantages and disadvantages of the transverse connection of beam bridges are related to the structural stability and bearing condition. To scientifically and accurately identify the damage location and evaluate the load transfer capacity of transverse connection members of beam bridges, a 16-m span simply-supported hollow slab beam bridge in the actual project was studied in this paper. A damage identification method of transverse connection based on the transverse change rate ratio of mid-span modal modes of the main beam and the modal deflection difference between adjacent main beams was proposed. Through a finite element simulation analysis, the validity of the damage identification indexes were verified, and the reduction factor ζ of transverse load transfer performance was defined to evaluate the load transfer capacity of transverse connection. The results show that the damage location of hinge joints can be determined using the position where the transverse change rate ratio of the first-order modal mode is increased. Based on the sudden change of the modal deflection difference between adjacent beams, the hinge joint damage location can also be accurately identified. ζ is the most significant index to judge the transverse connection of bridge. The load transfer capacity of transverse connection is decreased with the increase in the value of ζ. Therefore, the reduction factor ζ based on modal tests can be used as a reliable index to evaluate the transverse load transfer capacity of hinge joints. The research results can provide a useful reference for the detection and evaluation of the transverse connection safety of simply-supported beam bridges.
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Seismic performance evaluation of transmission towers based on capacity spectrum method
WANG Wenming, SHENG Hanke, LI Rongshuai
2024,46(5):1052-1062, DOI: 10.20000/j.1000-0844.20220812002
Abstract:
A seismic performance evaluation for the transmission tower-line system was conducted using the capability spectrum method. First of all, the transmission tower-line system was simplified into a concentrated mass model for Pushover analysis. This allowed for the creation of a relationship curve between vertex displacement and base shear force. Based on the site category and seismic fortification intensity of the transmission tower, the design response spectrum was transformed into a demand spectrum. The seismic performance of transmission towers was divided into five grades using control indexes. A corresponding quantitative evaluation model was constructed. Then, the capacity spectrum method was used to plot both the capacity spectrum curve and the 〖HJ2demand spectrum curve of the transmission tower. This helped determine the performance points and evaluate the seismic performance of the transmission power. Finally, the seismic performance of an actual transmission tower was evaluated using the capacity spectrum method and was verified against dynamic time-history analysis. The analysis results from the capacity spectrum method closely matched those from the time-history analysis, meeting the requirements of engineering accuracy. Using the square root of the sum of the squares (SRSS) load distribution, the relative error of horizontal displacement at the top point of the transmission tower obtained by the capacity spectrum method is within 5% fortification, and rare earthquakes, so it is recommended to carry out. Therefore, it is recommended to perform a Pushover analysis on the transmission tower by using the SRSS distribution mode.
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Shaking table test on the dynamic interaction of pile-soil-tunnel systems
XU Hongchun, ZHANG Ya'nan, ZHAO Dongxu, BAI Xiaoxiao
2024,46(5):1063-1073, DOI: 10.20000/j.1000-0844.20220921002
Abstract:
This paper aims to study the dynamic response characteristics of bridge pile-soil-tunnel systems under seismic action. Eight test conditions are designed based on actual projects, three different seismic wave types and intensities are then selected, and shaking table model tests with a geometric similarity ratio of 1/30 are conducted to analyze the system from the aspects of natural frequency and acceleration response. The results show that the presence of the bridge pile weakens the acceleration responses of surrounding soil and lateral tunnel, while the existence of the tunnel amplifies the acceleration responses of site soil and nearby bridge pile. Different types of seismic waves have various effects on the dynamic response of the pile-soil-tunnel system. The experimental results can provide theoretical guidance for the seismic design of similar projects.
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Impact of second tunnel blasting on the stability of a separated tunnel
JIA Jianqing, WANG Xin, XI Boqi, ZHANG Bangxin, LIU Zhongshuai
2024,46(5):1074-1083, DOI: 10.20000/j.1000-0844.20230209001
Abstract:
The separated highway tunnel was taken as an example to study the stability influenced by the blasting construction of the second tunnel on the first one. In the process of blasting construction of the second tunnel, the variation of displacement and vibration velocity of the initial support of the first and second tunnels were studied through theoretical calculation, numerical analysis, and in-site monitoring, and the influence range of blasting vibration was also determined. Results indicated that the blasting construction of the second tunnel has a considerable impact on the blasting side of the initial support of the first tunnel than on the back-blasting side, and the impact on the arch waist at the blasting side is the largest. The deformation of the initial support fluctuates within 10 m before and after the monitoring section. The blasting construction of the second tunnel has minimal impact on the stability of the initial support of the first tunnel when the control standard is 10 cm/s. During the blasting construction, the maximum vertical and horizontal displacements occur at the vault and arch waist of the second tunnel, respectively, and the vertical and horizontal displacements are convergent after the 10th excavation step. In this process, the blasting influence of the upper bench on the displacement of the initial support is greater than that of the lower bench. When the control standard is 10 mm/d, the influence range of blasting vibration on the initial support of the second tunnel is 20 m, which is consistent with the safe distance of 19.7 m determined by Saskatchewan theory. In addition, the variation rules of arch waist convergence and vault settlement of the second tunnel obtained from numerical simulation are consistent with the in-site monitoring results, but the former is slightly smaller than the latter, reducing by 1.2% and 2.3%, respectively.
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Experimental study on the evaluation method of damping effect of linings in tunnel crossing landslides in high-intensity seismic zone
MA Zhigang, WU Honggang, YI Zhongqiang
2024,46(5):1084-1096, DOI: 10.20000/j.1000-0844.20221207002
Abstract:
To evaluate the seismic reduction effect of damping structures in landslide tunnels located in high-intensity seismic areas, a shaking table model test was performed. This test measured the acceleration and dynamic strain of the model under seismic waves of varying intensities. By combining these measurements with the observed macroscopic deformation characteristics, a multi-index evaluation method was used to reveal the regional spatial dynamic response characteristics of the tunnel damping structure. Using the elastoplastic effect, the plastic damping coefficient of the tunnel structure was defined to clarify the damage evolution law. Key results from the study include: (1) Landslide failure exhibits continuous regional damage and failure, with noticeable differences in the sites of tunnel structure damage. (2) There are differences in the number and timing of acceleration, velocity, and displacement peaks at different positions within the tunnel structure. These local and overall dynamic responses are affected by seismic waves of different frequency bands. (3) The use of sponge rubber material as a damping layer for the tunnel lining shows damping properties but does not change the form of tunnel structural damage or spectral response characteristics. (4) Tunnel structure shows an obvious cumulative effect, which can be divided into three stages: elastic deformation, elastic-plastic deformation, and plastic deformation. Anti-seismic designs for actual tunnel projects should aim to prevent the tunnel structure from prematurely entering the plastic deformation stage. The research results provide a theoretical reference for understanding the deformation mechanisms and developing prevention and control measures for tunnels crossing landslides in high-intensity seismic zones.
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Finite element analysis of the seismic performance of transfer beam structures with hybrid reinforcement of steel-FRP bars
GONG Hongwei, LIU Yuanxue, CHEN Jin, YAO Weilai, WANG Yunxiao
2024,46(5):1097-1108, DOI: 10.20000/j.1000-0844.20221202001
Abstract:
This paper presents a study in which four specimens of transfer beam structures, each reinforced using different methods, were tested under pseudo-static loading. The analysis focused on the hysteretic curves, skeleton curves, and stiffness degradation curves of these specimens. A numerical analysis model for the transfer beam structure was established using the macro beam column fiber element based on the stiffness method in OpenSees, considering a suitable material constitutive model and the bond-slip of reinforced materials. The results from the numerical simulations were compared with experimental data to validate model accuracy. Results show that the specimens with hybrid reinforcement demonstrated good seismic performance. The numerical model accurately simulated the pinching effect observed in the hysteresis curves and provided high accuracy in the load values at characteristic states. Further analysis showed that increasing the concrete strength or the longitudinal reinforcement ratio of the column improved the seismic performance of specimen ZHL-4. Conversely, increasing the axial compressive ratio of the wall is harmful to the seismic performance of specimen ZHL-4.
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Numerical simulation of the seismic response of gabion support-slope systems and analysis of influencing factors
2024,46(5):1109-1117, DOI: 10.20000/j.1000-0844.20230213009
Abstract:
A numerical model simulating the seismic response of gabion support-slope systems was established based on the dynamic analysis module of the finite element numerical simulation software ABAQUS to study the seismic stability of gabion support-slope systems, and the model was verified with shaking table test results. The parameters that may affect the seismic stability of the gabion support-slope system were also analyzed. The results show that the displacement time-history curves of the gabion units under seismic action follow a similar pattern: the displacement abruptly reaches the peak at the peak acceleration and then gradually settles down. Afterward, the displacement gradually increases along the elevation, and the maximum displacement increase occurs at the bottom and top gabion units. The key to controlling the displacement of gabion units lies in the reduction of the relative misalignment between adjacent gabion units and the deformation of gabion units under seismic action. Increasing the elastic modulus of gabion units, raising the friction coefficient between gabion units, and decreasing the relative length of steps can notably enhance the stability of the gabion support-slope structure.
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Finite element analysis of seismic behavior of bottom-flange-bolted and top-flange-welded steel beam-column joints with reduced flange connection plate
2024,46(5):1118-1125, DOI: 10.20000/j.1000-0844.20231011001
Abstract:
This study investigates the impact of various parameters on the seismic performance of beam-column joints, contributing to the design reference for bottom-flange-bolted and top-flange-welded steel beam-column joints with reduced flange connection plates. Seven specimens were designed based on the changes in the reduced zone length of lower flange connection plates and different cross-sectional sizes of frame beams. The finite element software ABAQUS was used to analyze the seismic behavior of beam-column joints, including the failure mechanism, hysteretic loop, skeleton curve, maximum load capacity, and bolt-hole expansion rate. The results show that a short length of the reduced zone in the lower flange will fail to facilitate the outward shift of plastic hinges, while an excessive length would result in notable out-of-plane buckling. The seismic performance of beam-column joints with reduced full-section is superior to the other two types. In this paper, the bottom-flange-bolted and top-flange-welded steel beam-column joints with reduced flange connection plates can effectively improve the energy consumption capacity of the structure.
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Isolation effect of double-layer wave impeding block barrier on S-wave in unsaturated foundation
2024,46(5):1126-1141, DOI: 10.20000/j.1000-0844.20221031001
Abstract:
This paper presents an improvement to the traditional wave impeding block (WIB) barrier by introducing a double-layer WIB with the same overall thickness. The investigation focuses on the isolation effect of the double-layer WIB on S-waves in an unsaturated soil foundation, Using wave theory in unsaturated porous and elastic media. Based on Helmholtz's principle, the vertical displacement at the ground surface under S-wave incidence after the installation of the double-layer WIB in an unsaturated foundation was derived and obtained. The study initially analyzed the influence of the material parameters of the double-layer WIB on its vibration isolation performance. It was found that the optimal vibration isolation effect could be obtained by adjusting the density and shear modulus of the double-layer WIB. Subsequently, the vibration isolation effects of double-layer WIB were compared with those of a single-layer homogeneous WIB composed of the same material. The analysis included examining the influences of various physical and mechanical parameters, such as incident angle, frequency, saturation, thickness, and buried depth of the WIB on its vibration isolation performance. Results indicated that for WIBs of the same thickness, the double-layer WIB exhibited significantly higher vibration isolation efficiency, 49.18% and 42.59% higher than that of the corresponding single-layer WIB with the same material properties. The double-layer WIB demonstrated an effective vibration isolation effect across low, medium, and high frequencies in environmental vibrations. The double-layer WIB has a good vibration isolation effect on environmental vibration at low, medium, and high frequencies.
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Numerical simulation of the seismic performance of high-performance foam concrete energy dissipation wall-RC frame structures
YANG Shoumeng, SUN Baitao, CHEN Xiangzhao
2024,46(5):1142-1150, DOI: 10.20000/j.1000-0844.20230518003
Abstract:
To address the adverse interactions between infilled walls and frame columns, such as short-column damage under earthquakes, this paper proposes the use of high-performance foam concrete as an energy dissipation wall in the contact area between infill walls and frame columns. This approach aims to mitigate damage to the frame columns. Building on existing tests, the energy dissipation wall-RC frame system was simulated. The model parameters and material constitutive relationships were carefully selected, and the element types of each member were identified. A detailed finite element model of the high-performance foam concrete energy dissipation wall was then developed by defining the interactions between elements. The energy dissipation wall-RC frame was subjected to hysteretic loading in simulations to observe its earthquake response. Simulation results indicated that the energy dissipation effect of the wall is not significant at small story drift ratios. However, as the story drift ratio increases, the energy dissipation capacity becomes more pronounced. Specifically, at a story drift ratio of 1/109, the energy consumption capacity of the wall increases by approximately 30.20% compared to an ordinary infilled wall. At a story drift ratio of 1/48, the capacity increases by approximately 21.54%. Compared with ordinary infilled walls, the maximum contact pressure between the frame column and the energy dissipation infilled wall is reduced by approximately 2/3 under the same displacement. These findings suggest that the proposed composite wall could provide valuable insights for the seismic design in areas with high seismic intensity.
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Kinematic characteristics of loess seismic landslides: a case study of landslides triggered by the Haiyuan great earthquake
DUAN Junjie, LI Xiaobo, ZHOU Xinghao, LIU Yaokuo, OUYANG Ganglei
2024,46(5):1151-1159, DOI: 10.20000/j.1000-0844.20231109001
Abstract:
Based on 568 typical loess landslides induced by the 1920 Haiyuan MS81/2earthquake, the study explores the kinematic characteristics of loess seismic landslides from three aspects: directivity, long run-out slip characteristics, and flow-slide characteristics. The main conclusions are as follows: (1) The main sliding directions of landslides induced by the Haiyuan earthquake are concentrated in two intervals: 60°-90° and 270°-300°, which are consistent with the dominant slope direction ranges of 50°-90° and 255°-290°, respectively, demonstrating a distinct characteristic of being along the slope direction. (2) Landslides whose main sliding direction is parallel to or intersects with the strike of a seismogenic fault at a small angle (0°-30°) account for 41.9%, and the sliding direction is substantially affected by the fault dislocation direction. (3) Landslides are densely distributed on the facing slope, the number of which is 1.98 times that on the back slope, demonstrating typical facing slope characteristics. (4) A correlation exists between the maximum horizontal distance of a landslide and the slope height. Landslides are densely developed at a slope height of 30-120 m, and the equivalent friction coefficients of landslides are all less than 0.4, showing typical run-out slip characteristics. (5) Landslides with an equivalent friction coefficient of less than 0.17 account for 70.95% of the 568 landslides, revealing flow-slide characteristics. As an important supplement to the research results on the development characteristics of loess earthquake landslides, the conclusions have a certain reference value for further research on the disaster mechanism and risk assessment of loess earthquake landslides.
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Modal identification of super high-rise structures under far-field long-period ground motions
2024,46(5):1160-1171, DOI: 10.20000/j.1000-0844.20230714001
Abstract:
This paper examines the impact of long-period components of far-field ground motion, which can resonate with the natural period of high-rises and super high-rises, potentially leading to significant earthquake damage. The study focuses on the M6.5, M5.7, M6.9, and M5.4 earthquakes that occurred in Hualien County, Taiwan, China, from 21:41 on September 17, 2022, to 17:39 the following day. Using the Hilbert-Huang transform method, the paper preliminarily analyzes the structural dynamic response data of a super high-rise in Wuhan, located more than 1 000 kilometers away from the epicenter. By analyzing the long-period characteristics of the intrinsic mode function components across different time scales, the ground motion of each structural layer was reconstructed. The power spectrum method was used to determine the frequency response function of each structural layer relative to the ground layer. The first modal frequency and vibration mode were identified using the complex-mode Exp-function method. The analysis results indicated that the modal frequencies and vibration modes of the super high-rise structure remained intact under the long-period ground motions from the four earthquakes. This finding provides a crucial reference for post-earthquake safety evaluations of super high-rises in Wuhan when exposed to long-period ground motions.
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Effect of dry density on mechanical properties of remolded loess under directional shear stress path
LIU Hong, ZHANG Wuyu, FENG Yongzhen
2024,46(5):1172-1178, DOI: 10.20000/j.1000-0844.20210328008
Abstract:
To investigate how different dry densities affect the mechanical properties of remolded loess under directional shear stress, a series of tests were carried out using a GDS hollow cylinder torsional shear apparatus on Qinghai remolded loess. The focus was on understanding how changes in dry density affect the strength and deformation of remolded loess when the average principal stress, intermediate principal stress coefficient, and principal stress direction angle remain constant. The results show that the failure strength of remolded loess increases as dry density increases under the directional shear stress. Furthermore, the initial dry density significantly affects the development patterns of octahedral shear strain and principal strain. The normalized strength of remolded loess shows an approximately linear increase with higher dry densities. During the later stages of shear failure, the principal stress direction and strain of remolded loess become inconsistent, showing an obvious non-coaxial phenomenon. Notably, at a dry density of 1.72 g/cm3, the non-coaxial angle at shear failure exceeds 12°.
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Advances in induced seismicity from shale oil and gas development: case studies in Canada, the United States, and China
LIU Hanqing, HU Caibo, SHI Yaolin
2024,46(5):1179-1195, DOI: 10.20000/j.1000-0844.20240520002
Abstract:
The development of shale oil and gas has significantly driven global growth in reserves and production, fundamentally altering the energy landscape. As shale oil and gas development progresses, including hydraulic fracturing and wastewater disposal, the frequency of induced seismic events near shale oil and gas fields has increased notably. While most of these events are microseismic, destructive earthquakes occasionally occur in regions such as the Midwestern United States, Western Canada, and Southwestern China. The triggering mechanisms of destructive induced earthquakes are complex, involving static Coulomb failure stress changes, poroelasticity, pore-fluid pressure diffusion, and aseismic slip, and have been studied worldwide. This review summarizes the distribution and mechanisms of major destructive induced earthquakes related to shale oil and gas globally. It systematically discusses the basic conditions and triggering mechanisms of typical induced earthquakes in several regions, including the Horn River Basin in British Columbia, Canada; the Fox Creek area in Alberta, Canada; the Raton Basin in southern Colorado and northern New Mexico, United States; Oklahoma in the United States; Rongchang in Chongqing, China; and the Changning-Xinjiang area in Sichuan, China. Additionally, this review presents prospective prediction and control measures for induced earthquakes and concludes with a summary and outlook on the current status and progress of research related to induced earthquakes from shale oil and gas development.
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A review of debates and new findings on the Ningcheng earthquake of 1290 AD
HU Tingrong, HUANG Ruibin, SUN Jialin
2024,46(5):1196-1202, DOI: 10.20000/j.1000-0844.20230514001
Abstract:
The 1290 Ningcheng earthquake is a significant historical event that occurred in the eastern part of Inner Mongolia. Over the years, there has been little consensus on the extent of the damage and the specific earthquake parameters. In 1960, the China Earthquake Catalogue, edited by Li Shanbang, provided the first estimation of the earthquake’s basic parameters, identifying the epicenter as being west of Ningcheng, with a magnitude of 63/4 and an intensity of IX. Twenty years later, influenced by the Yuan History: Biography of Zhao Mengfu, which noted that “hundreds of thousands were injured or killed” by the earthquake, foreign experts speculated that the earthquake either “killed 100 000 people” or had a magnitude significantly above 7. After 1983, seismologists in Inner Mongolia conducted in-depth investigations and studies on the earthquake, including analyses of historical documents and archaeological examinations of ancient pagodas and quake-related relics. The findings, published in the China Earthquake Yearbook and Acta Seismologica Sinica, corroborated Li Shanbang's identification of the earthquake parameters. This paper reviews previous research findings and their discrepancies, offering a new historical verification of the 1290 Ningcheng earthquake and further clarifying the characteristics of its seismic impact.
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Strong motion records from the Luding M6.8 earthquake in Sichuan Province on September 5, 2022, and characteristics of typical strong motion stations
PAN Zhangrong, ZHOU Yang, ZHU Yongli, MIAO Zaipeng, WANG Feng, ZHANG Rong
2024,46(5):1203-1213, DOI: 10.20000/j.1000-0844.20230102003
Abstract:
A total of 205 strong motion records from the Luding M6.8 earthquake in Sichuan Province on September 5, 2022, were processed and analyzed. According to the calculated ground motion parameters, contour maps of peak acceleration and peak velocity were created, and the attenuation law of the M6.8 earthquake was examined. The analysis revealed that the ground motion parameters in the NS direction were larger than those in the EW direction, indicating a significant directional difference. The peak period, 90% important duration, and predominant period of the acceleration response spectrum at near-field stations were calculated. The 90% important duration ranged from 10 to 30 s, with an average duration of 20 s. The acceleration response spectrum and Fourier spectrum ratio for the typical stations 51LDJ and 51LDL were analyzed. The results indicate that, for different magnitudes and similar epicentral distances, the spectral shape is mainly influenced by the source. Specifically, as the magnitude increases, the response spectrum exhibits slower attenuation. The ratio of the vertical and horizontal acceleration response spectra for the two stations during the M6.8 main shock and its aftershocks was calculated. The predominant frequency shift at the 51LDL station was not significant, while the predominant frequency at the 51LDJ station exhibited a notable shift to lower frequencies (longer periods) during the strong earthquake, which may be attributed to the nonlinear response of the site.
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Variation of b-value before and after the Luding MS6.8 earthquake and its aftershocks in Sichuan Province on September 5, 2022
LI Mengya, ZENG Xianwei, YAO Huajian, LI Xinyan, ZHANG Zhi, YANG Shuo
2024,46(5):1214-1222, DOI: 10.20000/j.1000-0844.20230302001
Abstract:
This study presents a collection of seismic data recorded in the Luding area of Sichuan Province, China (29.28°-30.04°N, 101.82°-102.28°E), covering the period from January 1, 2012, to February 8, 2023. The spatial scanning of the b-value using the maximum likelihood method reveals the spatiotemporal variation characteristics of the b-value in the Luding source area and its surroundings. The results indicate that five months prior to the Luding MS6.8 earthquake in 2022, the b-value in both the source area and the southeastern region of Luding experienced a rapid decrease, suggesting that local rocks were approaching a critical state of stress deformation. Before the MS5.6 strong aftershock, the b-value in the epicentral region remained anomalously low, indicating that the stress level in the area was still high and suggesting the potential for further strong aftershocks. Following the MS5.6 aftershock, the anomalous area noticeably shrank but did not disappear entirely, implying the likelihood of continued aftershocks, though the possibility of another strong aftershock is low.
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Relocation of the 2022 MS6.1 and 2013 MS7.0 earthquake sequences in Lushan, Sichuan Province, and their tectonic relationship
ZHANG Shengxia, MA Xiaomei, YIN Xinxin, JU Huichao, WANG Zudong, WAN Wenqi
2024,46(5):1223-1233, DOI: 10.20000/j.1000-0844.20221124002
Abstract:
This paper studies two earthquakes that occurred in Lushan County, Sichuan Province: the MS7.0 earthquake on April 20, 2013, and the MS6.1 earthquake on June 1, 2022. First, the double-difference location method (HypoDD) was used to relocate the two main shocks and their aftershock sequences. This method provided precise hypocenters and spatial distributions, as well as the epicenter locations and focal depths of the two main shocks and the rupture ranges of the aftershock areas. By analyzing the temporal and spatial distribution of aftershocks and the focal depth profiles of the two earthquakes, we found that the main shocks and their aftershocks are distributed on different sides of the Dachuan-Shuangshi fault, which is not the seismogenic fault for either earthquake. The seismogenic fault for the MS .0 earthquake is the Longmenshan front slip zone located between the Dachuan-Shuangshi and Dayi-Mingshan faults. In contrast, the MS .1 earthquake occurs to the northwest of the Dachuan-Shuangshi fault, with its seismogenic fault dipping to the southeast. This fault is considered to strike nearly NS and is part of the Longmenshan piedmont structural system, along with the Dachuan-Shuangshi fault. Finally, the correlation analysis between the two earthquakes indicates that, although their spatial locations are close, the MS .1 earthquake is considered an independent seismic event. This is due to the differences in the seismogenic faults and the expansion directions of the two earthquakes, as well as the relatively independent clusters of their aftershocks.
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Design and implementation of an emergency decision support system for strong earthquakes affecting dams
2024,46(5):1234-1242, DOI: 10.20000/j.1000-0844.20230511002
Abstract:
To enhance the emergency response capability of reservoir dams during strong seismic events and reduce randomness and uncertainty in emergency decision-making, an emergency decision support system for dam earthquake response was designed and developed. The system underwent a thorough functional requirements analysis, which informed the design of its overall framework. In-depth studies were conducted on its key functions, structural system, database, and functional processes. The core structure of the system includes a database, model library, methods library, and knowledge base. The system was developed using a hybrid of browser/server (B/S) and client/server (C/S) architectures, facilitating comprehensive information management, seismic analysis and early warning, decision support, and emergency management. The information management subsystem integrates extensive data on dams and earthquakes, providing a solid foundation for decision-making. The seismic analysis subsystem monitors seismic signals in real time, offering early warnings for potential post-earthquake hazards to the dam. The decision support subsystem utilizes warning alerts and comprehensive information to provide a scientific basis for emergency decisions, while the emergency management subsystem devises and implements response plans based on these decisions. Moreover, with its user-friendly interface, the system significantly enhances practicality and user experience. This research contributes to a technical defense system that extends beyond structural safety measures for dam seismic safety, helping to reduce disaster risks from seismic events and protect the lives and properties of people downstream of reservoir dams.
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Practice on the popularization of science and technology projects through new media: a case study of the “research and application of vibration control technology for throwing blasting in Heidaigou coal mine” project
2024,46(5):1243-1250, DOI: 10.20000/j.1000-0844.20230825001
Abstract:
With the increasing application of seismic technology across various fields, the output of scientific research outcomes is growing significantly. However, transforming these achievements into products that are easily understood and accepted by the public has become a significant challenge for earthquake science communicators. This study addresses the theme of “popularization of science and technology projects” by selecting a specific technology service program in the seismological field, namely the “Research and Application of Vibration Control Technology for Throwing Blasting in Heidaigou Open Pit Coal Mine,” as a practical case study and developing a comprehensive publicity plan. While disseminating earthquake science achievements and expanding the sources of popular science content, this paper proposes strategies for the popularization of science and technology projects related to earthquake prevention and disaster reduction: (1) In the evaluation phase, researchers should continue science communication efforts by exploring nonconfidential basic research, cutting-edge technologies, and projects within the earthquake industry that are closely related to public welfare. (2) In the development phase, the entire project lifecycle, from initiation and implementation to completion, should be monitored, and science communication plans should be designed for the content of each stage. (3) In the promotion phase, appropriate presentation formats should be selected according to the project characteristics, promotion channels, and audience demographics.
Earthquake Engineering
Earthquake Research
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Strong ground motion characteristics of the M4.9 earthquake in Baiyin Pingchuan District, Gansu Province in 2023
DOI: 10.20000/j.1000-0844.20240120001
Abstract:
The China Earthquake Early Warning Network obtained 197 sets of three-component ground motion acceleration records during the 4.9 magnitude earthquake in Pingchuan District, Baiyin, Gansu, among which there were 165 sets within a 100km range. This is the first time a large number of near-fault strong-motion observation records have been obtained near the Haiyuan fault zone. We investigate the characteristics of strong ground motion in terms of response spectrum, attenuation relationship and spatial distribution of ground motion. The results indicate that: the horizontal acceleration response spectrum of the 6 stations built in the soil site is greater than the design spectrum value of 8 degrees frequent earthquakes at the excellent period,and the response spectrum of GS.D003E in the EW direction even exceeds the design spectrum value of 8 degrees earthquake protection at the excellent period. However, because its excellence period is lower than the natural vibration period of local urban and rural buildings, the damage degree of nearby buildings with seismic measures is small.The observed value of PGA, PGV, SA(0.2s) and SA(0.5s) are generally greater than the predicted ground motion values, while the observed value of SA(1.0s) and SA(2.0s) are consistent with the predicted values, which indicates that the ground motion of the high frequency component of the earthquake is excellent.The attenuation relationships of ground motion at soil and bedrock stations, and the results of soil/bedrock spectrum ratio show that the soil site has an obvious amplification effect on ground motion compared with the bedrock site.The amplitudes of PGA, SA(0.2s) and SA(0.5s) are both larger along the fault strike and on the southwest side of the epicenter. However, the larger amplitude of SA(1.0s), SA(2.0s) and SA(3.0s) is more obvious only on the southwest side perpendicular to the fault strike.This phenomenon may be related to the rupture characteristics of the source and the site of the observation station in the loess hilly area.
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New activity characteristics of the southern Wenshushan fault at the western end of the Hexi Corridor
Liu Xingwang, Yao Yunsheng, Zhu Junwen, Zhao Xiaoming
DOI: 10.20000/j.1000-0844.20240222003
Abstract:
The southern Wenshushan fault, which located on the southern side of the Jiayuguan–Wenshushan Uplift in the Hexi Corridor, was a newly discovered active fault. Studying its activity characteristics was of great significance for improving the regional tectonic image and understanding the seismic risk of the region. Based on the remote sensing image interpretation, field geological survey, aerial photogrammetry, and chronological testing, we conducted comprehensive research on the fault. The results showed that the southern Wenshushan fault extended NW for approximately 25 km, dipping NE. According to the dating of faulted and un faulted landforms, the latest seismic activity on the southern Wenshushan fault occurred between 0.8 ± 0.1 ka and 1887-1725 cal a BP. Using high-precision DEM data, the height of the fault scarps wwere obtained, and combined with the corresponding geological age, the vertical slip rate of the fault was estimated to be between 0.2-0.25 mm/a. Based on the empirical formula of between earthquake magnitude and rupture length, and displacement, the potential seismic magnitude of the southern Wenshushan fault was estimated to around 6.8. This magnitude may have a significant impact on nearby towns and Jiayuguan urban area.
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Earthquake disaster defense; Risk survey; Service platform; Gansu Province; Three levels of province, city and county
SUN Yanpin, CHEN Wenkai, LI Dagui, MA Yupeng
Abstract:
Gansu is one of the provinces in China with high seismic intensity. Although some achievements and progress have been made in the informatization of earthquake disaster defense in Gansu province in recent years, the technical systems for earthquake disaster defense at the municipal and county levels have still not been established, resulting in problems such as ineffective integration of resources across the province and a low level of data information services. Building on the foundation of the earthquake disaster risk survey work in Gansu Province, this paper aims to construct a comprehensive earthquake disaster defense service platform at the three levels of province, city, and county, integrating the display, query, and services of achievements in earthquake hazard, disaster-bearing bodies, and earthquake disaster risk assessment. The platform facilitates the unified aggregation and service of risk survey results at the provincial, municipal, and county levels. Through various forms such as web pages, maps, statistical charts, etc., the platform provides informatization services for earthquake disaster risk prevention and control throughout the province, maximally meeting the operational needs of earthquake departments at all levels and comprehensively enhancing the seismic damage prevention and control service capabilities across the entire province. Key words：Earthquake disaster defense; Risk survey; Service platform; Gansu Province; Three levels of province, city and county
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Analysis of influencing factors and characteristics of residential housing damage in typical earthquake-stricken areas of Sichuan Basin
PengQiaoqiao, MengXiangrui, DiBaofeng, ZengYajie, LUO Xiaolong, Hu Shunzhong
DOI: 10.20000/j.1000-0844.20230309001
Abstract:
A Ms. (surface wave magnitude)6 .0 earthquake occurred on September 16th, 2021, and affected 18 towns in Luxian County, Sichuan Province with different impacts. Through an on-site survey, we quantitatively analyzed the damage of the earthquake to residential houses in affected areas, assessed relationships among the house structures, epicentral distance, and degree of residential damage. This led to the development of a matrix of residential housing vulnerability to show the earthquake-affected areas in the Sichuan Basin with different intensities. Based on this analysis, the study compared the difference in average earthquake damage indexes between the affected areas and other regions that had previously experienced earthquakes of the same magnitude. In doing so, we were able to identify some of the key characteristics and factors that contributed to the degree of housing damage observed in the study areas. The following results were drawn: (1) housing vulnerability ranked from high to low involving brick-concrete structure, brick-wood and other structures (civil, wood and stone masonry structure), steel-concrete structure; (2) the areas within 6,600 meters from the epicenter experienced 90% of the earthquake damages; (3) earthquakes of similar magnitude cause 1~2 times less damage to residential housing within the Sichuan basin than areas in the mountainous regions. The results herein can be used as scientific references for the rapid assessment of damages, planning, and reconstruction of residential housing in the post-earthquake period in the Sichuan Basin and other settings prone to earthquakes .
