Monitoring seismicity in real time provides significant benefits for timely earthquake warning and analyses.In this study,we propose an automatic workflow based on machine learning(ML)to monitor seismicity in the sout...Monitoring seismicity in real time provides significant benefits for timely earthquake warning and analyses.In this study,we propose an automatic workflow based on machine learning(ML)to monitor seismicity in the southern Sichuan Basin of China.This workflow includes coherent event detection,phase picking,and earthquake location using three-component data from a seismic network.By combining Phase Net,we develop an ML-based earthquake location model called Phase Loc,to conduct real-time monitoring of the local seismicity.The approach allows us to use synthetic samples covering the entire study area to train Phase Loc,addressing the problems of insufficient data samples,imbalanced data distribution,and unreliable labels when training with observed data.We apply the trained model to observed data recorded in the southern Sichuan Basin,China,between September 2018 and March 2019.The results show that the average differences in latitude,longitude,and depth are 5.7 km,6.1 km,and 2 km,respectively,compared to the reference catalog.Phase Loc combines all available phase information to make fast and reliable predictions,even if only a few phases are detected and picked.The proposed workflow may help real-time seismic monitoring in other regions as well.展开更多
During the period from October 2014 to March 2015, a total number of 82 seismic tremors and 66 ice-quakes were identified in both three-component short-period seismographs (HES) and broadband seismographs (STS-1) at S...During the period from October 2014 to March 2015, a total number of 82 seismic tremors and 66 ice-quakes were identified in both three-component short-period seismographs (HES) and broadband seismographs (STS-1) at Syowa Station (SYO), Antarctica. Statistics of the number of these tremors indicated that many tremors were likely to occur when large increases in temperature and/or wind speed during the period. This implied that the rapid increase in temperature enhanced a melting speed of cryosphere environment with generating seismic energy;the tremors were also excited by stormy conditions, associated with interactive resonance between sea-ices and oceanic swells. The characteristic tremors of harmonic overtones with strong amplitudes were explained by repetitive sources, suggesting inter-glacial asperities such as the collision of icebergs and fast sea-ice, calving of glaciers/ice-streams at the coastal environment of Antarctica. These high amplitude tremors occurred independently from other majority types of events, characterized by non-linear, small amplitude and weak signals at the stormy condition and rapid increase in temperature.展开更多
Much effort has been made in investigating the seismic response and failure mechanism of rectangular subway stations,however,the influence of earth retaining systems has generally been ignored in previous studies.This...Much effort has been made in investigating the seismic response and failure mechanism of rectangular subway stations,however,the influence of earth retaining systems has generally been ignored in previous studies.This paper presents a numerical study on the seismic performance of a rectangular subway station with/without earth retaining systems by taking fender piles as the example,and aims to illustrate how the existence of fender piles affects seismic responses on subway stations.The loading conditions of subway stations and their surrounding soils prior to earthquakes are discussed.Next,seismic responses of subway stations with or without fender piles were simulated.Afterward,earthquake-induced deformations of stations and surrounding soils,as well as the internal forces and damage modes of the structural components,were systematically studied.Consequently,the seismic performance of the stations was affected by the existence of fender piles.In addition,earthquake intensity is illustrated.The study showed that deformation modes of surrounding soils and damage modes of stations were different with regard to the existence of fender piles.Meanwhile,earthquake intensity influencing the seismic performance of stations with or without fender piles were found to be opposite.展开更多
Research to reliably predict the seismic response of nuclear power stations with a pile-raft foundation is needed to meet the high safety requirements of nuclear power stations.In this study,a scaled superstructure wi...Research to reliably predict the seismic response of nuclear power stations with a pile-raft foundation is needed to meet the high safety requirements of nuclear power stations.In this study,a scaled superstructure with a 4×3 pile-raft foundation,which is constructed in Shanxi kaolin clay,is modelled.Accordingly,the characteristics of seismic response for nuclear power stations with a pile-raft foundation are analyzed using dynamic centrifuge tests.In particular,multiple earthquake motions with different magnitudes and frequency properties are utilized to map the relationship between structural response and properties of earthquake motions.The results show that the seismic response of the soil,raft,and structure are significantly affected by the natural frequency and magnitude of the earthquake motion.The soil surface acceleration is lower than the raft acceleration.The results provide a reliable reference to better understand the seismic response of nuclear power stations.展开更多
This paper summarizes the basic situation of the Binchuan Transmitting Seismic Station and the geophysical observations of the area where it is located,with a focus on the constitution of the observation system of the...This paper summarizes the basic situation of the Binchuan Transmitting Seismic Station and the geophysical observations of the area where it is located,with a focus on the constitution of the observation system of the transmitting seismic station,the excitation characteristics and propagation distance of signals excited by the airgun source in the reservoir and well. The paper also summarizes and discusses on the results of the observations and problems encountered since the Transmitting Seismic Station was built.Finally,this paper proposes the main research to be carried out on the basis of the project aims.展开更多
When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should...When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should be alleviated.To enhance the seismic performance of the mid-plate,a new isolation design method has been mentioned while the elastic sliding bearings are set at the top of the mid-columns and between the side end of the mid-plate and the side wall at the same time.By establishing a nonlinear finite element analysis model for the static-dynamic coupling interaction system,the seismic response characteristics of the cast-in-place station structure without a sliding bearing have been analyzed and compared with those of the station structure with the sliding bearing fixed only at the top of the middle columns,and those of the station structure with sliding bearing be fixed between the mid-plate and the sidewall at the same time.The results show that the new isolation station structures suffer fewer earthquake damages at the mid-plate and mid-columns at the same time,which can improve the overall seismic performance of the subway station structure.展开更多
In this study,under the assumption that the two huge leveling deformation anomalies at Linfen seismic station were caused by the Luoyunshan fault( Tumen-Yuli section)movement, we computed the vertical deformation fiel...In this study,under the assumption that the two huge leveling deformation anomalies at Linfen seismic station were caused by the Luoyunshan fault( Tumen-Yuli section)movement, we computed the vertical deformation field distribution based on the rectangular fault dislocation model and measured the ground deformation field of the study area using D-InS AR technology. The results are as follows:( 1) Theoretically,the ground vertical deformation field caused by fault movement could be within the elliptical deformation area with the long axis parallel to the fault strike. The largest deformation region is located in the center of the area in the hanging wall of the fault,and the deformation gradually decreases to zero toward the periphery; the impact range induced by the two deformations is respectively as follows: The long axes are about 18 km and26km,the short axes are about 12 km and 17 km and the obvious deformation amplitude is about 1- 3mm and 4- 14 mm.( 2) The measured deformation field by D-InS AR shows that there is no continuous deformation area consistent with the fault strike,and only the presence of land subsidence possibly caused by groundwater excessive exploitation,with the deformation amplitude about 10- 12 mm and 1- 5mm.( 3) The measured deformation field is not consistent with the theoretical result on deformation area and amplitude,which indicates that the fault movement is not the main cause of Linfen huge leveling deformation,but may rather be because of local deformation of the soil layers in the hanging wall of the fault.( 4) By combining the fault dislocation model simulation with the D-InS AR technology measurement,we can determine effectively the nature of the anomalyof the huge cross-fault leveling deformation,thus provide scientific basis for verification of significant leveling anomalies.展开更多
It is necessary to pay particular attention to the uncertainties that exist in an engineering problem to reduce the risk of seismic damage of infrastructures against natural hazards.Moreover,certain structural perform...It is necessary to pay particular attention to the uncertainties that exist in an engineering problem to reduce the risk of seismic damage of infrastructures against natural hazards.Moreover,certain structural performance levels should be satisfied during strong earthquakes.However,these performance levels have been only well described for aboveground structures.This study investigates the main uncertainties involved in the performance-based seismic analysis of a multi-story subway station.More than 100 pulse-like and no pulse-like ground motions have been selected.In this regard,an effective framework is presented,based on a set of nonlinear static and dynamic analyses performed by OpenSees code.The probabilistic seismic demand models for computing the free-field shear strain of soil and racking ratio of structure are proposed.These models result in less variability compared with existing relations,and make it possible to evaluate a wider range of uncertainties through reliability analysis in Rtx software using the Monte Carlo sampling method.This work is performed for three different structural performance levels(denoted as PL1ePL3).It is demonstrated that the error terms related to the magnitude and location of earthquake excitations and also the corresponding attenuation relationships have been the most important parameters.Therefore,using a faultestructure model would be inevitable for the reliability analysis of subway stations.It is found that the higher performance level(i.e.PL3)has more sensitivity to random variables than the others.In this condition,the pulse-like ground motions have a major contribution to the vulnerability of subway stations.展开更多
In east Europe and north Asia the majority of nuclear power-stations (NPS) as well as large hydro-electric (HES) and thermal electric stations (TES) are located within the north Eurasian lithosphere plate, which is ch...In east Europe and north Asia the majority of nuclear power-stations (NPS) as well as large hydro-electric (HES) and thermal electric stations (TES) are located within the north Eurasian lithosphere plate, which is characterized by the low seismicity and weak modern tectonic activity besides the different exogenetic processes. Some operating and projected NPS are relatively near to zones of the moderate seismicity in the Kaliningrad Region of northwest Russia and in south Ukraine. HES and TES in Baltic, Byelorussia and Ukraine are in the same position. Zones of more intensive seismicity and existence of active faults include NPS, HEP and TEP in the Urals, the Kola Peninsula, south Siberia, Transbaikal and Far East regions of Russia. Some of these stations are situated within crust blocks in transit zones, which separate main lithosphere plates and are characterized by increased tectonic mobility. The electric power-stations are most danger in the transit zones between north Eurasian, Arabian and Indian lithosphere plates, where collision processes have yet not stopped. This concerns electric stations in central Asia and Caucasus including NPS in Armenia. Seven schemes of the seismic energy distribution are composed for different parts of east Europe and north Asia. The location of nuclear and main other electric power-stations on them makes it possible to form a correct estimate of negative consequences connected with the up-to-date inner-continental tectonic activity.展开更多
基金the financial support of the National Key R&D Program of China(2021YFC3000701)the China Seismic Experimental Site in Sichuan-Yunnan(CSES-SY)。
文摘Monitoring seismicity in real time provides significant benefits for timely earthquake warning and analyses.In this study,we propose an automatic workflow based on machine learning(ML)to monitor seismicity in the southern Sichuan Basin of China.This workflow includes coherent event detection,phase picking,and earthquake location using three-component data from a seismic network.By combining Phase Net,we develop an ML-based earthquake location model called Phase Loc,to conduct real-time monitoring of the local seismicity.The approach allows us to use synthetic samples covering the entire study area to train Phase Loc,addressing the problems of insufficient data samples,imbalanced data distribution,and unreliable labels when training with observed data.We apply the trained model to observed data recorded in the southern Sichuan Basin,China,between September 2018 and March 2019.The results show that the average differences in latitude,longitude,and depth are 5.7 km,6.1 km,and 2 km,respectively,compared to the reference catalog.Phase Loc combines all available phase information to make fast and reliable predictions,even if only a few phases are detected and picked.The proposed workflow may help real-time seismic monitoring in other regions as well.
文摘During the period from October 2014 to March 2015, a total number of 82 seismic tremors and 66 ice-quakes were identified in both three-component short-period seismographs (HES) and broadband seismographs (STS-1) at Syowa Station (SYO), Antarctica. Statistics of the number of these tremors indicated that many tremors were likely to occur when large increases in temperature and/or wind speed during the period. This implied that the rapid increase in temperature enhanced a melting speed of cryosphere environment with generating seismic energy;the tremors were also excited by stormy conditions, associated with interactive resonance between sea-ices and oceanic swells. The characteristic tremors of harmonic overtones with strong amplitudes were explained by repetitive sources, suggesting inter-glacial asperities such as the collision of icebergs and fast sea-ice, calving of glaciers/ice-streams at the coastal environment of Antarctica. These high amplitude tremors occurred independently from other majority types of events, characterized by non-linear, small amplitude and weak signals at the stormy condition and rapid increase in temperature.
基金National Natural Science Foundation of Beijing under Grant No.8212007the National Natural Science Foundation of China under Grant Nos.51808028,52025084 and 51778026+1 种基金the Pyramid Talent Training Project of Beijing University of Civil Engineering and Architecture under Grant No.JDYC20200311the Fundamental Research Funds for Beijing University of Civil Engineering and Architecture(X18147)。
文摘Much effort has been made in investigating the seismic response and failure mechanism of rectangular subway stations,however,the influence of earth retaining systems has generally been ignored in previous studies.This paper presents a numerical study on the seismic performance of a rectangular subway station with/without earth retaining systems by taking fender piles as the example,and aims to illustrate how the existence of fender piles affects seismic responses on subway stations.The loading conditions of subway stations and their surrounding soils prior to earthquakes are discussed.Next,seismic responses of subway stations with or without fender piles were simulated.Afterward,earthquake-induced deformations of stations and surrounding soils,as well as the internal forces and damage modes of the structural components,were systematically studied.Consequently,the seismic performance of the stations was affected by the existence of fender piles.In addition,earthquake intensity is illustrated.The study showed that deformation modes of surrounding soils and damage modes of stations were different with regard to the existence of fender piles.Meanwhile,earthquake intensity influencing the seismic performance of stations with or without fender piles were found to be opposite.
基金Supported by:Scientific Research Program of China General Nuclear Power Corporation(CGN)under Grant No.K-A2017.054Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant No.KYCX19_0093。
文摘Research to reliably predict the seismic response of nuclear power stations with a pile-raft foundation is needed to meet the high safety requirements of nuclear power stations.In this study,a scaled superstructure with a 4×3 pile-raft foundation,which is constructed in Shanxi kaolin clay,is modelled.Accordingly,the characteristics of seismic response for nuclear power stations with a pile-raft foundation are analyzed using dynamic centrifuge tests.In particular,multiple earthquake motions with different magnitudes and frequency properties are utilized to map the relationship between structural response and properties of earthquake motions.The results show that the seismic response of the soil,raft,and structure are significantly affected by the natural frequency and magnitude of the earthquake motion.The soil surface acceleration is lower than the raft acceleration.The results provide a reliable reference to better understand the seismic response of nuclear power stations.
基金jointly sponsored by the National Natural Foundation of China(41474048)the Special Fund of Academician Chen Yong Workstation Project of Yunnan Province(2014IC007)
文摘This paper summarizes the basic situation of the Binchuan Transmitting Seismic Station and the geophysical observations of the area where it is located,with a focus on the constitution of the observation system of the transmitting seismic station,the excitation characteristics and propagation distance of signals excited by the airgun source in the reservoir and well. The paper also summarizes and discusses on the results of the observations and problems encountered since the Transmitting Seismic Station was built.Finally,this paper proposes the main research to be carried out on the basis of the project aims.
基金financially supported by the National Natural Science Foundation of China(Nos.51778290,51978333)。
文摘When the sliding bearing is fixed only at the top of the middle column of the underground structure,the cracks at the side end of the middle plate should be aggravated while the seismic damage of the mid-column should be alleviated.To enhance the seismic performance of the mid-plate,a new isolation design method has been mentioned while the elastic sliding bearings are set at the top of the mid-columns and between the side end of the mid-plate and the side wall at the same time.By establishing a nonlinear finite element analysis model for the static-dynamic coupling interaction system,the seismic response characteristics of the cast-in-place station structure without a sliding bearing have been analyzed and compared with those of the station structure with the sliding bearing fixed only at the top of the middle columns,and those of the station structure with sliding bearing be fixed between the mid-plate and the sidewall at the same time.The results show that the new isolation station structures suffer fewer earthquake damages at the mid-plate and mid-columns at the same time,which can improve the overall seismic performance of the subway station structure.
基金supported by the Science and Technology Project of Shanxi Province(20140313023-1)the special earthquake research project of China Earthquake Administration(201208009)+1 种基金Natural Science Foundation of ShanxiChina(2011021024-1)
文摘In this study,under the assumption that the two huge leveling deformation anomalies at Linfen seismic station were caused by the Luoyunshan fault( Tumen-Yuli section)movement, we computed the vertical deformation field distribution based on the rectangular fault dislocation model and measured the ground deformation field of the study area using D-InS AR technology. The results are as follows:( 1) Theoretically,the ground vertical deformation field caused by fault movement could be within the elliptical deformation area with the long axis parallel to the fault strike. The largest deformation region is located in the center of the area in the hanging wall of the fault,and the deformation gradually decreases to zero toward the periphery; the impact range induced by the two deformations is respectively as follows: The long axes are about 18 km and26km,the short axes are about 12 km and 17 km and the obvious deformation amplitude is about 1- 3mm and 4- 14 mm.( 2) The measured deformation field by D-InS AR shows that there is no continuous deformation area consistent with the fault strike,and only the presence of land subsidence possibly caused by groundwater excessive exploitation,with the deformation amplitude about 10- 12 mm and 1- 5mm.( 3) The measured deformation field is not consistent with the theoretical result on deformation area and amplitude,which indicates that the fault movement is not the main cause of Linfen huge leveling deformation,but may rather be because of local deformation of the soil layers in the hanging wall of the fault.( 4) By combining the fault dislocation model simulation with the D-InS AR technology measurement,we can determine effectively the nature of the anomalyof the huge cross-fault leveling deformation,thus provide scientific basis for verification of significant leveling anomalies.
文摘It is necessary to pay particular attention to the uncertainties that exist in an engineering problem to reduce the risk of seismic damage of infrastructures against natural hazards.Moreover,certain structural performance levels should be satisfied during strong earthquakes.However,these performance levels have been only well described for aboveground structures.This study investigates the main uncertainties involved in the performance-based seismic analysis of a multi-story subway station.More than 100 pulse-like and no pulse-like ground motions have been selected.In this regard,an effective framework is presented,based on a set of nonlinear static and dynamic analyses performed by OpenSees code.The probabilistic seismic demand models for computing the free-field shear strain of soil and racking ratio of structure are proposed.These models result in less variability compared with existing relations,and make it possible to evaluate a wider range of uncertainties through reliability analysis in Rtx software using the Monte Carlo sampling method.This work is performed for three different structural performance levels(denoted as PL1ePL3).It is demonstrated that the error terms related to the magnitude and location of earthquake excitations and also the corresponding attenuation relationships have been the most important parameters.Therefore,using a faultestructure model would be inevitable for the reliability analysis of subway stations.It is found that the higher performance level(i.e.PL3)has more sensitivity to random variables than the others.In this condition,the pulse-like ground motions have a major contribution to the vulnerability of subway stations.
文摘In east Europe and north Asia the majority of nuclear power-stations (NPS) as well as large hydro-electric (HES) and thermal electric stations (TES) are located within the north Eurasian lithosphere plate, which is characterized by the low seismicity and weak modern tectonic activity besides the different exogenetic processes. Some operating and projected NPS are relatively near to zones of the moderate seismicity in the Kaliningrad Region of northwest Russia and in south Ukraine. HES and TES in Baltic, Byelorussia and Ukraine are in the same position. Zones of more intensive seismicity and existence of active faults include NPS, HEP and TEP in the Urals, the Kola Peninsula, south Siberia, Transbaikal and Far East regions of Russia. Some of these stations are situated within crust blocks in transit zones, which separate main lithosphere plates and are characterized by increased tectonic mobility. The electric power-stations are most danger in the transit zones between north Eurasian, Arabian and Indian lithosphere plates, where collision processes have yet not stopped. This concerns electric stations in central Asia and Caucasus including NPS in Armenia. Seven schemes of the seismic energy distribution are composed for different parts of east Europe and north Asia. The location of nuclear and main other electric power-stations on them makes it possible to form a correct estimate of negative consequences connected with the up-to-date inner-continental tectonic activity.