A 3D model of deep crustal structure of the Archaean Karelia Craton and late Palaeoproterozoic Svecofennian Accretionary Orogen including the boundary zone is presented.The model is based on the combination of data fr...A 3D model of deep crustal structure of the Archaean Karelia Craton and late Palaeoproterozoic Svecofennian Accretionary Orogen including the boundary zone is presented.The model is based on the combination of data from geological mapping and reflection seismic studies,along profiles 1-EU,4 B,FIRE-1-2 a-2 and FIRE-3-3 a,and uses results of magnetotelluric soundings in southern Finland and northern Karelia.A seismogeological model of the crust and crust-mantle boundary is compared with a model of subhorizontal velocity-density layering of the crust.The TTG-type crust of the Palaeoarchaean and Mesoarchaean microcontinents within the Karelia Craton and the Belomorian Province are separated by gently dipping greenstone belts,at least some of which are palaeosutures.The structure of the crust was determined mainly by Palaeoproterozoic tectonism in the intracontinental settings modified by a strong collisional compression at the end of the Palaeoproterozoic.New insights into structure,origin and evolution of the Svecofennian Orogen are provided.The accretionary complex is characterized by inclined tectonic layering:the tectonic sheets,~15 km thick,are composed of volcanic-sedimentary rocks,including electro-conductive graphite-bearing sedimentary rocks,and electro-resistive granitoids,which plunge monotonously and consecutively eastward.Upon reaching the level of the lower crust,the tectonic sheets of the accretionary complex lose their distinct outlines.In the seismic reflection pattern they are replaced by a uniform acoustically translucent medium,where separate sheets can only be traced fragmentarily.The crust-mantle boundary bears a diffuse character:the transition from crust to mantle is recorded by the disappearance of the vaguely drawn boundaries of the tectonic sheets and in the gradual transition of acoustically homogeneous and translucent lower crust into transparent mantle.Under the effect of endogenic heat flow,the accretionary complex underwent high-temperature metamorphism and partial melting.Blurring of the rock contacts,which in the initial state created contrasts of acoustic impedance,was caused by partial melting and mixing of melts.The 3 D model is used as a starting point for the evolutionary model of the Svecofennian Accretionary Orogen and for determination of its place in the history of the Palaeoproterozoic Lauro-Russian intracontinental orogeny,which encompassed a predominant part of the territory of Lauroscandia,a palaeocontinent combining North American and East European cratons.The model includes three stages in the evolution of the Lauro-Russian Orogen(-2.5,2.2-2.1 and 1.95-1.87 Ga).The main feature of the Palaeoproterozoic evolution of the accretionary Svecofennian Orogen and Lauroscandia as a whole lay in the causal link with evolution of a superplume,which initiated plate-tectonic events.The Svecofennian-Pre-Labradorian palaeo-ocean originated in the superplume axial zone;the accretionary orogens were formed along both continental margins due to closure of the palaeo-ocean.展开更多
Statistic analyses of sectional focal depth frequency relation for 1739 M S≥4.0 events in North China, 541 M S≥4.0 events in Xingtai seismic region and 999 M S≥4.0 events in Tangshan seismic region ...Statistic analyses of sectional focal depth frequency relation for 1739 M S≥4.0 events in North China, 541 M S≥4.0 events in Xingtai seismic region and 999 M S≥4.0 events in Tangshan seismic region have been carried out for the first step of the study. Then the sectional focal depth frequency diagrams (H N diagram) for each region were obtained. The study shows that: (1) The intraplate earthquakes in North China occur within the continental crust, and are mainly concentrated within a certain depth range of the middle and upper crust, making up a seismic source layer; (2) The seismic source layer consists of a main layer and an auxiliary layer adjacent to it. The tops and bottoms of the main and auxiliary layers correspond to the G and C, as well as to B and G geologic boundaries respectively; (3) The H N diagrams for Xingtai and Tangshan seismic regions are significantly different from each other, indicating the regionality and localization of the seismic source layers; (4) DSS and MTS observations show that the regionality and localization of the seismic source layer depend mainly on the environment of the deep structures of the region; (5) The seismic source layer is a substance of medium layer, which can be related to the brittle ductile transition zone within the crust. The seismic source layer is also a stress conducting layer. As the media above and below this layer are subjected to failure or flowage, then the stress will concentrate in the stress conducting layer, in which the earthquake occurs.展开更多
Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field ...Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field surveys,and loss evaluations.The paper focuses on the intensity distribution and structural damage characteristics of the 2025 M7.9 Myanmar earthquake,yielding the following key findings.(1)The seismogenic fault rupture propagated in a nearly N-S direction,with a surface rupture length of approximately 450 km.The seismic impact zone exhibited an elongated N-S distribution and a shorter E-W span,distributed like a belt around the seismogenic fault.(2)Within the seismic impact zones,existing buildings comprised five primary structural types,with timber(bamboo)structures constituting the largest proportion(≈80%in rural areas,≈50%in urban areas).The relatively low disaster losses and casualties were primarily attributable to the good seismic performance and low damage ratio of timber(bamboo)structures across varying intensity zones.(3)An anomalous zone of intensityⅨwas located at the boundary between intensityⅥandⅦregions in Nay Pyi Taw.Here,ridge topography combined with soft soil layers significantly amplified ground motion,exacerbating structural damage.(4)Directional effects of ground motion were observed,with the structural damage phenomena and peak ground acceleration(PGA)values in the N-S direction exceeding those in the E-W direction.This validates that the maximum PGA distribution of strike-slip fault earthquakes aligns with the fault strike.The research is expected to provide technical support for post-disaster reconstruction planning,site selection,and disaster mitigation strategies in Myanmar.展开更多
The Longmenshan(LMS)fault zone is located at the junction of the eastern Tibetan Plateau and the Sichuan Basin and is of great significance for studying regional tectonics and earthquake hazards.Although regional velo...The Longmenshan(LMS)fault zone is located at the junction of the eastern Tibetan Plateau and the Sichuan Basin and is of great significance for studying regional tectonics and earthquake hazards.Although regional velocity models are available for the LMS fault zone,high-resolution velocity models are lacking.Therefore,a dense array of 240 short-period seismometers was deployed around the central segment of the LMS fault zone for approximately 30 days to monitor earthquakes and characterize fine structures of the fault zone.Considering the large quantity of observed seismic data,the data processing workflow consisted of deep learning-based automatic earthquake detection,phase arrival picking,and association.Compared with the earthquake catalog released by the China Earthquake Administration,many more earthquakes were detected by the dense array.Double-difference seismic tomography was adopted to determine V_(p),V_(s),and V_(p)/V_(s)models as well as earthquake locations.The checkerboard test showed that the velocity models have spatial resolutions of approximately 5 km in the horizontal directions and 2 km at depth.To the west of the Yingxiu–Beichuan Fault(YBF),the Precambrian Pengguan complex,where most of earthquakes occurred,is characterized by high velocity and low V_(p)/V_(s)values.In comparison,to the east of the YBF,the Upper Paleozoic to Jurassic sediments,where few earthquakes occurred,show low velocity and high V_(p)/V_(s)values.Our results suggest that the earthquake activity in the LMS fault zone is controlled by the strength of the rock compositions.When the high-resolution velocity models were combined with the relocated earthquakes,we were also able to delineate the fault geometry for different faults in the LMS fault zone.展开更多
The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismi...The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.展开更多
Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simu...Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simultaneous observations of numerous stations for extensive coverage.To conduct a comprehensive karst feature investigation with limited stations,we designed a new synchronous-asyn-chronous observation system that facilitates dense array observations.We conducted two rounds of asynchronous observations,each lasting approximately 24 h,in combination with synchronous backbone stations.We achieved wide-ranging coverage of the study area utilizing 197 nodal receivers,with an average station spacing of 7 m.The beamforming results revealed distinct variations in the noise source distributions between day and night.We estimated the source strength in the stationary phase zone and used a weighting scheme for stacking the cross-correlation functions(C ^(1) functions)to suppress the influ-ence of nonuniform noise source distributions.The weights were derived from the similarity coefficients between multicomponent C^(1)functions related to Rayleigh waves.We employed the cross-correlation of C ^(1) functions(C^(2)methods)to obtain the empirical Green’s functions between asynchronous stations.To eliminate artifacts in C ^(2) functions from higher-mode surface waves in C^(1)functions,we filtered the C^(1)functions on the basis of different particle motions linked to multimode Rayleigh waves.The dispersion measurements of Rayleigh waves obtained from both the C^(1)and C^(2)functions were utilized in surface wave tomography.The inverted three-dimensional(3D)shear-wave(S-wave)velocity model reveals two significant low-velocity zones at depths ranging from 40 to 60 m,which align well with the karst caves found in the drilling data.The method of short-term synchronous-asynchronous ambient noise tomography shows promise as a cost-effective and efficient approach for urban geohazard investigations.展开更多
Earthquakes pose significant perils to the built environment in urban areas.To avert the calamitous aftermath of earthquakes,it is imperative to construct seismic resilient cities.Due to the intricacy of the concept o...Earthquakes pose significant perils to the built environment in urban areas.To avert the calamitous aftermath of earthquakes,it is imperative to construct seismic resilient cities.Due to the intricacy of the concept of urban seismic resilience(USR),its assessment is a large-scale system engineering issue.The assessment of USR should be based on the notion of urban seismic capacity(USC)assessment,which includes casualties,economic loss,and recovery time as criteria.Functionality loss is also included in the assessment of USR in addition to these criteria.The assessment indicator system comprising five dimensions(building and lifeline infrastructure,environment,society,economy,and institution)and 20 indicators has been devised to quantify USR.The analytical hierarchy process(AHP)is utilized to compute the weights of the criteria,dimensions,and indicators in the urban seismic resilience assessment(USRA)indicator system.When the necessary data for a city are obtainable,the seismic resilience of that city can be assessed using this framework.To illustrate the proposed methodology,a moderate-sized city in China was selected as a case study.The assessment results indicate a high level of USR,suggesting that the city possesses strong capabilities to withstand and recover from potential future earthquakes.展开更多
0 INTRODUCTION The forecast of abnormal geological structures(e.g.,fracture zones,faults,aquifers and karst)during tunnel drilling remains a demanding task:detecting faults and other geological features impacting the ...0 INTRODUCTION The forecast of abnormal geological structures(e.g.,fracture zones,faults,aquifers and karst)during tunnel drilling remains a demanding task:detecting faults and other geological features impacting the area ahead of the tunnel is crucial for safety and engineering considerations(Meng et al.,2024;Wu et al.,2024).展开更多
On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vert...On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vertical direction and 0.631 g in the horizontal direction.The earthquake caused collapse or severe damage of numerous buildings,resulting in thousands of fatalities and injuries,as well as substantial economic losses.The authors participated in the post-earthquake emergency response as members of the China Search and Rescue Team.During the rescue operations,an investigation into the characteristics of collapsed structures was conducted and the stability of building debris was assessed to ensure the safety of rescue efforts.Subsequently,a rapid seismic safety assessment of affected structures was carried out,including nine city residential blocks,two hospitals,and two apartments.Preliminary analyses indicate that the main causes of structural failure were insufficient cross-sectional dimensions of beams and columns,inadequate stirrup reinforcement,and lack of structural redundancy.展开更多
Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus ...Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.展开更多
Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude ...Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude M_(L)≥1.5 in the Changning shale gas field from January 2016 to May 2017 by fitting three-component waveforms.We then constrain the directions of the maximum horizontal stress(σ_(H_(max)))for four dense earthquake clusters using the stress tensor inversion method.The stress drops of 121 earthquakes with M_(L)≥1.5 are calculated using the spectral ratio method.We examine the spatiotemporal heterogeneity of stress field,and discuss the cause of non-double-couple(non-DC)components in seismicity clusters.Following the Mohr-Coulomb criterion,we estimate the fluid overpressure thresholds from FMS for different seismic clusters,providing insights into potential physical mechanisms for induced seismicity.The FMS results indicate that shallow reverse earthquakes,with steep dip angles,characterize most events.The source mechanisms of earthquakes with M_(L)≥1.5 are dominated by DC components(>70%),but several earthquakes with M_(L)>3.0 and the microseismic events nearby during injection period display significant non-DC components(>30%).Stress inversion results reveal that the σ_(H_(max)) direction ranges from 120°to 128°.Stress drops of earthquakes range between 0.10 and 64.49 MPa,with high values occurring on reverse faults situated at a greater distance from the shale layer,accompanied by a moderate rotation(≤25°)in the trend of σ_(H_(max)).The seismic clusters close to the shale layer exhibit low fluid overpressure thresholds,prone to being triggered by high pore-pressure fluid.The integrated results suggest that the diffusion of high pore pressures is likely to be the primary factor for observed earthquakes.The present results are expected to offer valuable insights into the origin of anomalous seismicity near the shale gas sites.展开更多
To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on...To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on postearthquake loss and recovery time is improved.A threelevel function tree model is established,which can consider the dynamic changes in weight coefficients of different category of components relative to their functional losses.Bayesian networks are utilized to quantify the impact of weather conditions,construction technology levels,and worker skill levels on component repair time.A method for determining the real-time functional recovery curve of buildings based on the component repair process is proposed.Taking a three-story teaching building as an example,the seismic resilience indices under basic earthquakes and rare earthquakes are calculated.The results show that the seismic resilience grade of the teaching building is comprehensively judged as GradeⅢ,and its resilience grade is more significantly affected by postearthquake loss.The proposed method can be used to predict the seismic resilience of buildings prior to earthquakes,identify weak components within buildings,and provide guidance for taking measures to enhance the seismic resilience of buildings.展开更多
Advanced geological prediction is a crucial means to ensure safety and efficiency in tunnel construction.However,diff erent advanced geological forecasting methods have their own limitations,resulting in poor detectio...Advanced geological prediction is a crucial means to ensure safety and efficiency in tunnel construction.However,diff erent advanced geological forecasting methods have their own limitations,resulting in poor detection accuracy.Using multiple methods to carry out a comprehensive evaluation can eff ectively improve the accuracy of advanced geological prediction results.In this study,geological information is combined with the detection results of geophysical methods,including transient electromagnetic,induced polarization,and tunnel seismic prediction,to establish a comprehensive analysis method of adverse geology.First,the possible main adverse geological problems are determined according to the geological information.Subsequently,various physical parameters of the rock mass in front of the tunnel face can then be derived on the basis of multisource geophysical data.Finally,based on the analysis results of geological information,the multisource data fusion algorithm is used to determine the type,location,and scale of adverse geology.The advanced geological prediction results that can provide eff ective guidance for tunnel construction can then be obtained.展开更多
Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hyd...Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hydraulic fracturing process in lab-scale coal samples with DFNs and the induced seismic activities by the discrete element method(DEM).The effects of DFNs on hydraulic fracturing,induced seismicity and elastic property changes have been concluded.Denser DFNs can comprehensively decrease the peak injection pressure and injection duration.The proportion of strong seismic events increases first and then decreases with increasing DFN density.In addition,the relative modulus of the rock mass is derived innovatively from breakdown pressure,breakdown fracture length and the related initiation time.Increasing DFN densities among large(35–60 degrees)and small(0–30 degrees)fracture dip angles show opposite evolution trends in relative modulus.The transitional point(dip angle)for the opposite trends is also proportionally affected by the friction angle of the rock mass.The modelling results have much practical meaning to infer the density and geometry of pre-existing fractures and the elastic property of rock mass in the field,simply based on the hydraulic fracturing and induced seismicity monitoring data.展开更多
On January 7,2025,01:05:15 UTC(9:05 a.m.local time)southern Tibet was rocked by a M_(W)7.1 earthquake(M_(W)=moment magnitude,USGS)centered(28.639°N 87.361°E)in the Lhasa Block north of the India/Eurasia Plat...On January 7,2025,01:05:15 UTC(9:05 a.m.local time)southern Tibet was rocked by a M_(W)7.1 earthquake(M_(W)=moment magnitude,USGS)centered(28.639°N 87.361°E)in the Lhasa Block north of the India/Eurasia Plate boundary,in a remote area about 180 km SW of Xigaze,in Dingri County of Shigatse of the Xizang Autonomous Region(Figure 1).展开更多
The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly impro...The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly improve our understanding of seismogenesis and our ability to evaluate seismic hazards.Utilising the SKUA GoCAD software,we constructed detailed seismic fault models for the 2021 M_(S)6.4 Yangbi earthquake in Yunnan,China,using two sets of relocated earthquake catalogs and focal mechanism solutions following a convenient 3D fault modeling workflow.Our analysis revealed a NW-striking main fault with a high-angle SW dip,accompanied by two branch faults.Interpretation of one dataset revealed a single NNW-striking branch fault SW of the main fault,whereas the other dataset indicated four steep NNE-striking segments with a left-echelon pattern.Additionally,a third ENE-striking short fault was identified NE of the main fault.In combination with the spatial distribution of pre-existing faults,our 3D fault models indicate that the Yangbi earthquake reactivated pre-existing NW-and NE-striking fault directions rather than the surface-exposed Weixi-Qiaohou-Weishan Fault zone.The occurrence of the Yangbi earthquake demonstrates that the reactivation of pre-existing faults away from active fault zones,through either cascade or conjugate rupture modes,can cause unexpected moderate-large earthquakes and severe disasters,necessitating attention in regions like southeast Xizang,which have complex fault systems.展开更多
Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)pl...Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)plume is crucial.This study focuses on four key parameters-permeability,porosity,formation pressure,and temperature-to characterize the reservoir and analyse the petrophysical and elastic response of CO_(2).First,we performed reservoir simulations to simulate CO_(2)saturation,using multiple sets of these four parameters to examine their significance on CO_(2)saturation and the plume migration speed.Subsequently,the effect of these parameters on the elastic properties is tested using rock physics theory.We established a relationship of compressional wave velocity(V_(p))and quality factor(Q_(p))with the four key parameters,and conducted a sensitivity analysis to test their sensitivity to V_(p) and Q_(p).Finally,we utilized visco-acoustic wave equation simulated time-lapse seismic data based on the computed V_(p) and Q_(p) models,and analysed the impact of CO_(2) saturation changes on seismic data.As for the above nu-merical simulations and analysis,we conducted sensitivity analysis using both homogeneous and heterogeneous models.Consistent results are found between homogeneous and heterogeneous models.The permeability is the most sensitive parameter to the CO_(2)saturation,while porosity emerges as the primary factor affecting both Q_(p) and V_(p).Both Q_(p) and V_(p) increase with the porosity,which contradicts the observations in gas reservoirs.The seismic simulations highlight significant variations in the seismic response to different parameters.We provided analysis for these observations,which serves as a valuable reference for comprehensive CO_(2)integrity analysis,time-lapse monitoring,injection planning and site selection.展开更多
A buckling-restrained steel plate shear wall(BRSPSW)structure with butterfly-shaped links on the lateral sides is introduced to improve the cooperative perfor-mance between the BRSPSW and the boundary frames.A one-spa...A buckling-restrained steel plate shear wall(BRSPSW)structure with butterfly-shaped links on the lateral sides is introduced to improve the cooperative perfor-mance between the BRSPSW and the boundary frames.A one-span two-story concrete-filled steel tube(CFT)column frame specimen equipped with lateral-side butterfly-shaped linked BRSPSWs(LBL-BRSPSWs)is evaluated under low-cycle reversed loading.A finite element(FE)model is developed and validated based on the test results.This FE model accurately simulates the failure modes and load-dis-placement curves.Parametric analyses are conducted on the butterfly-shaped links.The results show that the interactions between the CFT column frame and LBL-BRSPSWs are sig-nificantly influenced by the width ratio of the butterfly-shaped links,while the taper ratio and aspect ratio have relatively minor influences.Compared with traditional steel shear walls with four-sided connections,LBL-BRSPSWs reduce the additional axial forces and bending moments in the frame columns by 28%to 73%and 17%to 87%,respectively,with only a 9%to 30%decrease in the lateral resistance.The experimental and parametric analysis results indicate that setting butterfly-shaped links on the lateral sides of BRSPSWs can significantly enhance their cooperative performance with the boundary frame.The butterfly-shaped link width ratio has a linear relationship with the lateral-resistance performance of the specimens and the additional internal forces in the frame columns.To ensure that LBL-BRSPSW fails prior to the column frames,the link width ratio should be optimized.展开更多
Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is es...Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.展开更多
Topological insulators with localized edge or interface states have been extensively studied,particularly in phononic crystals and related fields;however,their application in seismic metamaterials remains largely unex...Topological insulators with localized edge or interface states have been extensively studied,particularly in phononic crystals and related fields;however,their application in seismic metamaterials remains largely unexplored.To address this gap,we designed a topological seismic metamaterial,where the topological interface is formed by joining the ends of two distinct one-dimensional periodic lattices.The first full-scale field experiment confirms the existence of topological interface states,which exhibit pronounced localization characteristics and induce a resonant amplification effect of 7.2 dB on the total energy of seismic surface waves.This study provides the first experimental validation for the implementation of topological principles in the design of seismic metamaterials,enabling novel approaches to high-sensitivity seismic detection and efficient energy localization for wave control.展开更多
基金the RF state project(No.0135-2019-0036)partly supported by the project(No.0135-20180039)of the Program of the Presidium of the RAS“Fundamental problems of geological and geophysical study of lithospheric processes”the Russian Foundation for Basic Research for supporting project(No.19-05-00336)。
文摘A 3D model of deep crustal structure of the Archaean Karelia Craton and late Palaeoproterozoic Svecofennian Accretionary Orogen including the boundary zone is presented.The model is based on the combination of data from geological mapping and reflection seismic studies,along profiles 1-EU,4 B,FIRE-1-2 a-2 and FIRE-3-3 a,and uses results of magnetotelluric soundings in southern Finland and northern Karelia.A seismogeological model of the crust and crust-mantle boundary is compared with a model of subhorizontal velocity-density layering of the crust.The TTG-type crust of the Palaeoarchaean and Mesoarchaean microcontinents within the Karelia Craton and the Belomorian Province are separated by gently dipping greenstone belts,at least some of which are palaeosutures.The structure of the crust was determined mainly by Palaeoproterozoic tectonism in the intracontinental settings modified by a strong collisional compression at the end of the Palaeoproterozoic.New insights into structure,origin and evolution of the Svecofennian Orogen are provided.The accretionary complex is characterized by inclined tectonic layering:the tectonic sheets,~15 km thick,are composed of volcanic-sedimentary rocks,including electro-conductive graphite-bearing sedimentary rocks,and electro-resistive granitoids,which plunge monotonously and consecutively eastward.Upon reaching the level of the lower crust,the tectonic sheets of the accretionary complex lose their distinct outlines.In the seismic reflection pattern they are replaced by a uniform acoustically translucent medium,where separate sheets can only be traced fragmentarily.The crust-mantle boundary bears a diffuse character:the transition from crust to mantle is recorded by the disappearance of the vaguely drawn boundaries of the tectonic sheets and in the gradual transition of acoustically homogeneous and translucent lower crust into transparent mantle.Under the effect of endogenic heat flow,the accretionary complex underwent high-temperature metamorphism and partial melting.Blurring of the rock contacts,which in the initial state created contrasts of acoustic impedance,was caused by partial melting and mixing of melts.The 3 D model is used as a starting point for the evolutionary model of the Svecofennian Accretionary Orogen and for determination of its place in the history of the Palaeoproterozoic Lauro-Russian intracontinental orogeny,which encompassed a predominant part of the territory of Lauroscandia,a palaeocontinent combining North American and East European cratons.The model includes three stages in the evolution of the Lauro-Russian Orogen(-2.5,2.2-2.1 and 1.95-1.87 Ga).The main feature of the Palaeoproterozoic evolution of the accretionary Svecofennian Orogen and Lauroscandia as a whole lay in the causal link with evolution of a superplume,which initiated plate-tectonic events.The Svecofennian-Pre-Labradorian palaeo-ocean originated in the superplume axial zone;the accretionary orogens were formed along both continental margins due to closure of the palaeo-ocean.
文摘Statistic analyses of sectional focal depth frequency relation for 1739 M S≥4.0 events in North China, 541 M S≥4.0 events in Xingtai seismic region and 999 M S≥4.0 events in Tangshan seismic region have been carried out for the first step of the study. Then the sectional focal depth frequency diagrams (H N diagram) for each region were obtained. The study shows that: (1) The intraplate earthquakes in North China occur within the continental crust, and are mainly concentrated within a certain depth range of the middle and upper crust, making up a seismic source layer; (2) The seismic source layer consists of a main layer and an auxiliary layer adjacent to it. The tops and bottoms of the main and auxiliary layers correspond to the G and C, as well as to B and G geologic boundaries respectively; (3) The H N diagrams for Xingtai and Tangshan seismic regions are significantly different from each other, indicating the regionality and localization of the seismic source layers; (4) DSS and MTS observations show that the regionality and localization of the seismic source layer depend mainly on the environment of the deep structures of the region; (5) The seismic source layer is a substance of medium layer, which can be related to the brittle ductile transition zone within the crust. The seismic source layer is also a stress conducting layer. As the media above and below this layer are subjected to failure or flowage, then the stress will concentrate in the stress conducting layer, in which the earthquake occurs.
基金National Natural Science Foundation of China under Grant No.U2239252National Natural Science Foundation of China under Grant No.52279128Natural Science Foundation of Heilongjiang Province of China under Grant No.YQ2022E013。
文摘Dispatched by the Chinese government,a multidisciplinary team of 30 researchers collaborated with a team from Myanmar to conduct a 14-day on-site investigation.The work encompassed seismic intensity assessments,field surveys,and loss evaluations.The paper focuses on the intensity distribution and structural damage characteristics of the 2025 M7.9 Myanmar earthquake,yielding the following key findings.(1)The seismogenic fault rupture propagated in a nearly N-S direction,with a surface rupture length of approximately 450 km.The seismic impact zone exhibited an elongated N-S distribution and a shorter E-W span,distributed like a belt around the seismogenic fault.(2)Within the seismic impact zones,existing buildings comprised five primary structural types,with timber(bamboo)structures constituting the largest proportion(≈80%in rural areas,≈50%in urban areas).The relatively low disaster losses and casualties were primarily attributable to the good seismic performance and low damage ratio of timber(bamboo)structures across varying intensity zones.(3)An anomalous zone of intensityⅨwas located at the boundary between intensityⅥandⅦregions in Nay Pyi Taw.Here,ridge topography combined with soft soil layers significantly amplified ground motion,exacerbating structural damage.(4)Directional effects of ground motion were observed,with the structural damage phenomena and peak ground acceleration(PGA)values in the N-S direction exceeding those in the E-W direction.This validates that the maximum PGA distribution of strike-slip fault earthquakes aligns with the fault strike.The research is expected to provide technical support for post-disaster reconstruction planning,site selection,and disaster mitigation strategies in Myanmar.
基金supported by the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology under Grant 2024yjrc64the National Key R&D Program of China under Grant 2018YFC1504102。
文摘The Longmenshan(LMS)fault zone is located at the junction of the eastern Tibetan Plateau and the Sichuan Basin and is of great significance for studying regional tectonics and earthquake hazards.Although regional velocity models are available for the LMS fault zone,high-resolution velocity models are lacking.Therefore,a dense array of 240 short-period seismometers was deployed around the central segment of the LMS fault zone for approximately 30 days to monitor earthquakes and characterize fine structures of the fault zone.Considering the large quantity of observed seismic data,the data processing workflow consisted of deep learning-based automatic earthquake detection,phase arrival picking,and association.Compared with the earthquake catalog released by the China Earthquake Administration,many more earthquakes were detected by the dense array.Double-difference seismic tomography was adopted to determine V_(p),V_(s),and V_(p)/V_(s)models as well as earthquake locations.The checkerboard test showed that the velocity models have spatial resolutions of approximately 5 km in the horizontal directions and 2 km at depth.To the west of the Yingxiu–Beichuan Fault(YBF),the Precambrian Pengguan complex,where most of earthquakes occurred,is characterized by high velocity and low V_(p)/V_(s)values.In comparison,to the east of the YBF,the Upper Paleozoic to Jurassic sediments,where few earthquakes occurred,show low velocity and high V_(p)/V_(s)values.Our results suggest that the earthquake activity in the LMS fault zone is controlled by the strength of the rock compositions.When the high-resolution velocity models were combined with the relocated earthquakes,we were also able to delineate the fault geometry for different faults in the LMS fault zone.
基金Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2023C01National Natural Science Foundation of China under Grant No.52478570Distinguished Young Scholars Program of the Natural Science Foundation of Heilongjiang Province,China under Grant No.JQ2024E002。
文摘The 2025 M_(w)7.7 Myanmar earthquake highlighted the challenge of near-fault seismic intensity field reconstruction due to sparse seismic networks.To address this limitation,a framework was proposed integrating seismic wave simulation with a data-constrained finite-fault rupture model.The constraint is implemented by identifying the optimal ground motion models(GMMs)through a scoring system that selects the best-fit GMMs to mid-and far-field China Earthquake Networks Center(CENC)seismic network data;and applying the optimal GMMs to refine the rupture model parameters for near-fault intensity field simulation.The simulated near-fault seismic intensity field reproduces seismic intensities collected from Myanmar’s sparse seismic network and concentrated in≥Ⅷintensity zones within 50 km of the projected fault plane;and identifies abnormal intensity regions exhibiting≥Ⅹintensity along the Meiktila-Naypyidaw corridor and near Shwebo that are attributed to soft soil amplification effects and near-fault directivity.This framework can also be applied to post-earthquake assessments in other similar regions.
基金supported by the National Natural Science Foundation of China(41830103)the Project of Nanjing Center of China Geological Survey(DD20190281).
文摘Dense-array ambient noise tomography is a powerful tool for achieving high-resolution subsurface imag-ing,significantly impacting geohazard prevention and control.Conventional dense-array studies,how-ever,require simultaneous observations of numerous stations for extensive coverage.To conduct a comprehensive karst feature investigation with limited stations,we designed a new synchronous-asyn-chronous observation system that facilitates dense array observations.We conducted two rounds of asynchronous observations,each lasting approximately 24 h,in combination with synchronous backbone stations.We achieved wide-ranging coverage of the study area utilizing 197 nodal receivers,with an average station spacing of 7 m.The beamforming results revealed distinct variations in the noise source distributions between day and night.We estimated the source strength in the stationary phase zone and used a weighting scheme for stacking the cross-correlation functions(C ^(1) functions)to suppress the influ-ence of nonuniform noise source distributions.The weights were derived from the similarity coefficients between multicomponent C^(1)functions related to Rayleigh waves.We employed the cross-correlation of C ^(1) functions(C^(2)methods)to obtain the empirical Green’s functions between asynchronous stations.To eliminate artifacts in C ^(2) functions from higher-mode surface waves in C^(1)functions,we filtered the C^(1)functions on the basis of different particle motions linked to multimode Rayleigh waves.The dispersion measurements of Rayleigh waves obtained from both the C^(1)and C^(2)functions were utilized in surface wave tomography.The inverted three-dimensional(3D)shear-wave(S-wave)velocity model reveals two significant low-velocity zones at depths ranging from 40 to 60 m,which align well with the karst caves found in the drilling data.The method of short-term synchronous-asynchronous ambient noise tomography shows promise as a cost-effective and efficient approach for urban geohazard investigations.
基金supported by the National Key R&D Program of China(No.2023YFC3805100)the National Natural Science Foundation of China(Nos.52222811 and 52494963)。
文摘Earthquakes pose significant perils to the built environment in urban areas.To avert the calamitous aftermath of earthquakes,it is imperative to construct seismic resilient cities.Due to the intricacy of the concept of urban seismic resilience(USR),its assessment is a large-scale system engineering issue.The assessment of USR should be based on the notion of urban seismic capacity(USC)assessment,which includes casualties,economic loss,and recovery time as criteria.Functionality loss is also included in the assessment of USR in addition to these criteria.The assessment indicator system comprising five dimensions(building and lifeline infrastructure,environment,society,economy,and institution)and 20 indicators has been devised to quantify USR.The analytical hierarchy process(AHP)is utilized to compute the weights of the criteria,dimensions,and indicators in the urban seismic resilience assessment(USRA)indicator system.When the necessary data for a city are obtainable,the seismic resilience of that city can be assessed using this framework.To illustrate the proposed methodology,a moderate-sized city in China was selected as a case study.The assessment results indicate a high level of USR,suggesting that the city possesses strong capabilities to withstand and recover from potential future earthquakes.
基金funded by the National Natural Science Foundation of China(Nos.41920104007 and 42227805)。
文摘0 INTRODUCTION The forecast of abnormal geological structures(e.g.,fracture zones,faults,aquifers and karst)during tunnel drilling remains a demanding task:detecting faults and other geological features impacting the area ahead of the tunnel is crucial for safety and engineering considerations(Meng et al.,2024;Wu et al.,2024).
基金National Natural Science Foundation of China for Distinguished Young Scholars under Grant No.52125806Scientific Research Fund of Institute of Engineering Mechanics,China Earthquake Administration under Grant No.2021B03。
文摘On March 28,2025,an M_(w) 7.7 earthquake struck near Mandalay,Myanmar,producing intense ground shaking.Strong motion recorded at a station close to the fault indicated a peak ground acceleration of 1.066 g in the vertical direction and 0.631 g in the horizontal direction.The earthquake caused collapse or severe damage of numerous buildings,resulting in thousands of fatalities and injuries,as well as substantial economic losses.The authors participated in the post-earthquake emergency response as members of the China Search and Rescue Team.During the rescue operations,an investigation into the characteristics of collapsed structures was conducted and the stability of building debris was assessed to ensure the safety of rescue efforts.Subsequently,a rapid seismic safety assessment of affected structures was carried out,including nine city residential blocks,two hospitals,and two apartments.Preliminary analyses indicate that the main causes of structural failure were insufficient cross-sectional dimensions of beams and columns,inadequate stirrup reinforcement,and lack of structural redundancy.
基金the National Natural Science Foundation of China(Nos.42076220,42206234,42476228)the Laoshan Laboratory Science and Technology Innovation Project(Nos.LSKJ202203404,LSKJ202203401)+2 种基金the Laoshan Laboratory‘14th FiveYear Plan’Major Project(No.2021QNLM020001-1)the Project of China Geological Survey(Nos.DD20230317,DD20230410,DD20190818,DD20191032,DD20160152)the Asia Cooperation Foundation‘China-Pakistan Oil and Gas Resource Potential Assessment and Capacity Training’。
文摘Recent advances in earth science and exploration have made deepwater channel-levee systems a research focus.We collected and analyzed over 10000 km of two-dimensional multichannel seismic data from the offshore Indus Basin to identify channellevee systems at various hierarchical levels depending on their seismic reflection characteristics.Seismic facies analysis was integrated with well data to map the spatial distribution of channel-levee systems in the offshore Indus Basin across various geological periods,and the factors influencing their development were discussed.These systems within the basin were identified using a developed,refined three-tier classification method.The first-order system consists of multiple spatially stacked complexes,the second-order system continuously developed multistage channel-levee bodies,and the third-order system represents the smallest identifiable sedimentary units on seismic profiles.Our findings demonstrate the evolution of the offshore Indus Basin from a single-stage channel with lateral migration to multistage vertical channel stacking from the Miocene to the Pleistocene.Tectonic activities exert their effect on channel-levee systems through their influence on the relative sea level.They also trigger volcanic or seismic events and affect siliciclastic supply.Warm and humid climate conditions form large river systems,which aid in the transport of terrestrial debris to the basin margin.Most channel-levee systems are assumed to have formed during low sea-level periods.This study offers new insights into the formation and evolution of turbidite sedimentary systems in the offshore Indus Basin and presents a practical classification method for comprehending gravity-flow sedimentary configurations and deepwater hydrocarbon exploration.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.U20A20266 and 12302503)Scientific and technological research projects in Sichuan province(Grant No.2024NSFSC0973).
文摘Source properties and stress fields are critical to understand fundamental mechanisms for fluid-induced earthquakes.In this study,we identify the focal mechanism solutions(FMSs)of 360 earthquakes with local magnitude M_(L)≥1.5 in the Changning shale gas field from January 2016 to May 2017 by fitting three-component waveforms.We then constrain the directions of the maximum horizontal stress(σ_(H_(max)))for four dense earthquake clusters using the stress tensor inversion method.The stress drops of 121 earthquakes with M_(L)≥1.5 are calculated using the spectral ratio method.We examine the spatiotemporal heterogeneity of stress field,and discuss the cause of non-double-couple(non-DC)components in seismicity clusters.Following the Mohr-Coulomb criterion,we estimate the fluid overpressure thresholds from FMS for different seismic clusters,providing insights into potential physical mechanisms for induced seismicity.The FMS results indicate that shallow reverse earthquakes,with steep dip angles,characterize most events.The source mechanisms of earthquakes with M_(L)≥1.5 are dominated by DC components(>70%),but several earthquakes with M_(L)>3.0 and the microseismic events nearby during injection period display significant non-DC components(>30%).Stress inversion results reveal that the σ_(H_(max)) direction ranges from 120°to 128°.Stress drops of earthquakes range between 0.10 and 64.49 MPa,with high values occurring on reverse faults situated at a greater distance from the shale layer,accompanied by a moderate rotation(≤25°)in the trend of σ_(H_(max)).The seismic clusters close to the shale layer exhibit low fluid overpressure thresholds,prone to being triggered by high pore-pressure fluid.The integrated results suggest that the diffusion of high pore pressures is likely to be the primary factor for observed earthquakes.The present results are expected to offer valuable insights into the origin of anomalous seismicity near the shale gas sites.
基金The National Key Research and Development Program of China(No.2023YFC3805003)。
文摘To quantify the seismic resilience of buildings,a method for evaluating functional loss from the component level to the overall building is proposed,and the dual-parameter seismic resilience assessment method based on postearthquake loss and recovery time is improved.A threelevel function tree model is established,which can consider the dynamic changes in weight coefficients of different category of components relative to their functional losses.Bayesian networks are utilized to quantify the impact of weather conditions,construction technology levels,and worker skill levels on component repair time.A method for determining the real-time functional recovery curve of buildings based on the component repair process is proposed.Taking a three-story teaching building as an example,the seismic resilience indices under basic earthquakes and rare earthquakes are calculated.The results show that the seismic resilience grade of the teaching building is comprehensively judged as GradeⅢ,and its resilience grade is more significantly affected by postearthquake loss.The proposed method can be used to predict the seismic resilience of buildings prior to earthquakes,identify weak components within buildings,and provide guidance for taking measures to enhance the seismic resilience of buildings.
基金National Natural Science Foundation of China(grant numbers 42293351,41877239,51422904 and 51379112).
文摘Advanced geological prediction is a crucial means to ensure safety and efficiency in tunnel construction.However,diff erent advanced geological forecasting methods have their own limitations,resulting in poor detection accuracy.Using multiple methods to carry out a comprehensive evaluation can eff ectively improve the accuracy of advanced geological prediction results.In this study,geological information is combined with the detection results of geophysical methods,including transient electromagnetic,induced polarization,and tunnel seismic prediction,to establish a comprehensive analysis method of adverse geology.First,the possible main adverse geological problems are determined according to the geological information.Subsequently,various physical parameters of the rock mass in front of the tunnel face can then be derived on the basis of multisource geophysical data.Finally,based on the analysis results of geological information,the multisource data fusion algorithm is used to determine the type,location,and scale of adverse geology.The advanced geological prediction results that can provide eff ective guidance for tunnel construction can then be obtained.
基金Australian Research Council Linkage Program(LP200301404)for sponsoring this researchthe financial support provided by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology,SKLGP2021K002)National Natural Science Foundation of China(52374101,32111530138).
文摘Discrete fracture network(DFN)commonly existing in natural rock masses plays an important role in geological complexity which can influence rock fracturing behaviour during fluid injection.This paper simulated the hydraulic fracturing process in lab-scale coal samples with DFNs and the induced seismic activities by the discrete element method(DEM).The effects of DFNs on hydraulic fracturing,induced seismicity and elastic property changes have been concluded.Denser DFNs can comprehensively decrease the peak injection pressure and injection duration.The proportion of strong seismic events increases first and then decreases with increasing DFN density.In addition,the relative modulus of the rock mass is derived innovatively from breakdown pressure,breakdown fracture length and the related initiation time.Increasing DFN densities among large(35–60 degrees)and small(0–30 degrees)fracture dip angles show opposite evolution trends in relative modulus.The transitional point(dip angle)for the opposite trends is also proportionally affected by the friction angle of the rock mass.The modelling results have much practical meaning to infer the density and geometry of pre-existing fractures and the elastic property of rock mass in the field,simply based on the hydraulic fracturing and induced seismicity monitoring data.
文摘On January 7,2025,01:05:15 UTC(9:05 a.m.local time)southern Tibet was rocked by a M_(W)7.1 earthquake(M_(W)=moment magnitude,USGS)centered(28.639°N 87.361°E)in the Lhasa Block north of the India/Eurasia Plate boundary,in a remote area about 180 km SW of Xigaze,in Dingri County of Shigatse of the Xizang Autonomous Region(Figure 1).
基金financial support from the National Key R&D Program of China (No. 2021YFC3000600)National Natural Science Foundation of China (No. 41872206)National Nonprofit Fundamental Research Grant of China, Institute of Geology, China, Earthquake Administration (No. IGCEA2010)
文摘The three-dimensional(3D)geometry of a fault is a critical control on earthquake nucleation,dynamic rupture,stress triggering,and related seismic hazards.Therefore,a 3D model of an active fault can significantly improve our understanding of seismogenesis and our ability to evaluate seismic hazards.Utilising the SKUA GoCAD software,we constructed detailed seismic fault models for the 2021 M_(S)6.4 Yangbi earthquake in Yunnan,China,using two sets of relocated earthquake catalogs and focal mechanism solutions following a convenient 3D fault modeling workflow.Our analysis revealed a NW-striking main fault with a high-angle SW dip,accompanied by two branch faults.Interpretation of one dataset revealed a single NNW-striking branch fault SW of the main fault,whereas the other dataset indicated four steep NNE-striking segments with a left-echelon pattern.Additionally,a third ENE-striking short fault was identified NE of the main fault.In combination with the spatial distribution of pre-existing faults,our 3D fault models indicate that the Yangbi earthquake reactivated pre-existing NW-and NE-striking fault directions rather than the surface-exposed Weixi-Qiaohou-Weishan Fault zone.The occurrence of the Yangbi earthquake demonstrates that the reactivation of pre-existing faults away from active fault zones,through either cascade or conjugate rupture modes,can cause unexpected moderate-large earthquakes and severe disasters,necessitating attention in regions like southeast Xizang,which have complex fault systems.
基金supported by the State Key Laboratory of Offshore Oil and Gas Exploitation, Open Fund Project (No. CCL2023RCPS0162RQN)the primary funding, National Natural Science Foundation of China (No. ZX20230400)
文摘Saline aquifers are considered as highly favored reservoirs for CO_(2)sequestration due to their favorable properties.Understanding the impact of saline aquifer properties on the migration and distribution of CO_(2)plume is crucial.This study focuses on four key parameters-permeability,porosity,formation pressure,and temperature-to characterize the reservoir and analyse the petrophysical and elastic response of CO_(2).First,we performed reservoir simulations to simulate CO_(2)saturation,using multiple sets of these four parameters to examine their significance on CO_(2)saturation and the plume migration speed.Subsequently,the effect of these parameters on the elastic properties is tested using rock physics theory.We established a relationship of compressional wave velocity(V_(p))and quality factor(Q_(p))with the four key parameters,and conducted a sensitivity analysis to test their sensitivity to V_(p) and Q_(p).Finally,we utilized visco-acoustic wave equation simulated time-lapse seismic data based on the computed V_(p) and Q_(p) models,and analysed the impact of CO_(2) saturation changes on seismic data.As for the above nu-merical simulations and analysis,we conducted sensitivity analysis using both homogeneous and heterogeneous models.Consistent results are found between homogeneous and heterogeneous models.The permeability is the most sensitive parameter to the CO_(2)saturation,while porosity emerges as the primary factor affecting both Q_(p) and V_(p).Both Q_(p) and V_(p) increase with the porosity,which contradicts the observations in gas reservoirs.The seismic simulations highlight significant variations in the seismic response to different parameters.We provided analysis for these observations,which serves as a valuable reference for comprehensive CO_(2)integrity analysis,time-lapse monitoring,injection planning and site selection.
基金The National Key Research and Development Program of China(No.2023YFC3805005)Shanghai Municipal Science and Technology Commission Research Program(No.22DZ1201404).
文摘A buckling-restrained steel plate shear wall(BRSPSW)structure with butterfly-shaped links on the lateral sides is introduced to improve the cooperative perfor-mance between the BRSPSW and the boundary frames.A one-span two-story concrete-filled steel tube(CFT)column frame specimen equipped with lateral-side butterfly-shaped linked BRSPSWs(LBL-BRSPSWs)is evaluated under low-cycle reversed loading.A finite element(FE)model is developed and validated based on the test results.This FE model accurately simulates the failure modes and load-dis-placement curves.Parametric analyses are conducted on the butterfly-shaped links.The results show that the interactions between the CFT column frame and LBL-BRSPSWs are sig-nificantly influenced by the width ratio of the butterfly-shaped links,while the taper ratio and aspect ratio have relatively minor influences.Compared with traditional steel shear walls with four-sided connections,LBL-BRSPSWs reduce the additional axial forces and bending moments in the frame columns by 28%to 73%and 17%to 87%,respectively,with only a 9%to 30%decrease in the lateral resistance.The experimental and parametric analysis results indicate that setting butterfly-shaped links on the lateral sides of BRSPSWs can significantly enhance their cooperative performance with the boundary frame.The butterfly-shaped link width ratio has a linear relationship with the lateral-resistance performance of the specimens and the additional internal forces in the frame columns.To ensure that LBL-BRSPSW fails prior to the column frames,the link width ratio should be optimized.
基金The insights gained through these works,particularly from projects IITD/IRD/CW14168,CW14469,and CW14378,have significantly contributed to the development of the analysis presented in this study。
文摘Earthquake-induced soil liquefaction poses significant risks to the stability of geotechnical structures worldwide.An understanding of the liquefaction triggering,and the post-failure large deformation behaviour is essential for designing resilient infrastructure.The present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of geotechnical structures.The coupled flowdeformation behaviour of soils subjected to cyclic loading is described using the PM4Sand model implemented in a three-phase,single-layer SPH framework.A staggered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energy modes and tensile instability.Further,non-reflecting boundary conditions for seismic analysis of semi-infinite soil domains using the SPH method are proposed.The numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level ground site,and liquefaction-induced failure of the Lower San Fernando Dam.Satisfactory agreement for liquefaction triggering and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading on field-scale geotechnical structures.The present study also serves as the basis for future advancements of the SPH method for applications related to earthquake geotechnical engineering.
基金supported by the National Natural Science Foundation of China(Grant No.11974044)。
文摘Topological insulators with localized edge or interface states have been extensively studied,particularly in phononic crystals and related fields;however,their application in seismic metamaterials remains largely unexplored.To address this gap,we designed a topological seismic metamaterial,where the topological interface is formed by joining the ends of two distinct one-dimensional periodic lattices.The first full-scale field experiment confirms the existence of topological interface states,which exhibit pronounced localization characteristics and induce a resonant amplification effect of 7.2 dB on the total energy of seismic surface waves.This study provides the first experimental validation for the implementation of topological principles in the design of seismic metamaterials,enabling novel approaches to high-sensitivity seismic detection and efficient energy localization for wave control.
