The Three Gorges Reservoir area hosts numerous high-risk columnar rock masses,but predicting their full-process of collapse dynamics in narrow-deep terrains remains challenging.This study investigated the Changdongzi ...The Three Gorges Reservoir area hosts numerous high-risk columnar rock masses,but predicting their full-process of collapse dynamics in narrow-deep terrains remains challenging.This study investigated the Changdongzi columnar dangerous rock mass(CCDRM)through field surveys and simulated its collapse dynamics with Material Point Method(MPM),and analyzed the collapse-diffusionsurge generation mechanisms.Field investigations revealed a 0.8 m-thick lotus-like extrusion structure at the base,severely degraded by cyclic water fluctuations,predisposing the rock mass to base-crushing failure.Numerical simulations indicate collapse velocities up to 42 m/s,amplified spreading with a 318 m deposition range and 11 m maximum thickness,and two major collisions causing 50%-60%velocity reduction.Gully topography buffers kinetic energy,retaining 5%debris on slopes and channeling 7%into the river.High-speed river impact generates a 20 m-diameter cavity,producing an 11 m surge,identifying the Guandukou Town waterfront 1.2 km downstream as a high-risk zone.These results clarify the collapse mechanisms of columnar dangerous rock mass and inform its hazard mitigation strategies.展开更多
Dangerous rock masses in cold regions subjected to repeated freeze–thaw cycles can cause progressive deterioration in structural planes and rock mechanical properties,which significantly reduces the overall stability...Dangerous rock masses in cold regions subjected to repeated freeze–thaw cycles can cause progressive deterioration in structural planes and rock mechanical properties,which significantly reduces the overall stability and often triggers collapses or landslides.Existing studies focus mostly on singlescale or single-factor analyses but cannot fully capture the coupled mechanisms driving instability under freeze-thaw conditions.This study aimed to establish a theoretical framework to quantitatively characterize the evolution of rock mass stability,thereby providing a sound basis for hazard prediction and prevention.By integrating limit equilibrium theory with rock frost heave and circular hole expansion theory,mechanical models for sliding-and toppling-type dangerous rock masses were established.Three key factors were incorporated:frost heave forces acting on throughgoing structural planes,rock property deterioration in nonpenetrative sections,and progressive freezing depth development.A theoretical relationship between the stability coefficient and the number of freeze-thaw cycles was derived.By considering the Zimei Peaks rock masses in Gansu Province as the case study and conducting parametric analyses,the results revealed that the stability coefficient rapidly decreases during the initial cycles,followed by a slower decrease and eventual stabilization.The coefficient decreased 4.5 times more during the first 15 cycles than during the subsequent 15 cycles.Moreover,stability degradation was strongly influenced by the freezing temperature,initial porosity,and rock debris loss ratio,with critical thresholds determined at a 3.8%porosity and a 0.83 debris loss ratio.The findings indicated that stability deterioration is governed by the coupled effects of frost heave loading,microstructural damage accumulation,and freezing depth development,with clear stagedependent and threshold-driven patterns.This work provides not only a quantitative explanation of instability mechanisms in cold-region rock masses but also practical guidance for engineering stability assessment and disaster mitigation.展开更多
Source identification and deformation analysis of disaster bodies are the main contents of high-steep slope risk assessment,the establishment of high-precision model and the quantification of the fine geometric featur...Source identification and deformation analysis of disaster bodies are the main contents of high-steep slope risk assessment,the establishment of high-precision model and the quantification of the fine geometric features of the slope are the prerequisites for the above work.In this study,based on the UAV remote sensing technology in acquiring refined model and quantitative parameters,a semi-automatic dangerous rock identification method based on multi-source data is proposed.In terms of the periodicity UAV-based deformation monitoring,the monitoring accuracy is defined according to the relative accuracy of multi-temporal point cloud.Taking a high-steep slope as research object,the UAV equipped with special sensors was used to obtain multi-source and multitemporal data,including high-precision DOM and multi-temporal 3D point clouds.The geometric features of the outcrop were extracted and superimposed with DOM images to carry out semi-automatic identification of dangerous rock mass,realizes the closed-loop of identification and accuracy verification;changing detection of multi-temporal 3D point clouds was conducted to capture deformation of slope with centimeter accuracy.The results show that the multi-source data-based semiautomatic dangerous rock identification method can complement each other to improve the efficiency and accuracy of identification,and the UAV-based multi-temporal monitoring can reveal the near real-time deformation state of slopes.展开更多
In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefo...In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.展开更多
The identification and characterization of concealed in-situ rock blocks on high-steep slope exposures are critical in rock engineering,but remain challenging.This study employs advanced UAV-based photogrammetry to ca...The identification and characterization of concealed in-situ rock blocks on high-steep slope exposures are critical in rock engineering,but remain challenging.This study employs advanced UAV-based photogrammetry to capture high-resolution discontinuity data and develops a fully automated rock block extraction method consisting of three steps:(1)determination of free face and non-free fracture intersections,(2)surface search for rock blocks on free face.and(3)extraction and analysis of rock blocks.This approach simplifies the determination of discontinuity intersections while maintaining high accuracy.By incorporating all types of discontinuities contributing to rock block formation,the method enables precise in-situ rock block identification and extraction.Application to a rock slope in China,produced results consistent with the rock blocks observed in the 3D model,highlighting its accuracy and practical value.展开更多
There are a large number of glaciers and lakes developed in the Nyang Qu Basin of China. Recent climate change has significant impacted on the high-mountain glacial environment. Rapid melting of glaciers contributes t...There are a large number of glaciers and lakes developed in the Nyang Qu Basin of China. Recent climate change has significant impacted on the high-mountain glacial environment. Rapid melting of glaciers contributes to the formation and expansion of moraine-dammed lakes which increase the probability of glacial lake outburst floods(GLOFs). We calculated a multi-temporal lake inventory based on(1) topographic maps in the 1970 s,(2) satellite imageries from 1990 to 2016,(3) First Chinese Glacier Inventory(FCGI),(4) Glacier Inventory of Southeastern Tibet(GIST) and(5) meteorological data. A total of 880 lakes(>0.01 km^2) have been mapped in 2016, with 318 being glacial lakes(GLs) and 462 non-glacier lakes(NGLs). Most of the lakes were mainly located at 4500 m a.s.l. and the lakes dominated by small lakes(<0.1 km^2) where the change of their actual sizes are more significant compared to the larger ones. Meanwhile, we found that there were 178 newly formed GLs and 51 of them had disappeared between 1970 and 2016. During the same period, there can be identified 157 newly formed GLs and 226 had disappeared. We additionally performed a hazard and risk assessment for GL in 2016 and exposed 14 potentially dangerous morainedammed lakes(PDMDLs), covering a total area of 5.88 km2 in the Nyang Qu Basin. There can be found 4 GLs with very high risk, 3 GLs with high risk, 4 GLs with medium risk and 4 GLs with low risk of GLOFs susceptibility. The findings of this study can be used for the future policy of risk management and also be adapted for promoting water resources management.展开更多
As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially foll...As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses （i.e. cantilever and upright） associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.展开更多
Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of...Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of slope and the corresponding minimum safety factor without supposing the geometric shape of the most dangerous slip surface. This improved genetic algorithm can simulate the genetic evolution process of organisms and avoid the local minimum value compared with the classical methods. The results of engineering cases show that it is a global optimal algorithm and has many advantages, such as higher efficiency and shorter time than the simple genetic algorithm.展开更多
Considering the accidents of ships for dangerous chemicals transportation in inland rivers,a numerical method for the simulation of the leakage and diffusion processes of dangerous chemicals in inland rivers is propos...Considering the accidents of ships for dangerous chemicals transportation in inland rivers,a numerical method for the simulation of the leakage and diffusion processes of dangerous chemicals in inland rivers is proposed in this paper.Geographic information,such as rivers and buildings in the model,is obtained through Google Earth and structures of rivers and buildings are described by Auto CAD.In addition,the Fluent is adopted to simulate the leakage and diffusion processes of the dangerous chemicals where the standard k-εmodel is used to calculate the turbulent flow.Considering the interaction between chemicals and water,the VOF method is used to describe the leakage,drift and diffusion process of dangerous chemicals groups on the water surface.Taking a section of the Yangtze River as an example,the leakage and diffusion processes from a ship carrying 3,000 tons of low-solubility and low-volatile dangerous chemicals are studied,and the characteristics of leakage and diffusion are analyzed in detail.During the simulation,the area of the maximum group of leaked dangerous chemicals reaches up to about 1800 m2,and the number reaches up to 45.Furthermore,the influence of density,viscosity,water velocity and leakage velocity on the leakage and diffusion processes is investigated in this paper.展开更多
The method of dangerous meteorological phenomenon detection using the data of coordinate measurement by receivers of global navigation satellite system （GLONASS） and global positioning system （GPS） is proposed. Th...The method of dangerous meteorological phenomenon detection using the data of coordinate measurement by receivers of global navigation satellite system （GLONASS） and global positioning system （GPS） is proposed. The possibility of thunderstorm courses and strong clouds detection on data of pseudo-distances and altitudes is shown theoretically and confirmed experimentally.展开更多
Building indoor dangerous behavior recognition is a specific application in the field of abnormal human recognition.A human dangerous behavior recognition method based on LSTM-GCN with attention mechanism(GLA)model wa...Building indoor dangerous behavior recognition is a specific application in the field of abnormal human recognition.A human dangerous behavior recognition method based on LSTM-GCN with attention mechanism(GLA)model was proposed aiming at the problem that the existing human skeleton-based action recognition methods cannot fully extract the temporal and spatial features.The network connects GCN and LSTMnetwork in series,and inputs the skeleton sequence extracted by GCN that contains spatial information into the LSTM layer for time sequence feature extraction,which fully excavates the temporal and spatial features of the skeleton sequence.Finally,an attention layer is designed to enhance the features of key bone points,and Softmax is used to classify and identify dangerous behaviors.The dangerous behavior datasets are derived from NTU-RGB+D and Kinetics data sets.Experimental results show that the proposed method can effectively identify some dangerous behaviors in the building,and its accuracy is higher than those of other similar methods.展开更多
Motion state of ship out of control in bridge area was analyzed.Motion procedure after losing control was divided into two steps.One is drift step within stopping period.The other is drift step without inertia,which i...Motion state of ship out of control in bridge area was analyzed.Motion procedure after losing control was divided into two steps.One is drift step within stopping period.The other is drift step without inertia,which is induced by wind and current.Mathematical model for motion of ship out of control,considering wind-induced drift,current-induced drift,stopping ability,etc.,was established.Dangerous collision areas for main pier and auxiliary piers were analyzed according to different calculation conditions.展开更多
The purpose of this study is to analyze economic impacts of reducing greenhouse gases emissions significantly. A large amount of emissions reductions are required throughout this century to avoid dangerous climate cha...The purpose of this study is to analyze economic impacts of reducing greenhouse gases emissions significantly. A large amount of emissions reductions are required throughout this century to avoid dangerous climate change, and understanding the economic consequences under such situations is important and meaningful. The AIM/CGE [Global] model, a recursive dynamic computable general equilibrium model on a global scale, is applied to analyze carbon prices and changes in GDP when implementing five policy scenarios represented by emissions pathways, respectively. As a result of the analysis, higher carbon prices and larger decreases in GDP compared to the baseline emissions scenario are observed when emissions are reduced more deeply. However, such GDP losses are rather small and insignificant compared to the GDP growth observed throughout the century. These results suggest that although it is challenging to reduce emissions until the level to avoid dangerous climate change, there is a sufficient possibility to achieve it from economic perspectives.展开更多
The southern continental margin of the South China Sea has documented multiphase continental rifting corresponding to the propagation of seafloor spreading.Here we investigate three multi-channel seismic reflection pr...The southern continental margin of the South China Sea has documented multiphase continental rifting corresponding to the propagation of seafloor spreading.Here we investigate three multi-channel seismic reflection profiles across different segments of the Dangerous Grounds with a NE-SW direction.Stratigraphic correlation reveals that the Cenozoic tectono-stratigraphic framework in the Dangerous Grounds is featured with diachronous rifting,which records the successive spreading of East Subbasin and Southwest Subbasin,South China Sea.By reconstructing the tectono-sedimentary evolution history in different segments,we combine the quantification of the brittle extension,tectonic subsidence,as well as the crustal thinning.Results provide evidence that the extensional stress migrated from northeast to southwest with the progressive propagation of the seafloor spreading in the oceanic basin.Besides,the impact of the tectonic propagation persists even after the cessation of seafloor spreading,evidenced by a longer stretching duration in the West-Dangerous Grounds than that in the eastern area.Moreover,a temporary syn-rift subsidence delay synchronously to the spreading of the adjacent oceanic basin is observed along the southern margin.This observation proves the secondary mantle convection during the seafloor spreading in the southern continental margin,which is related to the propagating rift.展开更多
This DC-YOLO Model was designed in order to improve the efficiency for appraising dangerous class of buildings and avoid manual intervention,thereby making the appraisal results more objective.It is an automated metho...This DC-YOLO Model was designed in order to improve the efficiency for appraising dangerous class of buildings and avoid manual intervention,thereby making the appraisal results more objective.It is an automated method designed based on deep learning and target detection algorithms to appraise the dangerous class of building masonry component.Specifically,it(1)adopted K-means clustering to obtain the quantity and size of the prior boxes;(2)expanded the grid size to improve identification to small targets;(3)introduced in deformable convolution to adapt to the irregular shape of the masonry component cracks.The experimental results show that,comparing with the conventional method,the DC-YOLO model has better recognition rates for various targets to different extents,and achieves good effects in precision,recall rate and F1 value,which indicates the good performance in classifying dangerous classes of building masonry component.展开更多
In this paper, we use differential game theory to study the three-dimensional two-aircraft air-to-air combat problem. We give the ways to determine the Capture Ranges (CR) and the Dangerous Ranges (DR) for these two a...In this paper, we use differential game theory to study the three-dimensional two-aircraft air-to-air combat problem. We give the ways to determine the Capture Ranges (CR) and the Dangerous Ranges (DR) for these two aircraft according to the target entry directions, barrier and isochronic lines respectively. The simulations are given by referring to two sets of real aircraft parameters. After discussing the simulation results, we have obtained some conclusions that match the real air-to-air combat situation quite well.展开更多
Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous acti...Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous activ-ity.Therefore,a recognition for frontal emergency stops dangerous activity algorithm based on Nano Internet of Things Sensor(NIoTS)and transfer learning is proposed.First,the NIoTS is installed in the athlete’s leg muscles to collect activity signals.Second,the noise component in the activity signal is removed using the de-noising method based on mathematical morphology.Finally,the depth feature of the activity signal is extracted through the deep transfer learning model,and the Euclidean distance between the extracted feature and the depth feature of the frontal emergency stops dangerous activity signal is compared.If the European distance is small,it can be judged as the frontal emergency stops dangerous activity,and the frontal emergency stops dangerous activity recognition is realized.The results show that the average time delay of activity signal acquisition of the algorithm is low,the signal-to-noise ratio of the action signal is high,and the activity signal mean square error is low.The variance of the frontal emergency stops dangerous activity recognition does not exceed 0.5.The difference between the appearance time of the dangerous activity and the recognition time of the algorithm is 0.15 s,it can accurately and quickly recognize the frontal emergency stops the dangerous activity.展开更多
Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass （e. g. by blast...Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass （e. g. by blasting） needs to be avoided, as this new damage could cause collapse. So the self-bearing capacity of the mountain mass must be used to treat the dangerous rock mass. This article is based on a practical example of the control of a dangerous rock mass at Banyan Mountain, Huangshi, Hubei Province. On the basis of an analysis of damage mechanism and the stability of the dangerous rock mass, a flexible network reinforcement method was designed to prevent the collapse of the rock mass. The deformations of section Ⅱ w of the dangerous rock mass before and after the flexible network reinforcement were calculated using the two-dimensional finite element method. The results show that the maximum deformation reduced by 55 % after the application of the flexible network reinforcement, from 45.99 to 20.75 ram, which demonstrates that the flexible network method is effective, and can provide some scientific basis for the treatment of dangerous rock masses.展开更多
The transport of dangerous goods always represents a potential risk to life,human health,property,and environmental protection.For this reason and in order to preserve the lives and health of the participants in the t...The transport of dangerous goods always represents a potential risk to life,human health,property,and environmental protection.For this reason and in order to preserve the lives and health of the participants in the transport process,adequate protection measures must be taken before,during,and after the transport of dangerous goods.Since the railway itself is a recipient of dangerous goods that are essential for its own operation,and is also a carrier of large quantities of various dangerous goods,these measures are of paramount importance.This paper examines,from a point of view of the protection of lives and health of the participants in the transport process and the safe transport of dangerous goods,the conditions of shipment and transport of dangerous goods,the obligations of the participants,and the essential ways for their proper handling.Proper application of safety at work prevents impromptu and indolent attitude in transporting dangerous goods,thus contributing to protection of people lives and health.Finally,this paper includes preventive measures and basic principles for implementation of safety at work in the transport of dangerous goods.展开更多
According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 veh...According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 vehicles (i.e. 95 in 2007/8). Road safety generally depends on humans, vehicles, and highway conditions. These factors influence road safety separately or in combination. One of the basic means to improve road safety is to reduce hazardous conditions of roads. The main objective of this study is to identify and rank hazardous locations and propose appropriate simple and inexpensive countermeasures along Hawassa-Shashemene-Bulbula main two-lane rural road. Accordingly, the road and traffic data were collected from field investigation and Ethiopian Road Authority and accident data were gathered from police stations. Then, the study road equally divided into short sections of 1.5 km and traffic volume and accident frequencies assigned for each road site to predict theoretical frequencies of accident. Empirical Bayes method and Safety Performance Function have been used to estimate an index known as Potential for Safety Improvement (PSI) for each site of the study area to identify and rank road sites. The result showed that out of 43 road segments 22 of them were identified as dangerous road segments. Moreover, based on further criterion established for screening the ranked road sections 8 road segments were found the most dangerous road segments as they have contributed 76% of total PSI values. The degree of haphazardness of a given road segment in the study area has directly associated with the availability of risk indicating road and traffic factors. Finally, it recommends that regulatory body of road safety in the study area should give high priority and immediate response for the improvement of most dangerous road segments.展开更多
基金supported by the Regional Innovation Development Joint Fund of the National Natural Science Foundation of China(U23A2045)the scientific research project of the Chongqing Municipal Bureau of Planning and Natural Resources(KJ-2023046)the scientific and technological project of the Hubei Provincial Bureau of Geological Survey(KJ2024-34)。
文摘The Three Gorges Reservoir area hosts numerous high-risk columnar rock masses,but predicting their full-process of collapse dynamics in narrow-deep terrains remains challenging.This study investigated the Changdongzi columnar dangerous rock mass(CCDRM)through field surveys and simulated its collapse dynamics with Material Point Method(MPM),and analyzed the collapse-diffusionsurge generation mechanisms.Field investigations revealed a 0.8 m-thick lotus-like extrusion structure at the base,severely degraded by cyclic water fluctuations,predisposing the rock mass to base-crushing failure.Numerical simulations indicate collapse velocities up to 42 m/s,amplified spreading with a 318 m deposition range and 11 m maximum thickness,and two major collisions causing 50%-60%velocity reduction.Gully topography buffers kinetic energy,retaining 5%debris on slopes and channeling 7%into the river.High-speed river impact generates a 20 m-diameter cavity,producing an 11 m surge,identifying the Guandukou Town waterfront 1.2 km downstream as a high-risk zone.These results clarify the collapse mechanisms of columnar dangerous rock mass and inform its hazard mitigation strategies.
基金the financial support provided by the Major Science and Technology Project of Xinjiang Uygur Autonomous Region(Grant NO.2024A01003)the National Natural Science Foundation of China(Grant NO.51508556)+3 种基金the Key Support Project of the National Natural Science Foundation of China Joint Fund(Grant No.U24B2039)the Natural Science Foundation of Jiangxi Province(Grant NO.20232BAB203079,20224BAB213045)Program of China Scholarship Council(Grant NO.202406430056)the Fundamental Research Funds for the Central Universities(Ph.D.Top Innovative Talents Fund of CUMTB)(Grant NO.BBJ2025081)。
文摘Dangerous rock masses in cold regions subjected to repeated freeze–thaw cycles can cause progressive deterioration in structural planes and rock mechanical properties,which significantly reduces the overall stability and often triggers collapses or landslides.Existing studies focus mostly on singlescale or single-factor analyses but cannot fully capture the coupled mechanisms driving instability under freeze-thaw conditions.This study aimed to establish a theoretical framework to quantitatively characterize the evolution of rock mass stability,thereby providing a sound basis for hazard prediction and prevention.By integrating limit equilibrium theory with rock frost heave and circular hole expansion theory,mechanical models for sliding-and toppling-type dangerous rock masses were established.Three key factors were incorporated:frost heave forces acting on throughgoing structural planes,rock property deterioration in nonpenetrative sections,and progressive freezing depth development.A theoretical relationship between the stability coefficient and the number of freeze-thaw cycles was derived.By considering the Zimei Peaks rock masses in Gansu Province as the case study and conducting parametric analyses,the results revealed that the stability coefficient rapidly decreases during the initial cycles,followed by a slower decrease and eventual stabilization.The coefficient decreased 4.5 times more during the first 15 cycles than during the subsequent 15 cycles.Moreover,stability degradation was strongly influenced by the freezing temperature,initial porosity,and rock debris loss ratio,with critical thresholds determined at a 3.8%porosity and a 0.83 debris loss ratio.The findings indicated that stability deterioration is governed by the coupled effects of frost heave loading,microstructural damage accumulation,and freezing depth development,with clear stagedependent and threshold-driven patterns.This work provides not only a quantitative explanation of instability mechanisms in cold-region rock masses but also practical guidance for engineering stability assessment and disaster mitigation.
基金financially supported by the Youth Innovation Promotion Association CAS(No.2021325)the National Natural Science Foundation of China(Nos.52179117,U21A20159)the Research project of Panzhihua Iron and Steel Group Mining Co.,Ltd.(No.2021-P6-D2-05)。
文摘Source identification and deformation analysis of disaster bodies are the main contents of high-steep slope risk assessment,the establishment of high-precision model and the quantification of the fine geometric features of the slope are the prerequisites for the above work.In this study,based on the UAV remote sensing technology in acquiring refined model and quantitative parameters,a semi-automatic dangerous rock identification method based on multi-source data is proposed.In terms of the periodicity UAV-based deformation monitoring,the monitoring accuracy is defined according to the relative accuracy of multi-temporal point cloud.Taking a high-steep slope as research object,the UAV equipped with special sensors was used to obtain multi-source and multitemporal data,including high-precision DOM and multi-temporal 3D point clouds.The geometric features of the outcrop were extracted and superimposed with DOM images to carry out semi-automatic identification of dangerous rock mass,realizes the closed-loop of identification and accuracy verification;changing detection of multi-temporal 3D point clouds was conducted to capture deformation of slope with centimeter accuracy.The results show that the multi-source data-based semiautomatic dangerous rock identification method can complement each other to improve the efficiency and accuracy of identification,and the UAV-based multi-temporal monitoring can reveal the near real-time deformation state of slopes.
基金Projects(52208369,52309138,52108320)supported by the National Natural Science Foundation of ChinaProjects(2023NSFSC0284,2025ZNSFSC0409)supported by the Sichuan Science and Technology Program,ChinaProject(U22468214)supported by the Joint Fund Project for Railway Basic Research by the National Natural Science Foundation of China and China State Railway Group Co.,Ltd.
文摘In the practical slope engineering,the stability of lower sliding mass(region A)with back tensile cracks of the jointed rock slope attracts more attentions,but the upper rock mass(region B)may also be unstable.Therefore,in this study,based on the stepped failure mode of bedding jointed rock slopes,considering the influence of the upper rock mass on the lower stepped sliding mass,the improved failure model for analyzing the interaction force(F_(AB))between two regions is constructed,and the safety factors(F_(S))of two regions and whole region are derived.In addition,this paper proposes a method to determine the existence of F_(AB) using their respective acceleration values(a_(A) and a_(B))when regions A and B are unstable.The influences of key parameters on two regions and the whole region are analyzed.The results show that the variation of the F_(AB) and F_(S) of two regions can be obtained accurately based on the improved failure model.The accuracy of the improved failure model is verified by comparative analysis.The research results can explain the interaction mechanism of two regions and the natural phenomenon of slope failure caused by the development of cracks.
基金supported by the National Key R&D Program of China(Grant No.2022YFC3080200)。
文摘The identification and characterization of concealed in-situ rock blocks on high-steep slope exposures are critical in rock engineering,but remain challenging.This study employs advanced UAV-based photogrammetry to capture high-resolution discontinuity data and develops a fully automated rock block extraction method consisting of three steps:(1)determination of free face and non-free fracture intersections,(2)surface search for rock blocks on free face.and(3)extraction and analysis of rock blocks.This approach simplifies the determination of discontinuity intersections while maintaining high accuracy.By incorporating all types of discontinuities contributing to rock block formation,the method enables precise in-situ rock block identification and extraction.Application to a rock slope in China,produced results consistent with the rock blocks observed in the 3D model,highlighting its accuracy and practical value.
基金the National Natural Science Foundation of China(No.41761144075,No.41861013)Yunnan University(YJRC3201702)National Natural Science Foundation of China Youth Fund Project(No.41801052)。
文摘There are a large number of glaciers and lakes developed in the Nyang Qu Basin of China. Recent climate change has significant impacted on the high-mountain glacial environment. Rapid melting of glaciers contributes to the formation and expansion of moraine-dammed lakes which increase the probability of glacial lake outburst floods(GLOFs). We calculated a multi-temporal lake inventory based on(1) topographic maps in the 1970 s,(2) satellite imageries from 1990 to 2016,(3) First Chinese Glacier Inventory(FCGI),(4) Glacier Inventory of Southeastern Tibet(GIST) and(5) meteorological data. A total of 880 lakes(>0.01 km^2) have been mapped in 2016, with 318 being glacial lakes(GLs) and 462 non-glacier lakes(NGLs). Most of the lakes were mainly located at 4500 m a.s.l. and the lakes dominated by small lakes(<0.1 km^2) where the change of their actual sizes are more significant compared to the larger ones. Meanwhile, we found that there were 178 newly formed GLs and 51 of them had disappeared between 1970 and 2016. During the same period, there can be identified 157 newly formed GLs and 226 had disappeared. We additionally performed a hazard and risk assessment for GL in 2016 and exposed 14 potentially dangerous morainedammed lakes(PDMDLs), covering a total area of 5.88 km2 in the Nyang Qu Basin. There can be found 4 GLs with very high risk, 3 GLs with high risk, 4 GLs with medium risk and 4 GLs with low risk of GLOFs susceptibility. The findings of this study can be used for the future policy of risk management and also be adapted for promoting water resources management.
基金Scientific Research Fund of the Hebei Education Department under Grant No.QN2015166
文摘As the economy of China develops, an increasing number of key traffic projects have been undertaken in the west of China, where there are high, steep rock slopes. The collapse of dangerous rock masses, especially following a strong earthquake, is one of common geological disasters known in rock slope engineering. Therefore, it is important to study the collapse mechanism of dangerous rock masses induced by an earthquake and the analysis approach of its stability. This study provides a simple and convenient method to determine the collapse mechanisms of two types of dangerous rock masses （i.e. cantilever and upright） associated with the definition and calculation of the safety factor, which is based on the flexure theory of a constant-section beam by combining with the maximum tensile-stress criterion to depict the process of crack propagation caused by seismic waves. The calculation results show that there are critical crack depths in each form of the dangerous rock masses. Once the accumulated depth of the crack growth during an earthquake exceeds the critical depth, the collapse will occur. It is also demonstrated that the crack extension amount of each step is not a constant value, and is closely associated with the current accumulated crack depth. The greater the cumulative crack depth, the more easily the crack propagates. Finally, the validity and applicability of the proposed method are verified through two actual engineering examples.
文摘Based on the slice method of the non-circular slip surface for the calculation of integral stability of slope, an improved genetic algorithm was proposed, which can freely search for the most dangerous slip surface of slope and the corresponding minimum safety factor without supposing the geometric shape of the most dangerous slip surface. This improved genetic algorithm can simulate the genetic evolution process of organisms and avoid the local minimum value compared with the classical methods. The results of engineering cases show that it is a global optimal algorithm and has many advantages, such as higher efficiency and shorter time than the simple genetic algorithm.
基金supported by the special fund for the basic research business of the central public welfare research institutes(TKS160222,TKS160211)the key technology projects of the transportation industry(TKS180403)+1 种基金the Tianjin Science and Technology Project(the project)(17YFZCSF01250)supported by National Natural Science Foundation of China(No.U1930402).
文摘Considering the accidents of ships for dangerous chemicals transportation in inland rivers,a numerical method for the simulation of the leakage and diffusion processes of dangerous chemicals in inland rivers is proposed in this paper.Geographic information,such as rivers and buildings in the model,is obtained through Google Earth and structures of rivers and buildings are described by Auto CAD.In addition,the Fluent is adopted to simulate the leakage and diffusion processes of the dangerous chemicals where the standard k-εmodel is used to calculate the turbulent flow.Considering the interaction between chemicals and water,the VOF method is used to describe the leakage,drift and diffusion process of dangerous chemicals groups on the water surface.Taking a section of the Yangtze River as an example,the leakage and diffusion processes from a ship carrying 3,000 tons of low-solubility and low-volatile dangerous chemicals are studied,and the characteristics of leakage and diffusion are analyzed in detail.During the simulation,the area of the maximum group of leaked dangerous chemicals reaches up to about 1800 m2,and the number reaches up to 45.Furthermore,the influence of density,viscosity,water velocity and leakage velocity on the leakage and diffusion processes is investigated in this paper.
基金Task Complex Program National Academy of Sciences of Ukraine on Space Research for 2012-2016
文摘The method of dangerous meteorological phenomenon detection using the data of coordinate measurement by receivers of global navigation satellite system （GLONASS） and global positioning system （GPS） is proposed. The possibility of thunderstorm courses and strong clouds detection on data of pseudo-distances and altitudes is shown theoretically and confirmed experimentally.
文摘Building indoor dangerous behavior recognition is a specific application in the field of abnormal human recognition.A human dangerous behavior recognition method based on LSTM-GCN with attention mechanism(GLA)model was proposed aiming at the problem that the existing human skeleton-based action recognition methods cannot fully extract the temporal and spatial features.The network connects GCN and LSTMnetwork in series,and inputs the skeleton sequence extracted by GCN that contains spatial information into the LSTM layer for time sequence feature extraction,which fully excavates the temporal and spatial features of the skeleton sequence.Finally,an attention layer is designed to enhance the features of key bone points,and Softmax is used to classify and identify dangerous behaviors.The dangerous behavior datasets are derived from NTU-RGB+D and Kinetics data sets.Experimental results show that the proposed method can effectively identify some dangerous behaviors in the building,and its accuracy is higher than those of other similar methods.
基金Supported by Disaster Reduction Foundation of Large Complex Project for Sutong Bridge(No.2006BAG04B06)
文摘Motion state of ship out of control in bridge area was analyzed.Motion procedure after losing control was divided into two steps.One is drift step within stopping period.The other is drift step without inertia,which is induced by wind and current.Mathematical model for motion of ship out of control,considering wind-induced drift,current-induced drift,stopping ability,etc.,was established.Dangerous collision areas for main pier and auxiliary piers were analyzed according to different calculation conditions.
文摘The purpose of this study is to analyze economic impacts of reducing greenhouse gases emissions significantly. A large amount of emissions reductions are required throughout this century to avoid dangerous climate change, and understanding the economic consequences under such situations is important and meaningful. The AIM/CGE [Global] model, a recursive dynamic computable general equilibrium model on a global scale, is applied to analyze carbon prices and changes in GDP when implementing five policy scenarios represented by emissions pathways, respectively. As a result of the analysis, higher carbon prices and larger decreases in GDP compared to the baseline emissions scenario are observed when emissions are reduced more deeply. However, such GDP losses are rather small and insignificant compared to the GDP growth observed throughout the century. These results suggest that although it is challenging to reduce emissions until the level to avoid dangerous climate change, there is a sufficient possibility to achieve it from economic perspectives.
基金financially supported by the Open Fund of Hubei Key Laboratory of Marine Geological Resources(No.MGR202004)the National Natural Science Foundation of China(Nos.41890811,41676027,41906070)。
文摘The southern continental margin of the South China Sea has documented multiphase continental rifting corresponding to the propagation of seafloor spreading.Here we investigate three multi-channel seismic reflection profiles across different segments of the Dangerous Grounds with a NE-SW direction.Stratigraphic correlation reveals that the Cenozoic tectono-stratigraphic framework in the Dangerous Grounds is featured with diachronous rifting,which records the successive spreading of East Subbasin and Southwest Subbasin,South China Sea.By reconstructing the tectono-sedimentary evolution history in different segments,we combine the quantification of the brittle extension,tectonic subsidence,as well as the crustal thinning.Results provide evidence that the extensional stress migrated from northeast to southwest with the progressive propagation of the seafloor spreading in the oceanic basin.Besides,the impact of the tectonic propagation persists even after the cessation of seafloor spreading,evidenced by a longer stretching duration in the West-Dangerous Grounds than that in the eastern area.Moreover,a temporary syn-rift subsidence delay synchronously to the spreading of the adjacent oceanic basin is observed along the southern margin.This observation proves the secondary mantle convection during the seafloor spreading in the southern continental margin,which is related to the propagating rift.
基金The work is supported by National key research and development plan of China(2016YFC0801408)the Graduate Science and Technology Innovation Project of Shandong University of Science and Technology(SDKDYC180344).
文摘This DC-YOLO Model was designed in order to improve the efficiency for appraising dangerous class of buildings and avoid manual intervention,thereby making the appraisal results more objective.It is an automated method designed based on deep learning and target detection algorithms to appraise the dangerous class of building masonry component.Specifically,it(1)adopted K-means clustering to obtain the quantity and size of the prior boxes;(2)expanded the grid size to improve identification to small targets;(3)introduced in deformable convolution to adapt to the irregular shape of the masonry component cracks.The experimental results show that,comparing with the conventional method,the DC-YOLO model has better recognition rates for various targets to different extents,and achieves good effects in precision,recall rate and F1 value,which indicates the good performance in classifying dangerous classes of building masonry component.
基金research was supported by Aviation Science Fund.
文摘In this paper, we use differential game theory to study the three-dimensional two-aircraft air-to-air combat problem. We give the ways to determine the Capture Ranges (CR) and the Dangerous Ranges (DR) for these two aircraft according to the target entry directions, barrier and isochronic lines respectively. The simulations are given by referring to two sets of real aircraft parameters. After discussing the simulation results, we have obtained some conclusions that match the real air-to-air combat situation quite well.
文摘Currently,it is difficult to extract the depth feature of the frontal emergency stops dangerous activity signal,which leads to a decline in the accuracy and efficiency of the frontal emergency stops the dangerous activ-ity.Therefore,a recognition for frontal emergency stops dangerous activity algorithm based on Nano Internet of Things Sensor(NIoTS)and transfer learning is proposed.First,the NIoTS is installed in the athlete’s leg muscles to collect activity signals.Second,the noise component in the activity signal is removed using the de-noising method based on mathematical morphology.Finally,the depth feature of the activity signal is extracted through the deep transfer learning model,and the Euclidean distance between the extracted feature and the depth feature of the frontal emergency stops dangerous activity signal is compared.If the European distance is small,it can be judged as the frontal emergency stops dangerous activity,and the frontal emergency stops dangerous activity recognition is realized.The results show that the average time delay of activity signal acquisition of the algorithm is low,the signal-to-noise ratio of the action signal is high,and the activity signal mean square error is low.The variance of the frontal emergency stops dangerous activity recognition does not exceed 0.5.The difference between the appearance time of the dangerous activity and the recognition time of the algorithm is 0.15 s,it can accurately and quickly recognize the frontal emergency stops the dangerous activity.
文摘Because the main failure type of a dangerous rock mass is collapse, the treatment of such a mass should focus on controlling collapse failure. When treating dangerous rock masses, disturbing the mass （e. g. by blasting） needs to be avoided, as this new damage could cause collapse. So the self-bearing capacity of the mountain mass must be used to treat the dangerous rock mass. This article is based on a practical example of the control of a dangerous rock mass at Banyan Mountain, Huangshi, Hubei Province. On the basis of an analysis of damage mechanism and the stability of the dangerous rock mass, a flexible network reinforcement method was designed to prevent the collapse of the rock mass. The deformations of section Ⅱ w of the dangerous rock mass before and after the flexible network reinforcement were calculated using the two-dimensional finite element method. The results show that the maximum deformation reduced by 55 % after the application of the flexible network reinforcement, from 45.99 to 20.75 ram, which demonstrates that the flexible network method is effective, and can provide some scientific basis for the treatment of dangerous rock masses.
文摘The transport of dangerous goods always represents a potential risk to life,human health,property,and environmental protection.For this reason and in order to preserve the lives and health of the participants in the transport process,adequate protection measures must be taken before,during,and after the transport of dangerous goods.Since the railway itself is a recipient of dangerous goods that are essential for its own operation,and is also a carrier of large quantities of various dangerous goods,these measures are of paramount importance.This paper examines,from a point of view of the protection of lives and health of the participants in the transport process and the safe transport of dangerous goods,the conditions of shipment and transport of dangerous goods,the obligations of the participants,and the essential ways for their proper handling.Proper application of safety at work prevents impromptu and indolent attitude in transporting dangerous goods,thus contributing to protection of people lives and health.Finally,this paper includes preventive measures and basic principles for implementation of safety at work in the transport of dangerous goods.
文摘According to the study made by United Nation Economic Commission for Africa, Ethiopia stands as one of the worst countries with respect to road safety performance in terms of traffic accident fatalities per 10,000 vehicles (i.e. 95 in 2007/8). Road safety generally depends on humans, vehicles, and highway conditions. These factors influence road safety separately or in combination. One of the basic means to improve road safety is to reduce hazardous conditions of roads. The main objective of this study is to identify and rank hazardous locations and propose appropriate simple and inexpensive countermeasures along Hawassa-Shashemene-Bulbula main two-lane rural road. Accordingly, the road and traffic data were collected from field investigation and Ethiopian Road Authority and accident data were gathered from police stations. Then, the study road equally divided into short sections of 1.5 km and traffic volume and accident frequencies assigned for each road site to predict theoretical frequencies of accident. Empirical Bayes method and Safety Performance Function have been used to estimate an index known as Potential for Safety Improvement (PSI) for each site of the study area to identify and rank road sites. The result showed that out of 43 road segments 22 of them were identified as dangerous road segments. Moreover, based on further criterion established for screening the ranked road sections 8 road segments were found the most dangerous road segments as they have contributed 76% of total PSI values. The degree of haphazardness of a given road segment in the study area has directly associated with the availability of risk indicating road and traffic factors. Finally, it recommends that regulatory body of road safety in the study area should give high priority and immediate response for the improvement of most dangerous road segments.
