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Characteristics and dynamic analysis of the February 2021 long-runout disaster chain triggered by massive rock and ice avalanche at Chamoli, Indian Himalaya

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Journal of Rock Mechanics and Geotechnical engineering 2023年第2期15卷 296-308页

作者： Tiantian Zhang Yueping Yin Bin Li Xiaojie Liu Meng Wang Yang Gao Jiawei Wan Kaushal Raj Gnyawali institute of Geomechanics Chinese Academy of Geological SciencesBeijing100081China China institute of geological Environment Monitoring China Geological SurveyBeijing100081China College of Geology engineering and Geomatics Chang’an UniversityXi’an710100China Sichuan geological Survey institute Chengdu610081China Natural Hazards Section Himalayan Risk Research Institute(HRI)Bhaktapur44800Nepal

A massive rock and ice avalanche occurred on the western slope of the Ronti Gad valley in the northern part of Chamoli,Indian Himalaya,on 7 February 7,*** avalanche on the high mountain slope at an elevation of 5600 m above sea level triggered a long runout disaster chain,including rock mass avalanche,debris avalanche,and *** disaster chain had a horizontal travel distance of larger than 17,600 m and an elevation difference of 4300 *** this study,the disaster characteristics and dynamic process were analyzed by multitemporal satellite *** results show that the massive rock and ice avalanche was caused by four large expanding discontinuity *** disaster chain was divided into five zones by satellite images and field observation,including source zone,transition zone,dynamic entrainment zone,flow deposition zone,and flood *** entrainment effect and melting water were recognized as the main causes of the long-runout *** on the seismic wave records and field videos,the time progress of the disaster was analyzed and the velocity of frontal debris at different stages was *** total analyzed disaster duration was 1247 s,and the frontal debris velocity colliding with the second hydropower station was approximately 23 m/*** study also carried out the numerical simulation of the disaster by rapid mass movement simulation(RAMMS).The numerical results reproduced the dynamic process of the debris avalanche,and the mechanism of long-runout avalanche was further verified by parametric ***,this study discussed the potential causes of disaster and flood and the roles of satellite images and seismic networks in the monitoring and early-warning.

关键词： Rock and ice avalanche Disaster chain Long-runout Entrainment Flood

Viscous liquid sloshing damping in cylindrical container using a volume of fluid method

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Science China(Technological Sciences) 2009年第6期52卷 1484-1492页

作者： Wei Yang ShuHong Liu Hong Lin Department of Thermal engineering State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China design and research institute of Launch Vehicle Beijing 100076 China

Liquid sloshing is a kind of very complicated free surface flow and exists widely in many *** order to calculate liquid sloshing damping precisely a volume of fluid method based on finite volume scheme is used to simulate free surface flows in partly filled cylindrical containers.A numerical method is pre-sented to simulate the movement of the free surface flow,in which a piecewise linear interface con-struction scheme and an unsplit Lagrangian advection scheme instead of Eulerian advection scheme are *** damping performance of liquid sloshing in cylindrical containers under fundamental sloshing mode is *** are four factors determining the surface-wave damping:free surface,boundary-layer,interior fluid and contact *** order to study different contributions from these four factors to whole damping,several examples are ***-slip and slip wall boundary conditions on both side wall and bottom wall of the cylindrical containers are studied to compare with the published results obtained by solving Stokes *** the present method the first three main factors can be *** simulation results show that the boundary-layer damping contribution increases while the interior fluid damping contribution decreases with increase of Reynolds number.

关键词： volume of fluid method unsplit Lagrangian advection scheme cylindrical container liquid sloshing damping

Study of control effects of vortex generators on a supercritical wing

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Science China(Technological Sciences) 2010年第8期53卷 2038-2048页

作者： HUANG JingBo 1 ,XIAO ZhiXiang 1 ,FU Song 1 &ZHANG Miao 2 1 School of Aerospace engineering,Tsinghua University,beijing 100084,China 2 Shanghai Aircraft design and research institute of COMAC,Shanghai 200232,China School of Aerospace engineering Tsinghua University Beijing China Shanghai Aircraft design and research institute of COMAC Shanghai China

Flows around vortex generators(VGs),which serve as one of the important flow control methods,are investigated by solving Reynolds-averaged Navier-Stokes(RANS)*** influences on the main flow of VGs are intended to ***, the flow around a single VG on a flat plane is computed to validate the schemes and to acquire basic knowledge of this kind of ***,transonic flow past a standard model,named by ONERA-M6 wing,is predicted to investigate the flow features of shockwave/boundary-layer interactions(SWBLI).Thirdly,the effects of a row of VGs mounted about 25%local chord on a supercritical wing are analyzed in transonic condition with strong ***,VGs are mounted more upwind(about 3.5%local chord)to explore the effects at low speed and high incidence *** numerical results show that seven VGs can effectively suppress the separations behind the strong SWBLI and decrease spanwise flow and wing-tip vortex in transonic *** also can decrease the large scope of separation over the wing at low speed with high angle of attack.

关键词： supercritical wing vortex generator(VG) shockwave/boundary-layer interactions(SWBLI)

Dynamic impact experiment and response characteristics analysis for 1:2 reduced-scale model of hydraulic support

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International Journal of Mining Science and Technology 2021年第3期31卷 347-356页

作者： Huaiwei Ren Desheng Zhang Shixin Gong Kai Zhou Chenyang Xi Ming He Tijian Li CCTEG Coal Mining research institute Beijing 100013China Mining design Ilnstitute China Coal Research InstituteBeijing 100013China School of Mechanical engineering Shanghai Jiao Tong UniversityShanghai 200240China

It is significant to research the impact resistance properties of hydraulic support due to its key support role in the fully mechanized mining ***,it is difficult for the entire hydraulic support to implement the impact experiment underground and analyze the response ***,a dynamic impact experiment for the entire hydraulic support was proposed in this paper,where a 1:2 reducedscale model of hydraulic support was designed and its response characteristics under dynamic impact load were ***,a comprehensive monitoring scheme was proposed to achieve an effective monitoring for dynamic response of hydraulic ***,a multi-scale impact experiment was carried out for the entire hydraulic support and dynamic behaviors of hydraulic support under the multi-scale impact load were revealed by experimental *** a dynamic impact experiment of the entire hydraulic support was simulated in ADAMS with the same experiment conditions,and the experimental and simulation data were verified ***,the characteristics of energy conversion and dissipation of the entire experiment system after impact were *** experiment results showed that the impact resistance properties of hydraulic support largely depended on the initial support conditions and different vertical rigidities affected energy distribution proportion of the entire support system.

关键词： Hydraulic support Impact experiment Characteristics analysis Dynamics simulation ADAMS

Seismic performance of a rectangular subway station with earth retaining system

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Earthquake engineering and engineering Vibration 2022年第1期21卷 221-236页

作者： Ma Chao Lu Dechun Du Xiuli Qi Chengzhi beijing Advanced Innovation Center for Future Urban design Beijing University of Civil Engineering andArchitectureBeijingChina institute of Geotechnical and Underground engineering Beijing University of TechnologyBeijingChina

Much effort has been made in investigating the seismic response and failure mechanism of rectangular subway stations,however,the influence of earth retaining systems has generally been ignored in previous *** paper presents a numerical study on the seismic performance of a rectangular subway station with/without earth retaining systems by taking fender piles as the example,and aims to illustrate how the existence of fender piles affects seismic responses on subway *** loading conditions of subway stations and their surrounding soils prior to earthquakes are ***,seismic responses of subway stations with or without fender piles were ***,earthquake-induced deformations of stations and surrounding soils,as well as the internal forces and damage modes of the structural components,were systematically ***,the seismic performance of the stations was affected by the existence of fender *** addition,earthquake intensity is *** study showed that deformation modes of surrounding soils and damage modes of stations were different with regard to the existence of fender ***,earthquake intensity influencing the seismic performance of stations with or without fender piles were found to be opposite.

关键词： rectangular subway station earth retaining system seismic soil-structure interaction damage mode inter-story drift ratio

Mission decision-making method of multi-aircraft cooperatively attacking multi-target based on game theoretic framework

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Chinese Journal of Aeronautics 2016年第6期29卷 1685-1694页

作者： Yao Zongxin Li Ming Chen Zongji Zhou Rui Shenyang Aircraft design and research institute Shenyang 110035China School of Automation Science and Electrical engineering Beihang UniversityBeijing 100083China

Coordinated mission decision-making is one of the core steps to effectively exploit the capabilities of cooperative attack of multiple aircrafts. However, the situational assessment is an essential base to realize the mission decision-making. Therefore, in this paper, we develop a mission decision-making method of multi-aircraft cooperatively attacking multi-target based on situational assessment. We have studied the situational assessment mathematical model based on the Dempster-Shafer(D-S) evidence theory and the mission decision-making mathematical model based on the game theory. The proposed mission decision-making method of antagonized airfight is validated by some simulation examples of a swarm of unmanned combat aerial vehicles(UCAVs)that carry out the mission of the suppressing of enemy air defenses(SEAD).

关键词： Antagonized airfight D-S evidence theory Fuzzy mapping function Game theoretic framework Mission decision-making Multi-aircraft coordination Situational assessment

Tube-based robust reinforcement learning for autonomous maneuver decision for UCAVs

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Chinese Journal of Aeronautics 2024年第7期37卷 391-405页

作者： Lixin WANG Sizhuang ZHENG Haiyin PIAO Changqian LU Ting YUE Hailiang LIU School of Aeronautical Science and engineering Beihang UniversityBeijing 100191China Shenyang Aircraft design&research institute Shenyang 110035China

Reinforcement Learning(RL)algorithms enhance intelligence of air combat AutonomousManeuver Decision(AMD)policy,but they may underperform in target combat environmentswith *** enhance the robustness of the AMD strategy learned by RL,thisstudy proposes a Tube-based Robust RL(TRRL)***,this study introduces a tube todescribe reachable trajectories under disturbances,formulates a method for calculating tubes basedon sum-of-squares programming,and proposes the TRRL algorithm that enhances robustness byutilizing tube size as a quantitative ***,this study introduces offline techniques forregressing the tube size function and establishing a tube library before policy learning,aiming toeliminate complex online tube solving and reduce the computational burden during ***,an analysis of the tube library demonstrates that the mitigated AMD strategy achievesgreater robustness,as smaller tube sizes correspond to more cautious *** finding highlightsthat TRRL enhances robustness by promoting a conservative *** effectively balanceaggressiveness and robustness,the proposed TRRL algorithm introduces a“laziness factor”as aweight of ***,combat simulations in an environment with disturbances confirm thatthe AMD policy learned by the TRRL algorithm exhibits superior air combat performance comparedto selected robust RL baselines.

关键词： Air combat Autonomous maneuver decision Robust reinforcement learning Tube-based algorithm Combat simulation

Pumpability of Manufactured Sand Self-compacting Concrete

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1382-1390页

作者： LI Huajian HUANG Fali TU Haifeng SUN Deyi WANG Zhen YI Zhonglai YANG Zhiqiang XIE Yongjiang Railway engineering research institute China Academy of Railway Science Corporation LimitedBeijing 100081China School of Civil engineering Beijing Jiaotong UniversityBeijing 100044China China Railway engineering design and Consulting Group Co. Ltd Beijing 100055China

By the addition of superplasticizer and air entraining agent,manufactured sand selfcompacting concrete(MS SCC)with slump flow varying from 500 to 700 mm and air content varying from 2.0%to 9.0%were prepared and the pumpability of MS SCC was studied by a sliding pipe rheometer(Sliper).According to the Kaplan’s model,the initial pump pressure and the pump resistance of MS SCC were ***,rheological properties including the yield stress and the plastic viscosity of MS SCC were measured by a *** experimental results show that the increase of slump flow contributes to a higher pumpability and a proper air content,i e,6%is beneficial for the pumpability of MS *** to the existence of stone powder and stronger angularity of MS,the initial pump pressure of MS SCC is only about 60%-88%that of river sand(RS)SCC with the same slump flow and air content,indicating that MS SCC possesses a higher pumpability than RS SCC.

关键词： manufactured sand self-compacting concrete pumpability sliding pipe rheometer rheology

Seismic collapse simulation of existing masonry buildings with different retrofitting techniques

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Earthquake engineering and engineering Vibration 2021年第1期20卷 127-139页

作者： Ge Dongdong Du Chunbo Miao Qisong Chen Xi College of Architecture and Civil engineering Beijing University of TechnologyBeijing 100124China Key Laboratory of Earthquake engineering and engineering Vibration Institute of Engineering MechanicsChina Earthquake AdministrationSanhe 065201China beijing institute of Architectural design Beijing 100045China

Masonry buildings are primarily constructed out of bricks and mortar which become discrete pieces and cannot sustain horizontal forces created by a strong *** collapse of masonry walls may cause significant human casualties and economic *** maintain their integrity,several methods have been developed to retrofit existing masonry buildings,such as the constructional RC frame which has been extensively used in *** this study,a new method using precast steel reinforced concrete(PSRC)panels is *** demonstrate its effectiveness,numerical studies are conducted to investigate and compare the collapse behavior of a structure without retrofitting,retrofitted with a constructional RC frame,and retrofitted with external PSRC walls(PSRCW).Sophisticated finite element models(FEM)were developed and nonlinear time history analyses were carried *** results show that the existing masonry building is severely damaged under occasional earthquakes,and totally collapsed under rare *** retrofitting techniques improve the seismic performance of existing masonry ***,it is found that several occasional earthquakes caused collapse or partial collapse of the building retrofitted with the constructional RC frame,while the one retrofitted by the proposed PSRC wall system survives even under rare *** effectiveness of the proposed retrofitting method on existing masonry buildings is thus fully demonstrated.

关键词： existing masonry structure seismic retrofit collapse simulation PSRCW nonlinear time history analysis