基于物质点法的新磨村滑坡动力特性分析
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摘要
2017年6月24日,四川省茂县叠溪镇新磨村突发特大滑坡碎屑流灾害,造成大量人员伤亡及房屋损坏,针对该滑坡特征及成因机制,相关学者已经取得一定研究成果,然对其动力学过程与特征的认知还相对缺乏。为解决这一问题,本文引入兼具欧拉算法和拉格朗日算法优势,适用于大变形及长距运动模拟计算的物质点法进行模拟分析。通过分析滑坡全程位移时程曲线、速度时程曲线和等效塑性应变变化特征,揭示其动力演化过程。现场调查与模拟结果表明,崩滑体启动后呈整体运移,与下方坡体碰撞解体,转化为碎屑流,不同时刻同一位置的坡体形态、质点等效塑性应变发展趋势以及能量时程变化曲线均进一步反映碎屑流碰撞破碎和刮铲侵蚀的过程。数值模拟计算与Scheidegger提出的理论计算方法获得的碎屑流速度特征吻合,可以在一定程度上反映滑坡的致灾能力。模拟结果综合反映了滑坡启动及动力演化过程。
On June 24,2017,a tremendous debris flow disaster occurred in Xinmo village,Diexi town,Maoxian county,Sichuan province,China. Approximately 2. 87 × 10~6 m~3 rock mass collapsed and the debris buried Xinmo Village,causing a large number of casualties and damages to houses. On the issue of the characteristics and formation mechanism of the landslide,relevant scholars have obtained certain research results in their researches.However,scientific comprehension is relatively lacking about dynamic processes and characteristics of this landslide. This paper introduced two-dimensional material point method( MPM),which combines the advantages of Langrangian and Eulerian algorithm,and is applicable to simulate mechanics with large deformation,to clarify this phenomenon. In the MPM simulation,the kinematic processes of the landslide were revealed through the analysis of time evolution of motion,velocity profile and contour of effective plastic strain. The overall duration time of motion and travelling distance were consistent with reality. Moreover,the results of simulation also suggested that rock mass moved as a whole at startup stage,and then translated into debris flow soon as the result of intense collision. In addition,the results can further reveal the process of debris flow collision and scraper erosion by comparing the slope morphology,the equivalent plastic strain development trend and the energy time history curve on the same position at different times. It showed that two-thirds of gravitational potential energy exhausted in the above processes,which revealed the energy dissipation capacity of collision and erosion. According to crushing collapse dilatancy and entrainment in travelling,the final volume of debris flow was far more than the initial rock mass. Furthermore,slide velocity obtained from numerical computation was basically consistent with the results calculated by the method of Scheidegger. It can be seen that the simulation results provide comprehensive information on the initiation and the dynamic evolution of the landslide.
On June 24,2017,a tremendous debris flow disaster occurred in Xinmo village,Diexi town,Maoxian county,Sichuan province,China. Approximately 2. 87 × 10~6 m~3 rock mass collapsed and the debris buried Xinmo Village,causing a large number of casualties and damages to houses. On the issue of the characteristics and formation mechanism of the landslide,relevant scholars have obtained certain research results in their researches.However,scientific comprehension is relatively lacking about dynamic processes and characteristics of this landslide. This paper introduced two-dimensional material point method( MPM),which combines the advantages of Langrangian and Eulerian algorithm,and is applicable to simulate mechanics with large deformation,to clarify this phenomenon. In the MPM simulation,the kinematic processes of the landslide were revealed through the analysis of time evolution of motion,velocity profile and contour of effective plastic strain. The overall duration time of motion and travelling distance were consistent with reality. Moreover,the results of simulation also suggested that rock mass moved as a whole at startup stage,and then translated into debris flow soon as the result of intense collision. In addition,the results can further reveal the process of debris flow collision and scraper erosion by comparing the slope morphology,the equivalent plastic strain development trend and the energy time history curve on the same position at different times. It showed that two-thirds of gravitational potential energy exhausted in the above processes,which revealed the energy dissipation capacity of collision and erosion. According to crushing collapse dilatancy and entrainment in travelling,the final volume of debris flow was far more than the initial rock mass. Furthermore,slide velocity obtained from numerical computation was basically consistent with the results calculated by the method of Scheidegger. It can be seen that the simulation results provide comprehensive information on the initiation and the dynamic evolution of the landslide.
引文
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[16]许强,李为乐,董秀军.四川茂县叠溪镇新磨村滑坡特征与成因机制初步研究[J].岩石力学与工程学报,2017(11):2612-2628.[XU Qiang,LI Weile,DONG Xiujun.The Xinmocun landslide on June 24,2017 in Maoxian,Sichuan:characteristics and failure mechanism[J].Chinese Journal of Rock Mechanics and Engineering,2017(11):2612-2628]
[17]祁生文,许强,刘春玲,等.汶川地震极重灾区地质背景及次生斜坡灾害空间发育规律[J].工程地质学报,2009,(01):39-49.[QI Shengwen,XU Qiang,LIU Chunling,et al.Slope instabilities in the severest disadter areas of 5.12 Wenchuan earthquake[J].Journal of Engineering Geology,2009,(01):39-49]
[18]廉艳平,张帆,刘岩,等.物质点法的理论和应用[J].力学进展,2013(02):237-264.[LIAN Yanping,ZHANG Fan,LIU Yan,et al.Material point method and its applications[J].Advances in Mechanics,2013(02):237-264]
[19]BARDENHAGEN S,BRACKBILL J,SULSKY D.The materialpoint method for granular materials[J].Computer Methods in Applied Mechanics and Engineering,2000,187(3-4):529-541
[20]殷跃平,朱继良,杨胜元.贵州关岭大寨高速远程滑坡—碎屑流研究[J].工程地质学报,2010(04):445-454.[YIN Yueping,ZHU Jiliang,YANG Shengyuan.Investigation of a high speed and long run-out rockslide-debris flow at Dazhai in Guanling of Guizhou province[J].Journal of Engineering Geology,2010(04):445-454]
[21]SCHEIDEGGER A E.On the prediction of the reach and velocity of catastrophic landslides[J].Rock Mechanics and Rock Engineering,1973,5(4):231-236
[2]FAN X,XU Q,SCARINGI G,et al.Failure mechanism and kinematics of the deadly June 24th 2017 Xinmo landslide,Maoxian,Sichuan,China[J].Landslides,2017,14(6):2129-2146
[3]YIN Y,WANG W,ZHANG N,et al.The June 2017 Maoxian landslide:Geological disaster in an earthquake area after the Wenchuan Ms 8.0 earthquake[J].Science China Technological Sciences,2017,60(11):1762-1766
[4]FAN J R,ZHANG X Y,SU F H.Geometrical feature analysis and disaster assessment of the Xinmo landslide based on remote sensing data[J].Journal of Mountain Science,2017,14(9):1677-1688
[5]FAN X,X U Q,SCARINGI G.Brief communication:Post-seismic landslides,the tough lesson of a catastrophe[J].Natural Hazards and Earth System Sciences,2018,18(1):397-403
[6]OUYANG C J,ZHAO W,HE S M,et al.Numerical modeling and dynamic analysis of the 2017 Xinmo landslide in Maoxian County,China[J].Journal of Mountain Science,2017,14(9):1701-1711
[7]SCARINGI G,FAN X,XU Q,et al.Some considerations on the use of numerical methods to simulate past landslides and possible new failures:the case of the recent Xinmo landslide(Sichuan,China)[J].Landslides,2018
[8]TANG C L,HU J C,LIN M L,et al.The Tsaoling landslide triggered by the Chi-Chi earthquake,Taiwan:insights from a discrete element simulation[J].Engineering Geology,2009,106(1):1-19
[9]BEYABANAKI S A R,BAGTZOGLOU A C,LIU L.Applying disk-based discontinuous deformation analysis(DDA)to simulate Donghekou landslide triggered by the Wenchuan earthquake[J].Geomechanics and Geoengineering,2016,11(3):177-188
[10]SULSKY D,CHEN Z,SCHREYER H L.A particle method for history-dependent materials[J].Computer Methods in Applied Mechanics and Engineering,1994,118(1-2):179-196
[11]ANDERSEN S,ANDERSEN L.Modelling of landslides with the material-point method[J].Computational Geosciences,2010,14(1):137-147
[12]LI X,WU Y,HE S,et al.Application of the material point method to simulate the post-failure runout processes of the Wangjiayan landslide[J].Engineering Geology,2016,212:1-9
[13]刘凤山,吴中海,张岳桥,等.青藏高原东缘新构造与活动构造研究新进展及展望[J].地质通报,2014(04):403-418.[LIU Fengshan,WU Zhonghai,ZHANG Yueqiao,et al.New progress and prospects of neotec-tonics and active tectonics synthetical study on eastern edge Qinghai-Xizang plateau[J].Geological Bulletin of China,2014(04):403-418]
[14]QIU J,WANG X,HE S,et al.The catastrophic landside in Maoxian County,Sichuan,SW China,on June 24,2017[J].Natural Hazards,2017,89(3):1485-1493
[15]SU L,HU K,ZHANG W,et al.Characteristics and triggering mechanism of Xinmo landslide on 24 June 2017 in Sichuan[J].China.Journal of Mountain Science,2017,14(9):2
[16]许强,李为乐,董秀军.四川茂县叠溪镇新磨村滑坡特征与成因机制初步研究[J].岩石力学与工程学报,2017(11):2612-2628.[XU Qiang,LI Weile,DONG Xiujun.The Xinmocun landslide on June 24,2017 in Maoxian,Sichuan:characteristics and failure mechanism[J].Chinese Journal of Rock Mechanics and Engineering,2017(11):2612-2628]
[17]祁生文,许强,刘春玲,等.汶川地震极重灾区地质背景及次生斜坡灾害空间发育规律[J].工程地质学报,2009,(01):39-49.[QI Shengwen,XU Qiang,LIU Chunling,et al.Slope instabilities in the severest disadter areas of 5.12 Wenchuan earthquake[J].Journal of Engineering Geology,2009,(01):39-49]
[18]廉艳平,张帆,刘岩,等.物质点法的理论和应用[J].力学进展,2013(02):237-264.[LIAN Yanping,ZHANG Fan,LIU Yan,et al.Material point method and its applications[J].Advances in Mechanics,2013(02):237-264]
[19]BARDENHAGEN S,BRACKBILL J,SULSKY D.The materialpoint method for granular materials[J].Computer Methods in Applied Mechanics and Engineering,2000,187(3-4):529-541
[20]殷跃平,朱继良,杨胜元.贵州关岭大寨高速远程滑坡—碎屑流研究[J].工程地质学报,2010(04):445-454.[YIN Yueping,ZHU Jiliang,YANG Shengyuan.Investigation of a high speed and long run-out rockslide-debris flow at Dazhai in Guanling of Guizhou province[J].Journal of Engineering Geology,2010(04):445-454]
[21]SCHEIDEGGER A E.On the prediction of the reach and velocity of catastrophic landslides[J].Rock Mechanics and Rock Engineering,1973,5(4):231-236