ACCUMULATION CHARACTERISTICS AND ENERGY CONVERSION OF HIGH-SPEED AND LONG-DISTANCE LANDSLIDE ON THE BASIS OF DEM: A CASE STUDY OF SANXICUN LANDSLIDE
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摘要: 高速远程滑坡-碎屑流运动速度、堆积特征和能量转化是研究其致灾机制的重要因素,而模型试验、野外调查并不能全面揭示其成灾机理。文章以三溪村滑坡为例,采用PFC3D离散元模拟方法,揭示滑坡运动过程中的前部、中部和后部岩土体的速度演化分布、堆积特征和能量转化关系。研究结果表明:三溪村滑坡的残余摩擦系数为0.2时,模拟结果与实际堆积特征一致。前部、中部、后部岩土体到峰值速度存在差异,前部岩土体速度分布表现为显著的单峰型特征,而后部岩土体速度分布为双峰型特征。滑坡不同部位的岩土体堆积呈现层序分布;滑坡重力势能的转化中,摩擦耗能占总能量的52%,动能峰值时刻仅有15%的重力势能转化为动能。研究结果可为高速远程滑坡的运动机理分析和防灾减灾治理工程提供重要参考。Abstract: The velocity, accumulation characteristics and energy conversion are important factors in the study of the disaster-causing mechanism of high-speed and long-stance landslide; however, model test and field investigation can't fully reveal the mechanism. In this study, the landslide in Sanxicun was simulated by PFC3D to reveal that the velocity evolution distribution, accumulation characteristics and energy conversion relationship of frent, middle and rear rock and soil during the landslide movement process. The results show that, when the residual friction coefficient of Sanxicun landslide is 0.2, the simulation results are consistent with the actual accumulation characteristics. When the front, middle and rear rock and soil achieve peak velocity, the time distribution is Sfront < Smiddle < Srear. The velocity distribution of the front rock mass shows significant unimodal characteristic, while that of the rear rock mass is bimodal. The accumulation of rock and soil mass presents sequence distribution. In the transformation of gravitational potential energy of the landslide, friction energy accounts for 52% of the total energy, and only 15% of the gravitational potential energy at the peak of kinetic energy is converted into kinetic energy. The research results can provide reference for the analysis of the disaster-causing mechanism of high-speed and long-stance landslide and the project of disaster prevention and reduction.
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表 1 数值模型微观参数
Table 1. The numerical micro-parameters of the PFC model
参数名称 单轴数值实验参数 微观参数取值 颗粒半径/m 0.0006~0.0015 0.975~2.437 球颗粒密度/(kg/m3) 2300 2300 球颗粒刚度比/(kn/ks) 1 1 球-球接触模量/GPa 1.48 1.48 平行粘结刚度比 1 1 球颗粒摩擦系数 0.677 0.1~0.4 平行粘结法向强度/Pa 6e6 6e6 平行粘结切向强度/Pa 6e6 6e6 正向临界阻尼比 0.22 0.22 切向临界阻尼比 0.2 0.2 -
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