基于PFC^(2D)软件的柿树沟泥石流运动过程数值模拟

Numerical Simulation of Movement Process of Shishugou Debris Flow Based on PFC^(2D)

为了解泥石流的启动及运动过程,以栾川县柿树沟泥石流堆积体为例,基于堆积体室内大型直剪试验指标,利用PFC2D模拟软件对其启动及运动过程进行仿真数值模拟,分析了不同工况下堆积体的运动速度场、应力场及位移场,研究了崩滑松散碎屑堆积物质启动、形成泥石流的过程和机制。结果表明,强降雨是柿树沟沟内松散堆积体启动形成泥石流的触发因素;中雨工况下,地表径流的冲刷力仅对堆积体表层有影响,但堆积体整体形态基本无变化;暴雨工况下,泥石流沟上游的洪水迫使土石颗粒脱离堆积体表面,后缘表层土体首先开始运动,产生的推挤力不断推动前方堆积土体向前运动,坡面形态发生显著变化;暴雨时间越长,堆积土体的运动速度和位移也越大,最终导致堆积体发生连锁式破坏,形成泥石流。

In this paper,the accumulation body of Shishugou debris flow in Luanchuan City was taken to be research object.Based on the intensity parameters of accumulation body by the large-scale direct shear experiment,the program PFC2 Dis applied to make numerical simulation to study the happened mechanism and movement process of debris flow in Shishugou by analyzing the velocity field,stress field and displacement field of the accumulation body.The results show that the heavy rainfall is the trigger factor for formation of debris flow due to the movement of accumulation body in Shishugou;under the condition of moderate rain,the surface runoff only has impact on the surface of accumulation body,which has a stable state;under the conditions of heavy rain,the particles start to break away from the surface of accumulation body;the pushing force produced by the trailing edge of the surface soils of accumulation body,which moved firstly,push the front accumulation soils moving forward constantly,which results in the surface morphology of accumulation body to change significantly;the longer the heavy rain is,the greater the movement speed and displacement of accumulation body are,which eventually leads to formation of debris flow in Shishugou.