河流作用下堵江滑坡运动特征差异性研究

Study on the difference of movement characteristics of river blocking landslide under river action

【目的】水因素在滑坡灾前变形、运动解体、堆积过程中均发挥重要作用。从水力学角度,讨论河流流水对滑坡堆积、堵塞河道、形成堰塞坝的影响有重要减灾意义。【方法】基于2018年金沙江白格滑坡基础信息,聚焦有、无河流作用下滑坡运动演化过程中滑速、能量、形态特征差异,分别考虑白格滑坡处于无河流流水、有河流流水作用两种情况,开展了其运动过程的DEM模拟、CFD-DEM耦合模拟。【结果】根据计算捕获的速度、能量、形态等滑坡运动特征,量化揭示了河流流水对堵江滑坡的具体影响。【结论】研究发现:(1)河流流水影响下,滑坡体平均速度偏小,因河流影响的滑体部分较少,河流流速变化对滑坡体运动的影响较小且无明显规律;(2)动能和应变能在滑坡高速运动阶段受河流影响更明显,重力势能及能量损失在滑坡堆积阶段受河流影响更为明显,较无河流作用对白格滑坡应变能的影响最大,为1.80%。(3)河流对滑坡体形态特征的影响主要体现为最终纵向堆积长度的变化,滑坡计算启动后70 s,不受河流流水影响时,滑体纵向长度稳定在1.7 km,考虑河流流水影响下稳定在1.5 km,考虑河流影响下的模拟结果与实际情况较为吻合。

[Objective]The water effect often plays a vital role during the process of deformation,movement,and accumulation of a landslide.It is nesessary to study the influence of river flow on landslide accumulation,river blockage and dam formation,from the perspective of hydraulics.[Methods]This paper focuses on the differences of sliding speed,energy and morphological characteristics in the process of landslide evolution with or without the action of river.According to the basic data of the Baige landslide in 2018,the DEM simulation and the CFD-DEM simulation of the landslide are carried out to simulate the landslide movement considering the two cases without or with river effect,respectively.[Results]According to the calculation of veloci-ty,energy and morphological characteristics,the specific influence of river flow on the landslide is quantitatively revealed.[Conclusion]The result show that:(1)The river has a small influence on the landslide mass due to the relatively shallow river depth,and the river velocity has almost none influence on the landslide movement;however,the averaged velocity of landslide mass under river action is less than that under no river action.(2)The kinetic energy and strain energy are more obviously affected by the river in the high-speed movement stage of the landslide.The gravity potential energy and energy loss are more obviously affected by river in the landslide accumulation stage.The influence of river on the strain energy of Baige landslide is the largest,which is 1.80%.(3)The influence of the river on the landslide size concentrates on the sectional width;the sectional width under no river action varies near 1.7 km,while sectional width under river action varies near 1.5 km at 70 s after the slope failure.The simulation result considering the influence of river flow are in good agreement with the actual situation.