典型平推式滑坡水力分布规律及启动机理研究

Study on hydraulic distribution law and start-up mechanism of typical translational landslide

平推式滑坡形成于近水平岩层中,地下水对平推式滑坡的启动和运动过程影响非常显著。为揭示平推式滑坡滑动面上水力分布与滑坡启动的相关性,以成都市狮子山滑坡为地质原型,自主研制试验设备,进行水力测试试验,测试近水平倾角(0°~10°)条件下,底滑面两种不同连通条件下不同位置的水压力,研究底滑面承压水压力分布规律及启动机理。结果表明:①底滑面渗流条件较差或滑坡前缘堵塞条件下,水压力分布呈现梯形分布;流通条件下,水压力在底滑面方向上呈曲线下降,自后缘至剪出口下降速率先增大后减小,底滑面倾角越增大,下降速率变化越显著。②层间裂隙水扬压力值比传统采用三角分布形式的扬压力值小约27.6%。③薄层状泥岩的软化、变形是滑坡启动的根本原因;暴雨情况下底滑面扬压力和后缘裂隙中高水压下的水平推力联合作用将滑体推出是滑坡启动的直接原因。研究结果对平推式滑坡的稳定性分析评价和治理方案确定具有一定参考和借鉴价值。

Translational landslides occur in nearly horizontal strata and groundwater plays a crucial role in their initiation and subsequent movement.This study aimed to explore the correlation between the hydraulic distribution on the shear plane and the initiation of the landslides.Using the Shizishan Landslide in Chengdu City as a geotechnical model,a bespoke apparatus was developed for hydraulic testing.The experiment measured the hydraulic pressure at various points along the base sliding plane of nearly horizontal angles from 0°to 10°,under two penetration conditions,to investigate the distribution pattern of hydrostatic pressure.The outcomes revealed that:①Under poor permeability on a bottom sliding plane or the landslide's front was obstructed,the hydraulic pressure exhibited a trapezoidal distribution.Conversely,under free-flow conditions,the hydraulic pressure decreased in a curvilinear pattern along the basal sliding plane,with the decreasing rate first ascending and then slowing from the rear to the front.The steeper the angle of the basal sliding plane,the more notable the decreasing rate change.②Hydraulic uplift pressure in interlayer fractures was found to be around 27.6%less than the pressures calculated using traditional triangular distribution models.③The softening and deformation of thin layers of mudstone were the root causes of landslide initiation.Specifically,the trigger for landslide initiation was the result of intense rainfall causing uplift pressure on the bottom and high-pressure water within the rear-edge fractures,which worked in tandem to thrust the landslide mass.These findings can offer an important reference for the stability analysis,assessment,and remediation plans for translational landslides.