降雨强度对双层软弱夹层边坡稳定性影响分析

Influence of rainfall intensity on stability of double-layer weak interlayer slopes

降雨入渗是导致滑坡灾害频发的关键因素,同时边坡岩体内存在的软弱夹层控制着岩体的稳定性。为揭示降雨入渗对双层软弱夹层边坡渗流及稳定性的影响规律,采用数值模拟不同降雨强度下边坡基质吸力和水的体积分数变化规律,并探究软弱夹层数量、降雨强度对边坡稳定性的影响规律。结果表明:对于降雨条件下含软弱夹层的滑坡,由于软弱夹层渗透性差,保水性强,易于泥化而强度大幅下降形成滑动带;降雨对双层软弱夹层边坡坡面基质吸力影响较大,降雨强度越大,基质吸力消散速率越快;当降雨总量恒定、软弱夹层位于滑坡中层时,降雨强度越强,软弱夹层数量越多,软弱夹层埋深越深,边坡变形越剧烈,边坡也越易从“稳定”状态转变为“不稳定”状态。

Rain infiltration is a critical factor in frequent landslides,and the existence of weak interlayers in slope rock mass controls the stability of rock mass.To reveal the effect of rainfall infiltration on the seepage characteristics and the stability of double-layer weak interlayer slopes,a numerical method is used to simulate the variations in matrix suction and moisture content of slope under different rainfall intensities and to explore the effect of number of weak interlayers and rainfall intensity on the stability of slopes.The results show that for landslide with weak interlayers under rainfall conditions,a sliding zone forms owing to poor permeability and strong water retention and great reduction in strength.Rainfall has a great influence on the matrix suction of double-layer weak interlayer slopes.The greater the rainfall intensity is,the faster the dissipation rate of matrix suction is.When the total rainfall is constant and the weak interlayer is located in the middle of the landslide,a stronger rainfall intensity,more weak intercalations,deeper weak intercalations,and a more intense slope deformation results in an easier transition from“stable”to“unstable”state of a slope.