降雨作用下堆积体滑坡物理力学参数沿高程演化规律研究

Laws of evolution of physico-mechanical parameters along the elevation of landslides under the effect of rainfall

摘要

降雨是引发山体滑坡的主要因素之一。为研究降雨对堆积体滑坡物理力学参数的影响，以我国西部地区堆积体滑坡为研究对象，制作室内堆积体滑坡物理模型，通过模拟典型降雨效应，在堆积体物理模型的不同高程取样，进行渗透和直接剪切试验，研究了堆积体的矿物含量、孔隙率、渗透系数和抗剪强度参数等物理力学参数沿着高程的演化规律。结果表明：降雨结束后，坡表顶部的孔隙率是坡表底部的2.2倍，代表河沙、黏土等细颗粒的矿物SiO₂与Al₂O₃的含量增加了约7%与3%;堆积体渗透系数、内摩擦角均随着高程的增加逐渐增大，而黏聚力c值则表现出相反的规律，逐渐降低；坡表的渗透系数、内摩擦角和黏聚力与坡体内部相比，其变化幅度更加明显。结合参数的定量变化规律分析和试验过程的现象观察，表明在降雨的径流与渗流作用，促进了堆积体的细颗粒向坡体的低高程处发生了迁移与堆积。研究过程和结果对降雨条件下堆积体滑坡的稳定性分析具有重要意义。

Abstract

To investigate the impact of rain on the physical and mechanical components of accumulation body landslides, a physical model was created in the western of China. Rainfall is a primary factor in such landslides. By simulating typical rainfall effect, samples were taken at different elevations of the accumulation body physical model, and permeability and direct shear tests were carried out. The evolution of mineral content, porosity, permeability coefficient and shear strength parameters along the elevation are analyzed in detail. The results show that the porosity at the top of the slope surface is 2.2 times that at the bottom of the slope surface, and the content of SiO₂ and Al₂O₃ representing fine particles such as river sand and clay increases by about 7% and 3%.The permeability coefficient and internal friction Angle of accumulation body increase gradually with the increase of elevation, but the c value of cohesion shows the opposite law and gradually decreases. The permeability coefficient, internal friction Angle and cohesiveness of slope surface change more obviously than that of slope interior. Combined with the quantitative analysis of parameters and the observation of phenomena in the test process, it is shown that the runoff and seepage of rainfall promote the migration and accumulation of fine particles to the low elevation of the slope. The research process and result are of great significance to the stability analysis of accumulative landslides under rainfall conditions.

关键词

降雨作用 / 堆积体 / 物理模型试验 / 高程 / 参数演化

Key words

rainfall effect / accumulation body / physical model test / elevation / parameter evolution