降雨入渗对边坡性状影响的模型实验研究

通过构建不同坡角边坡物理模型分别进行人工模拟降雨实验,对坡体进行分层监测。采用自动水份传感器测定坡体不同位置处含水率;用光纤传感器测定坡体内不同深度处应变;用压力盒测定坡体前端不同深度处推力。得到在降雨入渗作用下边坡性状的变化规律:①边坡坡体含水率、坡前推力、坡体变形在降雨期增大,雨后随时间逐渐减小。②受降雨入渗作用影响,土体含水率增长由坡面开始逐渐向下发展,坡体表层附近的含水率变化最大,底层变化最小。坡前推力、坡体变形在坡体深度方向上,由浅入深受降雨影响逐渐减弱,即表层受影响最大,底部受影响最小,这解释了降雨诱发的均质土坡破坏容易出现在浅层的原因。③受相同降雨条件的影响,20°坡角边坡模型产生变化较大,但响应较晚,而10°坡角边坡模型产生变化较小,但响应较早。

Influence of rainfall infiltration on slopes by physical model test

By constructing physical models for slopes with different slope angles and experimentizing under artificial rainfall, variations of the slopes are monitored by layers continuously. The water content of the soil measured by water sensors buried in different places of the slope and the strain at different depths of the slope determined by optical fiber sensors are obtained, and the pressures at different depths at front end of the slopes are measured by pressure cells. The varation of monitored indexes of the slopes are obtained as follows: ①The water content of the slope, the pressure at front end of the slope, the strain of the slope body increase under the rainfall, and decrease with time after rainfall. ②Under the rainfall, the water infiltrates from the slope surface to the bottom; the greatest change of water content appears nearby the slope surface and the least change appears nearby the slope bottom; the influence of rainfall on the pressure at front end of the slope and the strain of the slope body gradually decrease with the increasing depth of the slope, that is, the influence near the surface layer is the largest, and that near the bottom layer is the least. It can explain why the failure of homogeneous soil-slope induced by rainfall is easy to occur in shallow layers. ③Under the same rainfall, the variations of the slope model with the slope angle of 20°are larger and occur relatively later; the variations of slope model with the slope angle of 10°are smaller, and occur relatively earlier.