降雨条件下土体坡度及含水率对边坡稳定性影响的试验研究

通过对坡度分别为30°、38°、45°的3种土坡进行人工降雨试验,对沿坡面的5个等分观测点进行土坡滑动位移及含水率的观测,并在各土坡靠近坡面的相同位置选取土样进行UU三轴试验,测算出相应的粘聚强度,并对试验过程中采集到的数据进行分析处理,探究土坡滑动的影响因素之间的内在机理。试验结果表明,在试验研究的坡度及含水率范围内,土坡稳定性的影响因素间存在以下规律:坡度较小的土坡沿坡面各分观测点竖向位移变化较小,而坡度较大的土坡竖向位移变化较大,且在上中部位置下滑更为明显;坡体的泥流率与坡度之间存在线性关系,坡度越大,泥流率越大;坡面各分观测点的含水率整体水平与坡度有关,坡度越小,则降雨后含水率越大,且在坡面中下部位置处的含水率变化更大;同等含水率的情况下,随着坡度的增加,土体粘聚强度有增长的趋势。而对于同坡度的土坡而言,含水率越小,则粘聚强度越大。针对试验中发现的规律,通过数值模拟提出了试验降雨条件下“坡度-泥流率”、“坡面位置-含水率”和“含水率-粘聚强度”的关系式。

Soil slope and water content on soil slope stability influence experimental study under rainfall

The inner mechanism between the two influence factors of slope sliding was studied. The artificial rainfall experiments were carried out on three kinds of slopes with 30, 38 and 45 degree angles. Observations of the sliding displacement and water content of five fixed points along the slope surface, and UU triaxial test on soil samples were taken in the same location on the slope. The following rules were finally concluded within the slope and moisture content range of this study. The slope with larger gradient had comparatively longer vertical displacement, which was especially obvious in the upper and middle part of the slope. There was a liner relationship between the mud flow rate and the gradient. The larger the gradient was, the greater the rate of mud flow was. The total moisture level of fixed points related to the gradient. The greater the gradient was, the higher the water content was. The water content changed more greatly at the lower part of the slope. Under the same moisture condition, the soil cohesive strength increased with the gradient increasing. With the same gradient, the cohesive strength increased as the water content decreasing. Based on the above conclusions and numerical simulation test, the slope mudflow rate, the slope position moisture content and the moisture content cohesive strength relations were proposed under the rainfall test condition.