含砾土坡坡面降雨和坡脚浸泡模型试验研究

降雨是诱发边坡失稳的重要因素，为此开展了含砾量分别为10%，20%和40%的含砾土坡的坡面降雨和坡脚浸泡的模型试验。利用体积含水率和吸力传感器测试了含砾土坡的水土特性，观测了边坡湿润锋的发展过程，利用PIV技术研究了边坡的位移变形过程；通过控制坡脚水位及坡顶后续加载研究了坡脚浸泡作用下土坡的沉降变形规律。试验结果表明:降雨条件下，含砾量越高，土坡坡面侵蚀发育越缓慢，边坡的细粒土越容易达到完全饱和状态；坡土饱和后，含砾量10%的土坡主要以坡面侵蚀和变形为主，不易发生整体破坏，含砾量20%和40%的坡土均发生了整体滑移破坏。坡脚浸泡过程中，含砾量越高，边坡变形量越小，在水位下降过程中基质吸力恢复越快，在浸水过程中边坡吸力丧失范围越小。在坡脚浸泡及后续坡顶加载作用下，含砾量10%的土坡会产生较大变形，含砾量20%的土坡最容易发生破坏，含砾量40%的土坡稳定性良好。

Model tests of gravel soil slope under rainfall and slope toe immersion

Landslide disaster is the main geological disaster faced by China at present, and rainfall is an important factor to induce slope instability. The model tests of rainfall and slope toe immersion on gravel soil slope with 10%, 20% and 40% gravel contents were conducted. The soil and water parameters of gravel soil slope were tested by volume moisture sensor and suction sensor. The development processes of wetting front of slope were observed. The displacement and deformation characteristics of slope were studied by PIV technology. By controlling water level and loading conditions, the law of settlement and deformation of soil slope under slope toe immersion was studied. The results showed that under rainfall condition, the higher the gravel content was, the slower the erosion development of the slope surface was, the easier the fine-grained soil of the slope to reach full saturation state was; after slope soil was saturated, the strength decrease of slope soil with 20% gravel content was the most, and the slope was most likely to have the disposable integral damage; the surface of soil slope with 40% gravel content was destroyed first, then the slope shoulder began to slide, which caused the large-scale sliding failure of the whole slope; the soil slope with 10% gravel content was mainly eroded and deformed in slope surface; slope erosion and deformation were the main variation of soil slope with 10% gravel content, less prone to overall damage. During the immersion of slope toe, the higher the gravel content were, the smaller the deformation of the slope was, the better the drainage characteristics of the slope was, and the faster the matrix suction recovery was during the water level decline; the lower the gravel content was, the larger the suction loss range of the slope was in the process of slope toe immersion. Under the action of slope toe immersion and slope top loading, soil slope with 20% gravel content was most vulnerable to failure; soil slope with 10% gravel content would produce large deformation; soil slope with 40% gravel content had good stability.