降雨条件下松散堆积体边坡稳定性离心模型试验研究

Centrifugal modeling tests on stability of deposits slope under rainfall

采用新型介质雾化喷嘴离心场降雨模拟设备,进行了模拟降雨及格栅支护措施条件下松散堆积体边坡的离心模型对比试验。离心机模型与原型试验比尺为1:80,试验过程通过非接触定点高速摄影系统并结合粒子图像测速(particle image velocimetry)技术分析了试验过程中边坡的位移场变化。试验结果表明,松散堆积体边坡在未降雨条件下是十分稳定的;在进行模拟降雨后,边坡顶部沉降及坡面水平位移随降雨量的增大逐渐发展,尤其边坡表面区域发生明显变形;边坡的破坏模式有别于传统的圆弧滑动,在持续强降雨作用下,坡面逐层产生破坏,最终形成泥石流形态;通过采取坡面土工防护格栅支护条件后,堆积体边坡在降雨条件下稳定性显著提高,故采用边坡防护格栅是提高松散堆积体边坡稳定性的有效途径。

In this study, a new media atomizing nozzle was adopted by rainfall simulation equipment for centrifugal model tests. Three comparative tests were conducted to simulate the behaviors of the deposits slope under the conditions of the rainfall and grid support. The scale of the centrifuge model to prototype was selected as 1：80. The displacement field of deposits slope was measured by a high-speed flash photography system, which had characteristics of non-contact and fixed-spot and was combined with program of particle image velocimetry （PIV）. It was found that deposits slope was very stable without rainfall, but with increasing rainfall time, the settlement at top of slope and the horizontal displacement at surface of slope were both enlarged. Particularly, obvious deformation was observed on the surface of slope. Under continuous intensive rainfall, the slope failure mode was different from the traditional circular slide, since the slope failed layer by layer until a ‘debris flow’ was generated. However, the stability of the slope was significantly enhanced once protective geogrids were applied. Thus the application of geogrid supports efficiently improve the slope stability under rainfall conditions.