接触带土层软化对排土场边坡稳定性的影响分析

针对排土场上部渣土层和下部基岩面接触处的软化接触带对其稳定性的影响问题,采用有限元极限分析法构建了含软化接触带的排土场边坡的数值模型,系统分析了堆填角度、基岩倾角、软化接触带厚度及软化度对排土场边坡稳定性的影响规律,并通过具体的排土场边坡实例验证了该分析方法的可行性。研究结果表明,同等条件下,接触带软化和堆填角度对排土场边坡稳定性的影响很大,而基岩倾角和接触带厚度的影响相对较小;随着接触带软化度的增大,排土场边坡下、上限安全系数的绝对衰减率可达50%左右;随着接触带土层的不断软化,排土场边坡滑动面穿过软化接触带的长度逐渐变大,滑坡总体积不断增大;因软化接触带土层的存在,排土场边坡中下部土体推挤坡脚前缘及牵引后部坡体滑动,最终形成由软化接触带到坡顶的贯通滑裂面。

Analysis on the Influence of Soil Softening in Contact Zone on Slope Stability of Soil Disposal Site

Aiming at the impact of softening contact zones between the upper waste and the lower bedrock on its stability, in this paper, the finite element limit analysis method was used to establish the numerical model of dump slopes with softening contact zones. And then the stability of dump slopes under different landfill angles, dip angles of bedrock, thicknesses of softening contact zones, softening degree was analyzed. At last the feasibility of this method was verified by a concrete dump slope. The results show that the softening of contact zones and the landfill angles have a great influence on the slope stability, while the dip angles of bedrock and the thicknesses of contact zones have a relatively small influence under the same conditions. With the increase of the softening degree of the contact zones, the absolute attenuation rate of the lower and upper limit safety factors of dump slopes can reach about 50%. With the continuous soil softening of contact zones, the length of sliding surface of the dump slope passing through the softening contact zones increases gradually, and the total volume of the sliding body increases continuously. Due to the existence of softening contact zones, the lower soil mass in the dump slopes pushes the front edge of the slope foot and pulls the back slope body to slide, and finally forms the through sliding surface from softening contact zones to the top of the slope.