坝坡外水体对土坝坝坡稳定性的影响分析

Analysis on influence of foreign water on dam slope on slope stability of earth dam

针对某土工膜斜墙坝在运行期由于泄洪、暴雨、坝体排水不畅、土工膜缺陷渗漏等原因导致的浸润线上升、下游水位上涨等情况,分析了坝坡外水体对坝坡稳定的影响。计算分别采用简化Bishop法和有限单元应力法,其中简化Bishop法通过静水压力法和置换容重法对坝坡外水体进行考虑。分析结果表明:由于浸润线上升和下游水位上升两者的共同作用,最小安全系数会随着出逸点的升高而减小,但考虑到上下游水位差减小,最小安全系数减小的速率会越来越慢。坝坡外水体对坝坡稳定的影响有利有弊,应合理利用。

Aiming at some problems of a geomembrane inclined core - wall dam such as rise of saturation line and downstream water level, which is induced by flood discharge, rainstorm, poor drainage in dam body and leakage of geomembrane, we study the influence of foreign water on dam slope on the slope stability by methods of simplified Bishop and FEM. For the simplified Bishop method, the foreign water on dam slope is simulated by hydrostatic pressure method and replaced unit weight method. Due to coupling effect of rise of saturation line and downstream water level, the minimum safety coefficient of dam body decreases with rise of overflow points, however, the decreasing rate of the minimum safety coefficient eases down because the water head differ- ence of upstream and downstream becomes smaller. It is noted that the influence of foreign water on dam slope on the slope stabil- ity has both adverse and favorable effects, so we should utilize the characteristics reasonably.