强降雨下元磨公路典型工程边坡稳定性研究

STABILITY ANALYSIS OF YUANMO HIGHWAY SLOPE UNDER INTENSIVE RAINFALL

根据饱和非饱和降雨入渗有限元模拟技术和非饱和土强度理论,研究考虑非饱和区强度变化及饱和区渗透力影响的降雨过程边坡稳定性强度折减分析法。将此方法应用于元磨公路K261段典型滑坡体工程边坡,进行降雨过程边坡变形情况及稳定性变化分析。分析结果表明:在强降雨条件下,地表水入渗将直接导致非饱和区范围缩小、压力水头升高及局部暂态饱和区出现;考虑非饱和区强度变化及饱和区渗透力影响,降雨入渗时边坡稳定性将明显下降;现实施的抗滑桩、预应力锚索等加固结构对提高工程边坡稳定性有重要作用,但目前边坡稳定程度仍处于较低的安全裕度状态;连续降雨同时存在地震的极端条件,边坡可能再次失稳滑移。加强坡面防渗坡体排水对提高边坡稳定性具有重要作用。为确保工程边坡长期稳定,建议在6级工程边坡平台位置局部增设预应力锚索抗滑桩。

Based on the finite element method of saturated and unsaturated rainfall infiltrations and the strength theory of unsaturated soils, a strength reduction method of slope stability analysis was presented. The method could consider the influence of strength variation of unsaturated zone and seepage load in saturated zone. It was applied to the deformation calculation and stability evaluation for the engineering slope K261 of Yuanmo highway under the influence of precipitation. It showed that the range of unsaturated zone would decrease： the pressure water head would increase and the transient saturated zone would appear because of the strong rainfall. The factor of safety of engineering slope would obviously decrease due to the unsaturated zone strength decreasing and the load changing of saturated zone seepage. The engineering slope would be unsteady under the extreme condition of constant rainfall accompanied with seismic loading. Preventing rainfall infiltration from slope and draining of slope could improve the stability of engineering slope effectively. At the same time, some resisting slip piles are suggested to for the 6-grade engineering slope.