下咱日堆积体非饱和渗流与稳定性评价

Unsaturated seepage and stability analysis of Xiazanri accumulative body

暴雨作用下边坡的稳定性问题一直是工程上非常关心的复杂系统问题.通过非饱和渗流理论和改进的Bishop法,考虑非饱和带基质吸力和暂态附加水荷载等作用,利用Geo-Slope公司系列软件进行耦合分析,对梨园水电站下咱日堆积体进行稳定性评价.结果表明:降雨开始时,地表点基质吸力迅速降低,基质吸力降低的起始时间明显滞后于降雨的起始时间;暴雨强度越大,相同降雨历时各关键点处位移量越大,直至堆积体内超孔隙水压力完全消散,各关键点位移才基本趋于稳定;随着降雨持续,堆积体安全系数不断降低,雨后2~3d安全系数才达到最小值,之后由于坡体内基质吸力回升、抗剪强度增加,从而堆积体安全系数又有所增大.

The stability analysis of slope under heavy rain has always been a complex engineering problem of great concern.Taking into account the matrix suction of unsaturated zone and temporary additional water load,the coupling analysis conducted by Geo-Slope software and Bishop’s unsaturated seepage theory was applied to a large accumulative body at Liyuan hydropower station.The analysis result reveals that the matrix suction of nodes on the near-surface slope decreases rapidly at the beginning of rainfall,and the starting time of suction decrease obviously lags behind rainfall.Larger rainfall intensity results into greater displacement at each node under the same rainfall duration,until the complete dissipation of excess pore water pressure and constant development of displacement.As the rainfall continues,the safety factor of accumulative body gradually decreases to the minimum at 2-3 days of rainfall,followed by an important increase due to an evident rebound in suction and shear strength.