乌井水库坝体防渗墙对坝坡稳定的影响研究

增建防渗墙是一种常见的土石坝加固手段,目前,关于土石坝除险加固工程中增建混凝土防渗墙后是否对坝坡稳定产生影响的研究较少,工程设计上也很少考虑.为分析增建防渗墙对坝体的影响,采用有限元法建立数值计算模型,分析增建防渗墙前后坝体渗流、应力场变化规律,对比计算不同运行工况条件下的坝坡稳定情况.计算结果表明:增设防渗墙后,上游坝坡浸润线有所抬高,下游坝坡浸润线明显降低;墙前土体孔隙水压力大于墙后土体,墙后土体的有效应力大于墙前土体;增建防渗墙后上游坝坡的稳定安全系数减小,但减小的幅度不大,相比上游坝坡,增建防渗墙对于下游坝坡的稳定安全系数影响更显著,安全系数提升了近10％;水位骤降速度越大,上游坝坡稳定安全系数下降越快,骤降达到的最小坝坡稳定安全系数越小,对于坝坡的稳定越不利.

Study on the influence of anti-seepage wall of Wujing reservoir dam on the stability of the dam slope

The construction of additional cut-off wall is a common reinforcement method for earth rock dam.At present,there are few studies on whether the construction of additional concrete cut-off wall will affect the stability of dam slope in the risk removal and reinforcement project of earth rock dam,and there is little consideration for engineering design.In order to analyze the impact of the additional cut-off wall on the dam,a numerical calculation model is established by using the finite element method to analyze the variation law of dam seepage and stress field before and after adding the cut-off wall,and the stability of dam slope under different operating conditions.The calculation results show that after the addition of cut-off wall,the phreatic line of upstream dam slope rises and that of downstream dam slope decreases obviously;The pore water pressure of the soil in front of the wall is greater than that behind the wall,and the effective stress of the soil behind the wall is greater than that in front of the wall;The stability safety factor of the upstream dam slope decreases after the construction of the cut-off wall,but the reduction range is small.Compared with the upstream dam slope,the construction of the cut-off wall has a more significant impact on the stability safety factor of the downstream dam slope,and the safety factor has increased by nearly 10%;The faster water level sudden drops,the faster the stability safety factor of upstream dam slope decreases,and the smaller the minimum stability safety factor of dam slope reached by sudden drop,which is more unfavorable to the stability of dam slope.