深厚复杂覆盖层上高土石围堰三维渗透稳定性分析

以某大坝深厚复杂覆盖层上的高土石围堰为例,运用三维渗流有限元理论及3D-seep计算软件,研究了围堰防渗墙的设计深度,研究发现单纯依靠增加防渗墙的深度并不能解决基坑渗流问题,也不经济,因此建议同时对左右岸岩体进行帷幕灌浆防渗处理。其次以帷幕防渗处理后左右岸岩体的绕渗流速与防渗墙底部的绕渗流速相等的原则,研究确定了帷幕灌浆的宽度。之后又对左右岸岩体和防渗墙的渗透系数进行了敏感性分析,得出左右岸岩体和防渗墙的渗透系数是敏感性参数,若能减小其渗透性,基坑渗流量将会明显减小。最后给出了推荐的围堰防渗方案,并对推荐方案的合理性进行了分析研究。

Three-dimensional seepage stability analysis of high earth-rock cofferdam built on complex layer of deep coverage

The finite element theory of three-demensional seepage and 3D-seep calculation software were used to analyze a high earth-rock cofferdam based on complex layer of deep coverage. The design depth of impervious wall of cofferdam was studied firstly. It was found that simply relying on increasing the depth of impervious wall could neither solve seepage problem of pit, nor economic. Therefore, curtain grouting arranged on both sides rock of upstream cofferdam was suggested at the same time. Based on the principle of seepage velocity of both side rock equal to seepage velocity of bottoms of impervious wall after curtain grouting, the width of curtain grouting was determined secondly. Sensitivity analysis was carried out for permeability coefficient of both side rock and impervious wall thirdly. It was shown that permeability coefficient was the sensitivity parameter, if permeability coefficient is reduced, seepage of pit will be significantly reduced. Finally, impervious measure of cofferdam was recommended.