深厚砂层坝肩绕坝渗流规律及防渗方案研究

为了研究深厚砂层坝肩绕坝渗流的规律,结合拟建的陕西省王圪堵水库土石坝工程,进行了左坝肩绕坝渗流的三维有限元分析,并以坝肩砂层渗透稳定为控制条件,进行了防渗墙延伸长度方案的比较研究,同时对传统的绕坝渗流计算方法水力学法所存在的问题进行了分析。结果表明,水力学法计算的绕坝渗流量结果偏小,据其进行防渗墙延伸长度方案的比较与选择缺乏理论依据;绕坝渗流沿河道方向的影响范围是有限的,主要影响发生在坝趾处的左岸坡上;随着防渗墙延伸长度的增加,坝趾处左岸横断面砂层的最大渗透坡降及出逸面的渗透坡降均逐渐减小;深厚砂层坝肩的绕坝渗流主要发生在砂层内,且随着防渗墙延伸长度的增加,砂层及左坝肩整体的绕坝渗流量均逐步减小,但差异不显著。

Finite element analysis of bypass abutment seepage in deep and thick sand layer

Three-dimensional finite element analysis of left dam abutment seepage is carried out based on a proposed earth dam in order to study the bypass seepage law of deep and thick sand layer.With the sand layer's seepage stability as control condition,cutoff wall extending length scheme is comparatively studied,and the problem in the traditional hydraulic method is also analyzed.The result shows that the dam bypass seepage quantity using hydraulic method is small,virtually the comparison and selection for cutoff wall extending length scheme is short of theory gist.The influence of bypass seepage is limited along the direction of river stream,but the effect on the left bank around the dam toe is great.With the increase of cutoff wall's extending length,maximum seepage gradient of sand layer and seepage gradient of exit surface gradually decrease in the cross section of left bank near the dam toe.Bypass seepages mostly occur in deep and thick sand layer of dam abutment,moreover with the increase of cutoff wall's extending length,bypass seepage quantity in sand layer and the whole left dam abutment gradually decreases,but without remarkable difference.