航运枢纽防渗措施优化*

姚家枢纽是钱塘江中上游衢江干流六级梯级开发的最后一级航运枢纽。针对枢纽强透水地基渗流控制问题开展三维渗流数值模拟分析，比较渗流控制措施的具体几何尺寸及其防渗效果，优化防渗形式，并预报防渗措施下的浸没、绕渗和渗漏。结果表明：地基粉细砂和砂砾石为主要渗透通道，易发生渗透变形，枢纽三维绕渗特征明显，两岸地下水水位较高，两侧边坡出逸位置较高。防渗墙水平长度越长，堤防坡脚处渗透坡降越小，但防渗效果随着延伸长度逐步降低，建议选取合理的防渗长度为400～600 m。防渗墙措施下下游边坡依然有出逸，需采取包括护坡反滤在内的多种防渗措施，提高渗透稳定性。

Optimization of seepage control for shipping hub

Yaojia shipping hub is the last downstream hub on the middle and upper reaches of Qiantang river main stream cascade development.In view of the seepage control of seriously permeable foundation,we carry out the 3-D seepage analysis,compare the geometry size of the cutoff wall and the anti-seepage effect,optimize the anti-seepage mode,and predict the immersion,shoulder seep and leakage.The results show that the fine sand and sandy gravel lay are the main leaking path,the feature of shoulder leak is obvious,the groundwater level at both banks and leak out height on slopes are high.The longer the horizontal length of the cutoff wall,the smaller the seepage gradient at the slope foot and the less obvious the anti-seepage effect. The length of cutoff wall is recommended to be no longer than 600 m.Leakage still exists on the lower side slope under the anti-seepage measures,so,various anti-seepage measures,such as inverted filter,shall be taken to enhance the seepage stability.