库水位等速上升中均质库岸塌岸现象及浸润线试验研究

Experimental study of homogeneous bank caving and phreatic line during uniform rising water level

为了研究库水位等速上升过程中均质水库岸坡的塌岸现象及岸坡内浸润线的变化特点,以取自三峡库区的含黏粒粉砂为主要试验土料,设计了3个不同结构的均质岸坡模型,对每个模型进行了4种不同速率的水位上升试验。试验结果表明,库水位上升速率越大,均质水库岸坡的塌岸现象越易发生;在库水位上升过程中,库水和地下水与岸坡土体的相互作用同时存在对岸坡稳定有利和不利的因素,其中地下水浸没区的毛细力消失是引起塌岸的关键因素;试验测得浸润线与理论计算结果的比较分析表明,浸润线的理论计算方法可能过高地估计浸润线的位置。

In order to investigate the homogeneous bank fall of reservoir and the changing features of the phreatic line during uniform rising water level,three homogeneous bank models with different structures are built with the sand containing little clay excavated from the Three Gorges Area;and four tests with different water level rising rates for each model are carried out.The model testing results indicate that the larger the rising water level rate,the more possible the bank fall.During rising water level,some factors advantaging or disadvantaging the bank stability may be induced by the interactions between the model soil mass and the ground water or reservoir water.In these factors,the vanishing of the capillary force induced by the rising water level is very important.The typical phreatic lines in the model slope obtained from the experiment are compared with those obtained from a published analytical solution.The comparison indicates that the published analytical solution may over-valuate the evaluation of the phreatic line.