防洪堤稳定性的研究

Study on stability of embankment for flood control

首先对防洪堤浸润线以上土体进行了不同浸泡时间的浸泡试验 ,试验结果表明 ,土体的凝聚力随浸泡时间的增长大幅度下降 ,浸泡 5d后土体的凝聚力将下降 71 8% ,但浸泡不改变土体摩擦角的大小。通过等效超固结比 (循环前后土体平均有效应力的比值 )的概念 ,研究了动水作用下土体强度的循环弱化 ,为综合考虑动水循环荷载及浸泡作用对防洪堤稳定的影响 ,用简化毕肖普法对防洪堤稳定进行了计算 ,结果表明只考虑波浪(潮汐 )作用 ,防洪堤的安全系数降低幅度不大 ,但同时考虑浸泡作用 ,特别是长时间浸泡后 ,防洪堤的安全系数降低最大可达 2 0 %。

The soil of embankment above the saturation line is soaked in water to study the change of its behavior.It is found that the soil cohesive greatly reduces with the increase of soaking duration but the friction angle does not changed.The concept of over consolidation ratio is introduced to investigate the strength degradation of soil under the dynamic action of water.Simplified Bishop method is applied to calculate the effects of soaking and cyclic load respectively.The results show that the safety factor of embankment is slightly reduced under the action of wave but it will be reduced remarkably if the soaking is maintained for a long time.