堤基渗流无害管涌试验研究

Experimental study on harmless seepage piping in levee foundation

在室内水槽中进行几何比尺1∶20及1∶40的堤基渗流引起的管涌试验,论证了双层地基粉细砂层发生管涌通道时影响大堤安全的水平渗流临界坡降平均值为0 1左右。试验结果表明,管涌与砂层厚度、砂层顶面接触糙度、出口水头损失、堤前冲深以及砂基结构性质等有关,管涌有害与否与沿程承压水头分布的不断调整和渗流量变化密切相关。文中还讨论了模型比尺问题。

The piping in levee foundation due to seepage was studied experimentally in laboratory. Two models with scale 1∶20 and 1∶40 were used. It is found that the critical horizontal seepage gradient in fine sand layer of stratified foundation endangering the safety of levee is 0.1 in average. The occurrence of seepage piping is dependent on the thickness of sand layer, roughness of top contacted surface, head loss at the exit, scouring depth in front of levee and sand layer structure.The danger of piping is related to the adjustment of pressure head distribution along the seepage path and variation of seepage flow rate.The scale effect in model study is also investigated.