江河大堤堤基砂砾石层管涌破坏危害性试验研究

江河大堤中下游堤基双层地基中下层渗透系数k>0.02cm/s的砂砾石土层居多数,这是一种管涌型土。研究了双层地基中这类土管涌破坏后的危害性,结果表明管涌破坏的后果,将在砂砾石层上部形成纯砾石的渗流通道,细颗粒的带出程度可达80%～100%。细料含量小于20%时带出程度可达100%,土骨架的结构不会产生明显变化,但渗流通道的渗透系数变为纯砾石的渗透系数,显著增大;细料含量大于20%时,渗流通道形成后将影响上部土层的稳定性。

Destructive tests on piping failure of sandy gravel layer of river dikes

The sandy gravel layer at the lower part of the double foundation of river dikes is dominant, its permeability coefficient is larger than 0.02 cm/s, and it is a kind of piping material. The destructive tests on piping failure of this material are performed. Experimental results indicate that the seepage passages occur at the upper part of the sandy gravel layer, and the percentage of fine particle carried out reaches 80% to 100%. When the percentage of fine particle is smaller than 20%, it reachs 100%. The structure of soil skeleton doesn’t change, but its permeability coefficient becomes larger. When the percentage of fine particle is larger than 20%, the seepage passages will affect the stability of the upper layer.