双层结构堤基渗透变形发展过程的数值模拟

通过算例采用分时段稳定流理论模拟了基于临界水力坡降的流砂动态发展过程，建立了双层结构提基发生流土的完整井流砂和半球形井底流砂物理模型。提基发生渗透变形而形成的集中渗漏通道，将自涌砂口沿垂直堤轴方向发展，并在平面上自涌砂口到河床不断扩大，在深度上不断加深。通道的规模取决于涌砂口的流量大小和水位高低，尤其在较低水位时通道规模将最大。减压井在降低了井附近水头的同时也加大了水力坡降，从而更易发展渗透变形，因此应特别重视减压井的反滤层设计和施工，以使土体保持在原位而不致发生渗透变形。

Numerical simulation of osmotic deformation progress of dyke foundations of double-layer structure

A physical model has been established on quick sand of complete wells and at the bottom of semi-spherical wells for dyke foundations of double-layer structure, and the dynamic progress of quick sand based on critical hydraulic gradient is simulated in calculation examples by using the time-division stable flow theory. The concentrated permeation channel resulted from osmotic deformation in the dyke foundation will develop from the sand gushing opening along the vertical axis of the dyke, and keep on expanding in horizontal direction from the opening to the river bed, with increasing depth. The size of the channel depends on the flow and water level at the sand gushing opening, and in particular, maximum channel size is possible at low water level. A relief well can lower the head in its adjacent area, but at the same time increase the hydraulic gradient, thereby making it more likely to develop osmotic deformation. Therefore special attention should be paid to the design and construction of the reversed filter of the relief well, so that the soil body can be kept at the original position without causing osmotic deformation.