Study on the Prevention Effect of Seepage Failure with Suspended Wall

Abstract

To simulate the dual subsoil layers foundation of levee on the middle and lower reaches of Yangtze River which always present with shallow relative impermeable layer and thick permeable layer, a new kind of seepage box has been conducted indoors for simulating seepage field of the dual subsoil layers foundation. The seepage prevention scheme has been designed to study the seepage prevention function on the effect of seepage failure prevention for the suspended seepage prevention wall. The different kinds of impermeable materials and the different depth of suspended wall are used to check the effect of suspended seepage prevention wall. The following conclusions are inferred from the testing results: (1) It is equivalent in seepage prevention function by two different kinds of materials of suspended seepage prevention wall. Generally, clay grouted cut-off wall is economical and convenient for construction. However, impermeable suspended seepage prevention wall such as concrete wall is safer and more stable for the higher flood control standard area. (2) The seepage prevention function of suspended seepage prevention wall increases obviously the increase of the depth of wall. However, the depth is not needs too much for the control of the development of seepage failure. BACKGROUND ENGINEERING AND EXPERIMENTAL DESIGN The water level is much higher than the ground behind the river bank along the middle and lower reaches of Yangzi River and many other rivers in China. The subsoils of the bank foundation have the typical kind which is called Dual Structure. The dual structure is that a clayey soil is located at the top and a thick sandy soil is covered by the clayey soil as shown in Fig.1. The sandy soil is usually contacted with river water at river bed. And there are leakages through the cover clayey soil in the behind of the bank. When the water level of the river goes up, the seepage failure may be occur from the leakages and developing through the sandy soil to the direction of river bed. The design of the experimental equipment is simulated this kind of dual structure bank foundation as shown in Fig.2. During the test, the upside water level can be changed to simulate the change of the water level of the river. There are several out