Abstract
A seepage failure problem of a piece-wise homogeneous sand column subjected to a vertically upward seepage flow is treated theoretically from the standpoint of design of a loaded filter (or an effective overburden pressure of a loaded filter) which is placed on the top of the sand column. Specifically, a five-layered sand column which is a typical example of the general multi-layer case is considered. The critical state chart for seepage failure of the five-layered sand column is obtained by using an analytical method developed by the authors. This chart indicates almost all the information about seepage failure of the sand column : the mode of failure of the sand column, the stability of the sand column in its critical state, the state within the sand column, the effects of a loaded filter, the safety factor for seepage failure of the sand column, and so on. Thus it is concluded that, in a seepage failure problem of a piece-wise homogeneous sand column (or, in design of a loaded filter which is placed on the top of the sand column), to obtain the critical state chart of the sand column is most important.
