Stability of sheet-pile walls subjected to seepage flow by slip lines and finite elements

Stability of sheet-pile walls is often very sensitive to seepage flow. In the presence of seepage flow, the reduction in passive pressure on one side and increase in active pressure on the other side of the wall increase the risk of the instability that may precede instabilities due to piping or ground heaving. In this research the earth pressure behind sheet-pile walls in granular soils is studied. The flow field is computed by the finite-element method and the slip lines (stress characteristics) method is utilised to compute the associated stress field required to compute the effective passive pressure. The same finite-element mesh and interpolation functions are used to solve the flow field and to interpolate the seepage forces in the stress field solved by the stress characteristics method. Comparisons are made to verify the numerical results with those values available in the literature; these show reasonable agreement. The stability of sheet-pile walls is then analysed for a number of different problems with varying geometries and boundary conditions. These different geometries and boundary conditions are expressed in terms of non-dimensional factors and results are plotted.