Numerical analysis of groundwater flow through a rectangular cofferdam

In this study, finite element analysis of groundwater flow in a rectangular shaped cofferdam model has been performed by taking into account of anisotropic permeability of soil layer. The results of numerical analyses indicate that: (1) An increase in the horizontal permeability to vertical permeability ratio K_h/k_h(kh/kv) from 1 to 2 leads to an increase in the pore water pressure on the sheet pile and particularly in the flow rate into the cofferdam. (2) Maximum pore water pressure arises in the corner regions of the cofferdam. This can induce in seepage failure analyses that safety factors obtained from three-dimensional models are overestimated. (3) The values of pore water pressure and flow rate obtained from three-dimensional models are higher than those in two-dimensional model. The difference between the values obtained from 2D and 3D analyses decreases with increasing L/B ratio. The difference can be very important in the seepage failure analyses and to estimate the required number and capacity of pumps in square shaped cofferdams.