Seepage Flow Analysis of Cofferdam in Deep Overburden Foundation

Abstract

Seepage problem is of great importance to the stability of the soil dams in deep overburden foundation which is composed of coarse-grained soils. With a discussion on the relationship between particle size distribution and seepage law of the coarse-grained soils, Darcy's law was applied to simulate the seepage flow process of the deep overburden foundation of the Wudongde project. The variational inequality approach of the Signorini's type was used to solve the seepage field of the cofferdam site to eliminate the singularity at the seepage points. The result illustrates that the seepage control system composed of a concreted cutoff wall and geo-membrane sloping wall exhibits perfect performance under normal operation conditions. The differences of the seepage field characteristics under different hydraulic conductivities combinations of overburden layers were discussed. Finally, stabilities under different operation situations were evaluated with linear and nonlinear analysis with a consideration of the effects of seepage process.