One-dimensional consolidation of double-layered ground considering the initial hydraulic gradient

The seepage in saturated clays with low permeability disaccords with the Darcy law,and there exists the initial hydraulic gradient,which is ignored in the Terzaghi's consolidation theory.The one-dimensional consolidation equations considering the initial hydraulic gradient for double-layered ground are presented and solved by the finite difference method.The analytical results indicate that,for the soils with the initial hydraulic gradient greater than zero,the rate of consolidation is less than that by applying the Terzaghi's consolidation theory,and there exists some residual pore pressure which cannot be completely dissipated in the soil layers at the end of primary consolidation,therefore the ultimate value of average degree of consolidation is less than one.In addition,the consolidation coefficient is not the sole parameter of soil governing the behavior of consolidation of double-layered ground.Besides the permeability coefficient and the compressibility modulus,the initial hydraulic gradient and the ground pressure also play important roles in the process of consolidation.