Numerical simulation of water content dependent undrained shear strength of clays

A nonlinear mathematical model for estimating the water content dependent undrained shear strength of clayey soils was developed. Three types of clay mixtures (kaolinite, bentonite, and kaolinite-bentonite) were considered. The shear strength of the given soil samples was determined via torvane tests. Experimental results were compared with three numerical results: (i) the analytical function fit, (ii) modeling without the water content effect, and (iii) modeling with the water content effect using the Mohr-Coulomb (M-C) model. There was good agreement among the experimental, analytical, and numerical results with and without the water content effect in the fully softening zone. However, there was a large difference between the numerical results obtained from the developed model with and without the water content effect in the flow zone with a high liquidity index, because the shear strength may decrease significantly to low value in the case of an abrupt increase of the water content. The greatest advantage of the developed model is that it can simulate the reduction of the shear strength and shear band development under the high water content condition, which may trigger a large mobile mass movement.