2006 Volume 46 Issue 5 Pages 595-604
It is important to estimate the seepage properties of unsaturated soils when performing an unsaturated-saturated seepage analysis, which is used to clarify the slope failure mechanism and predict the occurrence time of slope failure due to rainfall. Kitamura et al. (1998) proposed a numerical model to quantitatively estimating the seepage properties of unsaturated soils. And they have compared numerical results with laboratory soil tests in order to examine the validity of the numerical model. Consequently, it has been found that the numerical model must be improved moreover. In this paper a practical numerical model for seepage behavior of unsaturated soil is proposed to improve the previous model proposed by Kitamura et al. (1998). Firstly, the basic theories of the previous model are explained. Calculation results are compared with those obtained from the laboratory soil tests in order to examine the validity of the previous model. Then, we perform some improvements of the previous model based on hydro-mechanical properties, and propose a new parameter, named “parallel translation index (Ipt)”. From the results we showed that the relationship between the new parameter and the uniformity coefficient (Uc), expressed by logarithm is linear relation. Therefore, the reasonable seepage properties of soils can be computed from the improved numerical model using only the popular soil parameters.
