Determining Bishop'S Parameter Chi Based On Pore Size Distribution

Extension of the effective stress concept to unsaturated soils has been a major concern for decades. Recent studies significantly contributed to the understanding of the fundamentals behind Bishop's parameter. which is generally used to define the effective stress for unsaturated soils. Examination of the recently proposed methods showed that the contribution of suction to effective stress was often overestimated, especially in high suction range. In this study, considering that soil pores with different sizes contribute differently to the overall hydro-mechanical behaviour, a new method to determine Bishop's parameter. is proposed. The key variable used in this method is the ratio of the change in water volume to the change in macro-pore void volume due to loading at constant suction. Shear strength data for a weakly expansive clay were used for validation. A good agreement was obtained between prediction and measurement, indicating the validity of the proposed method.