Abstract: Quantifying pore water pressure, a stress acting on the space among soil particles, is of essential significance for investigating the shear strength and other mechanical properties of soil. Traditional calculation method for pore water pressure neglects the influence of fluid flow and flow rate change on pore water pressure in soil, which results in a small calculation result. In view of this, a formula between pore size and fractal dimension of soil granular material is derived based on number-size fractal model of soil to correct the error, and the functional relationship between pore water pressure and fractal dimension, pore water compression modulus and pore flow change of saturated soil is further deduced based on pore water flow equation and pressure equation. A saturated clayey soil slope is taken for numerical analysis to verify the accuracy and practicality of the proposed calculation formula. Result demonstrates that the formula can be used to calculate and revise the effective stress and shear strength of saturated soils, and to analyze the macro-micro multi-scale liquid-solid coupling seepage of saturated soils.

Key words: saturated soil, pore water pressure, fractal model, porosity, measuring sphere, seepage analysis