A novel equation for determining the suction stress of unsaturated soils from the water retention curve based on wetted surface area in pores

A novel equation is proposed for the evaluation of the suction stress of an unsaturated soil. The equation, based on the assumption that suction is transmitted to soil solid particles only through their wet external surface, allows to easily derive the soil suction characteristic curve from the water retention curve. The proposed equation has been verified against published experimental data of suction stress smaller than 1 MPa for soils of various characteristics. In all cases, an excellent agreement between predicted and observed values of suction stress is achieved, showing that the proposed equation performs better than other currently adopted expressions for the evaluation of soil suction stress. Key Points: A novel equation for soil suction stress is proposed The proposed equation fits experiments better than other used equations The proposed equation allows to calculate effective stress of unsaturated soils