Experimental investigation of the collapsibility of loess subjected to water invasion

Loess is widely distributed in China and it is commonly considered as the problematic soil due to its collapsibility subjected to the water invasion. The microstructure plays an important role in the mechanical properties of the loess soil. In this note, the microstructures of intact loess samples and the inundated loess sample were investigated by using both mercury intrusion porosimetry (MIP) and nuclear magnetic resonance cryoporometry (NMRC). It is observed from the results of both MIP and NMRC tests that the intact loess has a multi-model pore size distribution function while the inundated loess has a unimodal pore size distribution function. As the coefficient of collapsibility (δ_s) is a key parameter commonly used for the evaluation of the engineering properties of the loess, the δ_s of the specimens tested under different conditions was measured. Subsequently, a new multi-variable linear model was proposed for the estimation of δ_s from the index properties based on the results of factor analyses. The estimated results of δ_s from the proposed model show good agreements with the measured data.