Changes in water chemistry and loess porosity with leaching: implications for collapsibility in the loess of North China

Abstract

The concentrations of ions and suspended particles in the percolation water varied in relation to the initial chemical composition of the samples. Some of the loess produced especially high concentrations of sodium carbonate in the leachates, inducing very basic pH and enhancing the dispersion of the micro-aggregates. Both dissolution and dispersion processes favour the changes occurring in the structure of the loess. SEM studies showed an enlargement of fissures and a more compact intergrain fabric in the leached samples. The formation of dominant drainage paths increases the heterogeneity of the material as well as the collapsibility of the loess, so contributing to slope instability. -from Authors