Evolution of lateral earth pressure and pore structure of expansive soil during swelling and consolidation

This study investigates and compares the evolution of the void ratio-vertical stress-lateral earth pressure (i.e., e-σ_V-σ_L) relationships and pore structure of an expansive soil following three hydromechanical paths, namely the swelling-under-load (SUL) path, constant-volume (CV) path, and swell-consolidation (SC) path. It was demonstrated that (i) the e-σ_V and σ_V-σ_L relationships show piecewise-linear and hysteretic characteristics when σ_V is less than 400 kPa. The e-σ_V-σ_L relationships obtained from different paths become identical when σ_V exceeds 400 kPa; (ii) the σ_V required to suppress the lateral swelling pressure is much higher than that required to restrain the vertical swelling strain, which indicates that simply restraining the swelling strain is not adequate to eliminate the swelling potential; (iii) the e-σ_V-σ_L relationships of different paths show consistency and can be reasonably fitted by a simple model; (iv) the pore structure of specimens following different paths becomes identical under σ_V of 700 kPa, which corroborates the convergence of the e-σ_V-σ_L relationships under high σ_V. Under σ_V less than 400 kPa, specimens following the SC path exhibit greater stress sensitivity in macropores, while those following the SUL path show higher stress sensitivity in micropores. These contrasting sensitivities of the macro- and micropores govern the differences in the e-σ_V-σ_L relationships.