Effect of pore structure response on compressibility characteristics of a preloaded soft clayey soil under dry-wet cycles

Abstract

ABSTRACT The stabilization of soft ground is essential before construction, with preloading being a widely used mechanical method. This study investigates the combined effects of preloading and cyclic drying–wetting (D–W) on the pore structure and compression behaviour of soft clay. Remoulded specimens (0 kPa) and specimens preloaded to 50 and 200 kPa were subjected to one-dimensional consolidation tests. Pore structure evolution was examined using Scanning Electron Microscopy (SEM) and Mercury Intrusion Porosimetry (MIP). SEM revealed a transition from a flocculated, well-packed structure after the first D–W cycle to an open, porous fabric by the sixth cycle. MIP showed a shift from a weak bimodal to a unimodal pore-size distribution. After the first cycle, compressibility decreased by 4.2%, 20%, and 30% for 0, 50, and 200 kPa preloading, respectively, but increased substantially by the final cycle. The results indicate that repeated D–W cycles progressively diminish the benefits of preloading, highlighting its temporary effectiveness in soft-ground stabilization.