The Effect of Hydraulic History on Shear Strength of Silt

Abstract

Weathering processes such as dry–wet (DW) cycles affect the hydromechanical properties of soils for earthen sites, in which significant proportions of the cross section could be influenced by climatic weathering, such as basal erosion of earthen sites. This study investigated the effects of the hydraulic history of silt samples that were subjected to nine DW cycles for ≤270 days on their mechanical properties. The results indicated that the proposed method of DW cycles was appropriate when determining soil strength profiles in earthen sites through soil column experiments. The mechanical properties of silt samples that were subjected to the same drying water content (w) under the same consolidation stress were significantly different when they had different hydraulic histories. When the wetting w was lower than the shrinkage limit, the silt in the upper soil layer that experienced lower wetting w generated a higher shear strength than samples that were not subjected to DW cycles. In contrast, silt samples in the lower soil layer that had been exposed to a higher wetting w than the shrinkage limit yielded a lower shear strength than the initial specimen. The hydraulic histories had a threshold effect on the strength profile of silt, where this was caused by the coupled effect of a stronger connection between its particles and the propagation of microcracks due to the DW cycles that intensified the heterogeneity of the strength profile of silt. These findings could help better understand basal erosion formation in earthen sites and protect our cultural heritage.