Effect of principal stress direction during consolidation on the shear strength properties of natural granite residual soil

Abstract

In numerous real-life civil engineering practices, including multi-stage embankment construction and foundation pit excavation, the direction of the major principal stress σ1 becomes rotated. In these cases, the granite residual soil may be subjected to inclined consolidation (IC) with σ1 being inclined, because of the relatively high permeability as a result of the fissures formed during weathering. While the effect of the σ1 direction during the shear on the strength of granite residual soil (inherent strength anisotropy) has been primarily established, little is known about how the soil strength is affected by the direction of σ1 during consolidation. This paper presents the effects of IC on the shear strength properties of natural granite residual soil through undrained hollow cylinder torsional shear tests. The effect of the soil structure is also considered by testing remolded soil specimens. The results reveal that while IC changes neither the shape of stress–strain curve nor the specimen features at failure, it leads to an increased ultimate shear strength in terms of both the undrained strength and stress ratio, with the remolded soil being more affected. The presented data provide new insights into the understanding of residual soil strength behaviors.