Mechanical behaviour of disintegrated carbonaceous mudstone under stress and cyclic drying/wetting

摘要

Seasonal rainfall causes a carbonaceous mudstone embankment to undergo cyclic drying/wetting. The soil mass inside the embankment is within a mechanically loaded and soaking environment, which results in a significant degradation of the shear strength of the soil and excessive deformation. Herein, to study the deformation and shear strength characteristics of disintegrated carbonaceous mudstone (DCM), a new type of wetting deformation test device was developed. Wetting deformation tests were carried out on the basis of an orthogonal experimental design, and direct shear tests and computed tomography (CT) scans were then conducted on the wetting deformed specimens. The test results show that the DCM exhibits a large vertical deformation at the time of the initial loading and water infiltration, termed compressive deformation and wetting deformation, respectively. The change in the shear strength during the wetting deformation is mainly due to the change in cohesion. The shear strength decreases sharply and then tends to stabilize with the increasing vertical deformation. The results of CT scans reveal that the changes in the shear strength and deformation of the DCM are associated with changes in the pore structure inside the specimen. (C) 2021 Elsevier Ltd. All rights reserved.