Abstract: Based on the condition of one selected weathered granite obtained from the subgrade of expressway, “single line” wetting deformation test is conducted by applying the GDS unsaturated triaxial apparatus, in which the stress path of weathered soil is close to the actual one. During the test, the wetting behaviors of the weathered soil under various confining pressures and stress levels are investigated. The data collection throughout the whole experiment includes the stress-strain curves and the axial strain-volume strain curves of the weathered soil before and after the wetting test. The results show that there are axial strain and volume strain in the process of wetting; moreover, the anisotropy occurs after the wetting deformation. When under the same initial effective confining pressure, the shear strength indices c and ? are similar at different wetting stress levels. Compared with the dry sample, the cohesion of wet sample reduces significantly; however, the internal frictional angle has little change. Under a lower initial effective confining pressure, the volume deformation of the sample changes from shear shrinkage to shear dilatation when the axial strain reaches about 10%. However, the similar phenomenon does not appear under a higher initial effective confining pressure.

Key words: weathered granite, wetting deformation, shear strength