Meso-structural change of remolded expansive soils during wetting-drying cycles and triaxial soaking tests

In order to study the production and closure rules of cracks of expansive soils, tests of wetting and drying cycles are carried out for remolded expansive soils under non-confined condition,and CT triaxial soaking tests under certain confining pressure and deviatoric stress are then conducted. The results indicate that both the wetting and the drying of expansive soils can induce the production and closure of the cracks. In the triaxial soaking tests, the cracks tend to close, and the closure degree relates with the stress condition. During the soaking process, there are three distinct phases of volumetric change of samples, which decrease firstly, then increase rapidly under swell effect, and finally decrease with the release of expansive force and the reduction of modulus. Structural repair parameters are defined, and the evolution equation of structural repair in the triaxial soaking tests is proposed.