Research on the Meso-mechanism of the Evolution of Wet - swelling Cracks in Expansive Soil based on Discrete Element Method

In order to study the crack evolution law of expansive soil caused by wet - swelling under rainfall conditions, the water migration model corresponding to the heat conduction equation is derived based on the heat conduction theory. Based on PFC, a discrete element numerical model of wet - swelling deformation of expansive soil under the coupling action of humidity and stress is established. The Meso-mechanism of the evolution of wet - swelling cracks is revealed, and the influence law of model parameters on crack development is analyzed. The research found that rainfall infiltration leads to slight wet - swelling deformation of the shallow surface. As rainfall continues further, the surface wet expansion deformation significantly expands to the deep soil layer. However, the depth of soil layer affected gradually stabilizes, and slight uplift and cracks appear in the shallow soil layer. Eventually, multiple through cracks are formed in the foundation and the ground surface significantly uplifts. At the same time, the adjustment of model parameters such as permeability coefficient, tensile strength, elastic modulus and expansion coefficient has a significant impact on cracks development. The research results can not only be used to avoid the problem of expansive soil characteristics, based on the influence of model parameters on the development of cracks, suggestions for foundation improvement of weak expansive soil are put forward, the modification and improvement of engineering foundation provides an important theoretical reference.