In order to explore the micro-mechanism of the macroscopic strength deterioration of cracked soil under the influence of dry-wet cycles, we carried out triaxial tests(CU) of cracked soil specimens under different cycles. At the same time, combined with the results of SEM microscopic test. a quantitative analysis of the mechanical strength reduction law and multiple microscopic parameters of the cracked soil is conducted. Based on the microscopic parameters such as the area probability distribution index, the content of micro-cracks, and the orientation probability entropy of the different dry and wet cycle stages, a multivariate nonlinear prediction model of the initial elastic modulus of the sample after the cycle is established based on the multivariate nonlinear regression. The results of the study show that high confining pressure can effectively close the initial micro-fractures, and the highest initial elastic modulus drops under high confining pressure and low confining pressure are 27.87% and 83.7%respectively. With the increase in the number of wet and dry cycles, the directional arrangement of particles and pores tends to be significant. In addition, the total number of pores presents a fluctuating trend, indicating that there is a repeated state of closure-through-particle refilling and closure during the dry-wet cycle. Meanwhile, we performed regression analysis on the micro-cracks content and the elastic modulus, and the results showed that the optimal model of the relationship between the micro-cracks and the elastic modulus is a quadratic model.
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