Microstructural changes of granite residual soil during humidification process

Abstract:

In order to explore the characteristics of microstructural changes of granite residual soil during wetting, the electron microscope scanning test was used to analyze the pore changes of the soil under unsaturated-saturated state by PCAS software to achieve quantitative characterization of the pore structure, and the three-dimensional fractal dimension characteristics were further analyzed by analyzing the T₂ of the soil under unsaturated-saturated state by nuclear magnetic resonance test. The research results show that under unsaturated state, with the increase of water content, the number of smaller pores decreases and the number of larger pores increases. In this process, small aggregates absorb coarse particles to expand and form larger aggregates; after reaching the saturated state, the aggregates disintegrate and show the opposite development trend; reaching the saturated state. Based on the transverse relaxation time (T₂), the pores can be divided into three categories: aggregate pores, intergranular pores, and microcracks. Among them, intergranular pores are most significantly affected by pore water, while aggregate pores and microcracks are less affected by pore water; the three-dimensional structural fractal dimension shows a decreasing trend with the increase of water content, and has an exponential function relationship with the water content. The study on the change law of microstructure during the wetting process of granite residual soil provides a theoretical basis for analyzing the initiation mechanism of mass landslides of granite residual soil. The microstructure evolution stage can be predicted by monitoring the changes in soil moisture content. The slope stability evaluation index can be established by combining the fractal dimension model, which provides a key criterion for early warning of granite residual soil landslides in the hilly areas of Fujian and Guangdong.