Experimental study on the disintegration mechanism of consolidated purple soil in Three Gorges Reservoir area of China

Purple soil is widely distributed in the Three Gorges Reservoir area of China, and the disintegration characteristics of this soil play an important role in the formation and development of various geological disasters. A series of laboratory disintegration tests were conducted to study the disintegration mechanism of consolidated purple soil. The test results show that fine flaky or granular soil particles peeled off from the soil surface. The disintegration velocity showed a decreasing trend when water content was between 12 and 28%. The average disintegration velocity decreased significantly with increase in water content, and low water content had a significant effect. Increasing the consolidation pressure effectively restrained soil disintegration when the water content was less than or equal to 16%, but the effect was opposite when the water content was high. The main reasons for the disintegration of purple soil can be summarized as the dissolution of cementitious material, the water absorption and expansion of montmorillonite, the increase of thickness of the electric double layer and pore water (gas) pressure.