Expansive Soil Slope Stability Analysis With Unloading Effect

Expansive soil is a kind of highly plastic clay, because of its special expansion and contraction, it may cause serious problems, such as landslides, Uneven Settlement of Foundation, etc. In the research of expansive soil slope, the researchers seldom pay their attention to slope instability refer to slope excavation. On the basis of the predecessors’research results and through theoretical analysis, The paper came to the conclusion that the unloading effect of confining pressure in the excavation of the expansive soil slope is an important incentive for expansive soil slope instability. In order to prove this inference, the paper selected typical expansive soil in Hefei, Anhui Province and did research on the mechanical properties of the soil under the condition of loaded and unloaded. Through the design of being unloaded triaxial compression experiment, the paper got the mechanical parameters of expansive soils, The results showed that:compared with the conventional stress path tests, the intensity of the expansive soil is lower under the influence of confining pressure. By a preliminary analysis, the cause is that in the being unloaded procession, the expansive soil releases part of its swelling stress and thus the soil intensity is reduced. At the same time, this paper selected the engineering software to obtain the slope safety factor under different soil parameters. The result shows that intensity decrease of the soil under the influence of confining pressure will reduce the slope safety factor. Together with the fissures on the soil surface, they will cause the Fs of the slope been greatly reduced. Finally, in accordance with the foregoing findings, this paper qualitatively discussed the main features of expansive soil slope reinforcement.