A Study On Rainfall Affect To The Stability And Engineering Properties Of Sliding-body And Sliding-zone Soil

Study of unsaturated soils are still in development stage,it is not enough mature, Now it through tests to improve the theory is a trend, Many scholars and experts have proposed a more comprehensive formula based on the tests, but some formula is still not easy using in engineering applications.The residual-slope deposits of soil have the nature of a non-saturated soil and widespread at Ailaoshan of Yunnan Province.The rainy season each year, As the rainfall infiltration, soil water content to change, resulting in the shear strength of soil degradation and some of the occurrence of shallow landslides in this region. In this paper take the soil of a landslide at Ailaoshan for studying, using the theory of unsaturated soil, By triaxial tests,to investigate the similarities and differences in law of the shear strength parameters about the landslide sloping-body and sliding-zone soil with the change of soil water content. On this basis, analysis the stability of the landslide due to the infiltration of rainfall produced by three different working conditions, further clarification of rainfall infiltration on landslide stability.Triaxial test results show that:When the water content of less than plastic limit moisture content, the stress-strain showed a peak form of softening. But when the water content greater than plastic limit water content, the stress-strain curves show the form of hardening. At 15% strain range, the sample was pressed only a short thicker, bulging phenomenon occurs.With the increase of moisture content, the strength parameters c andφof the sliding-body and sliding-zone soils have a tendency to diminish, while the change of strength parameters about sliding-body is more obvious. But for the same moisture content, the strength of sliding-body soil is larger than the sliding-zone soil.Analysis of the experimental data shows that:the change of moisture content, the cohesion of sliding-body and sliding-zone soil is better fit to the exponential function c=AeBw,and the internal friction angle is better fit to quadratic functionφ=α+βw+ψw2.The analysis of stability about the slope of 10%,13%,17% moisture content with Geo-slope software. The results show that:as the rainfall infiltration, the moisture content has increased, in the course of increasing about moisture content The trend of attenuation about landslide factor of safety is similar as the change of the shear strength, further explanation of rainfall infiltration on slope stability.