Research On Slope Seepage Charactersitics And Stability Under Rainfall Infiltration

The rainfall is one of the main causes of sliding failure of slop. According to statistics, the sliding of slop occurred after the heavy rainfall or long period of rain. Obviously, there is a close relationship between slop sliding and rain infiltration. The saturated-unsaturated seepage field of slop is calculated .Meanwhile, the stability of slop is analyzed and the result is very important for predicting the sliding failure of slop under the conditions of rainfall. In this paper, the characteristics of seepage field are analyzed comprehensively under the conditions of rainfall, applying the saturated-unsaturated theory and rain infiltration theory. And it is known that the formation and variation of pore water pressure, volumetric water content, transient saturated zone under the conditions of rainfall. On this basis, the dynamic study of the stability of slop is carried out with the method of combining the finite element and the limit equilibrium. This paper focuses on the contributions of the rainfall intensity and rainfall duration on slop stability. So research efforts have been carried on in the aspects as follows:(1) The study of computing method of saturated-unsaturated infiltration. Based on the energy conservation law and Darcy's law, the saturated - unsaturated seepage equation is derived. At the same time, the transient saturated - unsaturated boundary conditions for calculation is studied, combining with the seepage theory. On this basis, according to the practical example, the numerical simulation model is established.(2) The study of rock infiltration coefficient. A lot of research shows that the saturated infiltration coefficient is very closely linked with the slope stability under rainfall. Through on-site water pressure test, the values of the saturated infiltration coefficient were studied. Through the porous and multi-stage tests, the saturated infiltration coefficient is calculated accurately.(3) The analysis of the infiltration characteristics of the transient seepage of slop under rainfall. In this paper, the different transient seepages of slop are calculated under the different rainfall intensity and different duration, applying two-dimensional finite element software. And the result is used to study the variation of pore water pressure, volumetric water content, transient saturated zone under the same condition. Especially the changes of pore water pressure and volumetric water content with the time and space are summarized and classified. It is very important for the analysis of the slop stability under rainfall.(4) The exposition of unsaturated shear strength theory and slope stability calculations. According to the conclusions of the transient analysis of slop, the slop stability is analyzed under rainfall. In the section, it focus on the influence of the slop stability and the changes of sliding surface under the conditions of different rainfall, different rainfall duration, different infiltration coefficients.