Based On The Interaction Of Water And Soil Slope Stability Analysis

An important factor of the landslide occurring is the seepage field varying in landslide body. On the one hand, the shear strength index of soil is reduced by the seepage field change; on the other hand, the stress field within slope is also directly impacted by the seepage field change, so the landslide is induced. From the start with the seepage field analysis to consider water level rapid fluctuations in slope, this paper conducted a series of studies.1. The derivation of three-dimensional saturated and unsteady seepage equation is strictly conducted; the initial conditions, the boundary conditions and the finite difference solving format are given. Then the seepage field which considers water level rapid fluctuation in slope is analyzed by calculates an example and gains some laws: the movement of saturation line in slope lags behind the reservoir water level fluctuation, showing concave on rising, convex on the decline, and the saturation line become steeper at more close to slope face; the distribution of flow velocity is higher at the steeper saturation line, is slower at the moderate saturation line; the distribution of pore pressure in slope cope with the height of saturation line (or free water surface).2. The expression of infiltration volume force is inferred, which is a function of hydraulic gradient. Based on strength reduction principle, and using the finite difference software FLAC-3D to carry out numerical simulation to homogeneous and anhydrous slope. Discuss the four kinds of limit state criterion, and analyze the sensitivity of slope stability to parameters, show that the shear strength parameter is most sensitive factor. Using a case simulated the trend of slope stability evolution of which considers water level rapid fluctuation in slope. The results show that: the safety factor changes with time is increase-down type and the safety factor changes with water level embody down-increase type during water level rising, and all behave down-increase type during water level dropping down, the condition of water level dropping down is most adverse factor to slope stability.3. The soil and water interaction mechanism is systematically analyzed, then establish the mathematical model and compare to Biot consolidation theory. For the same example, numerical simulation is carried out by use coupled and uncoupling calculation method. The results show that: the Cryer effect is generated in shallow slope body during the early term of water level sudden jump, so the pore pressure is higher than uncoupling and effective stress is lower than uncoupling. With the dissipation of excess pore pressure and stress field impact on permeability, the distribution of pore pressure gradually lags behind the uncoupling, effective stress difference gradually decreased. The Cryer effect is also generated in shallow slope body during the short time of water level sudden drop; pore pressure does not decrease but increase and quickly dissipate. The decreasing of pore pressure lag behind uncoupling, effective stress is higher than uncoupling at the initial stage, and the differences gradually decrease with time.4. For the same example of water level rapid fluctuations, numerical simulation is carried out by use coupled and uncoupling calculation method, and compare with the uncoupled results. The results show that: the safety factor of coupled calculation is lower than uncoupled calculation in process of the water level quickly rising, but the safety factor of coupled calculation is higher than uncoupled calculation in process of the water level fast decline.