Abstract
The modeling of transient flow in unsaturated soils for rainfall-induced landslides using a novel spacetime collocation method is presented. A numerical solution obtained in the spacetime coordinate system is approximated by superpositioning Trefftz basis functions satisfying the linearized Richards equation for collocation points on the spacetime domain boundary. The Gardner exponential model is adopted to derive the linearized Richards equation to describe the soil-water characteristic curve in unsaturated soils. To deal with the rainfall-induced landslides, the infinite slope stability analysis coupled with the proposed meshless method with the consideration of the fluctuation of time-dependent matric suction is developed. The proposed method is validated for several test problems. Application examples of transient modeling of flow for rainfall-induced landslides in homogenous unsaturated soils are also conducted. Numerical results demonstrate that the proposed method is highly accurate to deal with transient flow in unsaturated soils for rainfall-induced landslides. In addition, it is found that the numerical method using the Richards equation with the Gardner model may provide a promising solution for different soil textures.
Highlights
In recent decades, global climate change impacts have increased the frequency of severe meteorological phenomena such as heavy rainfall events [1, 2]
For the modeling of transient flow in unsaturated soils, we proposed a pioneering work based on the proposed boundary-type meshless method and utilized the spacetime coordinate system instead of that in the original Euclidean space [10]
Since the proposed spacetime collocation method is advantageous in solving problems of irregular geometry, the third verification example is the twodimensional transient subsurface flow problem in homogenous unsaturated soil enclosed by an irregular boundary
Summary
Global climate change impacts have increased the frequency of severe meteorological phenomena such as heavy rainfall events [1, 2]. Due to the flexibility in solving practical problems involving complex geometry and boundary conditions such as tidal fluctuation which is usually difficult for finding the analytical solution, meshless methods have attracted considerable attention recently [26, 27]. Because the boundary-type meshless method is originally developed to deal with the boundary value problems in Euclidean space, the study of transient flow in unsaturated soils for rainfall-induced landslides using the proposed method has not been reported yet. To deal with the rainfallinduced landslides, the infinite slope stability analysis coupled with the proposed meshless method with the consideration of the fluctuation of time-dependent matric suction is developed. The formulation of the proposed method is described as follows
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