Numerical study of the effect of soil–atmosphere interaction on the stability and serviceability of cut slopes in London clay

The stability of cut slopes is greatly influenced by seasonal pore water pressure variations under the combined effect of rainfall and vegetation. However, predicting soil-atmosphere interaction is not straightforward, due to the complexity of both the boundary conditions involved and the hydro-mechanical behaviour of soils, which is coupled and highly nonlinear, rendering the use of numerical tools, such as finite element analysis, necessary. The paper discusses the numerical modelling of soil-atmosphere interaction and presents the analysis of a slope cut in London clay in a highly vegetated area. The whole life cycle of the slope is considered with phases of low and high water demand vegetation and vegetation clearance. The analysis results indicate that dense vegetation is associated with high factors of safety, but may induce large differential displacements which are likely to affect the serviceability of the slope. Vegetation clearance, however, may initiate instability, highlighting the need for effective vegetation management in order to achieve a balance between serviceability and ultimate limit states. Although the case considered is representative of South East England, it introduces the necessary tools for realistic numerical analysis of soil-atmosphere interaction