Slope Stability Analysis of Dhaka Chittagong Highway at Feni Section Considering Soil-Water Interaction

Abstract

The stability of a soil slope is governed by slope geometries, stress conditions, and soil properties. External water loading, pore-pressure changes, and hydrodynamic impact from water flow are factors being either influencing, or completely governing the actual soil properties. This thesis focuses on slope stability analysis of a highway road embankment section considering impact of water level fluctuation on the stability of slope due to which soil water coupling occurs and also considering the variation in dimension of slopes. In these analyses we have done our numerical analyses with the Finite Element Method computer program named FEMtij-2D. The finite element method needs additional information regarding the potential performance of a slope but just basic parameter information is needed when we using traditional methods. A distinction should be made between drained and undrained strength of cohesive materials. Shortly, drained condition refers to the condition where drainage is allowed, while undrained condition refers to the condition where drainage is restricted. Most likely the worst case scenario occurs when the deposited water level is increased rapidly, and then the water table in the embankment is retained on an extremely high level so that the low effective stresses might lead to failure. Though, improved accessibility of high computer capacity allows for more and more advanced analyses to be carried out. In this study, advanced approaches used for soil water coupling in FEM-modeling of slope stability, were evaluated. A real slope section consisting of a well graded post-glacial till was exposed to a series of water-level fluctuation cycles. The evaluation was carried out by comparing results concerning stability, vertical displacements, pore pressures, flow, and model-parameter influence.