Plastic Stability Approach for the Collapse Mechanism of Embankments

摘要

Generating a collapse mechanism and estimating the depth of the slip surfaces are the main problems in the design of embankments built on soft soils. The purpose of this study is developing a new embankment design method by estimating the failure depth and generating a collapse mechanism consisting of both embankment and soft subsoil. The main concern is to find the depth of the critical slip surfaces and this has been achieved by analyzing the foundation soils layer by layer and analyzing the stability of the embankment-subsoil system giving the most critical condition. Soil plasticity theorems and limit equilibrium analyses have been used to estimate the critical slip surface depth. The observations accumulated over the years indicated that, non-circular slip surfaces are more critical and realistic than circular slip surfaces during the failure of slopes and embankments. This consideration is the first step of the new method that has been developed in this study. Generally short-term conditions are more critical for embankments on soft soils because sudden implementation of loads may cause large increases in excess pore water pressures resulting in reduced effective stresses and thus shear strength. For modelling the short-term conditions, undrained loading has been used in the method and lower bound theorem of plasticity has been applied.