Simulation Of The Development Process And Stability Of The Plastic Belt Of Coarse-grained Soil Slope

The unstable failure of soil is closely related to the expansion of plastic belt.The simulation and experimental study of plastic belt will help to understand and explain the progressive failure of slopes,which of great significance and influence on reveling the failure of slopes.In this paper,the model test and numerical simulation are conduct to explore the law of instability for coarse-grained soil slope at limit state,and the model test of the expansion of plastic belt is also researched.Depending on these researches above,this paper analyzes the stability of slopes,and the conclusions are as follows:(1)Based on the self-developed tank,some experiments are carried out to investigate changes of the plastic belt in coarse-grained soil slope.The experiments record the forms of slope slide and the displacements of key points at limit state.At the same time,the width,the stress and strain data of the plastic belt is effectively supervised and collected.These experimental data shows some characteristics of the plastic belt,which mean the process of plastic belt is gradual.In other words,the change starts before the peak of stress-strain curve,and the plastic belt forms after the peak.In addition,the slip type of failed slope is a combination of straight-line segment and arc segment.(2)Some relevant parameters that influence the plastic belt are studied.On the basis of experiments and the finite element method,this paper conducts numerical analysis of the effects caused by variations of the cohesion,internal friction angel,gravity of soil and particle diameter on the width and position of the plastic belt,so that acquires influences of the soil strength parameters and finds that there may be relation between the area of plastic belt changes and slip types at failure state.Furthermore,the width and the time that the plastic belt comes about are related to the soil particles.With smaller soil particles,the start time is earlier and the width is more narrower.(3)Combined limit equilibrium strict solution method with strength reduction FEM,the numerical simulation of plastic belt is performed.It analyzes the internal connection the plastic belt has,with ultimate bearing capacity and critical slip surface,which are the factors of influencing the slope stability.The position of critical slip surface and the differences of ultimate bearing capacity within and outside the plastic belt show that changes of the plastic belt is significant to control the stability of slopes.The slip of doesn’t appear on one surface,but with some thickness,which meets the experimental phenomena well and indicates that the plastic belt is vital to the slope stability.