Study On Distribution Characteristics Of Earth Pressure On Retaining Wall Under Over-consolidation Based On Particle Flow Code

Natural slope or artificially excavated and filled roadbed is often reinforced by retaining wall.Excavation and unloading or excessive compaction of the soil behind the retaining wall will change the stress state of the soil,resulting in the change of the lateral pressure of the soil.When the backfill of the wall is over-consolidated,the earth pressure acting on the back of the wall decreases.If the shear strength index of normal consolidated soil is still used to calculate the earth pressure during the design.The economy will be reduced under the condition of ensuring safety.Therefore,it is necessary to study the effect of over-consolidation fill on the earth pressure of retaining wall,which is an important factor to determine the reasonable and economic design of retaining wall structure.In this paper,model test and particle flow numerical simulation are used to study this problem.There are the following aspects of work:(1)In this paper,the influence of over-consolidation ratio on the shear strength indexes c andφof the clay was studied by laboratory triaxial test.The relationship between the two indexes was fitted with formula.The fitting results showed that the values of c andφincreased logarithmically with the increase of over-consolidation ratio.(2)In this paper,the active earth pressure distribution,earth pressure resultant force and the action point of resultant force of the backfill under different over-consolidation states were studied by model tests under the modes of translational movement(T),rotation around the bottom of the wall(RB)and rotation around the top of the wall(RT).Comprehensively consider the safety and economy of the retaining wall,and provide a certain reference for the selection of various parameters in the design process.(3)This paper established the biaxial compression test of flexible boundary by particle flow code,and the effective modulus and stiffness ratio that affect the macroscopic deformation parameters of the soil were calibrated by comparing the stress-strain curves of laboratory triaxial tests.On this basis,the effects of bond strengthτ_c and friction coefficientμon the macroscopic strength characteristics of the material were studied.The quantitative relationship between the macroscopic strength parameters c andφand the meso-parameters of friction coefficientμand bond strengthτ_c is established.The quantitative relationship between the over-consolidation ratio and meso-parameters was further established based on the relationship between c,φand over-consolidation ratio obtained from laboratory tests.(4)According to the quantitative relationship between the over-consolidation ratio of soil and the meso-parameters of particles,a numerical model of the retaining wall with different over-consolidation states was established.This paper researched the soil displacement field,contact force chain and contact force direction of the retaining wall under three basic displacement modes and under different over-consolidation states of the fill.According to the displacement field of the fill,the geometry of the potential slip surface and the variation of the angle between the slip surface and the horizontal plane under each working condition can be inferred.