Numerical Simulation Analysis Of Soil Arching Effect Of Piled Embankment Based On Limit Equilibrium Theory

Piled-supported embankment is a new type of embankment developed in the soft soil area,mainly composed of embankment fillings,pile caps and foundation soil.The stress traits are more complicated.Under the action of the upper embankment,the soil settlement at the top of the pile is lower than that between the piles.There is a relative displacement between the two.This relative movement trend is limited by the shear stress.The exertion of the soil shear stress increases the pressure acting on the top of the pile and reduces the pressure on the foundation soil.This kind of load transmission mechanism is called "the soil arching effect".At present,theoretical calculation methods often neglect the effect of differential settlement of piles and soils on the soil arching effect in embankments when studying the effect of pile-supported soil arching.Although some methods consider the effect of differential settlement of piles and soils,it is usually assumed that the shape of soil arches is a standard circular arc or a reasonable arch axis,which does not consider the influence of differential settlement of piles and soils on the shape of the soil arch,and has certain limitations.For this,based on the previous research results,this paper carries out theoretical analysis and numerical simulation of the soil arching effect of the piled embankment in the limit equilibrium state.The main work is as follows:Firstly,consider the effect of differential settlement of piles and soils on the shape of soil arches in embankments.That is,the differential settlement of piles and soils affects the stress ratio of pile-soil of embankment by controlling the change of soil arch shape.This paper assumes that the differential settlement of piles and soils is approximately two-part settlement,one is the differential settlement caused by different stiffness of piles and soils,and the other one is the soil rebound of the upper part of the pile top due to the formation of soil arching effect,and the vertical strain of the dome rebound soil is equal in the thick region of the arch;at the same time,the arch height in the soil arch is assumed to be constant,and the outer arch curve is an indefinite fourth-order polynomial function.Secondly,the Mohr-Coulomb strength limit equilibrium condition was introduced to analyze the arching effect of the piled embankment on the limit equilibrium theory.The stress equilibrium equations of the limit equilibrium occurred at the vault and the arch leg were calculated respectively,and the radius of c urvature of the soil arch was calculated.The geometric relationship was deduced to calculate the pile-soil stress ratio taking account of the differential settlement of piles and soils and the load sharing ratio of the pile body.Finally,aiming at the three-dimensional stress problem of soil arching effect of piled embankment under limit equilibrium theory,a three-dimensional numerical model of embankment was established based on ABAQUS finite element software platform.The arching effect of various parameters was analyzed and discussed by stress cloud map and isosurface map.The influence of the differential settlement of piles and soils and the ratio of pile-soil stress ratios are obtained,and compared with the theoretical calculation method and the results of the indoor model test and project example to verify the rationality of the study.