Research On The Calculation Method Of Internal Force Of Pile Foundation Joist Retaining Wall

At present,China's engineering construction is in a rapid development period,both in the infrastructure construction projects such as highways,railways,water conservancy,and in the estate projects,pile foundation joist retaining wall has been widely used.The pile foundation under the retaining wall firstly improves the bearing capacity of the foundation,even in some cases,it can also play a role in stabilizing the slope.However,the research on the calculation of the internal force of the pile foundation joist retaining wall lags behind its practical application,and the calculation result often deviates from the actual situation,which also bring a high engineering cost.In order to improve the internal force calculation theory of pile foundation joist retaining wall and save engineering cost,the internal force calculation theory of retaining wall with pile foundation joist has been studied as follows:(1)An overview of the research development of pile foundation joist retaining wall are summarized,the problems existing in the calculation of the internal force of the pile foundation joist retaining wall are analyzed,and the calculation method and distribution form of the main load acting on the pile foundation joist retaining wall are summarized.(2)The internal force calculation of pile foundation joist is studied.At the same time,considering the actual force situation of the pile foundation joist retaining wall,the reaction of lower ground on the joist,the effect of the lower pile foundation on the joist,combining the initial parameter solution of the Winkler elastic foundation beam model,the analytical solutions of the deflection,rotation angle,shear force and bending moment at different sections of the joist are given,and the degradation verification is carried out.The influence of the span of joist on the internal force of joist is studied by an example.(3)Study on the internal force and deformation of pile foundation of single-row pile joist retaining wall is carried out.Considering the stratification of soil,the soil layer is divided into three layers from top to bottom,which are softer soil layer,harder soil layer and lower bedrock layer.Considering the difference of filling heights between the inside and outside of retaining wall,it is assumed that the pile in the softer soil layer is subject to a trapezoid load,and combining the continuous condition of pile foundation,the analytical solutions of the deflection,rotation angle,shear force and bending moment of the pile foundation are given,and the degradation verification is carried out.The influence of bending rigidity of pile,m value of softer soil,m value of harder soil on the internal force and displacement of the pile foundation are studied by numerical examples.(4)Study on the internal force and deformation of the pile foundation of the double-row pile joist retaining wall is conducted.The pile foundation and joist are considered as a whole,and the soil layer is also divided into three layers from top to bottom,which are softer soil layer,harder soil layer,and lower bedrock layer.It is assumed that the rear row pile in the softer soil layer is subjected to a trapezoidal load.Based on the analysis of the stress on the bottom of the joist,the analytical solutions of the deflection,rotation angle,shear force and bending moment of both the front row pile and the rear row pile are given,and the degradation verification is carried out.The influence of bending rigidity of pile,m value of softer soil,m value of harder soil on the internal force and displacement of the front row pile and rear row pile are studied by numerical examples.(5)Numerical analysis on the pile foundation joist retaining wall is carried out by using the ABAQUS finite element software.Combining a project case,analysis on the stress and strain in the joist and pile foundation are carried out,and the results of numerical analysis are compared with the corresponding analytical solutions.Present study can enrich the calculation theory of the internal force in the pile foundation joist retaining wall,and also provide a reference for the design of the pile foundation joist retaining wall.