Study On Calculation Model Of The Soil Between Piles In Deep Foundation Pit Double Row Piles Supporting Structure And The Stress Mechanism

Double row piles supporting structure system shows some advantages that large lateral stiffness,strong ability against overturning,convenient construction,and less influence on surrounding environment,etc.And double row piles supporting structure system is more suitable for the foundation pit engineering with strict deformation control and poor soil conditions,also it is one of the most potential supporting forms in the future.However,due to the mechanism about the double row piles supporting structure system of deformation and bearing capacity is highly complex,so leads to the research on the calculation theory is still not mature,thus seriously hindered the development of double row pile foundation pit supporting system.This paper are starts from the equivalent substitution of soil between piles,the calculation method of double row piles supporting structure and the characteristics of double-row pile supporting structure stress and deformation has been well-informed studied.Contents completed in the paper are as follows.(1)Through the analysis and summary the calculation method of double row piles in the current state and some local technical specification for retaining and protection of buiding foundation excavations,and based on the equivalent stiffness of the horizontal equivalent structure system,three rules for improvement of double row pile retaining structure based on the calculation model are proposed.(2)Based on the equivalent truss theory,the quadrilateral soil solid element between the piles is equivalent to six bar truss elements.Thus,the improved calculation model of the double row piles supporting structure based on the equivalent truss theory is proposed.Meanwhile,make a detailed description to the use of the calculation model.(3)Based on the matrix displacement method,the improved calculation model is solved.Fistly,set up the mechanical model of double row piles supporting structure by the plane bar structure finite element method.Besides,the matrix displacement method is used to write the MATLAB calculation program,and realize the solution to the internal force and deformation of double row piles supporting structure by MATLAB calculation program.Then,through comparative analysis of the two specific examples,the feasibility and the advantages and disadvantages of double row pile improved calculation model is discussed in detail.(4)The proposed improvement double row pile calculation theory that based on the equivalent truss model is applied to a typical engineering case,and the self-compiled MATLAB program is used to analyze the engineering case.Firstly,Each construction conditions of the project typical section is analysis and calculation by myself edited MATLAB programming,then the variation law of internal force and displacement of double row pile supporting structure was researched under various construction conditions.The influence of the compressive modulus of soil on the stress and deformation of double row piles supporting structure was emphatically analyzed by using self compiled MATLAB program.