Simplified Calculation Method Of Double-row Piles For Foundation Pits Based On Biparameter Method

Double-row piles retaining structure is a supporting structure of foundation pit that was first used in late 1980 s,due to its small horizontal deformation,low costs and short terms etc,it has been widely used in foundation pit engineering.However,there is no mature design calculation methods now,and the study on its stress mechanism,working behavior and applicable conditions is not thorough enough.Based on the previous research results,by analyzing the stress and the displacement of the structure,this thesis proposes a new simplified calculation method for double-row piles.meanwhile,its rationality is verified.The main tasks is as follows:(1)In this thesis,a large number of related documents have been consulted and collated,the main research methods and results of the double-row piles for foundation pits are enumerated,the existing calculation methods are summed up.And thier calculation principles,applying ranges,advantages and disadvantages is analyzed.(2)According to the theory of limit equilibrium,suppose sliding surface start from the bottom of foundation pit,and the angle between the sliding surface and the vertical direction is 45 degrees.The shear slip surface will be used for piecewise analysis of double-row piles.Above the shear slip surface,the volume ratio method can be used for solving earth pressure,and the below used biparameter method.Then,the differential deflection of each section can be established,and the calculation method and procedure of the internal force and deformation of double row piles based on the finite difference method are presented.According to the above principle,the MATLAB calculation program is compiled.(3)Combining with the project examples,the internal force and deformation of double-row piles are calculated by this new method.And the setting process of double row pile retaining structure is simulated by the finite element software ABAQUS.Then the calculation results are compared with the measured statistics and the results of the numerical simulation.The results show that the new simplified calculation method is reasonable.