Study On Lateral Deformation Of Underground Diaphragm Walls Based On High-order Shear Deformation Plate Theory

As a common form of foundation support,internally braced diaphragm wall has the advantages of clear force,good economic efficiency and simple construction,etc.Scholars from both home and abroad have devoted a great deal of consideration to the economical and effective regulation of its lateral distortion.Therefore,it is especially important to obtain the lateral deformation of the whole wall of the underground diaphragm wall efficiently and accurately.However,no complete design theory and design procedure have been developed yet,and the influence of wall thickness on the lateral deformation pattern is ignored when the design is carried out by the normative method.Theoretical calculations,indoor model tests,and comparative analysis of engineering examples are the research methods employed in this paper to examine internally braced underground diaphragm walls.The method of calculating internal force and deformation based on higher order shear deformation plate theory is proposed;the calculation method optimizes the wall thickness,depth of entry and internal support arrangement in actual projects,and provides guidance for the construction design of internally braced underground diaphragm walls.The main work done is as follows.(1)A complete set of procedure for lateral deformation calculation of internally braced underground diaphragm walls is formed by using higher-order shear deformation plate theory,combined with the principle of minimum potential energy and Pb-2 Ritz method.And by comparing and verifying the indoor model test and engineering actual measurement data,a complete procedure for calculating the lateral deformation of underground diaphragm walls was established by giving the above theoretical basis.The procedure contains six modules,which can quickly calculate the lateral deformation of underground diaphragm walls for different working conditions and obtain the deformation curve of the whole wall.(2)Indoor physical model tests were carried out to compare the test results and theoretical calculations of soil pressure and lateral deformation of the diaphragm wall model under different wall thickness conditions,and it was found that the active soil pressure calculated by using Rankine’s soil pressure theory is large compared with the actual value,which needs to be corrected in order to be closer to the actual project.The lateral deformation test results and the theoretical calculation results are significantly different due to the deviation of the active earth pressure calculation,but after the active earth pressure correction,the two basically agree,which proves that the obtained theoretical calculation study is feasible.(3)Using the calculation method proposed in this paper to verify the lateral deformation of a subway station pit in Nanchang,the error rate between the calculation method and the measured data is within 10%,which verifies the validity and applicability of the calculation method.It is also used for parameter optimization analysis of the project example,and it is found that increasing the wall thickness can effectively reduce the maximum lateral deformation of the underground diaphragm wall and improve the safety of the supporting structure;the depth of the wall into the soil has a greater impact on the lateral deformation of the diaphragm wall,and its influence mainly comes from two aspects,one is the depth of entry itself,the greater the depth of entry,the smaller the maximum lateral deformation value of the wall,on the other hand,the different depth of entry On the other hand,the difference of the depth of entry will lead to the difference of the soil layer where the bottom of the wall is located;the lateral deformation of the wall can be significantly lessened by decreasing the horizontal spacing of the inner support,yet this also results in a considerable rise in the total number of supports.