Calculation Method Of Ground Displacement Caused By Excavation Of Soldier Pile Or Diaphragm Wall Supported Foundation Pit

With the development of high-rise buildings and underground municipal engineering,the environment around foundation pit becomes more and more complex,so the prediction and control of the ground displacement caused by the excavation is becoming more and more important.At present,the research works on the.ground deformation caused by excavation of foundation pit is mainly focused on predicting the subsidence around the foundation pit,and rarely involves the deformation of the soil below the surface.Moreover,the methods are mainly empirical and semiempirical methods,which lacks the necessary theoretical basis,so the calculation inevitably results in a large deviation.To solve this problem,a method for calculating the deformation caused by excavation of foundation pit based on Melan's displacement solution is proposed.The main contents and achievements of this paper are as follows:(1)The correctness of the Melan's stress solution is verified by the equilibrium equation and the stress geometric equation in elastic mechanics.The errors in the solution were corrected and the corresponding displacement solution was deduced.(2)The displacement solution formula obtained by different methods is studied,and the reason of the difference is analyzed.Aiming at the deformation characteristics of excavation,the method of Melan displacement solution for excavation of foundation pit is proposed.(3)By integrating the Melan's displacement solution,the displacement solution under the uniform load was obtained,which can be used to simulate the released load of excavation.(4)The calculation of deformation caused by the excavation of the foundation pit is taken as a plane strain problem of elastic semi-infinite plane.Using the principle of antisymmetric mapping,the load on the supporting structure in the foundation pit is taken as the load in the elastic semi-infinite plane.The lateral displacement of the the retaining structure is regarded as the displacement of a vertical plane in the elastic semi-infinite plane,and the corresponding distribution load is calculated by the Mela's displacement solution.After the distribution load is obtained,the displacement of any point in the elastic semi-infinite plane can be calculated by Melan's displacement solution,which is the displacement of the soil at any point around the foundation pit.(5)An example of deep foundation pit was calculated by the method proposed in this paper,and the reasonable results verified the validity of this method.