Stability Analysis For Deep Excavation Projects Of The MTR Stations During The Construction Process

The metro construction in Nanchang is in full swing, followed by a large number of deep excavation projects of the MTR stations.The MTR stations are always located in downtown area of the city, the stability of the deep excavations during construction has a tremendous impact on the surrounding environment.In Nanchang, we don't have abundant experience on the design and construction of such deep excavation projects, so, do some research and analysis of the deep excavation projects of the MTR stations, the construction of which have been started has a certain significance for the MTR stations which will be constructed.This paper's background is based on a deep excavation project of MTR station in Nanchang, the construction of which have been started. Collecting and processing the monitoring data of this deep excavation project will do some help to find out the main laws of the deformation of the deep excavation project.This paper processes the monitoring data of the horizontal displacement of the envelope structure by least-squares method.Combined with the principle of control charts, it gives an alarm when abnormal points of the horizontal displacement of the envelope structure appear.Using ANSYS finite element analysis software, this paper establishes two-dimensional numerical model of the excavation project to simulate the excavation of pit construction process step by step dynamically.Through comparative analysis of the calculated value and the monitoring data of the envelope structure, it validates the correctness of the numerical model. Using the built numerical model, this paper study the main laws of the deformation of the envelope structure under different conditions, such as different embedment depth of the envelope structure, different pile diameter, different construction loads on the ground.The inverse analysis of optimization is made to forecaste the displacement of envelope structure by three stages.and it's validated that the method is feasible in the actual process of deep excavation construction.also, two points of this method are summarized.In the final, linking the construction monitoring, the numerical simulation, the inverse analysis of optimization closely is discussed, at the same time, establishing effective communication and feedback between design and construction is discoursed to give better direction to the information construction of the deep excavation.