Research On The Problem Of Tunneling Passing Across The Adjacent Pile-foundation In Shield

This paper designs a comprehensive analysis method including geotechnical parameter sensitivity analysis, displacement back analysis and FEM simulation against the background of Dalian subway construction. Using the existing construction data, this paper tries to verify the original construction plan, and meanwhile, provide the theory basis for the subsequent construction. This paper mainly completes the following aspects of jobs:1. This paper uses the method of sensitivity analysis to research the influence of various physical and mechanical stability of surrounding rock parameters, and finds out sensitive factors and evaluate them. We will build a2D FEM model, using the data of Dalian subway construction, based on the geology data and "Standard for engineering classification of rock masses"(GB50218-94). It will also use LHS sampling way to get20groups of random parameters. At last, we will win the variation value of feature points in the elastic zone and plastic zone. By using the rank of rock parameters and displacement variation value, we will get the rock parameters which make a significant impact to elastic zone and plastic zone. The result shows that, elastic modulus, weight density, Poisson’s ratio and internal friction Angle are the greatest sensitivity in the FEM model.2. On the base of geotechnical parameter sensitivity analysis, we will get displacement back analysis to the high sensitivity of the parameters, to find out the more reasonable calculations. Based on "Standard for engineering classification of rock masses"(GB50218-94), we will sample90groups of random high sensitive parameters, with method of LHS way, to calculate the crown displacement and clearance converge in FEM model. And a BP neural network will be built, with crown displacement and clearance convergency as input and sampling parameters as output. Then inputting the construction data to the trained neural network, we will gather the forecast rock parameters. At last, put the forecast rock parameters into REM, we will verify the result, compared with construction data. We find that the results of the inversion result and construction data are close, which means that the forecasting of rock parameters by neural network is reasonable.3. This paper studies the shield construction under the method of FEM simulation. With the basic parameters of displacement back analysis, we research and analyze the influence to surface and underground caused by tunneling passing in shield, and get change of the settlement and horizontal displacement over time and depth.4. This paper researches on the problem of effect on adjacent pile-foundation caused by tunneling passing in shield and find out the change laws of pile body displacement and stress in the case of different pile lengths and different distance to the axis of tunnel. Meanwhile, we also summarize the effect on ground deformed caused by tunneling passing in shield, with the pile existed or not.