Analysis Methods Of Shield Tunnel Environment Effects Based On Measured Data

Shield tunneling method has extensive promotion and application in tunnel engineering. With the continuous development of construction technology, the development direction of shield tunnel turns out to be large diameter, long span and complex construction environment. When constructing tunnels in big cities, it is inevitable to pass through existing underground structures at short range. Under this circumstance, micro disturbance control requirements are proposed to ensure the safe operation of existing underground structures. As a result, accurate evaluation of newly built tunnel is in need urgently. Soil parameters have properties of discrete and mutation, it is whether accurate parameters can be obtained that has a significant influence on risk analysis of projects. In this paper, an method to obtain accurate soil parameters based on the measured data is proposed, and a simplified modeling method is proposed combined with the finite element simulation. The main work and research results are as follows:(1) The impact of tunnel construction on the surrounding environment has been analyzed using the parameter back analysis method. Back analysis suitable for tunnel engineering has been developed on the basis of predecessors combined with finite element analysis software, and effective iterative convergence criteria is also proposed.(2) Based on Pareto optimal theory of multi-objective optimization, a more efficient and accurate method for multi-objective parameters back analysis is proposed combined with a variety of genetic evolution algorithm. By taking the lateral displacement, ground subsidence and pore pressure distribution as two multi-objective of back analysis, the practical application of this method has been achieved. By comparing the results obtained from single objective analysis and multi-objective analysis, the accuracy and feasibility of multi-objective analysis has been affirmed.(3) To overcome the large amount of iterative calculation and increase efficiency, a simplified modeling method of two-dimension is proposed, which avoid the time-consuming problem of the three-dimensional model and make this analytical methods feasible to be applied on actual project.