| Metro tunnel construction method is very important in tunnel construction area since its convenience and high-efficiency. Surface subsidence caused by tunnel construction, in which shield machine has been used, has a significant impact on the surrounding environment. It is a major destabilizing factor in the construction process. Thus, in order to control and the accurate prediction of surface subsidence, efforts on exploring the relationship between tunnel construction parameters and the surface subsidence will make difference to theoretical significance and application value for the subway tunnel construction safety.The thesis begins with a literature review of selection of shield machine and relationship between parameters and surface subsidence induced by tunneling excavation. The factors that influence the selection of shield machines are summed up based on the previous studies. The evaluation system consisting of 11 indicators and their weights has been established. Based on general contents of shield machine selection, different applicable selection options are developed using the TOPSIS method. Taking a metro project as an example, the evaluation system established and TOPSIS method is used to select the appropriate shield machine in this project. Then a novel approach to identify key parameters of surface subsidence induced by metro construction is proposed using the rough set principle and support vector machines. A case is used to verify the applicability of the proposed approach. At first, continuous data should be discrete, and three sets of parameters and their weights are identified. Support vector machines are used to study the non-linear relationship between the above three sets and their corresponding surface subsidence, respectively. Differences between the observed subsidence values and the predicted ones indicate that the superior and accuracy of the rough set can be taken into consideration when identifying the key parameters in the proposed approach. |
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