Study on Influencing Factors of Surrounding Rock Deformation of TBM Tunnel With High Ground Stress Based on Regression Orthogonal Test.

This paper, based on a national key railway project crossing the high ground stress TBM construction section, studies the test results by means of the combination of refining three-dimensional numerical simulation and regression orthogonal design experiment and multiple linear regression method. The sensitivities of different supporting factors are studied, their advantages and disadvantages in controlling surrounding rock deformation are identified. At the same time, multiple linear regression equation of the experiment is obtained, which provides a fast calculation formula for structural optimization, so as to adjust the support parameters and optimizing the structure. In linear regression orthogonal experiment, the length of short anchor bolt, the length of long anchor bolt, the longitudinal spacing of steel arch, the circumferential and longitudinal spacing of anchor bolt, and the shotcrete grade and ground stress level are selected as the influencing factors. Regression orthogonal design experiment with L₈(2⁷) orthogonal table is conducted without considering interaction effect. The constant term and coefficients of partial regression term are calculated, and the multiple linear regression equation is established, and the results are analyzed in terms of variance and testing lose effectiveness of fit. The results show that the F value of ground stress is greater than F_0.001, and the ground stress has a decisive influence on the deformation of the surrounding rock. The F values of the length of short anchor bolt, the longitudinal spacing of the anchor bolt and steel arch are all greater than F_0.025, which have a significant impact on controlling the deformation of the surrounding rock. The established regression equation is significant, the test of misfit is not significant, so the regression equation has a good degree of fitting. Therefore, measures should be taken to release ground stress in design and construction first, and then the length of short anchor bolt, the spacing of steel arch and the longitudinal spacing of anchor bolt should be taken into account when selecting support parameters. [ABSTRACT FROM AUTHOR]