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摘要
Research purposes: In order to reveal the deformation response characteristics of the tunnel during the vertical jacking process of the shield shaft, the vertical jacking model test device was developed, and the jacking test was carried out to explore the reasonable damage range of overburden soil, the jacking reaction force and the tunnel deformation law in the jacking stage. The finite element method is used to analyze the deformation of the tunnel in the vertical jacking stage of the shield shaft, and the results are compared with the test results. The sensitivity of tunnel deformation to different reinforcement factors is discussed, and the idea of tunnel deformation control is proposed. Research conclusions: (1 ) The failure characteristics of the overlying soil layer in the vertical jacking stage do not follow the empirical assumption of the existing research, and the understanding of the failure mechanism and shape of the overlying soil layer in the existing research is insufficient, and the empirical calculation method of the jacking force proposed also has obvious errors. (2) The jacking force causes the outer opening and shear dislocation of the segment circumferential seam, and causes the inner opening of the longitudinal seam, and the longitudinal characteristics of the segment are more affected by the jacking force. (3)The opening amount can be reduced by using special segment in the open ring, but the shear dislocation trend between rings is aggravated, and the special segment is not suitable for practical engineering. (4)The deformation of the segment is inversely nonlinear with the stiffness of the ring joint, and the deformation tends to be stable when the stiffness increases by 5 times. In practical engineering, only the stiffness of the bottom joint between the rings is increased. (5) The grouting reinforcement outside the segment can effectively inhibit the tunnel deformation induced by the jacking construction, and the reasonable reinforcement range is 30° at the bottom of the segment. The existing results suggest that the circumferential reinforcement of 120° or all-round reinforcement is unreasonable, which causes waste and increases the construction risk. (6) The research results can provide reference for the application and promotion of vertical jacking construction method of shield shaft. ? 2023 Editorial Department of Journal of Railway Engineering Society.
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