Research On Structural Mechanics Characteristics Of Segment In The Process Of Shield Tunnel Construction

Segments are generally used for lining in the shield tunnel to ensure the tunnel's long-term stability and waterproof requirements which must ensure the quality of the lining. The characteristics of structural mechanics analysis of segment in the shield tunnel are a technical problem of the shield tunnel construction. With the shield tunnel construction technology development and standardization of the requirements, segments floating and dislocation caused the cracking of the segments, assembled difficulties and waterproof hidden dangers and so on, which are affecting the construction and operation increasingly, and directly impact on the quality of works, operation and maintenance. As the Guangzhou Shiziyang shield tunnel as the background, it is researched that the phenomenon of segment dislocation and broken and segment floating and the factors to make suggestions for construction. The main content and results in this paper are as follows:(1) It is researched that the factors of segments-floating in the construction process by the mechanics and mathematical methods and the segments-floating of Shiziyang shield tunnel is calculated by the formula. It is indicated that the segments-floating is occurred, when the factors, such as the exaction of tunnel and injected mortar, lead to a losing of resisting float ability. Segments will take a rising displacement and become stabile at last in the process.(2) With the method of theoretical analyzing and numerical simulation, we conclude that the cause resulting in dislocation of shield segment is the differential settlement which induced by segment binding force not enough to against buoyant force and we put forward three kinds of measures to eliminate dislocation. Based on the force analysis on longitudinal dislocation of shield segment, we deduce the calculation formula of longitudinal dislocation which relate to the driving force of jacks, the adjacent segments, the geologic strata circumstance and so on.(3) Changed beam-joint discontinuous simulation model, whose joint elements is considered to construction plane and bolt, has been built with different conditions including to different strata, jack thrust, grouting and the role of the assembly and bolt-linked comparative analysis so that further study characteristics of structural mechanics of segment. It is indicated that these factors affect the characteristics of structural mechanics of segment.