Study On Influence Of Rotational Stiffness Degradation Of Shield Segment Joint On Lining

Shield tunnel has played a more and more important role in the construction of urban subway,which has little influence on the traffic,fast construction speed and is easy to adopt mechanized construction,and so on.Made by prefabricated segment erection,shield tunnel segment joint is itself weak position of the shield ring,while the shield tunnel seepage,water leakage,lining drop,material deterioration will also weaken the mechanical properties of the segment and segment joint.The rotational stiffness is an important parameter for evaluating the mechanical properties of the segment joints.The rotational stiffness of the segment joint has a great influence on the deformation and internal forces of the segment ring.Therefore,it is of great significance to study the influence of the rotational stiffness degradation on the segment ring of the shield.In this paper,the influence of the rotational stiffness degradation of the segment joint on the segment ring is analyzed by numerical analysis of the shield ring.The following research work is carried out:(1)According to the beam-spring model theory,the finite element model considering the effect of segment joints is established.The segment is modeled by a beam element,and the joint between the segments is equivalent to a spring element,and the mechanical effect of the joint is controlled by the rotational stiffness of the spring.Compared to the calculation results of internal force of the routine method,the correctness and rationality of the joint model are verified.(2)For the two analysis conditions of the single joint and double joint,based on the joint finite element model,the effect of the joint stiffness degradation on shield segment ring is studied and the regularity of joint rotation stiffness degradation on rotational angle and internal force in the process summarized.(3)The effects of the rotational stiffness degradation of the single joint and double joint on the maximum positive and negative angles and bending moments are investigated and the single or double connections that affect the maximum and the extent of the impact are analyzed.(4)The variation of the bending moment of the segment ring in the reference position of the single joint and double joint during the rotational stiffness degradation is studied.