Full-scale Model Test Of Shield Tunnel Segment And Simulation Analysis Of Circumferential Joint

The development and utilization of urban underground space is of great significance to the development of modern and future cities.The study of underground engineering construction on existing underground grounding facilities,especially adjacent subway shield tunnels,is an important topic in the development of underground space.There have been instances in which the construction near subway shield tunnels has had a major impact on the structural safety of subway shield tunnels in many cities.Relevant departments and groups are formulating and improving relevant subway structure protection standards.Among them,the force mechanism analysis and deformation control of shield tunnel are the key content of subway protection.As the assembled underground structure,the segment joint is the key to the force analysis of the shield tunnel,which has a decisive influence on the overall deformation and deformation performance of the segment structure.According to the protect project and engineering examples of Shenzhen Qianhai Exchange Square,this paper study on the mechanical properties of the ring joint of the shield tunnel of Shenzhen Metro.The specific work contents are as follows:(1)Full-scale model test of shield tunnel segmentThe single-ring full-scale model test of shield tunnel segment is used to test the mechanical properties of the representative ring and the joint of the Liyumen-Front Bay section of Shenzhen Metro Line 1,and the key deformation performance points and performance points of the shield tunnel structure are obtained.The whole process of structural deformation,longitudinal joint opening,joint bolt stress and tunnel structure failure,the deformation law of segment joints was preliminarily studied.(2)Shield tunnel segment circumferential joint modelCombined with LS-DYNA and ABAQUS,large-scale general finite element software,the partial joint model of the segment is established.The model establishes the finite element model of bolt and joint concrete.Having considered the influence of bolt and concrete contact pressure and friction,the model can be used to perform refined analysis of segment joint.By comparing with the test results,the model can simulate the process of deformation and failure of the segment joint well.The model can be used as a good tool for the analysis of joint deformation mechanism.(3)Simulation Analysis of Deformation Performance of Segmental JointsUsing the segmental joint model and the test results,this paper preliminarily studied the force deformation mechanism of the joint and the influence of joint pressure on the bending stiffness of the joint.Through analysis,the following results can be obtained: joint pressure and seam angle have a great influence on the joint bending stiffness.As the joint pressure increases,the joint bending stiffness increases.When the concrete contact surface partially yields,bending stiffness decreases rapidly as the joint angle increases.When the yield point is reached(the bending moment is about 140 kN·m),the bending stiffness is 5127kN·m/rad when the axial force is 1000 kN,and the bending stiffness is 6734 kN·m/rad when the axial force is 1500 kN.When the axial force is 1700 kN,the bending stiffness is 7381kN·m/rad.