Study On Mechanical Behavior Of Pipe Joint In Urban Deep Tunnel And Shield Tunnel

As the utilization of shallow underground space tends to be saturated,the construction of urban deep drainage tunnel by shield tunneling method has become an important subject of urban drainage network reconstruction.Contrary to traffic of shield tunnel,deep drainage tunnel lining structure of shield tunnel not only in large buried depth,at the same time also by the effect of internal water pressure during tunnel operation,which makes the axial force of lining structure compared with traffic tunnel produced pressure decrease gradually and becomes tensile process,so as to further the cause of joint mechanical behavior?open quantity,ctoa and bending stiffness,etc.?change,the joint bearing capacity and water leakage.However,there are few domestic studies on the connection of deep tunnel and drainage shield tunnel,most of which focus on the traffic tunnel.The research in this paper has proved the mechanical characteristics of the connection of deep tunnel and drainage shield tunnel,providing guidance for specific projects.Based on the sewage transmission system project in the core area of wuhan east lake,this paper studies the mechanical characteristics of deep drainage shield tunnel joints.The main research work and results are as follows:1.According to the geological conditions of the tunnel,a representative section for calculating the external soil and water load is selected.Based on the calculated load and the actual internal water pressure of the project,the single and double layer lining structure model established by the finite element software was loaded,the variation law of internal force of lining structure under different external soil and water loads and internal water pressure was studied,and the value range of internal force of lining structure was determined.2.Single-layer lining joint refinement model was established based on finite element software,through has calculated the scope of single-layer lining structure internal force,to load model,studies the construction and operation period,the amount of single-layer lining joint open,ctoa,bending stiffness and joint surface stress along with the change of bending moment and axial force.The calculation results show that the maximum opening capacity of the joint during operation is 2.7mm,which is an increase of 371%compared with the construction period.During construction,the bending stiffness of the joint is between 26²45MN·m·rad^-1 During operation,the bending stiffness of the joint is between 6 and25MN·m·rad^-1.3.Double-layer lining joint refinement model was established based on finite element software,through has the scope of double lining structure internal force is calculated,to load model,studies the construction and operation period,the double lining joint open quantity,ctoa,bending stiffness and joint surface stress along with the change of bending moment and axial force.The calculation results show that the joint opening is controlled within 1mm during operation,and the bending stiffness of the joint is within the range of 4⁹0 MN·m·rad^-1.4.Through the contrast analysis of equivalent load?soil load and pressure?is the maximum number of open orders,double lining joint,the latter is smaller than the former,and during the tunnel body drainage systems operating under the same load conditions,double lining of the segment joint bending stiffness is single-layer lining joint,the equivalent conditions of double-layer lining joint deformation ability weak in single-layer lining joint.Therefore,considering the bearing capacity of the joint and the prevention of sewage leakage,it is suggested that double lining be adopted in the deep tunnel and shield tunnel engineering of wuhan dadonghu district.The flexural rigidity of the joint obtained in this paper can be used as a reliable value for the design and construction of the dependent project joint.