The Longitudinal Response Of Prestressed Cylinder Concrete Pipe With Bell-spigot Joints Subjected To Fault

Prestressed Concrete Cylinder Pipes(PCCPs)are widely used in large-diameter,high-pressure,and long-distance water transfer and transit projects because of the tensile and impermeability properties of the steel cylinder,compression and corrosion resistance of the concrete core,and slight angle deflection of semi-rigid joints.With the complexity and Megascale of water diversion and transfer project,the coverage area of buried pipeline is becoming wider and wider,and it is inevitable that it will cross the fault area with complex geological conditions.Under the action of fault dislocation,if the joint rotation and pipe body deformation of the segmented pipeline exceed the corresponding limit,the sealing performance of the pipeline may be reduced or even the structure may be unstable,which may pose a certain threat to the safe operation of the pipeline.Therefore,the research on the longitudinal response characteristics of pipeline under fault dislocation is of great significance to the safe and stable operation of pipeline.Based on the finite element software,this paper simulates the whole process of single-section PCCP from manufacturing,construction to operation,deeply studies the longitudinal response and parameter influence law of PCCP pipeline under fault,and puts forward the calculation formula and prediction model of maximum joint rotation under fault dislocation.The main research contents are as follows:(1)Based on the comprehensive consideration of geometric nonlinearity,material nonlinearity and contact nonlinearity,the pipe-soil finite element model is established,and the bearing mechanism,pipe deformation,stress and strain distribution and change law of each component of PCCP in the whole process of pipeline manufacturing,construction and operation are simulated and analyzed.The results show that under the construction and operation loads,the inner and outer concrete cores,steel cylinder and steel wires can maintain a good working state,and the pipe waist of mortar belongs to the weak part of the pipeline,which should be paid more attention to;(2)On the basis of considering the geometric size and structural characteristics of the bell-spigot joints,the finite element model of PCCP pipeline-fault is established and verified.The effects of location,displacement,dip angle of fault,internal pressure and burial depth on the rotation angle and axial translation of bell-spigot joints,as well as the effects on the deformation of pipe bodies are studied,and the generation and expansion of micro-cracks in the socket and socket are discussed preliminarily.The results show that the PCCP can be deflected at a small angle to adapt to certain foundation deformation,but when the deformation is too large and the rotation angle exceeds the allowable value,the micro-cracks in the bell-spigot joints will rapidly expand and accelerate the deterioration of the structural performance;(3)Based on the finite element analysis results,the dimensionless analysis of each parameter is carried out,and the regression calculation formula of maximum rotation angle under fault dislocation is fitted by multiple nonlinear regression analysis method.The maximum rotation angle prediction model is established by using BP neural network,and compared with the results calculated by the formula proposed in other published literature,the rationality of the prediction model is verified.