Numerical Simulation Research On Multi-field Coupling Dynamic Response Of Concrete Drainage Pipe

Concrete pipes in various municipal water and drainage systems have been widely used by people.Drainage pipes are usually buried underground,for buried concrete pipes,they will be subject to external forces including fluid in the pipe,the surrounding soil and road traffic load,so that it occurs lateral and longitudinal deformation,or worse,it will cause damage to the pipe and leakage and other hazards,the actual project pipeline is composed of multiple short sections,socket At the same time,due to the existence of some ions in the concrete drainage pipe fluid to destroy the stability of the concrete structure,causing corrosion in the concrete pipe,reducing the mechanical properties and deformability of the concrete,causes the pipeline to leak,or even make the road collapse,etc.,which causes great harm to people’s health and the social ecological environment.In this paper,we adopt the elastic foundation beam model to derive the parameters for corroded concrete pipeline,and the axial force,shear force and bending moment at each point of the corroded pipe section are obtained;we consider the relative stiffness between pipe and soil to derive the theoretical formula for calculating the vertical soil pressure of flexible pipe;then take the normal pipe and corroded pipe as the research object,consider the pipe socket interface and the comprehensive effect of fluid,soil pressure and traffic load inside the pipe,and conduct the multi-field coupled dynamic response analysis of the pipe.Multi-field coupled dynamic response analysis,so as to obtain the following conclusions.(1)The axial stress of the pipeline decreases with the increase of the pipeline subsidence length,buried depth and pipe diameter,and increases with the increase of the maximum subsidence depth.For the corroded pipe,the required axial stress is less than the normal pipe can make it reach the same sink state with the normal pipe.(2)The passive soil support force on the pipe side caused by the flexible pipe after corrosion in the vertical soil pressure calculation of the trench buried pipe is greater than that of the flexible pipe and the rigid pipe,which will relieve most of the soil load on the top of the pipe.When the buried depth of the vertical earth pressure of the buried pipe is small,the top of the flexible pipe will bear most of the load after corrosion,and the passive soil supporting force caused by the pipe side will be relatively reduced.(3)The maximum main stress value at the bottom of the pipe is always greater than the top of the pipe,the existence of the socket will make the top and bottom of the pipe maximum main stress value has different degrees of increase.(4)With the increase of flow rate in the pipeline,the maximum principal stress at the elbow of the top,bottom,inner wall and outer arch of the pipeline will gradually increase,and with the increase of flow rate,the maximum principal stress at the elbow of the inner arch will gradually increase,and the maximum principal stress first increases and then decreases.(5)The vehicle wheel pressure in the vehicle load has a greater impact on the pipe,while the vehicle speed is relatively small.With the increase of wheel pressure,the vertical displacement of the top of the tube,the maximum principal stress values in the circumference and longitudinal direction of the tube gradually increase,and the maximum principal stress values of the outer arch at the top and bottom of the tube gradually increase.The inner arch at the bottom of the pipe is the largest.As the buried depth of the pipeline increases,the maximum principal stress value in the longitudinal and circumferential directions of the pipeline decreases.(6)Different vehicle wheel pressure,speed,flow rate and depth of burial on the impact of corrosion of the pipeline is greater than the normal pipeline.(7)The maximum principal stress of pipeline increases with the increase of corrosion depth,corrosion length,corrosion width,fluid velocity and vehicle wheel pressure.With the increase of buried depth,the maximum principal stress of longitudinal and socket gradually decreases,and the maximum principal stress of longitudinal and socket decreases with the increase of vehicle speed at 20km/h,and then decreases with the increase of vehicle speed.(8)The maximum principal stress at the top and bottom of the corroded pipe section will change obviously.The abrupt change value increases with the corrosion depth,corrosion width,corrosion length,flow rate and vehicle wheel pressure,the bottom of the socket is more susceptible to tensile damage.(9)The maximum principal stress of the inner wall of the corroded bend in different corrosion factors,flow rate,vehicle load and burial depth is mainly concentrated in the outer arch of the inner wall of the pipe bottom and the inner arch of the inner wall of the pipe top,and its maximum principal stress changes under different influencing factors are the same as the maximum principal stress changes along the longitudinal length of the socket and pipe.