Study On Structural Safety Evaluation Of Cracked Concrete Pressure Pipeline In Hydropower Station

The rupture and damage of pressure pipe of hydropower station will cause serious consequences.Based on the theory of fracture mechanics,a theoretical analysis based on the theory of fracture mechanics is carried out to analyze the safety of the bearing capacity and cracks of the reinforced concrete pressure pipeline,which is still in service in a hydropower station.The large finite element analysis software ABAQUS is used to simulate the pipeline,and the safety of the pipeline is analyzed according to the numerical simulation results,which provides a certain analysis basis for similar pipeline problems.The main research conclusions of this study are as follows:(1)By establishing the finite element analysis model of the reinforced concrete pressure pipe,combined with the actual boundary conditions and using the damage plastic model of the ABAQUS6.14 finite element analysis software,the stress analysis of the pipe under the action of uniform internal water pressure is carried out.The results show that the maximum equivalent stress produced by the combined load is small.In terms of C25 concrete strength and HPB235 reinforcement strength,pipeline operation is safe under such conditions.(2)Based on the research results of the existing steel lined reinforced concrete pipes,the ABAQUS damage plastic model is verified.The results show that the calculated results are basically the same as the existing research results.At the same time,it is proved that the concrete damage plastic model is feasible,and the correctness of the previous results is explained from the side.(3)According to the basic theory of water hammer,the numerical calculation is carried out by FORTRAN software,and the change law and specific value of water hammer pressure with time are obtained.According to the change law of water hammer pressure,the finite element analysis and calculation of pipe body and interface have been carried out.The results show that under the action of water hammer pressure,the bearing capacity of pipe body meets the requirements of operation and does not appear cracks.And safe.(4)Based on the surface semi elliptical crack model in the finite body,the fracture strength of the reinforced concrete pipe is analyzed by fracture mechanics,and the calculation formula is obtained.The applicability of the formula is verified by theoretical calculation and rebound measurement.The results show that the pipeline is in accordance with the operation requirements and is safe.(5)According to the specification,the calculation of the carrying capacity of the pipeline is carried out.The calculation results show that the bearing capacity of the pipeline meets the operation requirements and the pipeline is safe.