Surface Crack Propagation And Strength Analysis Of Underground Pipeline Structures

The underground pipeline is widely used in production and life,it is called lifeline engineering,but in practice,it is inevitable to have crack,deboned,corroded and other defects.In recent years,crack defects and corroded parts caused a lot of accidents.In order to reduce the occurrence of such accidents,it is necessary to predict the crack opening displacement of the pipeline and analyze the strength of corroded pipeline.Based on the elastic wave scattering theory,the elastic dynamic model of partially deboned or corroded pipeline is established,and the surface crack opening displacement of partially deboned pipeline and the dynamic stress response of partially corroded pipelines are studied in detail.The main contents are as follows:(1)Based on the elastic wave scattering theory,the elastic dynamic model of partially deboned pipeline is established,and the crack opening displacement is calculated by using the wave function expansion method for partially deboned pipeline under the action of SH wave.The crack opening displacement is represented by the Chebyshev polynomial.The influence of initial crack size and dimensionless wave number on crack opening displacement(COD)is discussed in detail in numerical examples.The results show that the crack opening displacement in the high frequency region is more sensitive to the initial deboned size.(2)The crack opening displacement of the partially deboned pipeline under the P wave is calculated by using the method of calculating the crack opening displacement of SH wave.The crack opening displacement is obtained by using the Chebyshev polynomial,and the influence of initial crack size and dimensionless wave number on crack opening displacement(COD)is discussed in detail.The results show that the frequency of the incident P wave has an important effect on the surface crack propagation.(3)According to the dynamic theory of Biot saturated porous elastic medium,the analysis and calculation model for dynamic response of partial corroded pipeline in saturated soil is established and the dynamic response of some corroded pipes in saturated soil under plane wave is solved.The dynamic stress distribution of the pipe under different incident wave frequencies is discussed in detail by numerical examples.The results show that the interfacial coefficient stiffness has an important effect on the dynamic stress response of the pipeline.