| With the rapid expansion of underground pipe networks and the increasing use of blasting operations in engineering,the contradiction between pipeline safety and blasting construction has become increasingly prominent.Especially when the design of blasting construction scheme is unreasonable and the pipeline safety criterion is not properly selected,the blasting vibration has more significant damage effect on the pipeline.Therefore,it is urgent to carry out research on the pipeline dynamic response to blasting vibration,and establish the pipeline safety assessment and risk under the action of blasting seismic wave,and then take targeted pipeline safety control measures.Based on the background of Lichuan urban roadbed blasting project,the paper studied the dynamic response of gas pipeline under the action of blasting seismic wave through theoretical analysis,field measurement and numerical calculation.The paper established a theoretical relationship between pipeline strain and pipe blasting vibration velocity when Rayleigh wave acts.At the same time,a three-dimensional finite element model of pipe soil was established to reveal the influence of different parameters on the dynamic response of the pipe during blasting vibration.By analyzing the numerical relationship between the pipe strain and the vibration velocity of the pipe and the numerical relationship between the vibration velocity of the pipeline and the vibration velocity of the surface directly above it,the minimum safety distance and the vibration speed safety allowable value of the pipeline during normal operation were clarified.The main research contents and conclusions of the paper are as follows:(1)Based on the propagation mechanism of blasting seismic waves,the influence characteristics of blasting vibration of underground gas pipelines were analyzed,and the theoretical relationship between axial and circumferential strains of buried gas pipelines and peak vibration velocity of pipelines under Rayleigh wave was established.Then the theoretical calculation formula of the minimum safe distance of the pipeline in engineering background was proposed.(2)The three-dimensional numerical model of pipe soil was established by using finite element software,and then the finite element calculation model was verified by regression analysis on the basis of vibration monitoring at the construction site of the blasting project.The results showed that the vibration velocity waveform of this method was consistent.(3)The dynamic response of blasting vibration to buried gas pipelines and surface soils under different charge and blasting conditions was analyzed.It was known that the magnitude of the velocity of the particles in all directions was related to the propagation direction of seismic waves.Also,the relationship between pipe diameter and the direction of seismic wave propagation was an important factor affecting the vibration velocity at different positions of the pipe section.The vibration velocity of the particle on the pipe increased with the increase of the explosive charge or pipe diameter,and decreased with the increase of the distance from explosive source or pipe wall thickness.(4)Numerical analysis of the gas pipeline strain and the peak vibration velocity of the particle point showed that the peak velocity of the gas pipeline,the peak velocity of the three-way composite and the strain of the gas pipeline were exponentially related.The fitting analysis of the peak vibration velocity of the pipeline and the soil showed the linear function relationship between them.(5)According to theoretical calculations and numerical calculations,it is known that there are large safety spaces for the relevant regulations of the pipeline safety management regulations.When the blasting distance increased to a certain value,the harmful effects of blasting vibration on the buried gas pipeline were rapidly weakened.The vibration speed control standard for pipeline safety in this project was conservative. |
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