The Dynamic Response Analysis Of Buried Pipeline In Liquefiable Soil

Sand liquefaction is one of the important reasons for the failure of buried pipelines.In order to reveal the reaction mechanism of buried pipeline in liquefiable soil layer,based on the finite difference theory,the numerical simulation was carried out in this paper by means of FLAC3 D software.The dynamic response of buried pipeline in liquefied soil was studied under different conditions,and the anti-liquefaction measures of sand foundation were simulated to verify its anti-liquefaction effect.Combining the method of layer summation with stress analysis of buried pipeline in subsidence area,the response of sand liquefaction settlement to buried pipeline after earthquake is obtained,The main contents are as follows:(1)FLAC3D was used in this paper to numerically simulate the saturated sand foundation.The dynamic characteristics of excess pore water pressure,pore water pressure ratio,horizontal acceleration and vertical displacement of sand foundation under seismic load effect were analyzed.The results showed that the pore pressure of shallow saturated sand foundation was relatively small and there was no liquefaction occurred under seismic effect;the liquefaction mainly concentrated in the middle and bottom of foundation.(2)The dynamic characteristics of buried pipelines in liquefied soil were analyzed and the effects on dynamic response were studied of different soil parameters and impact load.The anti-liquefaction measures were briefly introduced and the excavation method was simulated numerically.The results showed that the pipeline joint stress was basically consistent with the development trend of displacement time-history curves under different working conditions;the influence of various parameters on the peak value of displacement was very small,but there was a great influence on the peak value of equivalent stress;in local liquefaction,the displacement of the pipe end is the largest,and the closer to the pipe end of the liquefied area,the greater the displacement of the pipe joint;The lateral displacement and vertical displacement increases with the increase of the length of liquefied area;The displacement amplitude of buried pipelines could also be reduced during seismic period and the reinforcement effect was obvious;Under the action of earthquake,the accumulation of pore pressure could be reduced by means of excavation method and the liquefaction could be eliminated effectively.(3)The dynamic response of pipeline was analyzed with considering of the traveling wave effect of earthquake.The results showed that there was some certain effect of traveling wave effect on the displacement peak value and equivalent stress amplitude of buried pipelines.Compared with the condition under coincident earthquake excitation,the displacement peak value and equivalent stress amplitude may be increased or reduced by traveling wave effect;the development trends of them were also not the same under different seismic waves.