Research Of Dynamical Response On Underground Pipes Impacted By Seismic Waves

Underground pipes are rarely considered to design to withstand the loads applied by earthquake ground motions, mainly because they have been held by surround soil or rock bound. However, the damage of underground pipelines observed in near-field earthquakes of inside and outside indicates that the occurrence of earthquake not only can damage the normal use of the underground pipelines directly, but also may lead to water, fire, explosion and serious diseases such as secondary disasters. In order to reduce conveying fluid pipelines damage caused by the seismic effect and ensure safety of lifeline works to prevent the emergence of secondary disasters, there is a need for improved analysis response of the buried pipelines under seismic wave forces, and has great significance to found theoretical design of underground pipeline to provide the necessary impetus.First of all, based on complex function of the wave theory and the assumption of large arc, the analytical solution of underground composite pipe in single-row under plane P wave, SV wave and SH-wave incidences is given, and the parameters of the pipe, media types, depth of pipe, as well as fluctuate parameters are investigated to explain the influencing rules.For the dynamic interaction problems of adjacent structures are often encountered in practical engineering, underground pipe system on dynamic interaction of each other is researched. A detailed theoretical calculation process is given and impact mechanism and the role of law of two surrounding conditions of pipes under incident P waves, SV waves and SH-waves on dynamic interaction between the pipes are analyzed to reveal the diffraction and scattering characteristics around underground pipes under different parameters of seismic waves.Making use of fluid-borne acoustic wave equation, analytical answer of the dynamic stress concentration to the underground liquid-filled pipe under the plane P wave, SV wave incident is given in order to better reveal the dynamic response characteristics of pipeline on the pipeline within the fluid effect of seismic waves. And the impact rules of fluid oscillation filled in pipe by the wave propagation is analysis.Analytical results show that steel-line thickness has a significant effect on peak dynamic stress concentration of the pipe, The thinner steel liner, a higher level of dynamic stress concentration; the peak values of hoop dynamic stress concentration impacted by the incident P waves, SV waves and SH waves are amplified obviously as the surrounding medium of pipeline is light soft and hoop dynamic stress concentration reduce when the surrounding medium of pipeline is very soft; The dynamic interaction between the pipes not only the distance of adjacent pipes but also has something to do with the layout of pipeline; the liquid filled in pipe impact the distribution of radial stress concentration.