Stochastic seismic response analysis and reliability evaluation of pipelines in liquefied soil

The liquefaction of saturated sand under the action of earthquakes can cause the buried pipeline to float up and the system failure. To investigate the seismic response and reliability level of buried pipelines in liquefaction sites, a probabilistic analysis method based on the probability density evolution method and equivalent extreme value distribution is proposed to fully consider the randomness and non-stationarity of ground shaking. According to the excess pore water pressure, acceleration and displacement of structures, the random dynamic analysis and reliability assessment of the buried pipeline are carried out. The results show that the randomness of ground motion has a significant effect on the dynamic response of buried pipelines, and the traditional deterministic analysis methods may underestimate the seismic response of pipelines. The proposed method can be use to comprehensively study the floating mechanism and reliability level of buried pipelines. Under the action of earthquakes, the pore water pressure increases, which leads to a decrease in the effective soil stress, and then liquefaction of the soil occurs, causing the pipe to float up. The compression of soil at both sides towards the bottom of the pipe and the seepage pressure towards the bottom of the pipe further aggravate the uplift of the pipe. Finally, the disaster mitigation effect and mechanism of U-shaped gravel drainage on buried pipelines are studied based on disaster mechanism. The proposed stochastic probability analysis method can be employed to accurately evaluate the buoyancy mechanism and reliability of pipelines.