Finite Element Analysis of Pipe Buried in Saturated Soil Deposit Subject to Earthquake Loading

A coupled stress-flow finite element procedure, based on dynamic Biot equations, was used to analyze the behavior of pipe buried in liquefiable soil. The governing equations, soil constitutive model, finite element discretization and solutions were described. The results of analysis were compared with two cases of dynamic centrifuge test of soil deposit and pipe conducted at 30-g acceleration field. The horizontal soil deposit was analyzed followed by the deposit having a buried pipe of diameter 10 cm (3 m in prototype). The deposit was composed of loose Nevada sand that was saturated with a viscous solution in satisfying the similitude rules of time for the dynamic event and diffusion phenomena. The response of the ground, such as acceleration and excess pore water pressure, and the earth pressure and uplifting of the pipe, were presented and compared. The results of analysis indicated that a coupled stress-flow finite element procedure where the soil was expressed by Pastor-Zienkiewicz Mark-III model was able to simulate the dynamic response of the soil and pipe up to the stage of liquefaction. Several other issues related to the analysis were discussed.