Experimental method for evaluation of soil-pipe interaction subjected to lateral or vertical cyclic load

Design of embedded pipelines in seismic areas require consideration of the interaction between pipeline and surrounding soil. The soil-pipe interaction is often numerically modeled using Winkler springs, where a simple bilinear or trilinear soil resistance-displacement relationship is employed. As Winkler spring modeling approach requires experimental data for calibration of spring parameters, extensive experimental studies have been carried out. However, most tests in previous studies have been carried out for pipeline specimens subjected to monotonic load, in which pipe lateral-vertical response coupling is hardly investigated. In the present research, a novel test method that enables testing of a pipe specimen under lateral or vertical cyclic loading is investigated. In the proposed method, a soil box is mounted on a 6-degree of freedom (DOF) displacement-controlled table, such that soil-pipe interaction in the lateral/vertical direction can be investigated. A series of tests considering various parameters such as pipe diameter, burial depth, soil density, and loading condition were performed. Test results provided evidence of the effect type of loading has on soil-pipe interaction and the strong coupling between pipe response along lateral and vertical directions.