Downwards force–displacement response of buried pipelines during dip–slip faulting in sandy soil

Abstract

In the numerical analysis of underground pipelines against dip-slip faulting, it is common practice to model the problem as a beam surrounded by soil-equivalent nonlinear springs. Previous studies have recognised the importance of the vertical bearing soil springs (VBSS) in the modelling of pipe–fault interaction. Nevertheless, prior studies on VBSS are limited. This study presents an analytical framework for determining a hyperbolic force–displacement (P–y) curve for VBSS in dry sand. This hyperbolic criterion was established based on the ultimate bearing resistance (UBR) of pipe and the elastic subgrade modulus of the soil. Different mechanisms such as flow, arching, bearing, and friction, and various parameters like soil compressibility, pipe–soil relative stiffness, and soil elastic properties have been used in the determination of these two parameters. The P–y curves were verified and calibrated with experimental data. More reliable curves have been obtained compared to the existing methods. A numerical study was also performed to compare the current study with a pipeline seismic design guideline. The results of the current study method are in good agreement with sample experimental data compared to the seismic guideline.