Shallow and deep failure mechanisms during uplift and lateral dragging of buried pipes in sand

Abstract

This paper presents results of a series of experiments modelling uplift and lateral drag of a rigid pipe buried in dry sand. The main aim of these tests is to document the gradual transition from shallow to a deep sand failure mechanism as the pipe embedment depth increases, identify which parameters affect this transition, and determine experimentally the critical embedment depth, beyond which the normalized reaction acting on the pipe remains constant with increasing pipe embedment. Measurements of the reaction as a function of the relative sand–pipe movement and analysis of images captured during the tests with the particle image velocimetry method suggest that the critical embedment depth depends on sand density, but not on the direction of pipe movement. Outcomes of this study contribute to identifying the limits of applicability of simplified methods used to determine the peak reaction on pipes subjected to ground movements and the estimation of rational parameters for the analysis of deeply buried pipes with beam-on-nonlinear Winkler foundation models.

Efficacy of simple continuum models for diverse granular intrusions

“…The visualizations of plastic strains and strain rates (Figure 3C and D) qualitatively agree with those reported in previous numerical and experimental studies 42,43 . Notably, the variation of the equivalent plastic strain shows a strong semblance with the work of Wu et al 44 . Additionally, we also plot the variation of the local hydrostatic pressure at four different depths in figure 3E.…”

“…Drag and lift forces on submerged objects in granular media are relevant in processes such as mixing, mining, soil-buried pipelines, and animal locomotion [35][36][37] . Over the past two decades, several studies [38][39][40][41] have explored the mechanisms and the variation of these forces by considering the horizontal dragging of submerged, rigid cylinders (at different depths) as a test case. We specifically consider the work of Guillard et al 39 , who find that the horizontal drag force on cylindrical objects moving horizontally increases with increasing depth while the vertical lift force plateaus for depths greater than a O(1) factor of the cylindrical diameter.…”

Buckling Mechanism of Offshore Pipelines: A State of the Art

“…Pipelines are often buried within the seabed to protect the pipelines from different hydrodynamic forces [47,48] and also from different human activities such as fishing or transportation. While in some cases, the pipeline is buried under a rubble-mound material, which acts as a protection, e.g., as similarly to [3], in others it may be buried within the actual soil [49].…”

“…Moreover, the upheaval buckling of pipelines often causes collapse of the buried pipelines, for example, the rupture of a buried pipeline at Guanabara Bay of Rio de Janeiro, Brazil [60]. Thus, a significant number of researchers showed interest in exploring the upheaval buckling phenomenon of a buried offshore pipeline [35,48,52,54,56,59]. In Figure 10, a schematic diagram of global upheaval buckling of buried pipeline is shown.…”

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

“…Many experimental studies considering various test parameters such as pipe dimension (i.e., diameter, length), embedment depth, and properties of a surrounding soil have been carried out for horizontal or inclined loading, and for monotonic loading, along a pipe's lateral direction 3–11 . Experimental studies have also been carried out to consider the test parameters along a pipe's vertical direction, especially for uplift direction 12,13,14,15,16–17 . Based on the test results, several researchers developed finite element (FE) model for predicting soil‐pipe interaction under uplift loading 18–20 or under differential ground motion associated with normal faulting 21 …”