Physical modelling of lateral sand–pipe interaction

Abstract

This paper presents a series of physical modelling tests performed to measure the resistance developing during lateral dragging of a rigid pipe buried in loose to very dense dry sand. The experiments were performed in a small-scale prototype developed to model sand–pipe interaction during relative ground movement episodes while accurately controlling the density and uniformity of sand around the pipe. Digital imaging and particle image velocimetry equipment are integrated with the rig, so as to track the evolution of the failure surface developing in sand with increasing pipe displacements. Auxiliary components of the rig allow investigation of the effects of pipe kinematic constraints and embedment method on the results obtained. Accordingly, the measurements obtained with the developed prototype are compared against results from similar studies, with the intention of shedding some light on the scatter observed in published data, and on the provisions from different pipe stress analysis guidelines. It is shown that current simplified methods may underestimate the lateral reaction developing on pipes in very dense sand beds, and analysis models built around these methods may under-predict pipe strains. To alleviate this, a modified expression is proposed for estimating the peak reaction of lateral elastoplastic soil springs, and an upper bound of this reaction is provided for design purposes.

Suction effects during uplift of steel pipes buried in compacted soil

“…The results of six uplift experiments performed in dry STK sand [2,3,38,39] are presented to establish a baseline for the experiments with the pipe buried in compacted soil beds. The experiments were performed with the pipe buried in loose (relative density D r = 27%, dry unit weight c dry-= 15.15 kN/m 3 ) to dense (D r = 93%, c dry = 17 kN/m 3 ) sand in shallow depths H/D = 1.5 and H/D = 3 to match the embedment depths of experiments on compacted sandy loam-Kaolin.…”

“…Numerous studies have resulted in methods for estimating the reaction force developing on a pipe as function of the mentioned problem parameters (e.g. [2,3,10,11,28,33,35,38,39]). Most of those are limited to the case of pipes buried in dry or fully saturated soil.…”

Ultimate lateral pressures exerted on buried pipelines by the initiation of submarine landslides

“…3a (e.g. Almahakeri et al 2013;Ansari et al 2019;Audibert and Nyman 1977;Calvetti et al 2004;Liu et al 2015;Ono et al 2017;Robert et al 2016;Roy and Hawlader 2012;Tian and Cassidy 2011;Trautmann and O'Rourke 1985;Zhang et al 2002). In reality, the pipes may be pulled by fishing gear or anchors.…”

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

“…For the tests under lateral loading, the pipe specimen's movement in a vertical direction was restrained to be zero such that a coupled response of pipe in lateral and vertical directions can be investigated by measuring soil resistance in a vertical direction. Therefore, it should be noted that the measured soil resistance in a lateral direction can be different from soil resistance of pipe without being restrained in a vertical direction 25 …”