Development of a prototype for modelling soil–pipe interaction and its application for predicting uplift resistance to buried pipe movements in sand

Abstract

This paper presents a testing rig for measuring the reactions on rigid pipes buried in sand during episodes of relative displacement. Following a detailed presentation of the 1g prototype, the test preparation procedure, and the characterization of the test sand’s shear strength and dilation potential under the low confining stresses pertinent to the problem, the paper focuses on the workflow devised to obtain accurate measurements of friction and arching effects, and accordingly normalize them to account for scale (stress level) effects. Emphasis is put on demonstrating the effectiveness of the sand deposition method for accurately controlling the density of the sample, and on quantitatively assessing its uniformity. Measurements obtained during a series of uplift tests, including reaction force – pipe displacement curves and images of the developing failure surface, facilitated by particle image velocimetry and close-range photogrammetry techniques, are compared against published data and analytical methods. The results lead to the development of a new simplified formula for calculating the uplift resistance to buried pipe movements in sand: capable of accounting for scale effects, yet simple enough to be used for the analysis of pipes in practice.

Buckling Mechanism of Offshore Pipelines: A State of the Art

“…The results obtained using eq 47 and 48 are shown in Figure 11. The results are also compared with the result obtained using DNV RP-F110 [62] and experimental means. It is observed that Equations (47) and (48) overestimate the uplift resistance in comparison to experimental results.…”

“…Several authors observed that soil strength is one of the crucial factors to influence the uplift resistance. They empirically or theoretically developed different models to predict the uplift resistance from undrained or drained soil resistance [62,63]. Thus, according to DNV RP F110 [64], the expression for uplift resistance was given as:…”

“…For cohesionless backfill, it was observed that the uplift resistance increased with increasing embedment depth (w) and displacement (δu) of the pipeline, as can be seen from Figure 12. Again, it was considered by DNV RP F110 [62] and ASCE guidelines that the displacement corresponding to the peak pipe resistance (δu,max) was hardly affected by the embedment depth for cohesionless backfill. While one researcher [77] observed that the displacement corresponding to the peak pipe resistance was significantly affected by the embedment depth ratio, especially for embedment depth (w) beyond 0.5 m. Moreover, δu,max was observed to decrease with an increasing relative density of soil and increase with increasing 'w' [72,78,79].…”

Vibration response analysis of free-spanning pipeline based on inner pipe excitation signal

“…In the simulation, the nonlinear spring (soil spring) with damper was used to simulate the coupling between the pipe and soil. [9][10][11][12][13] By setting the spring stiffness and damping coefficient, the soil supporting the pipeline can be simulated. In order to facilitate the analysis and calculation, following assumptions were made in this study:…”

“…This method is not only generally used to detect the reliability of product structure but also used for structural damage detection. 11,19 In the simulation, the sweep range was taken as 1-300 Hz. The sweep rate was set to 1 Hz and the value of excitation force was 0.3 N in this simulation, as shown in Figure 5.…”