A Novel in-situ Test Setup for Measuring the Interface Resistance between Pipelines and Underlying Soils-Paper

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The paper presents a proof-of-concept test setup designed to measure the drained interface resistance between offshore pipelines and soil. Existing laboratory and field methods can be costly or affected by passive resistance, uneven loading, and difficulty maintaining a consistent normal stress. The proposed system aims to provide a simpler, more economical alternative that could eventually be adapted for field deployment.<br /><br />The apparatus uses a modular, 1 m-long half-pipe divided into five sections. During consolidation, the sections act together under dead-weight loading. Before shearing, two short dummy sections are removed to create a clear path for the central test section, while the end sections anchor the system. A motor then displaces the central section horizontally, with a load cell measuring resistance.<br /><br />The setup was tested in normally consolidated clay against a stainless-steel interface. After consolidation, the pipe was sheared slowly through three displacement cycles under drained conditions. The measured peak interface friction angle was about 24°, and the residual angle was about 18°. Residual results were comparable to measurements from tilt-table and direct-shear tests on similar soil and interface, supporting the setup’s ability to estimate residual resistance.<br /><br />The authors conclude that the design is promising: it reduces end effects and eccentric loading and uses dead weights rather than costly external normal-load controls. However, it remains an early-stage laboratory model. Further testing across different soils, interfaces, and shearing rates is needed, and field use will require automated section removal and waterproofing.

Keywords

drained interface resistance

offshore pipelines

soil-pipe interaction

half-pipe apparatus

dead-weight loading

normally consolidated clay

stainless-steel interface

direct shear test

residual friction angle

laboratory prototype