UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Shear strength of soil-pipeline interfaces under low confining stresses and large displacements Amarasinghe, Ruslan Shanth


The design of onshore and offshore energy pipelines requires that the geotechnical aspects of the soil-pipe interaction are adequately captured. The soil-pipe interface shear strength is an important design parameter that is required for assessing soil loads on pipelines. Laboratory element and physical model testing conducted under relatively large displacements and soil confining stresses relevant to the soil-pipe interaction problem (typically within the range of 3 to 30 kPa) is required to derive appropriate soil-pipe interaction parameters for use in designs and for the validation and improvement of design guidelines. However, laboratory test methods for assessing soil-solid interface shear strength under low confining stresses and large displacements are not well developed, and the availability of laboratory test data conducted under the above conditions is very limited. A novel macro-scale interface direct shear apparatus capable of testing soil specimens of 1 m x 1 m footprint on various solid surfaces under low confining stresses (2 to 40 kPa) and large displacements (up to 1 m) while providing the means to measure pore-water pressure and total normal stress at the soil-solid interface was developed, and a series of macro-scale interface direct shear tests were conducted to study the effect of soil type, confining stress level, and surface roughness of the solid surface on the drained large displacement soil-solid interface friction angle using a number of soils and epoxy coated steel surfaces. A novel full- scale axial soil-pipe interaction physical model test apparatus capable of testing pipes of up to 0.45 m (18 inch) in diameter in saturated fine-grained soil was developed and a limited number of tests were conducted using an NPS18 (0.45 m diameter) epoxy coated steel pipe on a fine-grained soil bed. This dissertation presents the details of the new apparatus and the tests conducted. The results of the experiments and important findings are presented and discussed.

Item Citations and Data


Attribution-NonCommercial-NoDerivatives 4.0 International