Effect of Tension on the Combined Loading Failure Envelope of a Pipeline on Soft Clay Seabed

Abstract

Offshore pipelines are commonly laid directly on the seabed, which is dominantly soft clayey deposits in deep-water areas. This article presents a numerical finite-element study of the undrained bearing capacity of a pipeline partially embedded in clay soil and subjected to combined vertical (V) and horizontal (H) loading. The effect of tensile capacity between the pipe and soil is considered. Expressions for bearing-capacity envelopes explicitly written in the V–H space and covering a practical range of embedment ratios and uplift tensile capacities are presented. This allows offshore engineers to estimate pipeline behavior under combined loading with consideration of the tension between pipe and soil.