State-of-the art knowledge on upheaval buckling of buried pipelines

This paper presents state-of-the-art knowledge on upheaval buckling, providing an overview on commonly used upheaval buckling soil models, latest uplift resistance results from experimental and numerical studies, investigations into the factors affecting the uplift resistance of soils and recommendations for design. The paper addresses the uplift resistance for both onshore and offshore pipelines. For onshore pipelines, the backfill soil cover could be dry, fully saturated or partially saturated. Thus, insight into the effects of degree of soil saturation on the uplift resistance is provided. For offshore pipelines, predicting the uplift resistance of buried pipelines has been a challenge due to uncertainty and randomness in the nature of soil cover created by various pipe burial techniques. This paper provides guidelines, supported by published literature, on the uplift resistance of different types of backfills such as sands, clays and blocky clays. An insight into the cyclic ratcheting mechanism, which is the driving mechanism leading to UHB pipeline failures, is also provided. It is expected that the paper will be a valuable source of information for designers and consultants undertaking pipeline designs both onshore and offshore.