Modeling of buried pipelines subjected to ground movement

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Buried pipelines are the prime mode of transportation of liquid hydrocarbon and natural gas products from field development areas to domestic and international markets. Safe, economic and reliable operation of pipeline transportation systems is the primary goal of the pipeline operators and regulatory agencies. The main objectives of applicant's ongoing and proposed research programs on pipelines are the development of new/improved design tools for buried pipelines subjected to ground movement from three different sources. (a) ICE GOUGING: The potential threat of seabed ice gouging on Arctic pipelines was identified a long time ago. One method to protect pipelines from ice gouging effects is to bury the pipelines to a sufficient depth. However, there is a significant controversy in modeling ice gouging events and in predicting safe burial depth. In the proposed research, an appropriate constitutive model that can represent the soil behavior properly, including the highly sheared zones below and around the keel, will be developed and implemented in Finite Element algorithm for modeling large displacement of soil. An improved method of estimating burial depth of pipelines will be developed. (b) SUBMARINE SLOPE FAILURE: The potential failure of deepwater slopes could affect exploration, production and transportation facilities. The proposed research will identify the potential causes of submarine slope failure. Physical modeling using geotechnical centrifuge and numerical modeling will be performed to develop a rational method for predicting the failure of submarine slopes and its effects on pipelines. (c) FROST HEAVE UNDER CHILLED GAS PIPELINES: A reliable design procedure for predicting frost-heave under chilled gas pipelines is required for northern pipeline design. In the proposed research, centrifuge tests and numerical modeling will be performed. The findings will be very useful for the verification of frost heave models, as full-scale tests are expensive, and will provide significant inputs to develop improved design methods. The grant will support training of 3 Master's and 4 Doctoral students.