Discrete element analysis of uplift and lateral capacity of a single pile in methane hydrate bearing sediments |
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| Institution: | 1. Department of Geotechnical Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China;2. State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China;3. Key Laboratory of Geotechnical and Underground Engineering, Tongji University, Ministry of Education, 1239 Siping Road, Shanghai 200092, China;1. Dipartimento di Ing. dell׳Informazione, Ing. Elettrica e Matematica applicata, Università di Salerno, Italy;2. Scuola di Ingegneria, Università degli Studi della Basilicata, Italy;1. Institute for Electrical Drive Systems and Power Electronics, Technische Universitaet Muenchen, Munich, Germany;2. Faculty of Electrical and Computer Engineering, Shahid Rajaee Teacher Training University, Tehran, Iran;3. Department of Electronics Engineering, University Federico Santa Maria, Valparaiso, Chile;1. College of Civil Engineering and Architecture, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China;2. MOE Key Laboratory of Soft Soils and Geoenvironmental Engineering, Zhejiang University, Hangzhou 310058, China;1. Faculty of Engineering, Zhejiang Institute, China University of Geosciences, Wuhan, Hubei, 430074, China;2. Research Center of Coastal Urban Geotechnical Engineering, Zhejiang University, Hangzhou 310058, China;3. Geotechnical Research Centre, Department of Civil and Environmental Engineering, Western University, London, ON, N6A 5B9, Canada |
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| Abstract: | Methane hydrate (MH) is extensively found in outer continental margins where offshore infrastructures with pile foundations are also common. The presence of MHs significantly alters the mechanical properties of the host marine sediments, and therefore affects the behavior of piles inside. This paper presents an attempt to investigate the performance of a single pile in methane hydrate bearing sands in seabed using the distinct element method. A novel bond contact model was employed for sandy grains cemented by MHs at contacts, and calibrated from the triaxial compression tests on synthetic specimens of methane hydrate bearing sands. The response of the pile subjected to axial pullout loads and lateral loads was simulated under different subsurface conditions characterized by different saturation levels of MHs. The results show that the presence of MHs increases the uplift capacity of the pile by changing the failure mode of the soils from the perimeter failure to the conical failure. The uplift capacity of the pile significantly deteriorates as a result of de-bonding, while the onset of the rapid de-bonding triggers the softening of the uplift load. In addition, the lateral capacity of the pile largely increases due to the presence of MHs. The pile in methane hydrate bearing sands is considered flexible rather than rigid as a result of the increased deformation modulus of soils due to MH cementation between particles. The lateral load–displacement diagram of the pile in methane hydrate bearing sands is not as smooth as that in clean sands with an abrupt drop associated with the onset of de-bonding. |
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| Keywords: | Methane hydrate bearing sand Pile Bearing capacity The distinct element method |
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