FAN Qinglai,MA Siqi,CHEN Xiaodi,et al.Local Scour Around Pile Leg of Offshore Platform and Its Influence on Foundation Bearing Capacity[J].Journal of Disaster Prevention and Mitigation Engineering,2023,43(06):1246-1254.
FAN Qinglai,MA Siqi,CHEN Xiaodi,et al.Local Scour Around Pile Leg of Offshore Platform and Its Influence on Foundation Bearing Capacity[J].Journal of Disaster Prevention and Mitigation Engineering,2023,43(06):1246-1254. DOI: 10.13409/j.cnki.jdpme.20221014001.
Local Scour Around Pile Leg of Offshore Platform and Its Influence on Foundation Bearing Capacity
During the installation and construction of spudcan foundations of offshore platforms, it is easy to cause damage due to penetration phenomena. It is suggested by the industry that an upward sleeve structure can be added around the pile shoe to suppress the backflow of the surrounding soil during penetration, so as to alleviate penetration damage. However, the presence of such sleeve structure will lead to local scour, and the scour pit formed will reduce the effective burial depth of the spudcan foundation, thus affecting its bearing capacity during its service life. A series of flume tests were conducted to examine the influence of factors such as the area ratio of different pile legs, the opening rate, the inflow angle on the shape of the scour pit. Then, numerical calculations of the bearing capacity of the spudcan foundation considering the impact of the scour pit were conducted, and the results were compared with those derived from the traditional model neglecting the soil above the maximum scour depth, and those from the simplified model assuming that the scour pit is in the shape of an inverted cone. The main results are as follows: (1) The erosion depth caused by the pile leg with the circular sleeve structure is smaller than that of the square sleeve structure. It is suggested in the project to use the circular sleeve structure with a relatively small area ratio to alleviate the punch-through damage. (2) The area ratio of pile leg, and inflow angle affect the shape of scour pit. The maximum scour depth decreases with the increase of the opening rate. When the opening rate is large, the scour phenomenon is similar to that of pile group and the scour depth first increases and then decreases with the increase of the inflow angle. (3) The simplified model can reasonably reflect the impact of the scour pit on the bearing capacity of the spudcan foundation when considering the influence of scour pit.
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