ABSTRACT

The variable cross-section structure (comprising a riser, surface casing and cementing cement ring) of an oil well associated with an offshore oil platform is similar to that of a steel pipe pile foundation. If a well structure with variable cross-section characteristics can be used to provide bearing capacity, the construction cost of platforms will be reduced. In this paper, the finite element analysis method is used to study the vertical bearing mechanism of composite piles composed of a riser and a surface casing in saturated clay and sand. Based on the theory of spherical cavity expansion, the calculation methods of end resistance and skin friction resistance of composite pile are established. Finally, based on a field test of the bearing capacity of composite piles, the accuracy of the proposed calculation method is verified.

摘要

与海上石油平台相连的油井的变截面结构（包括立管、表层套管和固井水泥环）类似于钢管桩基础。如果可以采用具有变截面特性的井结构提供承载力，将降低平台的建设成本。本文采用有限元分析方法研究了隔水管和表层套管在饱和粘土和砂土中组合桩的竖向承载机理。基于球腔膨胀理论，建立了复合桩端部阻力和蒙皮摩擦阻力的计算方法。最后，通过复合桩承载力的现场试验，验证了所提出的计算方法的准确性。