孙立强¹，刘政卿^{1, 2}，齐玉萌^{1, 2}，封晓伟³
AuthorsHTML:孙立强¹，刘政卿^{1, 2}，齐玉萌^{1, 2}，封晓伟³
AuthorsListE:Sun Liqiang¹，Liu Zhengqing ^{1, 2}，Qi Yumeng ^{1, 2}，Feng Xiaowei³
AuthorsHTMLE:Sun Liqiang¹，Liu Zhengqing ^{1, 2}，Qi Yumeng ^{1, 2}，Feng Xiaowei³
Unit:1. 天津大学水利工程仿真与安全国家重点实验室，天津 300072；
2. 天津大学建筑工程学院，天津 300072；
3. 西澳大学海洋基础研究中心，澳大利亚 珀斯 WA 6009
Unit_EngLish:1. State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300072，China；
2. School of Civil Engineering，Tianjin University，Tianjin 300072，China；
3. Centre for Offshore Foundation Systems，University of Western Australia，Perth WA 6009，Australia
Abstract_Chinese:桶形基础因其安装方便、可重复使用等优点而广泛应用于海洋工程中，在服役期间或者退役回收时会受到上拔承载力作用，准确计算桶形基础的上拔承载力是保证基础稳定工作和顺利回收的重要前提，桶形基础的上拔承载力与桶的几何尺寸、上拔速率、土体参数以及在自重等预压荷载下的固结情况等因素有关．本文采用有限元的方法对桶形基础上拔承载特性进行研究，通过对不同长径比、上拔速率、土体参数及预压荷载等影响因素进行正交组合计算，研究了其不同上拔速率下破坏模式及负压发展规律，提出归一化上拔速率vs/C_v(其中v为实际上拔速率，s为排水路径，C_v为固结系数)对桶形基础上拔过程的排水条件进行划分．根据破坏模式及抗拔力各组分比重提出了桶形基础在不排水和完全排水条件下上拔承载力计算公式，在此基础上建立了归一化的上拔承载力与桶形基础几何形状L/D、归一化上拔速率vs/C_v以及土体强度之间的对应关系，并提出了部分排水条件下上拔承载力计算方法．结合算例给出了该成果在工程上的应用步骤和方法，成果可直接用于工程设计．
Abstract_English:Owing to its convenient installation and reusability，bucket foundations have been widely used in the ocean engineering field．Bucket foundations need resist considerable tensile loads during service or decommission，therefore，the accurate calculation of the uplift bearing capacity of bucket foundations is important for ensuring stable operation and facilitating future recycling．The uplift bearing capacity of offshore bucket foundations is related to the geometry of the foundation，uplift velocity，soil properties，and preloading owing to self-weight．In this paper，the finite-element method is employed to investigate the tensile capacity of bucket foundations．The failure mechanisms and variation in negative pressure are analyzed through the joint calculation of key factors，such as aspect ratio，uplift velocity，soil properties，and preloading．The normalized uplift velocity vs/C_v，where v denotes the uplift velocity，s represents the characteristic length of a drainage path，and C_v is the consolidation coefficient，is proposed to determine the drainage conditions of the bucket foundation uplift process．The calculation formulas of the tensile capacity of offshore bucket foundations under undrained and drained conditions are derived by considering the failure mechanisms and components of mobilized resistance．Further，a unique expression of uplift bearing capacity under the partial drainage condition is derived as a function of the length-to-diameter aspect ratio L/D，normalized loading velocity vs/C_v，and shear strength of a soil．An example application assisting the routine design of the engineers is included to demonstrate the proposed calculation procedure of uplift bearing capacity using the numerical results derived from the current study，which can be directly applied to the engineering design．
Keyword_Chinese:桶形基础；排水条件；上拔承载力；预压荷载
Keywords_English:bucket foundation；drainage condition；uplift bearing capacity；preloading

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