吸力桶基础安装过程贯入阻力和运行过程承载性能演化及分析方法是海洋岩土工程领域的一个重要课题。对于常用的吸力桶基础土塞清除方法，原理上未充分考虑吸力桶基础吸力贯入过程中的渗流作用。本研究以现有研究成果为基础，基于吸力桶基础安装运行过程离心模型试验和数值计算方法开展深入研究，以期揭示吸力桶基础安装过程贯入阻力和运行过程承载力的演变规律，研发吸力桶基础土塞清除设备结构，发展可清除土塞的吸力桶基础安装方法。主要取得以下创新性成果：（1）建立了吸力桶基础安装运行过程离心模型试验和数值计算方法。研制了吸力桶基础安装运行过程离心模型装置；开发了大变形流固耦合数值计算方法，以太沙基一维固结和动力固结算例验证了数值模拟方法的有效性。（2）揭示了吸力桶基础吸力贯入和压力贯入的基本受力机制。在吸力贯入过程中由于负压的存在导致吸力桶基础内部产生明显的渗流，引起吸力桶基础内部土体产生流土，从而降低了内摩擦阻力和端阻力。在黏土中，负压的影响主要集中在桶内土体顶部，并未在吸力桶基础内部土体中形成较大的渗透力，吸力桶基础内摩擦阻力也未受负压的影响而明显降低。在压力贯入过程中，由于基础的贯入导致土体压缩，增加了土体的总应力，该总应力最初表现为吸力桶基础桶端的超静孔压，随着超静孔压的扩散，有效应力逐渐增加。（3）分析了安装方式、土体特性、基础顶部排水条件、安装-运行时间间隔对吸力桶基础承载性能的影响规律。发现了压力贯入完成后吸力桶基础的抗拔性能明显高于吸力贯入的安装方式，基础顶部不排水条件工况下吸力桶基础的抗拔性能明显高于排水条件的工况，短期和长期时间间隔工况下抗压和抗拔性能随着循环圈数的不断增加而基本趋于一致。（4）提出了可清除土塞的吸力桶基础安装方法。研制了一种用于土塞清除和桶内土体加固的吸力桶基础复合结构设备，同时研制了该设备的1g模型，试验测试验证了基于该设备的除塞方法在黏土和砂土中的有效性和适用性。
The evolution process and calculation method of suction caisson penetration resistance during installation process and the bearing capacity during operation process are important research topics for offshore geotechnical engineering. For the commonly used suction caisson soil plug removal method, the seepage effect of suction caisson during suction penetration process is not fully considered. Based on existing research results, this study conducts in-depth research through centrifuge tests and numerical simulation method to reveal the evolution mechanism of penetration resistance and bearing capacity during installation and operation process of suction caisson. A suction caisson soil plug removal equipment and installation technology have been developed. The main achievements are concluded as follows:(1) The centrifuge tests and numerical simulation method for suction caisson during the installation and operation process were established. The centrifuge model for suction caisson installation and operation process was developed. A large deformation solid-fluid coupled analysis method was developed. The Terzaghi one-dimensional consolidation and dynamic consolidation are established by this method. The numerical results are in excellent agreement with the analytical solution, proving the validity of the implemented coupled formulation.(2) The physical mechanism of suction caisson suction penetration process and jacked penetration process was revealed. During suction penetration process, the existence of suction pressure causes obvious seepage inside the suction caisson. This seepage generates an upward seepage force, which causes the soil in suction caisson reaching liquefaction state. The reduction of penetration resistance during suction penetration is mainly due to the reduction of internal friction resistance and tip resistance. In the clay, the influence of suction pressure is mainly concentrated on inside caisson soil surface. There is no large seepage force formed in the soil inside suction caisson. The internal friction resistance is not significantly reduced by the suction pressure. During jacked penetration process, the insertion of the caisson walls compresses the soil to increase the total stress, which is first reflected in the increase of excess pore pressure. As the excess pore pressure spreads, the effective stress also increases.(3) The influence of installation method, soil characteristics, drainage conditions and short-term and long-term interval on the suction caisson bearing capacity was analyzed. The bearing capacity of jacked penetration installation method is significantly larger than that of suction penetration. As for drainage conditions, the bearing capacity under undrained condition is significantly higher than that under drained condition. In addition, for the influence of installation to operation time interval, the bearing capacity of short-term interval and long-term interval tend to be consistent.(4) An installation technology of removing soil plug for suction caissson is proposed. A suction caisson composite structure equipment was developed to solve the soil plug and improve the bearing capacity of suction caisson. The 1g model of this equipment was developed, which verified the applicability of this installation technology in both clay and sand.
