自升式平台桩土效应与桩腿结构构型研究

发布时间：2018-07-24 14:03

【摘要】：自升式平台是海洋石油勘探与开发的重要装备,在海洋油气开发中已被广泛应用。由于海底地质条件复杂和平台作业水深增加等因素的影响,对自升式平台的运营安全和研制成本提出了更高的要求。提升平台作业安全性,优化平台结构,降低研制成本,对于提升该类装备的市场竞争力有着重要的意义,已引起业界的广泛关注。本文以辽宁省科技重大专项“350英尺自升式钻井平台研制”为依托,选取自升式平台海底层状土承载力、平台插桩入泥深度、平台拔桩阻力、桩腿结构构型等为研究对象,以提升作业安全性,降低研制成本为目标,开展以下研究工作:1)鉴于传统地基承载力计算方法在处理参数复杂的海底地质条件下的局限性,开展浅基础地基极限承载力的经验计算方法及其适用性研究。依据土壤弹塑性力学性征,对承压土层以滑移破坏面为边界进行区域划分,基于极限平衡理论,对承压地基进行力学平衡求解,从理论上研究地基土主动区、过渡区和被动区的土体应力和应变行为。通过研究单层不同质土壤的极限承载力计算方法,给出一种新的圆形浅基础站立于层状海洋地基土,在不同失效模式下的承载力计算方法。2)针对自升式平台因插桩深度的预估不足可能导致刺穿的隐患,开展桩靴与土体相互作用机理研究。考虑桩靴与土体相互作用涉及到的非光滑摩擦准则、土体大变形和材料非线性等力学特性,构建有限元模型,模拟平台插桩时桩土相互作用及土体的破坏过程。计及桩靴形状特点、插桩过程和桩坑深度等因素的影响,修正桩靴入泥深度规范计算公式,给出一种实用的入泥深度计算方法。采用经验公式、数值模拟和实验技术对桩靴入泥过程进行分析,并与修正的规范公式计算结果进行比较,结合平台实际作业井位记录的插桩深度,验证有限元方法计算的准确性和修正公式计算的实用性。3)针对平台拔桩阻力预估不足可能导致的安全隐患,基于桩-土相互作用机理和流-固耦合理论,考虑桩周土体回填后淤积固结强度等因素的影响,对平台在典型区块拔桩过程中土体运动、土体破坏和孔隙水压变化等进行研究。采用经验公式和有限元方法,对典型井位的拔桩阻力进行计算比较,重点研究土体孔隙压力、冲桩和上顶力等因素对基底吸附力的影响,给出不同持力层的吸附力和冲桩效果对比分析结果,提出拔桩阻力有效的计算方法,结合实际井位拔桩阻力数据比较,验证方法的有效性。4)针对自升式平台因作业水深增加所带来的桩腿结构柔性凸显的问题,以母型桩腿为参考,对自升式平台桩腿结构构型进行研究。在风洞中按1/100缩尺比模型进行五分量测力试验,获取目标平台的风载荷数据。基于STOKES五阶波理论,通过SESAM软件计算获取波流载荷。通过模态分析,获取计及DAF效应和P-△非线性效应的惯性载荷。以拖航和自存工况下桩腿总强度的满足为校核条件,选取桩腿节距和弦管间距进行离散,结合参数化建模技术,对自升式平台在拖航工况和自存工况下的14种构型的桩腿总强度进行综合评估,以降低桩腿重量,提高经济性为目标,对现有平台桩腿结构形式进行优化,给出优化后的桩腿参数,形成自升式平台桁架式桩腿结构选型方法。
[Abstract]:The jack up platform is an important equipment for offshore oil exploration and development. It has been widely used in the development of marine oil and gas. Due to the complex geological conditions of the seabed and the increase of the depth of the platform operation, a higher requirement for the operation safety and development cost of the jack up platform is put forward. The operation safety of the platform and the structure of the platform are optimized. Reducing the cost of development is of great significance to improving the market competitiveness of this kind of equipment. It has aroused extensive concern in the industry. Based on the "development of 350 foot jack up drilling platform" in Liaoning Province, this paper selects the bearing capacity of the submarine layered soil in the jack up platform, the depth of the platform inserting the mud into the mud, the drag resistance of the platform and the pile leg. In order to improve the safety of operation and reduce the cost of development, the following research work is carried out to carry out the following research work: 1) in view of the limitations of the traditional foundation bearing capacity calculation method under the complex submarine geological conditions, the empirical calculation method and its applicability of the ultimate bearing capacity of shallow foundation foundation are carried out. On the basis of the theory of limit equilibrium, the mechanical equilibrium of the bearing foundation is solved. The soil stress and strain behavior of the active, transition and passive areas of the foundation soil is theoretically studied by the theory of limit equilibrium. The ultimate bearing capacity of the single layer soil is studied by the calculation of the ultimate bearing capacity of the soil. Method, a new type of circular shallow foundation stand on layered ocean foundation soil, the calculation method of bearing capacity in different failure modes.2) is used to study the mechanism of interaction between pile boots and soil. The finite element model is constructed to simulate the interaction of pile and soil and the failure process of soil soil during the platform inserting pile. Considering the influence of the shape characteristics of the pile boots, the process of piling and the depth of the pits, a practical formula for the depth of mud depth is revised and a practical depth meter is given. An empirical formula, an empirical formula, numerical simulation and experimental technique are used to analyze the mud process of the pile boots, and compared with the revised standard formula calculation results. The accuracy of the finite element method calculation and the practicability of the revised common formula.3) are verified by the comparison with the revised standard formula calculation results. On the basis of pile soil interaction mechanism and flow solid coupling theory, the effect of soil movement, soil failure and pore water pressure change in typical block pile pulling process is studied based on the pile soil interaction mechanism and the flow solid coupling theory, and the empirical formula and finite element method are used to study the soil movement, soil failure and pore water pressure change during the pile pulling process of typical blocks. The effect of soil pore pressure, pile and top force on the base adsorption force is studied, and the results of the comparison and analysis of the adsorption force and the effect of the pile impact are given. The effective calculation method of the resistance of the pile pulling resistance is put forward, and the validity of the method is verified by the comparison of the actual hole pulling resistance data. .4) in view of the problem that the pile leg structure flexibility of the jack up platform is highlighted by the increase of the working water depth, the structure of the pile leg structure of the jack up platform is studied. The five component force test is carried out in the wind tunnel according to the 1/100 scale ratio model in the wind tunnel, and the wind load data of the target flat are obtained. Based on the theory of the STOKES five order wave, the wind load data are obtained. Through the SESAM software calculation, the wave flow load is obtained. Through the modal analysis, the inertia load of the DAF effect and the nonlinear effect of P- delta is obtained. Taking the total strength of the pile leg under the towing and self storage conditions as the checking condition, the spacing of the leg and the spacing of the string are discretized. The total strength of 14 types of pile legs under the storage condition is evaluated comprehensively. In order to reduce the weight of the pile legs and improve the economy, the structure of the pile legs in the existing platform is optimized and the optimized pile leg parameters are given, and the structure selection method of the truss type leg structure of the jack up platform is formed.
【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P742

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