【作者】 张爱霞；

【导师】 段梦兰； 黄一；

【作者基本信息】 大连理工大学 ， 船舶与海洋结构物设计制造， 2013， 博士

【摘要】 自升式平台是近海油气田开发中广泛使用的平台结构型式。由于海底地质条件复杂,平台在上硬下软的地基上插桩时,经常会发生穿刺事故,严重威胁着平台生产作业的安全。本文以渤海十二号自升式钻井平台为研究对象,对方形桩靴的单层及双层地基极限承载力进行了深入的理论分析,并对平台预压载求解方法及穿刺过程中的结构响应进行了研究,主要研究内容包括：1、构造了方形桩靴三维地基复合滑移破坏面,并根据极限平衡理论,由塑性体的平衡条件推导出一种新的方形桩靴单层地基承载力计算公式。2、以迈耶霍夫-汉纳冲剪理论为基础,对双层地基土体破坏面提出了合理的假设,建立了一种新的方形桩靴双层地基承载力的计算方法。3、为准确判断发生穿刺的可能性,提出了一种基于动力分析的计算平台预压载的科学方法,该方法的计算结果比现有工程方法更接近实际情况,从而可有效避免结构发生穿刺。4、针对平台穿刺,建立了方形桩靴自升式平台有限元分析模型,并就三种穿刺工况分析了穿刺前后的桩腿及船体形态、危险点分布、穿刺速度对结构的影响及预压载分布的变化,首次探讨了自升式平台穿刺过程中的结构响应特征；并通过计算平台极限穿刺深度,评估了平台的抗穿刺能力。更多还原

【Abstract】 Jack-up platform is widely used in the offshore exploration in China. Owing to the complicated subsea geological condition, punch-through accidents occur frequently, which threaten the operation safety of Jack-up.In this paper, in-depth theoretical study for the ultimate bearing capacity assessment for Jack-up platform with square spud-can is carried out. In addition, methods of preload prediction and structure response assessment during Jack-up punch-through are discussed. The main contents are as follows:1、For the ultimate bearing capacity of square spud-can in single soil layer, slide failure surface for the3D soil is created and a new ultimate bearing capacity expression is obtained from the static equilibrium conditions of plastic body based on the ultimate balance theory.2、A reasonable assumption is presented for the failure surface of double-layer foundation based on the analysis of Meyerhof-Hannah punching theory. Then one new method for calculating the ultimate bearing capacity of double-layer foundation is developed.3、In order to predict the risk of punch-through more precisely, one new method-dynamic analysis method is proposed and the result by this method is found to be more accurate, so that the Jack-up punch-through can be avoided effectively.4、To analyze the structure response of Jack-up in punch-through accident, a detailed finite element model is built. The status of leg and hull before and after punch-through, distribution of dangerous points, effects of punch-through speed on the structure and change of preloads are studied in three working conditions. The response characteristics of Jack-up in the accident are investigated and an ultimate punch-through depth is found out to determine the structure ability against punch-through.更多还原