【作者】 齐剑峰；

【导师】 冯秀丽； 杨少丽；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2003， 硕士

【摘要】 本文是国家自然科学基金项目“海上平台桶形基础及其作用下的粉质土海床失稳机制的研究”的前期研究内容，主要通过模型试验对负压沉贯过程的渗流梯度及其桶内粉质土的失稳机制进行研究，并探讨和分析了不同比尺的桶基的沉贯效应。主要研究内容与成果有： 根据模型实验结果对不同比尺的桶基的沉贯行为进行了研究，并初步分析了沉贯行为产生的原因。 通过对土单元体的力学分析，提出渗流出口的临界渗流梯度的计算方法，根据桶基端部处是否出现最大渗流梯度，对负压沉贯过程中渗流梯度的分布形式进行了划分。 桶基端部土体的破坏形式是高渗流梯度下的剪切破坏，并通过计算得出沉贯阻力主要是桶基端部阻力，模型实验中桶基侧壁摩擦力可以忽略，壁厚大的桶基，所削减的端部阻力也大。 通过多种试验对土塞形成的原因进行了分析，提出土塞产生的流变原因，该流变的一个显著特点是作为塑性变形区整块土体受负压作用，而塑性变形区内部土体受向上的渗流作用，这两种作用都是土塞形成和发展的积极因素。通过对实验数据的整理、分析，提出了土塞大小的计算方法，建立了土塞大小的统计模型：H=β₀+β₁（?）+ζ，并指出了模型参数β₀和β₁的实际意义；通过大量的实验数据验证，该模型是可靠的。更多还原

【Abstract】 The thesis is the initial research content of the project "Bucket Foundation and Unstability Mechanism Research Influenced by Bucket foundation on Silty.Sand Seabed", which is supported by the national natural science fund. It mainly carry about the research of seepage gradient in the process of suction penetration and unstability mechanism of silty sand in the bucket foundation, and it also discuss and analyze the penetration effect of bucket foundation of the different ratio size.The penetration effect of the different ratio size in the process of penetration is studied and analyzed according to the result of experiment.The calculating method of critical seepage gradient is brought forward through the mechanics analysis of the soil unit. Seepage gradient is divided into three different distributing style, through the analysis of data from sensors, on the basis of the position of the end of bucket foundation and the maximum seepage gradient.The conclusions are drawn that the soil body’s failure style at the end of bucket foundation is shear failure under condition of the high seepage gradient;Penetration resistance is mainly the resistance of the end of bucket foundation, because friction can be omit according to calculation, the bucket foundation of the thicker wall reduces more resistance in the soil body.The five reason of the formation and development of the plug is considered , and the rheology of soil body in the plastic deformation area is especially pointed out; The statistic model is built in order to calculate the plug’s length, and the practical significance of the model parameters is given out. It plays an important role on predicting the length of the plug in the process of penetration.更多还原