动态贯桩桩—土相互作用数值分析及试验研究

发布时间：2018-05-19 05:44

本文选题：ALE + 桩端极限承载力　；参考：《浙江海洋学院》2015年硕士论文

【摘要】：自升式钻井平台广泛应用于近海石油开发,但由于海底地基以及自升式平台插拔桩过程中桩土作用的复杂性,经常会发生地基不稳、桩腿沉降不匀、平台倾斜、冲刷与淘空现象,给平台的作业安全带来极大挑战。按现行规范,自升式平台结构计算的边界条件是将地基的作用简化为泥面下某处约束,这种简化忽略了海底地基与平台结构的相互影响,从而会引发平台结构安全问题。本文以渤海湾“胜利五号”在作业平台桩靴模型为研究对象,采用试验及数值分析方法探究桩土动态贯入过程,并提出针对我国渤海海域地基影响下自升式平台强度计算的修正方法,为自升式平台结构设计的改进提供依据。论文的重点研究内容有以下几点:1.介绍ALE(任意拉格朗日欧拉法)在处理桩土大变形有限元分析中的优越性,引入以处理桩端极限承载力为主要研究对象的土体MPC模型,同时对桩靴及地基进行简化,并建立桩靴及土体模型。2.利用有限元分析软件ABAQUS/ALE模拟桩土动态贯入过程,探究贯入过程中桩侧土体流动机理以及桩靴上部空腔的形成、发展和破坏机理。并提取桩端上下端面土体的速度差来研究空腔上部土体回流对桩端承载的影响。3.以渤海湾某井位作业地质条件为依据,利用静压贯桩试验验证桩靴底部压力分布规律,并同数值模拟与《海上移动平台入级与建造规范》中对于桩靴底部压力分布的假定进行比较。同时在复合地基基础上研究穿刺现象对桩靴结构的影响。4.通过上述方法对桩土贯入的动态过程进行试验及数值模拟,提出一种桩靴支护结构的优化方法,分析该支护结构对土体流动及桩端承载的影响。
[Abstract]:The jack-up drilling platform is widely used in offshore oil exploitation. However, because of the complexity of pile-soil action in the process of subsea foundation and jack-up platform, the foundation is often unstable, the pile leg settlement is uneven, and the platform is inclined. Scour and scouring bring great challenge to the platform operation safety. According to the current code, the boundary condition for the calculation of jack-up platform structure is to simplify the action of the foundation to a constraint somewhere under the mud surface. This simplification ignores the interaction between the seabed foundation and the platform structure, thus causing the safety problem of the platform structure. In this paper, the pile-boot model of "Shengli No. 5" in Bohai Bay is studied, and the dynamic penetration process of pile-soil is investigated by means of test and numerical analysis. A modified method for the strength calculation of the jack-up platform under the influence of the foundation in the Bohai Sea area of China is put forward, which provides the basis for the improvement of the structural design of the jack-up platform. The main contents of this paper are as follows: 1. This paper introduces the superiority of Ale (arbitrary Lagrangian Euler method) in the finite element analysis of large deformation of pile and soil, and introduces the MPC model of soil mass, which takes the ultimate bearing capacity of pile end as the main object of study, and simplifies the pile boots and foundation at the same time. The model of pile boots and soil is established. The finite element analysis software ABAQUS/ALE is used to simulate the dynamic penetration process of pile and soil, and the flow mechanism of soil around the pile and the formation, development and failure mechanism of cavities in the upper part of the pile boots are explored. The velocity difference between the upper and lower end of the pile is extracted to study the influence of the reflux of the upper part of the cavity on the bearing capacity of the pile. Based on the operating geological conditions of a well in Bohai Bay, the pressure distribution at the bottom of the pile boot is verified by static pressure pile test. It is compared with the assumption of the pressure distribution at the bottom of the pile boot in numerical simulation and the Code for entry and Construction of Offshore moving platform. At the same time, on the basis of composite foundation, the influence of puncture phenomenon on the structure of pile boots is studied. Through the experiment and numerical simulation of the dynamic process of pile-soil penetration, an optimization method of pile-boot support structure is put forward, and the influence of the supporting structure on soil flow and pile end load is analyzed.
【学位授予单位】：浙江海洋学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U674.381

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