本文選題：ALE + 樁端極限承載力��； 參考：《浙江海洋學(xué)院》2015年碩士論文

【摘要】：自升式鉆井平臺(tái)廣泛應(yīng)用于近海石油開發(fā),但由于海底地基以及自升式平臺(tái)插拔樁過(guò)程中樁土作用的復(fù)雜性,經(jīng)常會(huì)發(fā)生地基不穩(wěn)、樁腿沉降不勻、平臺(tái)傾斜、沖刷與淘空現(xiàn)象,給平臺(tái)的作業(yè)安全帶來(lái)極大挑戰(zhàn)。按現(xiàn)行規(guī)范,自升式平臺(tái)結(jié)構(gòu)計(jì)算的邊界條件是將地基的作用簡(jiǎn)化為泥面下某處約束,這種簡(jiǎn)化忽略了海底地基與平臺(tái)結(jié)構(gòu)的相互影響,從而會(huì)引發(fā)平臺(tái)結(jié)構(gòu)安全問(wèn)題。本文以渤海灣“勝利五號(hào)”在作業(yè)平臺(tái)樁靴模型為研究對(duì)象,采用試驗(yàn)及數(shù)值分析方法探究樁土動(dòng)態(tài)貫入過(guò)程,并提出針對(duì)我國(guó)渤海海域地基影響下自升式平臺(tái)強(qiáng)度計(jì)算的修正方法,為自升式平臺(tái)結(jié)構(gòu)設(shè)計(jì)的改進(jìn)提供依據(jù)。論文的重點(diǎn)研究?jī)?nèi)容有以下幾點(diǎn):1.介紹ALE(任意拉格朗日歐拉法)在處理樁土大變形有限元分析中的優(yōu)越性,引入以處理樁端極限承載力為主要研究對(duì)象的土體MPC模型,同時(shí)對(duì)樁靴及地基進(jìn)行簡(jiǎn)化,并建立樁靴及土體模型。2.利用有限元分析軟件ABAQUS/ALE模擬樁土動(dòng)態(tài)貫入過(guò)程,探究貫入過(guò)程中樁側(cè)土體流動(dòng)機(jī)理以及樁靴上部空腔的形成、發(fā)展和破壞機(jī)理。并提取樁端上下端面土體的速度差來(lái)研究空腔上部土體回流對(duì)樁端承載的影響。3.以渤海灣某井位作業(yè)地質(zhì)條件為依據(jù),利用靜壓貫樁試驗(yàn)驗(yàn)證樁靴底部壓力分布規(guī)律,并同數(shù)值模擬與《海上移動(dòng)平臺(tái)入級(jí)與建造規(guī)范》中對(duì)于樁靴底部壓力分布的假定進(jìn)行比較。同時(shí)在復(fù)合地基基礎(chǔ)上研究穿刺現(xiàn)象對(duì)樁靴結(jié)構(gòu)的影響。4.通過(guò)上述方法對(duì)樁土貫入的動(dòng)態(tài)過(guò)程進(jìn)行試驗(yàn)及數(shù)值模擬,提出一種樁靴支護(hù)結(jié)構(gòu)的優(yōu)化方法,分析該支護(hù)結(jié)構(gòu)對(duì)土體流動(dòng)及樁端承載的影響。
[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.
【學(xué)位授予單位】：浙江海洋學(xué)院
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：U674.381

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