海底能源土斜坡稳定性影响因素的敏感性分析

发布时间：2018-04-07 18:54

本文选题：海底能源土斜坡　切入点：有限元强度折减法　出处：《青岛理工大学》2016年硕士论文

【摘要】：海底能源土斜坡是指含天然气水合物(俗称“可燃冰”)的海底斜坡。天然气水合物储量大、分布广、能量密度高,是21世纪最具有商业开发前景的新型清洁战略性替代能源。但天然气水合物高压低温的赋存条件极其苛刻,环境变化和人类工程活动引起的温度轻微增加或压力释放都有可能使水合物分解,进而导致海底滑坡。海底滑坡是具有巨大危害的海洋地质灾害之一,不但严重威胁可燃冰的安全开采,而且还能破坏水合物矿藏,导致大量甲烷气体泄漏,引发海底生态环境破坏和温室效应。影响海底能源土斜坡稳定性的因素较多,而且相互影响。对海底能源土斜坡稳定性影响因素进行敏感性分析,对有效预测海底能源土斜坡滑坡失稳灾害,保证天然气水合物安全开采具有重要意义。本文简要分析了海底斜坡稳定性及敏感性研究现状,在此基础上主要完成了以下工作:1、简介了有限元强度折减法的基本原理、岩土体材料屈服准则的的选取、正交试验设计原理及敏感性分析方法、大型非线性有限元软件ABAQUS,通过实例计算验证了基于ABAQUS的有限元强度折减法在边坡工程中的可行性。2、根据南海某研究区海域相关研究资料建立了海底能源土斜坡典型剖面的有限元模型,选取水合物分解程度、水合物埋深、水合物厚度、上覆海水压力等4种影响海底斜坡稳定性的重要因素,根据正交试验原理确定了影响海底能源土斜坡稳定性多因素多水平组合,形成了各影响因素水平组合下的正交试验设计矩阵。3、利用ABAQUS有限元软件对正交试验矩阵中各因素组合方案进行了计算,得到相应因素水平组合方案对应的海底斜坡稳定性安全系数,并给出了失稳可能出现的塑性区、位移等信息。分别采用正交设计极差分析法和方差分析法对正交试验各影响因素水平组合方案下得到的海底斜坡稳定性安全系数进行了分析,得到了海底能源土斜坡稳定性影响因素敏感性分析结果。4、提出了天然气水合物临界埋深的概念,研究了理想海底斜坡模型的水合物临界埋深问题,针对特定海底坡型进行了数值模拟计算得到了水合物临界埋深的初步分析结果。
[Abstract]:Submarine energy slope refers to submarine slope containing natural gas hydrate (commonly known as combustible ice).Natural gas hydrate has large reserves, wide distribution and high energy density. It is a new type of clean and strategic alternative energy with the most potential for commercial development in the 21 ~ (st) century.However, the conditions for the occurrence of high pressure and low temperature of natural gas hydrate are extremely harsh. Environmental changes and the slight increase in temperature or pressure release caused by human engineering activities may lead to the decomposition of hydrates and lead to submarine landslides.Submarine landslide is one of the marine geological hazards with great harm. It not only seriously threatens the safe exploitation of combustible ice, but also destroys hydrate deposits, resulting in a large amount of methane gas leakage, causing damage to the marine ecological environment and Greenhouse Effect.There are many factors which affect the stability of submarine energy soil slope and influence each other.The sensitivity analysis of the influencing factors on the stability of submarine energy soil slope is of great significance to effectively predict the landslide instability disaster of submarine energy soil slope and ensure the safe exploitation of natural gas hydrate.In this paper, the stability and sensitivity of submarine slopes are briefly analyzed. Based on this, the following work is accomplished: 1. The basic principle of the finite element strength reduction method and the selection of yield criteria for rock and soil materials are briefly introduced.The principle of orthogonal design and sensitivity analysis,Abaqus, a large-scale nonlinear finite element software, verifies the feasibility of the finite element strength reduction method based on ABAQUS in slope engineering. Based on the relevant research data of a certain area in the South China Sea, the submarine energy soil slope code is established.The finite element model of the section,Four important factors affecting the stability of submarine slope are selected, such as the degree of hydrate decomposition, the depth of hydrate burial, the thickness of hydrate, and the overlying sea pressure.According to the principle of orthogonal test, the multi-factor and multi-level combination of influencing the stability of submarine energy soil slope is determined.The orthogonal test design matrix. 3 is formed under the horizontal combination of various factors. The combination scheme of each factor in the orthogonal test matrix is calculated by using ABAQUS finite element software.The safety factor of submarine slope stability corresponding to the corresponding horizontal combination scheme is obtained, and the information of plastic zone and displacement which may occur in instability are given.The orthogonal design range analysis method and the variance analysis method are used to analyze the stability safety factor of submarine slope under the horizontal combination scheme of each influencing factor of orthogonal design.The sensitivity analysis results of influencing factors on slope stability of submarine energy soil are obtained. The concept of critical burial depth of natural gas hydrate is proposed, and the critical buried depth of hydrate in ideal submarine slope model is studied.The preliminary analysis results of the critical depth of hydrate are obtained by numerical simulation for the specific submarine slope.
【学位授予单位】：青岛理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P744;P642.2

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