插入式大圆筒蠕变沉降的影响因素及灵敏度分析

发布时间：2019-05-07 03:31

【摘要】：插入式大圆筒结构对于港口工程中常见的软土地基有很强的适应性,其沉降问题与软土地基的性状有密切关联,传统的沉降计算方法只考虑地基土的弹塑性,不考虑土体的流变性,忽视了软土地基的长期蠕变变形。本文基于滨海相软土流变理论,对插入式大圆筒蠕变沉降的发展变化规律进行了深入研究。本文以滨海相软土的蠕变试验数据为基础,选用弹塑性本构关系与时间硬化蠕变率,反映土体的应力-应变-时间关系,并通过模拟滨海相原状土的三轴蠕变试验对参数的选取予以验证。在此基础上,应用有限元软件ABAQUS建立了插入式大圆筒结构的三维有限元模型,对结构的蠕变沉降进行了深入的探索和研究,得到10年内蠕变沉降的发展变化规律。进一步探究结构蠕变沉降的影响因素,探讨了圆筒直径、入土深度、外部荷载、布置方式对结构10年内蠕变沉降的发展变化规律的影响。并引入无量纲参数灵敏度,表征各参数改变时蠕变沉降的响应量变化程度,量化各因素对蠕变沉降的影响程度。基于单一因素分析法,得到了一些有意义的结论:圆筒直径越大,结构的蠕变沉降越大;圆筒入土深度越大,结构的蠕变沉降越小;作用于结构的外部荷载越大,结构的蠕变沉降越大;圆筒单个插入产生的蠕变沉降及总沉降小于圆筒连排插入,单排插入产生的蠕变沉降及总沉降小于双排插入;各影响因素对结构蠕变沉降产生的影响程度由大到小依次为圆筒直径、入土深度、布置方式、外部荷载。依据研究成果,可为结构的优化设计提供一些有益的建议:在工程中,减小圆筒直径,增大圆筒入土深度,均是降低结构蠕变沉降的有效途径;在施工条件和吊装运输条件允许时,应尽量采用单排布置。
[Abstract]:The inserted large cylinder structure has strong adaptability to the common soft soil foundation in port engineering. The settlement problem is closely related to the behavior of the soft soil foundation. The traditional settlement calculation method only considers the elastoplastic properties of the foundation soil. The long-term creep deformation of soft soil foundation is neglected without considering the rheology of soil. Based on the rheological theory of coastal soft soil, the development and variation of creep settlement of inserted large cylinder have been deeply studied in this paper. Based on the creep test data of coastal soft soil, the elasto-plastic constitutive relation and time hardening creep rate are selected to reflect the stress-strain-time relationship of soil. The selection of parameters is verified by simulating the triaxial creep test of undisturbed coastal soil. On the basis of this, the three-dimensional finite element model of the inserted large cylinder structure is established by using the finite element software ABAQUS. The creep settlement of the structure is deeply explored and studied, and the development and change rule of creep settlement within 10 years is obtained. The influence factors of creep settlement and the influence of cylinder diameter, depth of soil entry, external load and arrangement mode on the development and variation of creep settlement of structure in 10 years are discussed. The sensitivity of dimensionless parameters is introduced to characterize the change degree of the response amount of creep settlement when each parameter is changed, and the influence degree of each factor on creep settlement is quantified. Based on the single factor analysis, some meaningful conclusions are drawn: the larger the diameter of the cylinder is, the greater the creep settlement of the structure is, the greater the depth of the cylinder entering the soil is, the smaller the creep settlement of the structure is. The greater the external load on the structure, the greater the creep settlement of the structure, the creep settlement and total settlement produced by single cylinder insertion is less than that by cylinder continuous insertion, and the creep settlement and total settlement by single row insertion is less than that by double row insertion, and the creep settlement caused by single row insertion is less than that by double row insertion. The influence degree of each influence factor on the creep settlement of the structure is the diameter of cylinder, the depth of entering soil, the arrangement mode and the external load from large to small. According to the research results, some useful suggestions can be provided for the optimum design of the structure: in the engineering, reducing the diameter of the cylinder and increasing the depth of the cylinder entering the soil are the effective ways to reduce the creep settlement of the structure; Single row arrangement should be used as far as possible when construction conditions and lifting transportation conditions permit.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU433

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