【作者】 赵英菊；

【导师】 王社良；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2007， 硕士

【摘要】 工程结构中的箱形基础、筏板基础以及桩基承台等往往是厚度或面积较大的大体积混凝土，施工期间混凝土水化热引起的温度作用和自身收缩等变形将产生较大的温度应力，如果设计和施工不当就会产生危害性裂缝。过去，我国大都采用设置伸缩缝或后浇带的方法来解决这种问题，但由于建筑与结构的整体性、使用功能和建设工期等方面的原因，现对这类结构均提出了无缝施工的要求，即在施工中不设伸缩缝或后浇带，同样能够满足设计和施工质量的要求。目前，国内外对大体积混凝土结构无缝施工方面的研究还比较欠缺，大多数设计和施工都是依靠以往的工程实践和经验，缺乏必要的理论支持和指导，其结果是有可能造成大量的浪费或损失，也有可能使工程质量存在内在隐患，影响结构的可靠性，因此迫切需要开展这方面的理论和应用研究。本文在对无缝施工技术进行总结和分析的基础上，结合西安万达商业广场实际工程筏板基础的无缝施工方案设计，提出了采用短距离释放应力的无缝施工方法，给出了跳仓浇筑的理论依据，研究了采用文中所提方案施工时温度应力的计算方法和分布规律，并且应用大型有限元分析程序ANSYS，对其施工阶段和使用阶段的温度应力进行了计算机模拟分析，主要研究工作如下：(1)以已有研究成果为基础，分析了大体积混凝土温度裂缝产生的机理和规律，选择合理的计算模型，进行了相应的无缝施工温度应力研究，提出了跳仓浇筑时温度、收缩应力及分块尺寸的计算方法。(2)结合西安万达商业广场筏板基础大体积混凝土结构的工程实例，运用文中所提方法，进行了实际工程大体积混凝土结构施工阶段的温度应力和开裂验算分析，检验了所提方法的可靠性。(3)运用有限元分析程序ANSYS，对西安万达商业广场筏板基础在施工阶段和正常使用阶段的温度和收缩应力进行了计算机模拟，得出了相应的温度场和应力场的分布情况，并与理论计算结果进行了对比，两者吻合较好。研究结果表明，文中所提方法能够较好地反映大体积混凝土结构的温度应力状态，具有较好的适用性，为同类结构的大体积混凝土基础设计与施工提供了理论依据，可供实际工程参考。更多还原

【Abstract】 The box foundation, raft foundation and pile caps in engineering structure usually with bigger thickness or area are mass concrete, in the casting phase the temperature load caused by the hydration heat and its shrinkage property will produce great thermal stresses, which will cause hazardous cracks if design and construction are inappropriate. In the past, we adopted expansion joints and post-pouring zone to solve this problem; but due to such reasons as the integrity of the building and structure, serviceable function and demand of construction time of a project etc., we put forward the requirement of seamless construction to these structures, that is to say, the requirements of design and the quality of construction can still be satisfied without adoption of expansion joints and post-pouring zone in the construction phase.At present, the researches on seamless construction of the mass concrete structures were relatively deficient in domestic and foreign countries, most designs and constructions strongly depended on past engineering practices and experiences, and lacked necessary theoretical support and guides; as a result, a large amount of waste or loss may be caused and possibly some hidden dangers are present in projects’ quality, thus which will influence the reliability of structures, so it is urgent to launch the theoretical and application research into this topic.On the basis of the analysis and summaries of seamless construction methods, combined with the design of seamless construction plan on Xi’an Wanda commercial plaza’s raft foundation, in this paper the seamless construction measure by releasing the stress in short-range is addressed, the theoretical basis for the sequential placement is given, the calculation method of the thermal stress and its distribution rule by the use of the construction method presented in this article are studied, and a large-scale finite element program ANSYS is utilized to simulate and analyze its thermal stress in construction and operation phases. The main research contents include the following aspects: (1) Based on the existing research findings, analyzed the mechanism and rules of temperature cracks of mass concrete, selected a reasonable calculation model and performed an analysis of the thermal stress with the seamless construction, proposed the calculation method of thermal-shrinkage stress and partitioned size under the sequential method.(2) Combined with the project example of mass concrete structure, the raft foundation structure of Xi’an Wanda commercial plaza, the use of the method presented in this paper carried on analysis on the thermal stress and cracking fracture checking in the construction phase, verified the reliability of the advanced method.(3) The use of the finite element analysis program ANSYS, simulated the thermal and shrinkage stress of Xi’an Wanda commercial plaza during construction and operation phases, obtained the corresponding distributions of temperature field and stress field. Compared to the theoretically calculating results, they are in a good agreement.The research results indicate that the method presented in this paper can better reflect the thermal stress state of mass concrete structures, and exhibit a better applicability; it can supply the theoretical support for their design and construction of mass concrete foundation for homogeneous structures, and then it can be referred to by engineering projects.更多还原