冻结深立井钢筋混凝土井壁温度场与温度应力研究

发布时间：2018-06-13 17:38

本文选题：深冻结井 + 钢筋混凝土井壁　；参考：《合肥工业大学》2013年博士论文

【摘要】：大体积混凝土结构由于温度的变化会产生很大的拉应力,要把这种由温度变化而产生的拉应力控制在允许范围内,就需要对混凝土的温度进行控制。影响控制混凝土温度的变化因素较多,引起混凝土裂缝的机理也较为复杂,目前为止,依然难以准确地模拟和预计各种多变因素对混凝土裂缝发生以及发展而产生的影响。本文以淮南矿业集团矿井井壁大体积高高性能混凝土为科学研究背景,首先从混凝土水化热分析的理论出发,阐述了热传导方程在混凝土裂缝控制中的应用,求解热力学所需要的边界条件和初始条件,有限元分析的显式与隐式解法,分析混凝土水化热仿真分析所需要的热力学参数;在对混凝土热力学参数进行确定之后,应用ANSYS结构热力学有限元分析软件热单元SOLID70对该集矿井井壁温度场、温度应力、应变进行了仿真分析,通过理论分析、现场监测、数值模拟研究探讨了井壁混凝土在冻结工况条件下温度场和应力场的变化及分布规律。研究的主要内容有： 1.对深冻结井井壁高强高性能混凝土的配合比进行了实验室和现场试验研究,在添加高效减水剂的前提条件下,通过使用三种矿物掺和料(粉煤灰、硅粉和磨细矿渣)技术,研究配制的混凝土满足了高强、早强的要求,同时还提高了混凝土的耐久性和后期强度。 2.依据冻土的物理力学性质和混凝土水化热特性,分析了冻结法施工凿井井壁混凝土的不同组成成分对混凝土强度等性能的影响,研究了井壁混凝土放热性能及水化热的产生机理和理论分析方法。 3.结合冻结法施工凿井施工过程,对井壁混凝土施工过程中温度、应力变化进行监测与分析,得到了井壁和冻结壁温度场分布变化规律,冻胀压力变化规律和井壁钢筋混凝土的受力规律。 4.对冻土进行室内物理力学性能试验研究,得出冻土比热、导热系数以及冻土力学基本参数。 5.混凝土水化热温升模型分别采用指数式、双曲线式和复合指数式进行试算,将计算结果与实测平均温度对比,确定了合适的的水化热升温模型。 6.考虑了混凝土水化放热情况,建立了冻结法施工凿井冻结壁井壁温度场数值计算模型,运用有限元软件ANSYS对冻结井壁温度场进行计算,得到了冻结井壁温度场分布变化特性。 7.导入温度场计算结果,采用三种不同计算方案,对井壁温度场应进行有限元分析计算计算,得出井壁温度应力分布。
[Abstract]:Because the temperature of mass concrete structure will produce great tensile stress, it is necessary to control the temperature of concrete in order to control the tensile stress caused by temperature change within the allowable range. There are many factors that affect the temperature of concrete, and the mechanism of causing concrete cracks is complex. So far, it is still difficult to accurately simulate and predict the influence of various factors on the occurrence and development of concrete cracks. In this paper, based on the scientific research background of large-volume high performance concrete of mine shaft wall of Huainan Mining Group, the application of heat conduction equation in crack control of concrete is expounded based on the theory of hydration heat analysis of concrete. The boundary conditions and initial conditions for solving thermodynamics, explicit and implicit solutions for finite element analysis, and thermodynamic parameters for hydration heat simulation of concrete are analyzed. The thermal element SOLID70 is used to simulate and analyze the temperature field, temperature stress and strain of the shaft wall in this mine by ANSYS structural thermodynamics finite element analysis software. The variation and distribution of temperature field and stress field of wellbore concrete under freezing condition are studied by numerical simulation. The main contents of the study are as follows: 1. The mixture ratio of high strength and high performance concrete of deep freezing well wall was studied in laboratory and in situ. Under the precondition of adding high efficiency water reducing agent, three kinds of mineral admixtures (fly ash, silica fume and fine abrasive slag) were used. The concrete prepared by the study meets the requirements of high strength and early strength, and at the same time improves the durability and later strength of concrete. 2. 2. Based on the physical and mechanical properties of frozen soil and the hydration heat characteristics of concrete, the influence of different components of concrete on concrete strength and other properties of shaft lining in freezing construction is analyzed. The mechanism and theoretical analysis method of heat release performance and hydration heat of wellbore concrete are studied. Combined with the freezing construction process, the temperature and stress changes during the shaft lining concrete construction are monitored and analyzed, and the distribution and variation of the temperature field of the shaft wall and frozen wall are obtained. Variation of frost heave pressure and stress law of reinforced concrete on shaft lining. 4. The physical and mechanical properties of permafrost were studied in laboratory, and the specific heat, thermal conductivity and basic mechanical parameters of frozen soil were obtained. The hydration heat temperature rise model of concrete is calculated by exponential, hyperbolic and composite exponent respectively. The calculated results are compared with the measured average temperature, and the suitable hydration heat rise model is determined. 6. Considering the hydration heat release of concrete, the numerical calculation model of freezing wall temperature field in freezing construction is established, and the temperature field of frozen shaft wall is calculated by finite element software ANSYS. The variation characteristics of temperature field distribution of freezing shaft wall are obtained. 7. 7. According to the calculation results of temperature field and three different calculation schemes, the temperature field of shaft wall should be analyzed and calculated by finite element method, and the distribution of temperature stress of shaft wall should be obtained.
【学位授予单位】：合肥工业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TD352;TU375

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