冻结内层井壁早期温度应力数值计算研究

发布时间：2018-01-20 21:44

  本文关键词： 冻结内层井壁 水化热 温度场 温度应力 数值模拟　出处：《辽宁工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：深厚冲积层冻结内层井壁大多采用高强大体积混凝土,内壁混凝土在浇筑初期释放大量水化热,井壁混凝土在温度应力作用下易产生温度裂纹。为将温度应力控制在允许范围内,进而确保井壁不产生贯穿性的温度裂纹,本文以矿井双层钢筋混凝土井壁的内层井壁为研究对象,主要研究内容如下:(1)从大体积混凝土水化热温度场的理论研究出发,详细阐述了热传导理论在井壁混凝土温度场中的应用,求解出了温度场所需热传导方程的初始条件和边界条件,以及有限单元法在非稳定温度场中的解法;(2)对井壁温度应力进行了理论研究,得出井壁不同方向上应力分量的计算公式,结果表明,井壁温度应力的主要构成为井壁内、外缘的温度差引起的自身温度应力、水化热作用下井壁在半径方向发生热膨胀受阻产生的径向温度应力、井壁沿深度方向发生热膨胀受阻产生的竖向温度应力以及同一深度处的环向切应力。(3)采用ADINA有限元程序,结合上述理论研究成果,在确定了混凝土热力学参数之后,开展了冻结内层井壁早期温度场和温度应力数值计算研究,详细阐述了不同因素影响下的温度场和温度应力的变化规律,分析了各个不同因素对井壁温度变化的影响规律,提出了控制井壁温度的有效方法,研究表明:①井壁表面和接近表面的温度比井壁内部的温度发展缓慢一些。内层井壁最高温度为79.94℃(内层井壁厚1.6m时),最大温差为38.01℃(内层井壁厚1.6m时);②井壁厚度越大,最高温度出现的位置离内缘距离越远;对流散热系数越小,最高温度越靠近内缘,且最高温度位置从内到外约是井壁厚度的12%~34%;③控制内层井壁厚度能明显地降低早期混凝土水化热温度及内、外缘的温差;④内层井壁内缘、中间段及外缘的环向应力普遍较大,径向应力次之,竖向应力最小。其中,当环向应力大于C55混凝土抗拉强度标准值(2.47MPa)时,极有可能诱发井壁的破裂;⑤内层井壁内缘的应力普遍大于外缘应力,表明温度应力将导致井壁内缘最先破裂;⑥内层井壁厚度达到0.8m时,温度应力已经超过混凝土抗拉强度。
[Abstract]:High strength concrete is used in deep alluvium frozen inner shaft lining, and the inner wall concrete releases a lot of hydration heat at the early stage of pouring. In order to control the temperature stress in the allowable range, it is easy to produce temperature cracks in wellbore concrete under the action of temperature stress, so as to ensure that no penetrating temperature cracks are produced in the wellbore. This paper takes the inner wall of the double-layer reinforced concrete shaft as the research object, the main research contents are as follows: (1) starting from the theoretical study of the heat field of mass concrete hydration. The application of heat conduction theory in the temperature field of wellbore concrete is described in detail. The initial and boundary conditions of the heat conduction equation in the temperature field are solved, and the solution of the finite element method in the unstable temperature field is given. 2) the theoretical study on the temperature stress of the shaft wall is carried out, and the formula for calculating the stress component in different directions of the shaft wall is obtained. The results show that the main composition of the temperature stress of the shaft wall is inside the shaft wall. The thermal stress caused by the temperature difference of the outer edge is the radial temperature stress caused by the thermal expansion of the shaft wall in the radius direction under the action of hydration heat. The vertical temperature stress caused by the thermal expansion along the depth and the circumferential shear stress at the same depth. After determining the thermodynamic parameters of concrete, the numerical calculation of temperature field and temperature stress in the early stage of frozen inner shaft wall is carried out, and the variation law of temperature field and temperature stress under the influence of different factors is expounded in detail. The influence of different factors on wellbore temperature is analyzed, and an effective method to control wellbore temperature is put forward. The results show that the temperature of the wall surface and near surface is slower than that of the inner wall, and the maximum temperature of the inner wall is 79.94 鈩，

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