深冻结井壁混凝土温度裂纹产生机理及其抗渗性试验研究

发布时间：2019-05-12 20:31

【摘要】：近年来,随着煤炭生产矿井浅部资源渐趋枯竭,为了确保矿井可持续发展,两淮矿区多数矿井需要实施安全改扩建工程、新建深立井井筒。这些新建井筒具有井筒深、直径大、穿过深厚冲积层含水丰富。当采用冻结法凿井时,设计的井壁厚度大、混凝土强度高,混凝土水化热大,在内、外大温差和约束作用下,井壁混凝土极易产生温度裂纹,从而给井筒的安全使用带来威胁。据此,为解决深冻结井筒的渗漏水难题,本论文采用现场实测、理论分析和模拟实验相结合的方法,对深冻结井壁混凝土温度裂纹产生机理及其抗渗性进行研究,为井筒的防治水工作提供基础。首先,以顾桥煤矿东回风井为工程背景,选取监测水平,对冻结段外层井壁的受力、变形和温度进行了现场实测工作,结果表明,竖向钢筋应力和混凝土竖向应变受拉严重,井壁极易产生环向温度裂纹。然后,根据弹性力学和热力学原理,对冻结井壁在约束条件下的温度应力进行了分析,推导了温度应力公式,分析了在冻结法凿井过程中井壁混凝土温度裂纹产生机理,并指出该裂纹对冻结井壁防治水工作十分不利。最后,通过模拟实验,对冻结井壁混凝土温度裂纹抗渗特性进行了研究。实验分为二个部分:(1)制作含有模拟温度裂纹的标准抗渗试件,进行抗渗试验研究,结果表明,抗渗特性主要取决于裂纹性质,与混凝土强度关系不大,贯通裂纹对井壁抗渗影响极大;(2)制作含有模拟温度裂纹的圆柱体试件,通过三轴渗透性试验分析了水压和围压对裂纹渗透性能的影响。结果表明,当控制轴压和围压一定时,混凝土裂纹的渗流速度随水压的增大而逐渐增大。而控制水压和轴压一定时,混凝土裂纹的渗流速度随着围压的增大而减小。
[Abstract]:In recent years, with the depletion of shallow resources in coal production mines, in order to ensure the sustainable development of the mine, most mines in Lianghuai mining area need to carry out safe reconstruction and expansion projects and build deep vertical wellbore. These new wellbore have deep wellbore, large diameter, rich in water content through deep alluvial layer. When the shaft wall is drilled by freezing method, the thickness of the shaft lining is large, the strength of concrete is high, the hydration heat of concrete is large, and the temperature crack of shaft wall concrete is easy to produce under the action of internal and external temperature difference and constraint, which brings threat to the safe use of wellbore. Based on this, in order to solve the leakage problem of deep frozen wellbore, the mechanism and impermeability of temperature crack in deep frozen wellbore concrete are studied by means of field measurement, theoretical analysis and simulation experiment. It provides the basis for the prevention and control of water in wellbore. First of all, taking the east return air shaft of Guqiao Coal Mine as the engineering background, the force, deformation and temperature of the outer shaft wall of the frozen section are measured on the spot by selecting the monitoring level. The results show that the vertical steel bar stress and the vertical strain of concrete are seriously pulled. Circumferential temperature cracks are easy to occur in the sidewall. Then, according to the principles of elasticity and thermodynamics, the temperature stress of frozen shaft lining under constraint conditions is analyzed, the formula of temperature stress is deduced, and the mechanism of concrete temperature crack in the process of freezing well drilling is analyzed. It is pointed out that the crack is very disadvantageous to the prevention and control of water from freezing shaft lining. Finally, the impermeability of temperature crack in frozen shaft lining concrete is studied by simulation experiment. The experiment is divided into two parts: (1) the standard impermeable specimen with simulated temperature crack is made and the impermeability test is carried out. the results show that the impermeability characteristics mainly depend on the crack properties and have little to do with the strength of concrete. The penetration crack has a great influence on the impermeability of the shaft lining. (2) the cylinder specimens with simulated temperature cracks were fabricated, and the effects of water pressure and confining pressure on the permeability of cracks were analyzed by triaxial permeability test. The results show that when the axial pressure and confining pressure are constant, the seepage velocity of concrete crack increases gradually with the increase of water pressure. When the water pressure and axial pressure are controlled, the seepage velocity of concrete crack decreases with the increase of confining pressure.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD265.3

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