花岗岩蠕变启动应力与长期强度研究

发布时间：2019-02-23 14:21

【摘要】：岩石蠕变是隧道与地下工程、构筑物基础产生大变形甚至失稳的重要原因之一,因此研究不同围压下的岩石蠕变启动应力和长期强度范围对岩体工程施工设计具有重要的指导意义。此文主要采用实验分析的方法并结合现有蠕变理论方法对实验所获得的曲线进行分析,分析找到该类岩石在不同围压下的蠕变启动应力条件以及岩石轴径向蠕变屈服阀值的应力范围,并得到岩石蠕变启动应力与轴径向长期强度的一定规律。该文前述部分对岩石蠕变发生的微观机理、岩石非线性蠕变的机理做了重要解释,阐明了岩石蠕变发生内部材料的微观变化。利用不同围压下的室内单轴、三轴压缩实验研究了岩石强度特征和变形变化,并求得了不同围压下的抗压强度、弹性模量、泊松比以及花岗岩石的内摩擦角及粘聚力等基本力学参数,并分析了围压对各力学参数的影响关系。该文后述部分参照不同围压下的偏应力采用单体分级加载方式对花岗岩采用单轴、三轴蠕变实验研究,获得不同围压下一系列的轴向、径向实验曲线,并通过数据处理转化成多种不同形式的轴径向各变形汇总表、轴径向蠕变速率曲线、轴径向等时应力应变曲线来对比分析轴径向蠕变特性,并分别确定每级围压下岩石蠕变启动应力条件以及轴径向蠕变长期强度范围。对不同围压下的岩石蠕变起始应力、长期强度范围作了比较分析,发现蠕变起始应力、长期强度随着围压的变化,其强度值与瞬时最大偏应力的比值基本上会固定在一定的范围内。同时得到同级围压下岩石蠕变径向长期强度值低于轴向长期强度值,并得到岩石长期强度应该以径向稳定蠕变阀值来确定。
[Abstract]:Rock creep is one of the important causes of large deformation and even instability in tunnel and underground engineering. Therefore, the study of rock creep starting stress and long-term strength range under different confining pressures is of great significance for rock engineering construction design. This paper mainly uses the experimental analysis method and the existing creep theory method to analyze the curve obtained from the experiment. The creep initiation stress conditions and the stress range of rock axial creep yield threshold under different confining pressures are found, and the certain rules of creep initiation stress and axial radial long-term strength of rock are obtained. In this paper, the microscopic mechanism of rock creep and the mechanism of rock nonlinear creep are explained, and the microscopic changes of internal materials are explained. The characteristics of rock strength and deformation were studied by uniaxial and triaxial compression experiments under different confining pressures, and the compressive strength and elastic modulus of rock under different confining pressures were obtained. Poisson's ratio, the angle of internal friction and cohesion of granitic rocks, and the influence of confining pressure on the mechanical parameters are analyzed. In this paper, a series of axial and radial experimental curves of granite under different confining pressures are obtained by using uniaxial and triaxial creep experiments, which refer to the deviant stress under different confining pressures. Through data processing, the creep characteristics of axial diameters are compared and analyzed by transforming them into various kinds of axial diametral deformation summary tables, axial radial creep rate curves and axial isochronous stress-strain curves. The creep starting stress conditions and the long term strength range of axial-radial creep are determined respectively under each confining pressure. The creep initial stress and long-term strength range of rock under different confining pressures are compared and analyzed. It is found that the creep initial stress and long-term strength change with confining pressure. The ratio of the strength value to the instantaneous maximum deflection stress is basically fixed in a certain range. At the same time, the radial long-term strength of rock creep under the same confining pressure is lower than that of axial long-term strength, and the long-term strength of rock should be determined by the radial stability creep threshold.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU45

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