【作者】 李杰林；

【导师】 周科平；

【作者基本信息】 中南大学 ， 采矿工程， 2012， 博士

【摘要】 冻融条件下的岩石力学特性及损伤机理一直是岩石力学领域关注的前沿方向。在寒区矿山中,由于岩性、水分、温度、冰雪、应力等多重因素的耦合作用,导致岩石冻融损伤和冻融灾害的发生,对寒区矿山工程的稳定性产生了重大影响。随着我国寒区矿产资源开发活动的日益增多,矿山冻融灾害的预防和治理成为一个重要的课题。因此,研究和掌握岩石冻融损伤的机理和演化规律,可为寒区矿山冻融灾害的防治提供理论依据；对于确保寒区矿产资源的安全开采,也具有重要的现实意义。论文结合寒区矿山工程需要,以室内实验和理论分析为基础,采用核磁共振技术对矿山岩石的冻融损伤机理和冻融损伤演化规律开展了以下方面的研究工作：(1)研究了岩石冻融损伤劣化理论及演化规律,分析了岩石冻融损伤的影响因素以及寒区工程冻融灾害特征；结合灾变链式理论,进行了寒区矿山冻融灾害致灾链式效应分析和断链减灾对策研究。(2)以寒区矿山花岗岩为岩样,进行了岩石冻融循环实验和单轴压缩力学实验,得出了冻融循环后岩样质量、单轴抗压强度、冻融系数和岩石风化程度系数的变化规律；归纳出了花岗岩的冻融损伤劣化模式,得出了抗压强度、弹性模量与冻融循环次数的关系曲线,并建立了花岗岩的冻融损伤演化方程。(3)采用核磁共振技术,对寒区花岗岩的孔隙结构、含水饱和度进行了测量,得出了花岗岩的核磁共振T2分布、孔隙度、谱总面积、核磁共振成像等核磁共振特性,揭示了岩石的孔隙结构特征。(4)首次应用核磁共振技术对冻融循环后的花岗岩进行核磁共振测量和成像分析,获得了不同冻融条件下岩石的T2谱分布、T2谱面积、核磁共振成像的变化特征和岩石微观结构特性,揭示了冻融循环条件下岩石的损伤特性,为冻融岩石力学的研究提供了一种新的方法和思路。(5)对经历不同冻融循环次数的同一块岩样进行了核磁共振测量,获得了不同冻融循环次数后花岗岩的核磁共振弛豫时间分布特性,得到了岩样的质量、孔隙度、核磁共振谱面积的变化规律,获得了孔隙度与冻融循环次数之间的关系式和以孔隙度为目标值的冻融损伤方程,并归纳出了岩石孔隙结构的冻融损伤演化过程。(6)利用核磁共振成像技术,对不同冻融循环次数后的同一块岩样进行了成像分析,获得了不同冻融循环条件下花岗岩的孔隙分布特征及变化特性,揭示了冻融循环条件岩石微观结构的损伤演化规律。(7)对冻融后的岩石开展了核磁共振测试及单轴压缩试验,研究了不同核磁共振特性条件下岩石的力学特征,并建立了岩石核磁共振特性与力学性质之间的关系。更多还原

【Abstract】 The mechanical properties and degradation mechanism of rock under freezing-thawing conditions have become one of front direction concerned with rock mechanics field. In cold region mine, coupling effect of rock, water, temperature, ice, stress and other factors are leading to rock freezing-thawing degradation happen and disaster appear, and it has significant impact to mine engineering stability in cold regions. With more and more mining activities in cold regions in China, how to predict and solve the freezing-thawing disaster have been became one of most important research issues. So, studying the rock freezing-thawing degradation mechanical and evolution mechanism could provide theoretical basis for research the freezing-thawing disaster. It has great significance for safety mining in cold regions.Considering the needs of mine engineering in cold regions and relies on the method of testing and theory analysis, this paper finish the research works of mine rock freezing-thawing degradation mechanism and evolution mechanism by NMR technology as in following:(1) Study the rock freezing-thawing degradation theory and evolution mechanism, the effect factors of rock freezing-thawing degradation and its disaster characteristics in cold regions engineering were analyzed too. Combined with the disaster chain theory, freezing-thawing disaster chain-effect and broken chain&disaster mitigation methods of mine in cold regions were discussed.(2) Granite rock which taken from cold regions mine were used as samples and the rock freezing-thawing cycles testing and uniaxial compression strength testing were conducted. The variation law of samples quality, uniaxial compression strength, freezing-thawing factor and rock weathering degree factor of rock after freezing-thawing cycles were obtained. The freezing-thawing degradation models of granite were summarized out and the relationship curve between uniaxial compression strength and freezing-thawing cycles, modulus of elasticity and freezing-thawing cycles were obtained. The freezing-thawing degradation evolution equation of granite was build. (3) The NMR technology was used to measure the pore structure and containing moisture saturation of granite. The characteristic of NMR T2distribution, porosity, T2spectrum and magnetic resonance imaging were obtained, and it has revealed the rock porosity structure characteristic.(4) The granite with freezing-thawing cycles were measured by NMR technology and the characteristic of NMR T2distribution, porosity, T2spectrum and magnetic resonance imaging were obtained. It has revealed the rock degradation characteristic under freezing-thawing condition, and provides a new method for research the freezing-thawing rock mechanics.(5) The NMR analysis on one rock sample with different freezing-thawing cycles was conducted by using the nuclear magnetic resonance technology. The NMR T2distribution characteristics of granite were obtained. And the variation law of rock quality, porosity degree, T2spectrum was obtained too. The exponential relation between rock porosity and freezing-thawing cycles and the rock freezing-thawing degradation equation which used rock porosity as target value were obtained. Degradation process of rock microstructure characteristic under different freezing-thawing cycles condition were summarized.(6) The MRI analysis on one rock sample with different freezing-thawing cycles was conducted by using the magnetic resonance imaging technology. The porosity distribution characteristics and its variation features of granite under different freezing-thawing cycles condition were obtained. It has revealed the degradation evolution law of rock microstructure characteristic under different freezing-thawing condition.(7) Rock NMR analysis and uniaxial compression strength testing have been conducted, and the mechanics characteristics of granite rock under the different NMR character conditions have been studied. The relationship between rock NMR characteristics and mechanics behavior have been built too.更多还原