弱胶结砂岩细观结构特征与变形破坏机理研究及应用

发布时间：2018-06-15 01:22

本文选题：弱胶结砂岩 + 类相变临界状态　；参考：《北京科技大学》2017年博士论文

【摘要】：弱胶结地层是广泛分布在我国西部矿区侏罗系、白垩系地层中的一类特殊沉积砂岩地层。该地层主要为成分成熟度及结构成熟度较低的弱胶结砂岩,富含刚性颗粒,具有弱胶结、低强度、遇水后泥化崩解、扰动敏感等特性,对许多深部地下工程支护方式及围岩稳定性控制产生了极大的影响。本文以弱胶结砂岩为研究对象,采用胶结砂岩细观结构试验、宏观岩石力学实验、理论分析和数值模拟等技术手段,研究了弱胶结砂岩的矿物成分和细观结构特征及其对静力学和动力学性能的影响;揭示了弱胶结砂岩水岩相互作用机理及对渗透特性的影响;建立了弱胶结砂岩重整化模型,证明了弱胶结砂岩受力变形破坏过程中类相变临界状态的存在并建立了相应判别条件,对弱胶结砂岩的类相变临界状态及判别特征进性了充分阐述;基于弱胶结砂岩受力加载变形破坏过程的类相变临界现象及其物理意义,分析了弱胶结地层中巷道开挖互相扰动特性,并对弱胶结围岩支护提出了有效的主动支护对策。本课题主要取得以下研究成果与进展:(1)采用QEMSCAN电镜、SEM扫描电镜、体式显微镜等手段对弱胶结砂岩的矿物组成、化学成分、晶体结构、微结构特征等进行了定量和定性研究。研究表明,弱胶结砂岩从细观结构分析主要以颗粒物质和胶结物质在压实和胶结作用下形成的胶结结构;弱胶结砂岩的矿物组成成分的差异性和颗粒之间的接触状态对其力学性质有重要的影响;通过对比分析发现其成熟度远低于我国中东部地区砂岩。(2)通过岩石力学静力学加载试验、动力学冲击实验和离散元数值分析的方法,对其受力变形破坏特征进行研究。研究表明,弱胶结砂岩的宏观力学行为主要由粒间接触决定,当边界荷载发生变化时,弱胶结砂岩颗粒间作用力随之发生变化,造成胶结砂岩颗粒体系细观结构的变化;弱胶结胶结砂岩细观颗粒接触参数对胶结砂岩的力学特性和变形破坏特征有重要影响。由于细观结构的胶结物质的强度较低,弱胶结砂岩在冲击破坏时能量消耗的较少,即在较低的冲击能量下破坏程度较高。(3)通过对弱胶结砂岩进行浸泡饱水实验、细观结构分析试验、饱水变角剪切试验、干湿循环条件下的声发射试验和渗透试验等力学实验方法研究了水岩相互作用机理及其对弱胶结砂岩力学性质的影响。研究表明:弱胶结砂岩颗粒间粘土胶结物质遇水泥化、膨胀以及弱胶结砂岩的高孔隙率致使水更容易进入岩石内部结构,矿物颗粒溶蚀破坏矿物集合体的结构,进而导致弱胶结砂岩内部细观结构发生变化,最终导致了弱胶结砂岩强度降低;水岩相互作用对剪切破坏形貌特征、声发射特性及渗透特性有重要影响。(4)通过对弱胶结砂岩矿物成分和细观结构的分析、力学实验、弱胶结砂岩细观结构受力理论分析,建立弱胶结砂岩的重整化群模型并结合弱胶结砂岩加载过程中的声发射特性,证明了弱胶结砂岩在受力加载变形破坏过程中存在一个类相变临界状态,即胶结颗粒发生由连续状态到离散状态的转化过程;弱胶结砂岩胶结度的差异,导致了达到类相变临界状态时对应的临界应力和临界应变也不相同,破坏状态也不相同;弱胶结砂岩在受力加载过程中接近类相变临界状态时,试件对振动或者扰动异常敏感,微小的应变△ε极易导致弱胶结弱胶结砂岩达到类相变临界状态,即弱胶结砂岩内部胶结颗粒发生连续到离散类相变转化过程。而△ε取决于颗粒矿物成分、弱胶结砂岩成岩过程中的颗粒压实特性及胶结物质胶结特性、胶结物质含量等细观结构因素,即取决于弱胶结砂岩的胶结度。弱胶结砂岩的胶结程度越差,类相变临界状态比硬岩达到屈服应力值的点相对要提前越多。(5)通过区域地应力特性分析,现场松动圈的测试以及数值模拟的方法,研究了弱胶结地层邻近巷道掘进的相互扰动因素;并基于弱胶结砂岩在受力加载过程中存在临界类相变点这一特性,分析得到,在弱胶结地层中进行工程挖时,由于扰动敏感的特性,应积极采取主动支护的方式,支护强度保证围岩受力状态维持在类相变临界状态以前是弱胶结砂岩支护对策的核心思想,并提出了合理的主动支护措施。
[Abstract]:Weak cemented strata are a kind of special sedimentary sandstone stratum, which are widely distributed in the Jurassic and Cretaceous strata of Western China. The formation is mainly composed of weak Cemented Sandstone with low composition maturity and low structural maturity. It is rich in rigid particles and has weak cementation, low strength, muddy disintegration after water and disturbance sensitivity and so on. The method of engineering support and the stability control of surrounding rock have great influence. This paper takes the weak Cemented Sandstone as the research object. Using the Cemented Sandstone microstructure test, the macroscopic rock mechanics experiment, the theoretical analysis and the numerical simulation, the mineral composition and the meso structure characteristics of the weak Cemented Sandstone and its statics and dynamics are studied. The interaction mechanism of the weak Cemented Sandstone water rock interaction and its influence on the permeability are revealed, and a weakly cemented sandstone renormalization model is established, which proves the existence of the critical state of the phase change of the weakly cemented Sandstone during the stress deformation and failure process and establishes the corresponding discriminant conditions for the critical state of the phase transition of the weakly cemented sandstone and the discrimination of the phase transition of the weakly cemented sandstone. The characteristics are fully expounded. Based on the critical phenomenon of phase change and its physical significance in the process of deformation and failure of the weak Cemented Sandstone, the interaction characteristics of tunnel excavation in the weak cemented strata are analyzed, and the effective active supporting measures are put forward for the weak cemented rock support. The main achievements and progress in this study are as follows: (1) mining The mineral composition, chemical composition, crystal structure and microstructural characteristics of weakly cemented sandstone are quantitatively and qualitatively studied by means of QEMSCAN electron microscope, SEM scanning electron microscope and body microscope. The study shows that the microstructure analysis of the weakly cemented sandstone is mainly composed of the cemented structure formed by the compaction and cementation of the granular material and the cemented substance. The difference in the mineral composition and the contact state between the weakly cemented sandstone and the contact state of the particles have an important influence on their mechanical properties. Through comparison and analysis, it is found that the maturity is far lower than the sandstone in the eastern part of China. (2) the mechanical static loading test, the dynamic punching experiment and the discrete element numerical analysis are applied to the force of the sandstone. The study shows that the macroscopic mechanical behavior of the weakly cemented sandstone is mainly determined by intergranular contact. When the boundary load changes, the intergranular interaction between the weakly cemented sandstone is changed, and the microstructure of the Cemented Sandstone particle system is changed, and the fine particle contact parameters of the weak Cemented Sandstone are cemented to the Cemented Sandstone. The mechanical properties and deformation and failure characteristics of sandstone have an important influence. Because the strength of the cemented material of the meso structure is low, the weakly cemented sandstone has less energy consumption during the impact damage, that is, it has a high degree of destruction under the lower impact energy. (3) through the experiment of soaking and filling the weak Cemented Sandstone, the microstructural analysis test, the satiety change. The mechanism of water rock interaction and its influence on the mechanical properties of weak Cemented Sandstone are studied by angular shear test, acoustic emission test and permeability test under dry and wet cycle. The study shows that the clay cementation material between weakly cemented sandstone particles is cemented, and the high porosity of the weak Cemented Sandstone makes water easier. In the inner structure of the rock, the dissolution of mineral particles destroys the structure of the mineral aggregate, which leads to the change in the inner microstructure of the weak Cemented Sandstone, and eventually leads to the decrease of the strength of the weak Cemented Sandstone. The interaction of water and rock has an important influence on the characteristics of the shear failure morphology, acoustic emission and permeability. (4) through the weak Cemented Sandstone ore It is proved that there is a critical state of the phase transition in the weak Cemented Sandstone during the loading and failure process of the weak Cemented Sandstone, that is, the cemented grain, which is proved by the analysis of the mechanics experiment and the weak Cemented Sandstone meso structure stress theory, the establishment of the renormalization group model of the weakly cemented sandstone and the acoustic emission characteristics during the loading process of the weak Cemented Sandstone. The difference in the cementation of the weakly cemented sandstone results in the difference between the critical stress and critical strain when the critical state of the phase transition is reached, and the failure state is different. When the weak Cemented Sandstone is near the critical state of the phase transition in the loading process, the specimen is vibrated or disturbed. Very sensitive, small strain delta epsilon easily leads to the weak cementation and weak Cemented Sandstone to reach the critical state of the phase like phase, that is, the continuous to the discrete phase transformation process in the weak Cemented Sandstone internal cementation particles, and the delta e depends on the particle mineral composition, the compaction property of the grains and cementation properties of the cemented material in the weak Cemented Sandstone diagenesis. The microstructural factors, such as material content, depend on the cementation degree of the weakly cemented sandstone. The worse the cementation of the weakly cemented sandstone, the more the critical state of the phase transition is higher than that of the hard rock. (5) the weak cementation is studied through the analysis of the regional stress characteristics, the test of the field loosening ring and the method of numerical simulation. On the basis of the characteristics of the critical phase transition point of the weak Cemented Sandstone during the loading process of the weak Cemented Sandstone, the characteristics of the critical phase transition point in the loading process of the weak Cemented Sandstone are analyzed. In the process of engineering excavation in the weak cemented stratum, the active supporting formula should be taken actively because of the sensitive characteristics of the disturbance, and the support strength ensures that the stress state of the surrounding rock is maintained in the class. The critical state of transformation before is the core idea of weak Cemented Sandstone supporting measures, and reasonable active support measures are put forward.
【学位授予单位】：北京科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU45

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