超声波振动岩石破坏速率的研究

发布时间：2018-03-01 10:02

本文关键词： 超声波振动时间岩石损伤时间阈值　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,矿产资源的勘探深度越来越大,硬岩地层越来越多,各国学者将解决硬岩钻进的基本问题集中在声波振动碎岩,超声波振动碎岩以其所需轴向力小,大体积破碎,设备轻便,有利降低钻进成本等优点深受各国喜爱。超声波振动碎岩运用超声波碎岩装置将放大后的机械振幅沿着钻杆、钻头,施加到岩石上。当岩石固有频率和施加给岩石的机械振动频率相等时发生共振,使岩样发生破坏,最终达到超声波振动碎岩的目的。但岩石由于自身材料的特殊性,包括节理、裂隙、孔洞等不可预见的损伤,岩石成为人工利用的天然材料中最为复杂的一种材料,随着超声波振动碎岩时间的延长,岩石内部孔隙开裂扩展,其内部进一步发育大量不规则、多尺寸的孔隙,进而影响岩石的物理力学性质。因此本文采用理论分析、有限元数值模拟与试验相结合的方法,探寻随着时间延长超声波振动对花岗岩孔隙结构及强度的损伤规律。目前对超声波振动碎岩做了大量试验,但超声波振动时间对碎岩效果的研究几乎是空白,所以超声波振动碎岩振动时间的研究,对进一步提高超声波碎岩效果具有重要参考意义。研究岩石在超声波不同振动时间下,强度下降的规律、岩石损伤规律(孔隙大小、多少变化规律),为下步将超声波振动器应用于硬岩钻进,深部探测,研发超声波振动碎岩钻机提供理论指导。采用岩石的疲劳破坏、损伤力学和格里菲斯理论对超声波振动时间对碎岩损伤影响规律的问题进行研究,得出超声波振动下岩石损伤机理:超声波振动随着振动时间的延长,疲劳碎岩存在最小阈值时间,只有当超声波振动时间大于该最小阈值时间时,加载能量使花岗岩内部微裂纹开裂汇聚为中裂纹,低于时间阈值时超声波振动能量导致花岗岩内部损伤累积,花岗岩发发育微裂纹。采用ANSYS有限元进行数据模拟关于超声波振动时间对碎岩损伤影响规律的问题进行研究。建立了符合实际的非均质岩石模型,通过计算机强大的运算能力得出随着时间延长超声波振动对花岗岩不同的损伤程度,并提出超声波振动时间阈值(仿真分析得到时间阈值在15-20分钟之间),对于进一步提高超声波振动碎岩,为试验提供理论指导。采用核磁共振试验和单轴抗压强度测试对超声波振动时间对碎岩损伤影响规律进行研究,得出:1.超声波频率作用下不同时间对脆性材料破坏规律,强度下降,孔隙变化情况,为定量分析岩体结构的破坏形式打下试验方面的基础。2.超声波频率振动下非均匀岩样中包含了从微观到宏观的各种尺寸的缺陷,岩样从原始状态直到最终破坏的整个过程中,裂纹扩展汇合微小裂纹在数目增多的状况下逐渐发育为大尺寸裂纹。超声波振动碎岩一般经历四个阶段:第一阶段(0-10分钟):岩石在疲劳作用下内部初始损伤发育,振动对岩石内部裂纹的影响较小主要集中在岩石浅层部分;第二阶段(15-20分钟):微裂纹开裂扩展,岩石初始损伤开始进一步加剧,岩石经过损伤累积阶段此时超声波振动能量用于微裂纹开裂,裂纹在低应力状态下进入裂纹开裂临界值;第三阶段(20-25分钟):裂纹处于平稳发展阶段,时间的延长能够对超声波振动下岩石破碎效率的提高起到促进作用,但递增幅度平缓,疲劳碎岩过程岩样裂纹以稳定速度扩展开裂;第四阶段(25-30分钟):岩石进入损伤快速累积阶段,岩石发生裂纹的扩展速度加快,内部大裂纹汇合贯通,岩石的强度下降速率大幅度升高,从而出现岩石损伤和破坏导致岩样断裂。
[Abstract]:In recent years, mineral resources exploration depth is more and more big, hard rock more and more scholars will solve the basic problems of hard rock drilling in rock acoustic vibration, ultrasonic vibration of broken rock with its required axial force is small, large volume breaking, portable equipment, reduce drilling cost into favorable advantages by countries like the use of ultrasonic. Ultrasonic vibration of broken rock broken rock mechanical device will be amplified along the drill pipe, drill bit, applied to the rock. When the resonance frequency and applied to solid rock mechanical vibration frequency equal to the rock, the rock failure, and ultimately achieve the purpose of ultrasonic vibration of broken rock. But because of the particularity of the rock. The materials including joints, cracks, holes and other unforeseen injuries, rocks become the most complex materials in artificial natural materials utilization, with the extension of ultrasonic vibration time of broken rock, rock The internal pore expansion cracking, the further development of a large number of irregular, multi pore size, thereby affecting the physical and mechanical properties of rock. So this paper uses the method of theoretical analysis, finite element numerical simulation combining with experiment, explore with the time of ultrasonic vibration damage law of granite pore structure and strength. At present, a great deal of testing the ultrasonic vibration of broken rock, but the research on rock ultrasonic vibration time effect is almost empty, so the ultrasonic vibration time of rock broken, has important reference significance to further improve the effect of ultrasonic broken rock. The rock in different ultrasonic vibration time, decreased the intensity of the rules and laws of rock damage (pore size. How many changes), for the next step of applying ultrasonic vibrator in hard rock drilling, deep exploration, research and development of ultrasonic vibration drilling theory broken rock By using the rock guidance. The fatigue damage mechanics and Griffith's theory of ultrasonic vibration time damage influence law on rock, it is concluded that the damage mechanism of rock under ultrasonic vibration, ultrasonic vibration with prolonging time of vibration, fatigue broken rock have a minimum threshold of time, only when the ultrasonic vibration time is greater than the minimum threshold time. The energy load of micro crack crack together as granite cracks, less than the time threshold of ultrasonic vibration energy leads to accumulation of internal damage of granite, granite develop micro cracks. Using ANSYS finite element simulation data about the ultrasonic vibration time for research on rock damage influence. A heterogeneous rock model is practical. Through the powerful computing ability of computer to draw with the time of ultrasonic vibration on the granite The extent of the damage, and put forward the ultrasonic vibration time threshold (analysis of the simulated time threshold within 15-20 minutes), to further improve the ultrasonic vibration of broken rock, to provide theoretical guidance for the experiment. Using magnetic resonance test and uniaxial compressive strength test of ultrasonic vibration time on rock damage are discussed as follows: 1. ultrasonic frequency under the effect of different time on the brittle failure law, strength decreased, changes in pore, for the quantitative analysis of failure modes of rock mass structure in uniform rock contains the defects from microcosmic to macroscopic dimensions of various non.2. based ultrasonic frequency vibration test lay under the whole process of samples from the original state until the final failure. Micro cracks propagation crack in the increase in the number of conditions gradually developed into large size crack. Ultrasonic vibration of broken rock generally experienced four stages Section: the first stage (0-10 minutes): rock in fatigue under the action of internal initial damage development, vibration has little effect on the crack in rock mainly concentrated in the shallow part of the rock; the second stage (15-20 minutes): micro crack propagation, the initial damage of rock began further exacerbated by rock damage accumulation stage at this time for ultrasonic vibration energy micro crack, crack stress state into the crack in the low critical value; the third stage (20-25 minutes): crack in a stable stage of development, the extension of time to rock under ultrasonic vibration crushing efficiency play a role in promoting, but the increasing rate of broken rock rock gently, fatigue crack extension at a stable speed cracking; fourth stage (25-30 minutes): rock damage into the rapid accumulation stage, expansion velocity of rock crack up, internal cracks through the rock strength The decline rate increases greatly, which leads to rock damage and failure to lead to rock fracture.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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