微波照射下岩石损伤机理的试验研究

发布时间：2018-01-29 10:03

本文关键词： 微波照射岩石损伤含水率矿物成分　出处：《西安科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：在隧道施工中,破碎岩石的主要方法有爆破法和机械破岩法。这两种方法各存在缺点或不足,爆破法对原岩的扰动大,往往造成隧道支护困难;机械破岩法一次投资费用高、遇硬岩时效率低等。为克服这些缺点,需要研究和发展新型的高效破岩方法。研究表明,利用微波对岩石进行照射,可以有效地降低其强度,有利于提高机械破碎的效率,“微波+机械”破岩有望成为一种新型的高效破岩方法。为实现这样的目标,需要对微波照射下岩石的损伤机理进行研究。本文通过设定不同的岩石含水率、岩石种类、微波照射功率和时间等因素,试验研究微波照射下岩石损伤机理,通过CT扫描和抗剪切试验探究微波照射下岩石损伤演化规律,具体研究内容及成果如下:(1)在理论分析的基础上,阐述微波照射下岩石的损伤机理,并分析微波照射下影响岩石损伤演化的内部因素。微波照射下岩石的损伤是由岩石中包含吸波物质的一些“热点”引起的。岩石矿物成分、含水率等因素对微波照射下岩石损伤具有一定程度的影响。在试验设定的含水率变化范围内,含水率高的岩石试件,经微波照射后,岩石的损伤变量大,损伤的离散性强。(2)进行不同参数的微波照射岩石试验,并对岩石抗剪强度的变化进行分析。结果表明:微波照射下由于岩石矿物晶粒的热膨胀,减弱了晶粒之间的结合力,最终导致岩石抗剪强度降低;大功率、短时间的微波照射,能够有效地降低岩石的强度。(3)对微波照射后的岩石试件进行CT扫描,确定相同参数微波照射下,不同岩石的损伤变量,分析矿物成分对微波照射下岩石损伤的影响。结果表明:微波照射下岩石的损伤演化表现出局部化特征。微波照射下花岗岩的损伤主要取决于黑云母、角闪石、磁铁矿等吸波矿物;玄武岩的损伤主要取决于橄榄石、辉石等吸波矿物。(4)本文的研究表明,利用大功率、短时间的微波照射,可以有效地降低岩石的强度,因此提出微波辅助破岩刀盘及井下微波辅助钻具的初步设计方案。微波辅助破岩刀盘的设计中,边滚刀与刀盘的连接方式为液压支撑连接,边滚刀两侧安装微波天线,刀盘在微波照射岩石的情况下对岩石进行切割,可以降低滚刀的磨损,提高破岩效率。井下微波辅助钻具通过钻头内微波天线发射的微波加热岩石,降低岩石强度,辅助钻头破岩,以提高花岗岩、玄武岩等硬岩钻进的机械钻速。
[Abstract]:In tunnel construction, the main methods of broken rock are blasting method and mechanical rock breaking method. These two methods each have shortcomings or shortcomings. The blasting method has a great disturbance to the original rock, which often results in the difficulty of tunnel support. Mechanical rock breaking method has high primary investment cost and low efficiency when it comes to hard rock. In order to overcome these shortcomings, it is necessary to study and develop a new type of high efficiency rock breaking method. It can effectively reduce its strength and improve the efficiency of mechanical crushing. "Microwave machinery" rock breaking is expected to become a new type of high-efficient rock-breaking method, in order to achieve such a goal. It is necessary to study the damage mechanism of rock under microwave irradiation. In this paper, the damage mechanism of rock under microwave irradiation is studied by setting different factors such as water content of rock, kinds of rock, power and time of microwave irradiation and so on. Through CT scanning and shear resistance test to explore the evolution of rock damage under microwave irradiation, the specific research contents and results are as follows: 1) on the basis of theoretical analysis, the damage mechanism of rock under microwave irradiation is expounded. The internal factors which influence the evolution of rock damage under microwave irradiation are analyzed. The damage of rock under microwave irradiation is caused by some "hot spots" which contain absorbing materials in rock. Water content and other factors have a certain degree of influence on the damage of rock under microwave irradiation. In the range of water content change set by the experiment, the damage variable of rock samples with high moisture content is large after microwave irradiation. The variation of shear strength of rock was analyzed by microwave irradiation with different parameters. The results showed that the thermal expansion of rock mineral grain was caused by microwave irradiation. The adhesion between grains is weakened and the shear strength of rock decreases. High-power and short-time microwave irradiation can effectively reduce the strength of rock.) CT scanning of rock samples after microwave irradiation can determine the damage variables of different rocks under the same parameters of microwave irradiation. The effect of mineral composition on rock damage under microwave irradiation is analyzed. The results show that the damage evolution of rock under microwave irradiation is localized. The damage of granite under microwave irradiation mainly depends on biotite and hornblende. Magnetite and other absorbing minerals; The damage of basalt mainly depends on the absorbent minerals such as olivine and pyroxene. The research in this paper shows that the strength of rock can be reduced effectively by microwave irradiation of high power and short time. Therefore, the preliminary design scheme of microwave-assisted rock breaking cutter head and downhole microwave assisted drilling tool is proposed. In the design of microwave-assisted rock breaking cutter head, the connection between edge hob and cutter head is hydraulic support connection. The edge hob is equipped with microwave antenna on both sides of the edge hob, and the cutter head cuts the rock under the condition of microwave irradiation, which can reduce the wear of the hob. In order to increase the drilling speed of hard rock such as granite and basalt, the underground microwave assisted drilling tool heats the rock by microwave radiation through the microwave antenna inside the bit, reduces the rock strength, and assists the bit to break the rock in order to improve the drilling speed of hard rock such as granite and basalt.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

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