超声波激励下岩石的物理力学特征试验研究

发布时间：2018-12-07 07:21

【摘要】：随着岩石破碎工作量日益增多,进一步提高破岩效率具有重要的现实意义。目前,现有常见的破岩方法中,还大都存在材料消耗大、破岩效率低等问题,超声波具有方向性好、穿透力强、能量集中等优点,在国民经济各个领域得到了广泛的应用。本文将超声波引入到岩石破碎当中,通过理论分析与实验室试验等方式,探索超声波激励下岩石的破碎机理,以期为坚硬岩层的高效破碎提供参考。论文取得的主要成果有:(1)围绕超声波循环冲击破岩与超声波共振破岩等现象,集中讨论了超声波激励下岩石破碎机理,明确了超声波激励破岩的可行性与优越性,初步确定出频率、功率及激励时间为影响超声波激励破岩的关键影响因素。(2)设计开发出一套超声波激励岩石试验测试系统,并采用该系统测试并对比分析了不同功率、不同激励时间下岩石试件的破坏特征。结果表明:随超声波功率的不断提高,在对岩石试件施加一定的压力基础上,试件的破坏效果明显加强,超声波功率提高至3200 W左右时,标准砂岩试件迅速破坏。(3)探索了不同激励方式下岩石试件力学与强度变化特征,对比分析了超声波激励前后岩石微观结构变化特征。试验表明:(1)岩石试件强度随激励时间的提高而降低,且两者近似为线性关系;(2)在不同激励方式下,短时间内岩石试件强度均有降低,安装能量扩散器时,40 s左右,岩石试件强度下降10%左右;(3)由微观扫描得出,经超声波激励后,岩石试样内部晶核表面及侧面产生较多的裂隙,晶核也被裂隙切割成不同形状的四边形。(4)采用数值模拟的方法,系统分析了超声波频率、振幅等变化时,岩石应力、应变及剪切应力的响应特征。结果表明:(1)当频率改变时,岩石内部应力、应变、剪切应力将在某一频率时达到峰值,而在其他频率条件下,应力、应变、剪切应力变化情况较小;(2)当振幅改变时,随着振幅提高,岩石内部应力、应变、剪切应力也将不断提高,且与振幅近似为线性关系。
[Abstract]:With the increasing of rock crushing workload, it is of great practical significance to further improve the rock breaking efficiency. At present, among the common rock breaking methods, there are still many problems such as high material consumption, low rock breaking efficiency and so on. Ultrasonic wave has the advantages of good directionality, strong penetration and energy concentration, and has been widely used in various fields of the national economy. In this paper, ultrasonic wave is introduced into rock breakage. By means of theoretical analysis and laboratory test, the mechanism of rock fragmentation under ultrasonic excitation is explored in order to provide a reference for the high efficiency crushing of hard rock. The main achievements of this paper are as follows: (1) focusing on the phenomena of ultrasonic wave cyclic rock breaking and ultrasonic resonance rock breaking, the mechanism of rock breaking under ultrasonic excitation is discussed, and the feasibility and superiority of ultrasonic stimulation are clarified. The frequency, power and excitation time are the key factors affecting the rock breaking induced by ultrasonic wave. (2) A set of ultrasonic exciting rock test and testing system is developed, and the different power is tested and analyzed by using the system. Failure characteristics of rock specimens under different excitation time. The results show that with the increasing of ultrasonic power, on the basis of applying certain pressure to the rock specimen, the failure effect of the specimen is obviously strengthened, when the ultrasonic power is increased to about 3200 W, (3) the mechanical and strength characteristics of rock specimens under different excitation modes are explored, and the characteristics of rock microstructure changes before and after ultrasonic stimulation are compared and analyzed. The results show that: (1) the strength of rock specimen decreases with the increase of excitation time, and the relationship between them is approximately linear; (2) under different excitation modes, the strength of rock specimen decreases in a short time, and when energy diffuser is installed, the strength of rock specimen decreases by about 10% about 40 s; (3) from the microscopic scanning, the surface and the side of the crystal nucleus of the rock sample produced more cracks after the ultrasonic excitation, and the nucleus was also cut into quadrangles with different shapes. (4) numerical simulation method was used. The response characteristics of rock stress, strain and shear stress with the variation of ultrasonic frequency and amplitude are systematically analyzed. The results show that: (1) when the frequency changes, the stress, strain and shear stress will reach the peak value at a certain frequency, but under other frequency conditions, the variation of stress, strain and shear stress will be small; (2) with the amplitude increasing, the stress, strain and shear stress in the rock will increase continuously, and the relationship between the amplitude and the amplitude will be approximately linear.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

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