微波辐射辅助机械冲击破碎岩石动力学试验研究

doi:10.11872/j.issn.1005-2518.2020.04.016

摘要/Abstract

摘要：

微波辅助冲击式破岩是实现快速破碎硬岩的重要手段，开展微波辐射对岩石抗冲击性能的研究具有重要的理论和实际意义。采用工业微波炉对砂岩进行不同功率和不同时间的辐射试验，测试了砂岩在辐射前后的波速、孔隙率和动态力学强度。结果发现：在5 kW的辐射功率下砂岩升温速率达到1.29 ℃/s，3 kW的辐射功率下达到1.04 ℃/s；微波辐射后砂岩波速不断降低，孔隙率不断增大，5 kW辐射4 min后波速降低了34%，孔隙率增加了近70%；在5 kW和3 kW辐射4 min后，砂岩动态压缩强度分别降低了60.4 MPa和44 MPa。研究结果说明微波辐射能够使砂岩快速升温，在热应力的作用下试样内部产生裂纹并扩展，使得波速下降而孔隙度增大。辐射加热大幅地降低了砂岩动态压缩强度。

关键词: 微波辐射, 动态压缩强度, 纵波波速, 孔隙率, 核磁共振

Abstract:

In industrial production，dynamic load rock breaking equipment is widely used in metal and non-metal mines，such as drill，downhole drill and cable drill.Mechanical rock breaking is often faced with such problems as low crushing efficiency，poor crushing effect and expensive equipment.Therefore，it is necessary to find an efficient，simple and safe method to break the rock.Microwave-assisted percussive rock breaking is an important means to break hard rock quickly.It is of great theoretical and practical significance to study the impact resistance of rock by microwave radiation.In this paper，an industrial microwave oven was used to test the radiation of sandstone with different power and time.The wave velocity of sandstone before and after radiation were measured and the porosity of rock before and after radiation were measured by nuclear magnetic resonance equipment.Then，the dynamic compressive mechanical strength of rock was tested by SHPB method，and the rock failure process and characteristics were recorded by high-speed camera.The results show that under the microwave radiation，the sandstone heating speed is very fast.Under the radiation power of 5 kW，the sandstone heating rate reaches 1.29 ℃/s，and under the condition of 3 kW，it reaches 1.04 ℃/s.After the microwave radiation，the wave velocity of sandstone decrease continuously and the porosity increase continuously.After 5 kW radiation for 4 min，the wave velocity decreases by 34% and the porosity increases by nearly 70%.The dynamic compressive strength of sandstone is also continuously reduced，and after 5 kW and 3 kW radiation for 4 min，it decreases by 60.4 MPa and 44 MPa respectively.Under the action of impact stress，rock shows radial failure modes and axial failure modes.The results show that microwave radiation can rapidly heat up sandstone.Because of the thermal stress，cracks are generated inside the sample then spread，which makes the wave velocity decrease and the porosity increase and the dynamic compressive strength decrease drastically.

Key words: picrowave irradiation, dynamic compressive strength, P-wave velocity, porosity, nuclear magnetic resonance

中图分类号:

TD05

胡毕伟, 尹土兵, 李夕兵. 微波辐射辅助机械冲击破碎岩石动力学试验研究[J]. 黄金科学技术, 2020, 28(4): 521-530.

Biwei HU, Tubing YIN, Xibing LI. Experimental Study on Mechanical Impact Breaking Rock with Microwave Radiation[J]. Gold Science and Technology, 2020, 28(4): 521-530.

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参数名称	参数值	参数名称	参数值
弹性模量E/GPa	14.76	密度ρ/ (g·cm^-3)	2.56
泊松比υ	0.36	单轴抗压强度σ/MPa	84.57
纵波波速V/（m·s^-1）	3 137.54

矿物类型	矿物质量百分比/%	矿物吸波能力	粒径/mm
石英	41.72	非常弱	0.06~0.40
长石	34.49	弱	0.05~0.40
蒙脱石滑石	9.35 6.18	弱弱	0.10~0.40 0.02~0.06
方解石	4.73	强	0.01~0.03
赤铁矿	5.53	很强	0.20~0.40

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