微波辅助机械破岩试验和理论研究进展

微波辅助机械破岩是微波加热技术和机械破岩技术相结合的一种混合型破岩方法。岩石内不同矿物成分对微波能具有不同的吸收特性,各矿物不同的热膨胀产生的内应力使岩石内发生沿晶断裂和穿晶断裂,使试样产生损伤和微裂纹,这会引起岩石强度的降低。辐射功率和辐射时间是影响岩石力学特性的重要参数,一定功率的微波辐射处理后,试样的点荷载强度、单轴抗压强度和抗拉强度发生显著降低,微波功率越高,辐射时间越长,对试样强度的折减效果越明显。数值研究结果与试验研究结果基本一致,增加功率的同时降低辐射时间对试样强度折减具有更好的效果。岩石点荷载强度、单轴抗压强度和抗拉强度的降低能够显著提高机械破岩设备刀具的侵入率和刀具寿命,解决机械刀具的磨损问题。微波辅助机械破岩对钻孔、TBM掘进和实现金属矿矿岩连续开采都具有重要影响作用。

Review of theoretical and experimental studies on mechanical rock fragmentation using microwave-assisted approach

The microwave-assisted mechanical rock breaking system is a rock fragmentation method which uses the combination of microwave heating technology and the mechanical excavating technology. Different minerals have different degrees of absorption to microwave energy, so intergranular and transgranular fractures occur within the specimen after microwave radiation treatment, and the specimen is weakened and micro cracks are generated due to the internal stress caused by thermal expansion of different minerals within the rocks. This causes the rock strength to be reduced. Microwave power and exposure time are the important parameters to influence the mechanical properties of rocks. The point load strength, tensile strength and compressive strength decrease significantly with a certain power level of microwave radiation. The higher the microwave power and the longer the exposure time, the more the strength reduction. The numerical results are compared with the experimental ones and show that the strength reduction is much quicker by increasing the power level of microwave in shorter time of exposure. The life and penetration rate of cutters of the rock mechanical equipment can be increased by the strength reduction of rocks, which can contribute to resolving the disc cutter wear problem. Microwave-assisted mechanical rock breaking has significant influence on drilling, TBM tunnelling and realizing the continuous mining of metal mine.