激光照射花岗岩抗拉强度及孔隙分布研究

Experimental study on tensile strength and pore distribution of granite by laser irradiation

激光辅助破岩技术有助于提高超硬、超深地层资源的开采效率。采用控制变量法开展了激光热裂花岗岩试验,分析了温度、射孔参数、比能、热裂效能、抗拉强度和孔隙分布等变化规律。结果表明,激光照射下花岗岩表面温度超过1000℃;花岗岩射孔直径、深度和射孔速率随照射参数呈非线性变化,最大射孔直径、深度和速率分别为10.0mm、12.0mm和2.70mm/s;花岗岩最大比能和热裂效能分别为87.8kJ/cm^(3)和39.5kJ/cm^(3)。激光照射后花岗岩单轴破坏模式为脆性破坏,抗拉强度最大降幅为74.11%。激光照射导致岩石内部中小孔隙连通形成大孔隙,并最终导致岩石断裂。

Laser-assisted rock-breaking technology contributes to enhance the mining efficiency of re sources in ultra-hard and ultra-deep formations.A laser thermal cracking test on granite is carried out using the controlled variable method,and the changing rules of radial temperature,borehole parame-ters,specific energy,thermal-cracking energy,tensile strength and pore distribution were researched.The results reveal that the temperature of granite surface under laser action is more than 1000℃,and the diameter,depth and rate of granite perforation vary nonlinearly with the irradiation parameters,and the maximum diameter,depth and rate of perforation are 10.0 mm,12.0 mm and 2.70 mm/s.The maximum specific energy and thermal-cracking energy of granite are87.8 kJ/cm^(3)and 39.5 kJ/cm^(3),re-spectively.The damage pattern of granite is brittle fracture after laser irradiation,and the maximum decrease of tensile strength is 74.11%.The large pores generate under laser action by connecting of small and medium-sized pores in the rock,which ultimately results in the fracture of the rock.