热损伤花岗岩力学劣化特性及损伤演化规律研究

Study on the mechanical degradation characteristics and damage evolution of thermally damaged granite

深部矿产开采面临的高地温环境导致岩石产生热损伤,易诱发深部工程地质灾害,探究高温后岩石力学性能劣化特性与损伤演化规律对深部高地温环境下的岩体工程具有重要意义。通过将花岗岩进行常温至1200℃范围内的温度处理,采用光学显微镜观测,探究了花岗岩试样在不同高温处理后杨氏模量和抗压强度的劣化特性,从微观角度分析热损伤花岗岩的内部裂纹和损伤演化规律。试验结果表明,高温处理将显著降低花岗岩的力学性能;岩石抗压强度和杨氏模量随着处理温度的升高而降低,裂纹发育程度随着温度的升高而增大;岩石力学性能与内部裂隙结构的发育程度高度相关,花岗岩在不同温度处理后的裂纹密度同抗压强度之间存在幂函数关系,裂纹密度能很好地反应花岗岩的热损伤程度。

The high geothermal environments encountered in deep mineral mining induce thermal damage to rocks,which can trigger geotechnical disasters in deep engineering projects.Therefore,exploring the degradation characteristics of rock mechanical properties and the damage evolution laws after high-temperature exposure is of significant importance for rock engineering in deep high-geothermal environments.By subjecting granite to the temperature range from ambient to 1200℃and conducting macro-microscopic studies using optical microscopy,the degradation characteristics of Young's modulus and compressive strength in granite samples post various high-temperature treatments were investigated.Additionally,an analysis was performed on the internal cracks and damage evolution in thermally damaged granite from a microscopic perspective.The experimental results demonstrate that high-temperature treatments significantly reduce the mechanical properties of granite.The granite's compressive strength and Young's modulus decrease with increasing treatment temperatures,and the extent of crack development increases with temperature.The mechanic cal properties of granite are highly correlated with the development of internal crack structures.There is a power function relationship between the crack density and compressive strength in granite after different temperature treatments,indicating that crack density can effectively reflect the extent of thermal damage in granite.