静态压剪载荷下岩石力学特征研究

Mechanical properties of granite under quasi-static compression combined shear loading

缓倾斜或倾斜矿体条件下,矿柱通常受压剪外载共同作用。本文使用一套新颖的岩石力学属性测试系统,结合声发射技术,得出花岗岩试样在静态压剪外载条件下力学属性的变化。花岗岩试样的微裂隙起裂应力和微裂隙损伤应力均随着试样倾角的增加呈线性下降趋势。微裂隙起裂应力与峰值强度的比值,在0°~10°倾角范围内基本不变,微裂隙损伤应力与峰值强度的比值当试样倾角增加至10°时逐渐降低。相较于单轴压缩状态,花岗岩试样的峰值强度在试样倾角为5°和10°时,分别下降了13.7%和29.8%,试样的破坏形式逐渐由轴向分离式断裂转变为剪切破坏。建议在矿柱强度经验公式中加入压剪外载下岩石强度这一新的参数,以考虑倾角对矿柱强度的影响。

Under the condition of mildly inclined or inclined orebody,the pillars are usually subject to compression combined shear loading.A novel rock mechanical property test system has been used in this paper,combined with the acoustic emission technology,to obtain the mechanical behavior change of granite sample under quasi-static compression combined shear loading conditions.Both the microcrack initiation threshold and microcrack damage threshold of granite sample are linearly decreased with the increase of the angle of the sample.The ratio of microcrack initiation stress to peak intensity is basically unchanged in the range of 0°to 10°inclination angle.The ratio of microcrack damage stress to peak intensity gradually decreases when the pattern inclination angle increases to 10°.Compared with the uniaxial compression state,the peak intensity of the granite pattern decreased by 13.7%and 29.8%when the sample inclination angles were 5°and 10°,respectively.The failure mode of the sample gradually changed from axially separated fracture to shear failure.It is recommended to add a new parameter of rock strength under compression and shear to the empirical formula of strength of the pillar taking the influence of the pillar inclination angle on pillar strength into consideration.