煤岩三轴破坏行为与能量演化规律的图像测量

Image measurement on triaxial failure behavior and energy evolution law of coal rock

为研究煤岩破坏过程中能量的演化规律,对标准煤试件进行了单轴压缩试验、常规三轴加载试验及三轴卸围压试验,利用基于亚像素点检测系统的数字图像测量方法探究煤岩体应变与破坏时能量演化间的关系,并通过体应变变化等值线图对煤岩变形特征进行量化。研究结果表明:三种试验路径下,煤样的轴向能量、总能量在峰值应力前以积聚能量为主,峰值应力后煤样破坏过程伴有大量耗散能。常规三轴加载试验路径下体应变变化大,能量积聚较多且与围压呈正相关,但由于加载至预设围压后围压恒定,煤岩破坏程度较小。三轴卸围压路径下由于伴随围压卸载,煤样径向束缚力变小,煤岩破坏程度较大。

To study the evolution of energy in the process of coal rock destruction,uniaxial compression test,conventional triaxial loading test and triaxial unloading enclosure test were conducted on standard coal specimens.The relationship between coal rock body strain and energy change during damage was investigated by using digital image measurement method based on sub-pixel point detection system,and the deformation characteristics of coal rock were quantified by contour map of body strain change.The results show that the axial energy and total energy of coal samples under the three test paths are dominated by accumulated energy before the peak stress,and the damage process of coal samples after the peak stress is accompanied by a large amount of dissipated energy.The conventional triaxial loading test path has a large variation of sub-body strain,and the energy accumulation is more and positively correlated with the surrounding pressure,but the coal rock damage is less because the surrounding pressure is constant after loading to the preset surrounding pressure.In the triaxial unloading path,the coal sample is less radially bound due to the unloading of the surrounding pressure,and the coal rock is damaged to a greater extent.