压缩荷载下煤岩损伤演化规律细观实验研究

Experimental Study on Meso-damage Evolution of Coal under Uniaxial Compression

利用计算机层析摄影技术 (CT)进行了单轴压缩荷载作用下脆性煤岩破坏全过程的细观损伤演化规律动态CT试验 ,得到了单轴荷载作用下各个应力阶段煤岩从微孔洞压密到微裂纹萌生、分叉、发展、断裂、破坏以及峰值后各个阶段清晰的CT图像和CT数 .根据实验结果可把白皎煤矿煤岩细观损伤演化规律全过程分为 5个阶段 :损伤弱化阶段、准线性阶段、损伤开始演化和稳定发展阶段、损伤加速发展阶段、峰后软化阶段 .通过对CT数及其方差进行分析 ,得到了单轴荷载作用下各个应力阶段煤岩的损伤演化规律 ,为从细观尺度探讨微裂纹的发生、发展提供了依据 .

Using the CT machine,the real-time computerized tomography testing of coal under the uniaxial compression was completed.Through CT scanning,the clear CT images which included the step from the micro-crack closure to the micro-crack growth,bifurcation,development,failure and the post-failure step were obtained.According to the CT values,the meso-damage evolution of coal under uniaxial compression was analyzed.Based on the results which tallied with micro-facture,cavity growth,and section forming obtained from CT scanning of coal,the study on the damage propagation of coal was carried out.It is demonstrated that in the process of unloading,the failure of coal is paroxysmal.Based on the change of the CT values and CT images obtained from scanning test,the propagation law of the meso-damage in coal is deduced.The change law of crack width and length related to creeping time has been quantitatively analyzed.In the light of the law and CT images,the macro-damage process of coal under uniaxial compression in Baijiao Mine has been divided into 5 steps;the damage-weakening step,the linear step,the step when the damage starts to evolve and damage develops steadily,the step when the damage development speeds up and the weakening step after reaching peak.We think it is important to study the production and evolution of micro-cracks.