三轴加卸载条件下岩石损伤破坏机理CT试验分析

CT Test Analysis on Rock Breakage Mechanism Under Triaxial Loading-Unloading Condition

利用RMT150岩石力学测试系统和高分辨率Sensation 40型医用CT机,对恒定围压下不同轴向加载应力阶段的粉砂岩试样进行多次CT扫描试验,得到了不同轴向应力条件下岩石断面的CT图像特征。基于CT数原理,分析了岩石不同应力状态下的损伤演化过程与损伤程度,通过试样CT图像三维重建,较真实地反应了岩石试样细观损伤过程。试验研究表明:试样在试验过程中经历压密、扩容及破坏阶段;岩石压缩损伤演化是有一个相对较长应力段的量变积累过程,裂纹产生及其扩展的质变过程具有突发性;试样破坏后,远离破裂面区域存在"密度回弹"现象。

Using the rock mechanics test system RMT150 and high-resolution CT medical machine,the siltstone specimen CT scan tests under a constant confining pressure and different axial loadings were carried out and clear CT images of rock section were obtained.On the basis of the CT number＇s principle,a quantitative analysis on damage evolution and damage degree was performed.The micro-damage process of rock was reflected by the sample＇s 3D CT image reconstruction.The test study results showed as follows： The test rock specimen experiences three stages including compaction,expansion and destruction.The compression damage evolution of the rock is a long-time accumulation process and the crack generation and its expansion process manifest a sudden change,and there exists a ＇density rebound＇ phenomenon in the region away from fracture plane.