岩石单轴压缩条件下裂纹扩展试验研究——以片状岩石为例

CRACK PROPAGATION STUDY OF ROCK BASED ON UNIAXIAL COMPRESSIVE TEST——A CASE STUDY OF SCHISTOSE ROCK

为研究片状岩石渐进性破坏,首先对其应力门槛值:裂纹起始应力σci、裂纹破坏应力σcd、单轴抗压峰值强度σf及相互间的关系进行系统的总结和论述。基于片状岩石——丹巴二云英片岩单轴压缩试验轴向应力-轴向/径向应变曲线,首次将岩石渐进性破坏过程应力门槛值分析应用于片状岩石,得出加载方向与片理面方向平行、垂直和成30°夹角3种加载条件下的应力门槛值,并将其与其他岩石种类的应力门槛值研究结果进行比较。结果表明裂纹扩展过程与岩石种类有关,不同岩石矿物颗粒、胶结状况、片理面发育情况等因素都会影响岩石的渐进性破坏过程,从而对应不同的应力门槛值范围。二云英片岩的试验结果直接表明,由于片理面的发育,片状单轴压缩条件下的裂纹扩展过程存在显著的各向异性,这一特点显著区别于其他种类岩石,在地下工程开挖中应对其进行具体的量化分析,以指导开挖设计和支护加固。

To study the progressive failure of schistose rock,three stress thresholds,i.e.crack initiation stress,crack damage stress and uniaxial compression peak strength,and their relationship between each other are summarized and discussed systematically.Based on the uniaxial compression axial stress-axial/radial strain curves of Danba quartz mica schist,analysis of stress thresholds of schistose rock in progressive failure process are firstly applied to schistose rock.Stress thresholds under the three conditions of schistose foliation oriented perpendicular,parallel,and at 30° to loading direction respectively are obtained,which are compared with those of other sorts of rock in references.Results show that the crack propagation are related to rock type.Grain size of mineral,cement bond quality between mineral grains and schistose and joint plane development are all the factors to influence the progressive failure process of rock.Different stress threshold ranges of different types of rock are then got accordingly.Experimental research results of quartz mica schist indicate that due to the joint plane developments,strong anisotropy exists in the schistose rock crack propagation under uniaxial compression.This distinguishing characteristics should be considered quantitatively during underground excavation and support design.