(1. Faculty of Architecture and Civil Engineering，Xinyang Normal University，Xinyang，Henan 464000，China；
2. Faculty of Engineering，China University of Geosciences(Wuhan)，Wuhan，Hubei 430074，China；
3. Faculty of Mining Engineering，Liaoning Shihua University，Fushun，Liaoning 113001，China)
Abstract：The progressive failure of brittle schist with schistose planes shows anisotropy under compression loading. In order to study the anisotropic properties of crack initiation stress and crack propagation of schist and their correlations with micro factors，three types of quartz mica schist samples were selected. Firstly，the optical section analysis of these samples was carried out，and the differences among the characteristics of micro- fissures(pores) of three type samples were quantitatively analyzed. The results show that the mica minerals in the samples are easy to form heterogeneous layers by directional aggregation，and that the micro-fissures are mainly distributed along the edge of the mineral while the developmental direction of the defects in other parts is irregular. Then，uniaxial compression tests were performed on cylindrical specimens with different schistose angles，and the failure morphology and stress-strain curve characteristics of the specimens were investigated. Theoretical analysis of fracture mechanics shows that，when the compression loading is oblique to( =30°) and perpendicular to ( =90°) the heterogeneous layer，the initiation of rock fracture is respectively controlled by the directional micro-fissures and the irregular micro-fissures(pores) with dominant angles. The guiding and promoting effect of the weak edge of directionally aggregated minerals on crack growth is closely dependent on the loading direction，which results in the difference of macro shear failure modes of specimens with different schistose angles. Statistical analysis results of stress and strain data as well as the data reflecting micro properties show that the initiation stress and the initiation stress level of specimens have good regularity，which is related to the heterogeneity of rocks and the characteristics of micro-fissures(pores) such as distribution，quantity，size and nature.
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2019, Vol. 38 
