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以贵州铜仁市某矿山层理板岩为研究对象,对其微观结构进行观测分析,然后选取7组不同θ角(加载方向与层理法向夹角)试样进行巴西劈裂试验。结果表明:在微观结构上,赤铁矿等刚性颗粒呈基底式胶结于黏土矿物中,层理面为软弱面;板岩的破坏模式存在显著方向效应,抗拉强度随夹角增大而减小;破坏模式总体上可分为4类,θ为0°时是基质拉伸型破坏,基质被逐层劈裂致使试样破坏,抗拉强度最大;θ为15°和30°时为基质拉剪型破坏,主要由于破坏面处的剪应力大于板岩基质的剪切强度致使试样破坏;θ为45°、60°、75°时为层理拉剪型破坏,层理面处的剪应力大于剪切强度时发生破坏;θ为90°时为层理拉伸型破坏,此时完全由于层面受张拉而破坏。
Taking the stratigraphic slate of a mine in Tongren, Guizhou as the research object, the microstructure was observed and analyzed. Then seven groups of specimens with different angles of θ (direction of loading and layering normal direction) were selected for Brazil splitting test. The results show that on the microstructure, the rigid particles such as hematite are matrix-grounded in clay minerals and the bedding plane is weak, and the failure mode of slate has significant directional effect. The tensile strength decreases with the increase of included angle The failure modes can be divided into four groups as a whole. When θ is 0 °, matrix tensile damage occurs, and the matrix is destroyed by layer splitting, resulting in the highest tensile strength. When θ is 15 ° and 30 °, The shear failure is mainly caused by the shear stress at the failure surface being greater than the shear strength of the slate matrix. When θ is 45 °, 60 °, and 75 °, the shear failure occurs at the layering plane Shear failure occurs when shearing stress is greater than shearing strength. When θ is 90 °, shearing failure occurs, which is completely destroyed by tensioning.