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采用反平面冲剪和反平面剪切盒实验研究反平面剪切(III型)加载下脆性岩石断裂特征。反平面冲剪试样的断裂轨迹是一空间螺旋面,断口微观特征表现为沿晶断裂,晶体大部分有3个陡峭的台阶面,晶面出现较多的河流状和鱼骨状张拉条纹,试件破坏以张拉断裂(I型)为主。反平面压剪试样的断裂轨迹基本上沿原裂纹面,断口微观特征表现为穿晶断裂,晶面上多而密的平行线条纹和较多的岩屑表现出强烈的剪切破坏特征,试件破坏以剪切断裂(III型)为主。增加侧压可抑制裂纹尖端的拉应力,导致岩石产生沿原裂纹面扩展的反平面剪切(III型)断裂。反平面压剪实验是实现岩石III型断裂和测定岩石III型断裂韧度KIIIC的一种有效实验方法。
The anti-plane shear (Type III) fracture characteristics of brittle rocks are studied by using anti-plane punching and anti-plane shear cases. The rupture trajectory of the anti-plane punched shear specimen is a space helical surface. The microscopic features of the fracture surface are intergranular fracture. Most of the crystals have 3 steep step surfaces, and more river-shaped and fishbone-like tension stripes appear on the crystal plane , Specimen damage to tension fracture (I type) based. The fracture trajectory of the anti-plane compressive shear specimen is basically along the original crack surface. The micro-features of the fracture surface show the transgranular fracture. The multi-parallel parallel lines and more cuttings show strong shear failure characteristics. Specimen failure to shear fracture (III type) based. Increasing the lateral pressure can suppress the tensile stress of the crack tip, resulting in the rock producing an anti-plane shear (Type III) fracture that extends along the original crack plane. The anti-plane pressure-shear test is an effective experimental method to realize rock type III fracture and determine the fracture toughness of rock III type KIIIC.