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岩石的破裂性质及破裂面的起伏粗糙特征对岩石的破裂机制及破裂面的参数取值具有重要的理论和应用意义。采用高精度的三维激光扫描和扫描电镜技术,结合分形理论,揭示高应力条件下大理岩卸荷破裂性质及破裂面的细微观形态特征,阐述主破裂面粗糙度分形维与卸荷岩体强度间的相关规律。在高应力卸荷条件下,大理岩岩样随着卸荷速率的递增宏观破裂性质由剪切、拉剪复合向张拉劈裂发展。初始围压越高卸荷速率越快,主破裂面越起伏粗糙,而初始围压越高卸荷速率越慢,主破裂面越平坦光滑。随卸荷速率的增大,微观上大理岩逐渐由穿晶剪切断裂、沿晶面张裂+穿晶剪切的复合断裂、沿晶面张裂或劈裂的变化特征。卸荷岩体的内摩擦角随破裂面粗糙程度分形维D的增大而增大,而黏聚力随D的增大而减小。
The rupture property of rock and the rough features of rupture surface have important theoretical and applied significance to the rupture mechanism of rock and the parameter of rupture surface. Using high-precision three-dimensional laser scanning and scanning electron microscopy techniques combined with fractal theory to reveal the unloading and cracking characteristics of marble under high stress and the microscopic morphological characteristics of rupture surface, the fractal dimension of main rupture surface and the strength of unloading rock mass Between the relevant rules. Under the conditions of high stress and unloading, the marble samples gradually developed from shear and tensile shear to tension and split with the increasing of unloading rate. The higher the initial confining pressure is, the faster the unloading rate is. The more rough the primary fracture surface is, the higher the initial confining pressure is. The slower the unloading rate, the more flat and smooth the main fracture surface. With the increase of unloading rate, the microscopic marble gradually by the transgranular shear fracture, along the plane crack + transgranular shearing composite fracture along the crystal plane crack or splitting changes. The internal friction angle of unloading rock mass increases with the fractal dimension D of the roughness of the fracture surface, while the cohesion decreases with the increase of D.