Abstract. We investigate the influence of stress conditions during fracture formation on the geometry and roughness of fracture surfaces. Rough fracture surfaces have been generated in numerical simulations of triaxial deformation experiments using the Discrete Element Method and in laboratory experiments on limestone and sandstone samples. Digital surface models of the rock samples fractured in the laboratory experiments were produced using high resolution photogrammetry. The roughness of the surfaces was analyzed in terms of absolute roughness measures such as an estimated joint roughness coefficient (JRC) and in terms of its scaling properties. The results show that all analyzed surfaces are self-affine, but with different Hurst exponents between the numerical models and the real rock samples. Results from numerical simulations using a wide range of stress conditions to generate the fracture surfaces show a weak decrease of the Hurst exponents with increasing confining stress and a larger absolute roughness for transversely isotropic stress conditions compared to true triaxial conditions. Other than that, our results suggest that stress conditions have little influence on the surface roughness of newly formed fractures.

中文翻译：

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数值模型和实验室实验中断裂表面的粗糙度

摘要。我们研究了裂缝形成过程中的应力条件对裂缝表面的几何形状和粗糙度的影响。在使用离散元方法的三轴变形实验的数值模拟以及在石灰石和砂岩样品的实验室实验中，已经生成了粗糙的断裂表面。使用高分辨率摄影测量法制作了在实验室实验中破裂的岩石样品的数字表面模型。根据绝对粗糙度度量（例如估计的接头粗糙度系数（JRC））及其缩放特性，分析了表面的粗糙度。结果表明，所有分析的表面都是自仿射的，但数值模型和真实岩石样本之间的Hurst指数不同。与真实的三轴条件相比，使用大范围应力条件生成断裂表面的数值模拟结果显示，随着围压的增加，Hurst指数的减小较弱，而横向各向同性应力条件的绝对粗糙度更大。除此之外，我们的结果表明应力条件对新形成的裂缝的表面粗糙度影响很小。