一种新的表征岩石节理粗糙度指标系统

A new 3D roughness parameter system for rock joint

基于长方体微凸体两种破坏模式提出了等效高差概念来反映微凸体几何参数对剪切强度贡献比例。不同剪切方向的等效高差分布不同可反映节理剪切方向性。进而提出了基于等效高差的节理三维粗糙度指标系统,其中平均等效高差表征了不同破坏形式的微凸体对强度的贡献,也可反映节理面的起伏方向性;分形维数表征了不同尺度粗糙度的关系,可从尺度上全面描述节理面信息,并且也可表示剪切方向性。最后基于三维测量系统获取了节理面离散点坐标值并计算出新指标系统具体数值,验证了指标系统可以描述剪切方向性,同时克服了采样间距的影响。新指标系统物理意义明确,可反映不同微凸体对强度贡献比例。

The concept of equivalent height difference is proposed based on the two failure modes of the rectangular-shaped asperities to reflect that the different geometric parameters of the asperities have different contribution to the shear strength.The distribution of the equivalent height difference in different shear directions can reflect the directional character of shear strength.Then,a 3D roughness parameter system is developed,which consists of two roughness parameters.One is the average equivalent height difference,which represents the contribution of asperities with different failure modes to the strength.It also can describe average undulation directivity.The other one is fractal dimension,which characterizes the relationship of roughness with different scales and can describe the information of the joint surface comprehensively from the scale.Finally,the new method is used to characterize the roughness of natural rock joint.Research results show that the new method can well reflect the 3D morphology of joint and it can also describe the anisotropy of roughness and overcome the influence of the sampling interval.The new parameter system has a clear physical meaning,which offers the foundation for further studying the shear strength.