Author:
Li Yingchun,Yang Hongwei,Sun Shengyue
Abstract
AbstractScale dependence of surface roughness of natural rock joints has long been an outstanding issue in rock mechanics. Controversial results were reported by various studies; however, the nature of scale dependency and the underlying mechanism for the conflicting observations remain unclear. Rock joints at different scales characterise two-order asperities, namely, waviness and unevenness; thus understanding how the individual roughness of waviness and unevenness vary as the joint size increases from the laboratory-scale to the large-scale is crucial for revealing the scale effect mystery. Here we digitise three natural granite joint surfaces with the same dimension of 1000 mm × 1000 mm through a high-resolution, three-dimensional scanner. Waviness and unevenness of each rock joint surface are quantitatively separated by selecting an appropriate sampling interval. The respective fractal dimensions of waviness and unevenness of joint surfaces sized from 100 mm × 100 mm to 1000 mm × 1000 mm are estimated through an improved roughness-length method. We find that the fractal dimensions of two-order roughness are scale-dependent but without generalised trends. The stationarity threshold beyond which the scale-dependency of roughness vanishes is absent for all the three joint samples, suggesting that the roughness of natural rock joints be assessed at the specific scale of the rock mass in-situ. We reveal that previous controversial results regarding scale effect are likely due to the composition of the roughness scaling of waviness and unevenness. Thus, accurate stability analysis of rock-engineering projects should consider separate contributions of multi-order asperities across scales to the strength and deformation of jointed rock masses.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China
Publisher
Springer Science and Business Media LLC
Reference44 articles.
1. Bandis, S., Lumsden, A. & Barton, N. Experimental studies of scale effects on the shear behaviour of rock joints. Int. J. Rock Mech. Min. 18(1), 1–21 (1981).
2. Tatone, B. & Grasselli, G. An investigation of discontinuity roughness scale dependency using high-resolution surface measurements. Rock Mech. Rock Eng. 46(4), 657–681 (2013).
3. Bahaaddini, M., Hagan, P., Mitra, R. & Hebblewhite, B. Scale effect on the shear behaviour of rock joints based on a numerical study. Eng. Geol. 181, 212–223 (2014).
4. Kutter, H. & Otto, F. Influence of parallel and cross joints on shear behaviour of rock discontinuities. Proceedings of Rock Joints, 243–250 (1990).
5. Hencher, S., Toy, J. & Lumsden, A. Scale dependent shear strength of rock joints. Proceedings of the 2nd International Workshop on Scale Effects in Rock Masses, Balkema Rotterdam, 233–240 (1993).
Cited by
2 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献