Abstract
Shear-box experiments, Rock Failure Process Analysis (RFPA) simulations, and box-counting fractal analysis on rock-like models are conducted to investigate the influence of intermittent artificial crack density on the shear fracturing and fractal behavior of rock bridges in jointed rock slopes. The artificial crack geometry of the conceptual rock bridge model is a combination of two edge-notched artificial cracks and imbedded artificial cracks with different intermittent artificial crack densities. By numerical shear-box tests, deep insight into the mesoscopic mechanism of crack evolution is gained, and the simulated failure patterns are in accordance with experimental results. Three types of failure patterns are identified: shear mode, mixed shear/tensile mode, and tensile mode. The RFPA simulations demonstrate that macroscale shear cracks form as damage belts consisting of many tensile/shear mesocracks, as typically observed in microscopic experimental work. The failure pattern is mostly influenced by the intermittent artificial crack density, whereas the peak shear strength is related to the failure pattern. As the intermittent artificial crack density increases, the failure pattern changes from shear mode to mixed shear/tensile mode and then to tensile mode, resulting in a decrease in the peak shear strength. The regression analysis shows that the relationship between the peak shear strength and intermittent artificial crack density can be expressed by an exponential decay model. Furthermore, digital image processing and box-counting fractal analyses are performed on the shear fracture surfaces of the physical and numerical models to describe the fractal behavior. The relationships between the fractal dimension and peak shear strength are analyzed, and strong correlations that display an exponential decay function are found.
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Abbreviations
- CNL:
-
Constant normal load
- OEDF:
-
One-phase exponential decay function
- RFPA:
-
Rock failure process analysis
- A :
-
Rock bridge area
- a1, b1, and t1 :
-
Undetermined coefficients
- a2, and b2 :
-
Undetermined coefficients
- a3, b3, x3, and t3 :
-
Undetermined coefficients
- b :
-
Edge-notched artificial crack half-length
- D :
-
Fractal dimension
- E m0 :
-
Elastic modulus of the undamaged mesoscopic element
- f c0 :
-
Compressive strength of the mesoscopic element
- f t0 :
-
Tensile strength of the mesoscopic element
- l :
-
Imbedded en-echelon artificial crack half-length
- m :
-
Shape of the distribution function
- N :
-
Number of artificial cracks
- N(δ):
-
Number of boxes
- P :
-
Axial loading applied by the machine
- P n :
-
Compressive loading
- P s :
-
Shear loading
- u :
-
Mechanical property of the mesoscopic element
- u 0 :
-
Mean mechanical property of the mesoscopic element
- α :
-
Die angle
- β :
-
Imbedded artificial crack inclination
- δ :
-
Scale length of box
- ε f :
-
Intermittent artificial crack density
- λ :
-
Residual strength coefficient
- v :
-
Poisson’s ratio
- σ c :
-
Uniaxial compressive strength
- σ t :
-
Tensile strength
- τ p :
-
Peak shear strength
- φ :
-
Friction angle
References
Bae D, Kim K, Koh Y, Kim J (2011) Characterization of joint roughness in granite by applying the scan circle technique to images from a borehole televiewer. Rock Mech Rock Eng 44(4):497–504
Baud P, Wong TF, Zhu W (2014) Effects of porosity and crack density on the compressive strength of rocks. Int J Rock Mech Min Sci 67(4):202–211
Bois T, Bouissou S (2010) Influence of tectonic fractures zones on gravitational rock slope failures: new insights from 2-D physical modeling. J Geophys Res: Earth Surface 115(F3):1–8
Brideau MA, Yan M, Stead D (2009) The role of tectonic damage and brittle rock fracture in the development of large rock slope failures. Geomorphology 103(1):30–49
Budiansky B, O’Connell RJ (1976) Elastic moduli of a cracked solid. Int J Solids Struct 12:81–97
Camones LAM, Amaral Vargas ED Jr, Figueiredo RPD, Velloso RQ (2013) Application of the discrete element method for modeling of rock crack propagation and coalescence in the step-path failure mechanism. Eng Geol 153(2):80–94
Cao RH, Cao P, Lin H, Pu CZ, Ou K (2016) Mechanical behavior of brittle rock-like specimens with pre-existing fissures under uniaxial loading: experimental studies and particle mechanics approach. Rock Mech Rock Eng 49(3):1–21
Cheng Y, Wong LNY (2018) Microscopic characterization of tensile and shear fracturing in progressive failure in marble. J Geophys Res. https://doi.org/10.1002/2017JB014581
Eberhardt E, Stead D, Coggan JS (2004) Numerical analysis of initiation and progressive failure in natural rock slopes–the 1991 Randa rockslide. Int J Rock Mech Min Sci 41(7):69–87
Einstein HH, Veneziano D, Baecher GB, O’Reilly KJ (1983) The effect of discontinuity persistence on rock slope stability. Int J Rock Mech Min Sci Geomech Abstr 20(5):227–236
El-Halim AAA (2017) Image processing technique to assess the use of sugarcane pith to mitigate clayey soil cracks: laboratory experiment. Soil Tillage Res 169:138–145
Gehle C, Kutter HK (2003) Breakage and shear behaviour of intermittent rock joints. Int J Rock Mech Min Sci 40(5):687–700
Ghazvinian A, Sarfarazi V, Schubert W, Blumel M (2012) A study of the failure mechanism of planar non-persistent open joints using PFC2D. Rock Mech Rock Eng 45(5):677–693
Guarino V, Guaccio A, Netti PA, Ambrosio L (2010) Image processing and fractal box counting: user-assisted method for multi-scale porous scaffold characterization. J Mater Sci Mater Med 21(12):3109–3118
Haeri H, Shahriar K, Marji MF, Moarefvand P (2014) Experimental and numerical study of crack propagation and coalescence in pre-cracked rock-like disks. Int J Rock Mech Min Sci 67(4):20–28
Huang D, Cen D, Ma G, Huang R (2015) Step-path failure of rock slopes with intermittent joints. Landslides 12(5):911–926
Hudson JA, Harrison JP (1997) Engineering rock mechanics. Pergamon Press, Amsterdam
Lajtai EZ (1969) Strength of discontinuous rocks in direct shear. Geotechnique 19(2):218–332
Lee H, Jeon S (2011) An experimental and numerical study of fracture coalescence in pre-cracked specimens under uniaxial compression. Int J Solids Struct 48(6):979–999
Li Y, Huang R (2015) Relationship between joint roughness coefficient and fractal dimension of rock fracture surfaces. Int J Rock Mech Min Sci 75:15–22
Liu S, Wu L, Wu Y (2006) Infrared radiation of rock at failure. Int J Rock Mech Min Sci 43(6):972–979
Liu Y, Dai F, Fan P, Xu N, Dong L (2017) Experimental investigation of the influence of joint geometric configurations on the mechanical properties of intermittent jointed rock models under cyclic uniaxial compression. Rock Mech Rock Eng 50(6):1453–1471
Mandelbrot BB (1983) The fractal geometry of nature. WH Freeman, San Francisco
Park CH, Bobet A (2009) Crack coalescence in specimens with open and closed flaws: a comparison. Int J Rock Mech Min Sci 46(5):819–829
Peng S, Tan H, Xu J, Liu Y, Wu S, Qu J (2017) Experimental study on shear mechanical properties of complete sandstone under different pore water pressures. Chin J Rock Mech Eng 36(s1):3131–3139 (in Chinese)
Petit J, Barquins M (1988) Can natural faults propagate under mode II conditions? Tectonics 7(6):1243–1256
Rao QH, Sun ZQ, Stephansson O, Li CL, Stillborg B (2003) Shear fracture (Mode II) of brittle rock. Int J Rock Mech Min Sci 40(3):355–375
Sagong M, Bobet A (2002) Coalescence of multiple flaws in a rock-model material in uniaxial compression. Int J Rock Mech Min Sci 39(2):229–241
Sarfarazi V, Ghazvinian A, Schubert W, Blumel M, Nejati HR (2014) Numerical simulation of the process of fracture of echelon rock joints. Rock Mech Rock Eng 47(4):1355–1371
Schindler C, Cuenod Y, Eisenlohr T, Joris CL (1993) The events of Randa, april 18th and may 19th 1991 an uncommon type of rockfall. Eclogae Geol Helv 86(3):643–665
Scholtès L, Donzé FV (2015) A DEM analysis of step-path failure in jointed rock slopes. CR Mécanique 343(2):155–165
Tang CA (1997) Numerical simulation of progressive rock failure and associated seismicity. Int J Rock Mech Min Sci 34:249–261
Terzaghi K (1962) Stability of steep slopes on hard unweathered rock. Geotechnique 12:251–270
Wang SY, Sloan SW, Tang CA, Zhu WC (2012) Numerical simulation of the failure mechanism of circular tunnels in transversely isotropic rock masses. Tunn Undergr Sp Tech 32(11):231–244
Wong LNY (2008) Crack coalescence in molded gypsum and Carrara Marble, Ph.D. Thesis, Massachusetts Institute of Technology, Cambridge, MA, p 784
Wong RHC, Chau KT (1997) The coalescence of frictional cracks and the shear zone formation in brittle solids under compressive stresses. Int J Rock Mech Min Sci 34(3–4):335
Wong LNY, Einstein HH (2008) Crack coalescence in molded gypsum and Carrara marble: Part 1. Macroscopic observations and interpretation. Rock Mech Rock Eng 42(3):475–511
Wong LNY, Einstein HH (2009) Systematic evaluation of cracking behavior in specimens containing single flaws under uniaxial compression. Int J Rock Mech Min Sci 46(2):239–249
Wong RHC, Chau KT, Tang CA, Lin P (2001) Analysis of crack coalescence in rock-like materials containing three flaws part I: experimental approach. Int J Rock Mech Min Sci 38(7):909–924
Xie H, Wang J, Xie W (1997) Fractal effects of surface roughness on the mechanical behavior of rock joints. Chaos Soliton Fractals 8(2):221–252
Yang SQ (2011) Crack coalescence behavior of brittle sandstone samples containing two coplanar fissures in the process of deformation failure. Eng Fract Mech 78(17):3059–3081
Yang L, Jiang Y, Li S, Li B (2013) Experimental and numerical research on 3d crack growth in rocklike material subjected to uniaxial tension. J Geotech Geoenviron 139(10):1781–1788
Yang XX, Jing HW, Tang CA, Yang SQ (2017) Effect of parallel joint interaction on mechanical behavior of jointed rock mass models. Int J Rock Mech Min Sci 92:40–53
Zhang HQ, Zhao ZY, Tang CA, Song L (2006) Numerical study of shear behavior of intermittent rock joints with different geometrical parameters. Int J Rock Mech Min Sci 40(5):802–816
Zhang K, Cao P, Meng J, Li K, Fan W (2015) Modeling the progressive failure of jointed rock slope using fracture mechanics and the strength reduction method. Rock Mech Rock Eng 48(2):771–785
Zhang K, Cao P, Ma G, Wang W, Fan W, Li K (2016) Strength, fragmentation and fractal properties of mixed flaws. Acta Geotech 11(4):901–912
Zhao Z, Zhou D (2016) Mechanical properties and failure modes of rock samples with grout-infilled flaws: a particle mechanics modeling. J Nat Gas Sci Eng 34:702–715
Zhao H, Zhang H, Li H, Wang F, Zhang M (2017) Formation and fractal characteristics of main fracture surface of red sandstone under restrictive shear creep. Int J Rock Mech Min Sci 98:181–190
Zhao Z, Peng H, Wu W, Chen Y (2018) Characteristics of shear-induced asperity degradation of rock fractures and implications for solute retardation. Int J Rock Mech Min Sci 105:53–61
Zhu WC, Tang CA (2004) Micromechanical model for simulating the fracture process of rock. Rock Mech Rock Eng 37(1):25–56
Acknowledgements
The authors would like to acknowledge the China National Natural Science Foundation (Project Nos. 41762021, 11862024), the China Postdoctoral Science Foundation (Project No. 2017T100715). and the Open Research Fund Program of the State Key Laboratory of Groundwater Protection and Utilization in Coal Mining (Project No. SHGF-17-13-09), which collectively funded this project. The authors are grateful to the anonymous reviewers for their useful comments and constructive suggestions.
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Zhang, K., Chen, Y., Fan, W. et al. Influence of Intermittent Artificial Crack Density on Shear Fracturing and Fractal Behavior of Rock Bridges: Experimental and Numerical Studies. Rock Mech Rock Eng 53, 553–568 (2020). https://doi.org/10.1007/s00603-019-01928-z
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DOI: https://doi.org/10.1007/s00603-019-01928-z