Parametric Study of Smooth Joint Parameters on the Shear Behaviour of Rock Joints

AbstractThis paper aims to study the shear behaviour of rock joints in a direct shear test using the particle flow code PFC2D. In this numerical approach, the intact rock is simulated by densely packed circular particles that are bonded together at their contact points; joint surfaces can be explicitly simulated using the modified smooth joint (SJ) model. In the modified SJ model for simulation of direct shear test, micro-scale slip surfaces (smooth joint contacts) are applied at contacts between the particles of the upper and lower blocks of the shear box and the mechanical behaviour of the joints is controlled by the micro-scale properties of the smooth joint contacts. Two joint profiles of standard JRC 10–12 and a sawtooth triangular joint with a base angle of 15° were selected for testing. The results of direct shear tests under different normal stresses on these two profiles show that for the sawtooth triangular joints under a normal stress of 1 MPa, the shearing mechanism is purely sliding, and for the JRC 10–12 profile under a normal stress of 4 MPa, the shearing of first-order asperities controls the shearing mechanism. A parametric study of the micro-properties of the smooth joints under these two different shearing mechanisms was undertaken. The results of this study show that the SJ normal stiffness and the SJ shear stiffness have insubstantial effect on the peak shear strength in sliding mode, but that the SJ normal stiffness has a significant effect on the dilation rate in both sliding and shearing modes.

[1]  Giovanni Grasselli,et al.  Quantitative three-dimensional description of a rough surface and parameter evolution with shearing , 2002 .

[2]  Vamegh Rasouli,et al.  Assessment of rock fracture surface roughness using Riemannian statistics of linear profiles , 2010 .

[3]  Nathan Deisman,et al.  Empirical and numerical approaches for geomechanical characterization of coal seam reservoirs , 2010 .

[4]  Peter A. Cundall,et al.  Numerical experiments on rough joints in shear using a bonded particle model , 2000 .

[5]  Jae-Joon Song,et al.  Numerical simulation of a direct shear test on a rock joint using a bonded-particle model , 2009 .

[6]  F. Patton.  Multiple Modes of Shear Failure In Rock , 1966 .

[7]  M. Bahaaddini,et al.  Direct Shear Tests to Model the Shear Behavior of Rock Joints By PFC2D , 2012 .

[8]  Nick Barton,et al.  Review of a new shear-strength criterion for rock joints , 1973 .

[9]  Buddhima Indraratna,et al.  Experimental and numerical modeling of shear behaviour of rock joints , 2000 .

[10]  Diego Mas Ivars,et al.  The synthetic rock mass approach for jointed rock mass modelling , 2011 .

[11]  Giovanni Battista Barla,et al.  A Bonded Particle Model Simulation of Shear Strength and Asperity Degradation for Rough Rock Fractures , 2012, Rock Mechanics and Rock Engineering.

[12]  J. P. Seidel,et al.  The application of energy principles to the determination of the sliding resistance of rock joints , 1995 .

[13]  Manuel J. A. Leal-Gomes,et al.  Proposal for Standardization of Pull Tests on Rock Joints , 2011 .

[14]  Giovanni Grasselli,et al.  Constitutive law for the shear strength of rock joints based on three-dimensional surface parameters , 2003 .

[15]  D. Stead,et al.  Asperity Degradation and Damage in the Direct Shear Test: A Hybrid FEM/DEM Approach , 2008 .

[16]  Melanie Hartmann,et al.  Engineering Rock Mechanics An Introduction To The Principles , 2016 .

[17]  Yuzuru Ashida,et al.  Simulation analysis of shear behavior of rock joint by distinct element method , 2005 .

[18]  Jae-Joon Song,et al.  Numerical method for the determination of contact areas of a rock joint under normal and shear loads , 2013 .

[19]  Joung-Min Oh,et al.  Three Dimensional Numerical Modeling of Excavation in Rock With Dilatant Joints , 2005 .

[20]  Ove Stephansson,et al.  Fundamentals of discrete element methods for rock engineering , 2007 .

[21]  M. S. Akram,et al.  Physical and numerical investigation of a cemented granular assembly of steel spheres , 2010 .

[22]  John Hadjigeorgiou,et al.  Stability analysis of vertical excavations in hard rock by integrating a fracture system into a PFC model , 2009 .

[23]  Fulvio Tonon,et al.  Experimental Validation of Modified Barton’s Model for Rock Fractures , 2010 .

[24]  John Hadjigeorgiou,et al.  Estimating geometrical and mechanical REV based on synthetic rock mass models at Brunswick Mine , 2010 .

[25]  G. Barla,et al.  A Laboratory Shear Cell Used for Simulation of Shear Strength and Asperity Degradation of Rough Rock Fractures , 2013, Rock Mechanics and Rock Engineering.

[26]  B. Ladanyi,et al.  Simulation Of Shear Behavior Of A Jointed Rock Mass , 1969 .

[27]  Bernard Amadei,et al.  Modelling rock joints under shear and normal loading , 1992 .

[28]  M. Bahaaddini,et al.  Numerical direct shear tests to model the shear behaviour of rock joints , 2013 .

[29]  N. Barton,et al.  The shear strength of rock joints in theory and practice , 1977 .

[30]  James D. Byerlee,et al.  Theory of Friction Based on Brittle Fracture , 1967 .

[31]  Bruce Hebblewhite,et al.  Numerical investigation of the effect of joint geometrical parameters on the mechanical properties of a non-persistent jointed rock mass under uniaxial compression , 2013 .

[32]  J. C. Jaeger.  Friction of Rocks and Stability of Rock Slopes , 1971 .

[33]  P. Cundall,et al.  A bonded-particle model for rock , 2004 .

[34]  P. A. Cundall,et al.  A Synthetic Rock Mass Model For Jointed Rock , 2007 .

[35]  J. Hadjigeorgiou,et al.  Stability Analysis of the 19A Ore Pass at Brunswick Mine Using a Two-Stage Numerical Modeling Approach , 2013, Rock Mechanics and Rock Engineering.

[36]  Giovanni Grasselli,et al.  Manuel Rocha Medal Recipient Shear Strength of Rock Joints Based on Quantified Surface Description , 2006 .

[37]  Nick Barton,et al.  An improved model for hydromechanical coupling during shearing of rock joints , 2001 .

[38]  Seungwon Lee.  Stability Around Underground Openings in Rock With Dilative, Non-Persistent and Multi-Scale Wavy Joints Using a Discrete Element Method , 2003 .