Rock Failure and Crack Propagation Beneath Disc Cutters

Analyses of rock failure mechanisms beneath disc cutters are presented. Full-scale cutting tests are conducted to assess the global energy input in comparison with rock chips and excavated volume. Small-scale cutting tests are subsequently used for macro- and microscopic analyses of rupture modes and crack propagation. A high spatial resolution allows to obtain pictures of crack networks in different rock types. It is shown that all specimens develop lateral cracks in sufficiently confined areas whereas median cracks typically develop in boundary regions. Regarding cutting forces, a hypothesis is proposed that associates sudden force drops accompanied by sudden sound emission with grain crushing in the proximity of the cutter tip.

[1]  Richard E. Gertsch,et al.  Rock toughness and disc cutting , 2000 .

[2]  Z. P. Bažant,et al.  Size effect on structural strength: a review , 1999 .

[4]  J. Rostami,et al.  Disc cutting tests in Colorado Red Granite: Implications for TBM performance prediction , 2007 .

[5]  Finn Ouchterlony,et al.  Suggested methods for determining the fracture toughness of rock , 1988 .

[6]  Michael V. Swain,et al.  Indentation fracture in brittle rocks and glasses , 1976 .

[7]  Timo Saksala.  3D numerical modelling of bit-rock fracture mechanisms in percussive drilling with a multiple-button bit: 3D NUMERICAL MODELLING OF BIT-ROCK FRACTURE MECHANISMS , 2013 .

[8]  J. Labuz,et al.  Indentation of rock by wedge-shaped tools , 2006 .

[9]  Hongyuan Liu,et al.  Numerical simulation of the rock fragmentation process induced by indenters , 2002 .

[10]  S. Nemat-Nasser,et al.  Brittle failure in compression: splitting faulting and brittle-ductile transition , 1986, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[11]  Observation of cracks at the bottom of percussion and diamond drill holes , 1988 .

[12]  T. Moon,et al.  A Study of Optimal Rock-Cutting Conditions for Hard Rock TBM Using the Discrete Element Method , 2011, Rock Mechanics and Rock Engineering.

[13]  Emmanuel M Detournay,et al.  Discrete element modeling of tool‐rock interaction II: rock indentation , 2013 .

[14]  Jian Zhao,et al.  Analysis and prediction of TBM performance in blocky rock conditions at the Lötschberg Base Tunnel , 2013 .

[15]  V. Hucka,et al.  Brittleness determination of rocks by different methods , 1974 .

[16]  R. Altindag,et al.  A brittleness index to estimate fracture toughness , 2004 .

[17]  Claudio Oggeri,et al.  Experimental and Numerical Studies on Rock Breaking with TBM Tools under High Stress Confinement , 2007 .

[18]  Robert Galler,et al.  Tunnel boring machine performance prediction with scaled rock cutting tests , 2014 .

[19]  A. A. Griffith.  The Phenomena of Rupture and Flow in Solids , 1921 .

[20]  A. Evans,et al.  Elastic/Plastic Indentation Damage in Ceramics: The Lateral Crack System , 1982 .

[21]  Per-Arne Lindqvist,et al.  Rock fragmentation by indentation and disc cutting : some theoretical and experimental studies , 1982 .

[22]  H. Wagner,et al.  The stamp-load bearing strength of rock an experimental and theoretical investigation , 1971 .

[23]  Soo-Ho Chang,et al.  Evaluation of cutting efficiency during TBM disc cutter excavation within a Korean granitic rock using linear-cutting-machine testing and photogrammetric measurement , 2013 .

[24]  Per-Arne Lindqvist,et al.  Indentation fracture development in rock continuously observed with a scanning electron microscope , 1984 .

[25]  Y. Nishimatsu,et al.  The mechanics of rock cutting , 1972 .

[26]  Qiuming Gong,et al.  Influence of rock brittleness on TBM penetration rate in Singapore granite , 2007 .

[27]  Gan-Yun Huang,et al.  Experimental investigation of deformation and failure mechanisms in rock under indentation by digital image correlation , 2012 .

[28]  A. Carpinteri,et al.  Numerical analysis of the cutting interaction between indenters acting on disordered materials , 2005 .

[29]  Robert Danzer,et al.  Fracture of Ceramics , 2008 .

[30]  Claudio Oggeri,et al.  Laboratory tests to study the influence of rock stress confinement on the performances of TBM discs in tunnels , 2011 .

[31]  Jamal Rostami,et al.  Study of pressure distribution within the crushed zone in the contact area between rock and disc cutters , 2013 .

[32]  Bernardino Chiaia,et al.  Fracture mechanisms induced in a brittle material by a hard cutting indenter , 2001 .

[33]  Leon Mishnaevsky,et al.  PHYSICAL MECHANISMS OF HARD ROCK FRAGMENTATION UNDER MECHANICAL LOADING: A REVIEW , 1995 .

[34]  Shaoquan Kou,et al.  In-situ Measurements of Cutter Forces on Boring Machine at Äspö Hard Rock Laboratory Part II. Characteristics of Cutter Forces and Examination of Cracks Generated , 2003 .

[35]  A. Evans,et al.  The Mechanics of Indentation Induced Lateral Cracking , 2005 .

[36]  Timo Saksala.  3D numerical modelling of bit-rock fracture mechanisms in percussive drilling with a multiple-button bit , 2013 .

[37]  M. Hood,et al.  Observations of crack growth in hard rock loaded by an indenter , 1984 .

[38]  E. Detournay,et al.  Normal Wedge Indentation in Rocks with Lateral Confinement , 1998 .

[39]  Shuting Lei,et al.  Experimental study of rock cutting under external hydrostatic pressure , 2005 .

[40]  B. Lawn,et al.  Indentation fracture: principles and applications , 1975 .

[41]  W. Goldsmith,et al.  Investigation of crack formation during loading of brittle rock , 1990 .

[42]  J. Cheatham,et al.  An Experimental Study of Single Bit-Tooth Penetration Into Dry Rock at Confining Pressures 0 to 5,000 psi , 1965 .

[43]  B. Atkinson,et al.  Fracture surface energy of olivine , 1978 .