Experimental simulation investigation on rockburst induced by spalling failure in deep circular tunnels

Abstract Spalling and rockburst are two common failure modes in deep hard-rock tunnels and they exhibit a strong correlation. In this paper, the process of rockburst induced by spalling is investigated. The uniaxial compressive strength and rockburst tendency of red sandstone are measured. Four different initial stress conditions are set up, and cubic red sandstone samples with a prefabricated hole are tested by a true-triaxial test system. During the experimental process, the failure of the hole sidewall is monitored and recorded in real time by a micro-camera. The process of rockburst induced by spalling damage in deep hard-rock tunnels is reproduced, and the mechanism by which spalling damage on induces rockburst is revealed. In addition, the evolution process and failure characteristics of rockburst induced by spalling damage are analysed. The experimental results indicated that the red sandstone has a moderate rockburst tendency, and its rockburst process can be divided into four periods: the calm period, the small grain ejection & spalling damage period, the slab buckling & fragment ejection period and the violent ejection period. The mechanism of spalling damage on inducing rockburst is mainly embodied in two aspects: promoting large buckling deformations (providing energy for rockburst) and to weakening the strength of the rock mass (creating conditions for the suddenly release of energy). The effect of lateral stress on spalling damage and rockburst is more obvious than that of axial stress, and the severity of rockburst can be significantly reduced by increasing the lateral stress. The diameter of the hole has a strength size effect on the sidewall damage, producing a certain inhibitory effect on the spalling damage and rockburst. Smaller lateral stress corresponds with greater depths of the V-shaped notch and much smaller width-to-length ratios in the rock fragments.

[1]  C. Martin,et al.  Seventeenth Canadian Geotechnical Colloquium: The effect of cohesion loss and stress path on brittle rock strength , 1997 .

[2]  B. H. Brady,et al.  Simulation of progressive fracturing processes around underground excavations under biaxial compression , 2005 .

[3]  Chuanqing Zhang,et al.  Case Histories of Four Extremely Intense Rockbursts in Deep Tunnels , 2012, Rock Mechanics and Rock Engineering.

[4]  Xia-Ting Feng,et al.  Estimation of in situ stress along deep tunnels buried in complex geological conditions , 2012 .

[5]  C. Dowding,et al.  Potential for rock bursting and slabbing in deep caverns , 1986 .

[6]  QiuShili,et al.  Estimation of rockburst wall-rock velocity invoked by slab flexure sources in deep tunnels , 2014 .

[7]  B. Haimson,et al.  Borehole breakouts and in-situ stress in sandstones , 2006 .

[8]  Arcady Dyskin,et al.  Mechanisms of brittle fracture of rock with pre-existing cracks in compression , 1994 .

[9]  Shili Qiu,et al.  Layered fractures induced by principal stress axes rotation in hard rock during tunnelling , 2011 .

[10]  Wancheng Zhu,et al.  Numerical simulation on rockburst of underground opening triggered by dynamic disturbance , 2010 .

[11]  C. D. Martin,et al.  Estimating the potential for spalling around a deep nuclear waste repository in crystalline rock , 2009 .

[12]  Ming Cai,et al.  Influence of Unloading Rate on the Strainburst Characteristics of Beishan Granite Under True-Triaxial Unloading Conditions , 2014, Rock Mechanics and Rock Engineering.

[13]  Wang Chunguang,et al.  EXPERIMENTAL STUDY ON ROCKBURST PROCESSES OF GRANITE SPECIMEN AT GREAT DEPTH , 2007 .

[14]  E. Hoek,et al.  Fracture initiation and propagation in intact rock – A review , 2014 .

[15]  Wu Shiyong,et al.  EXPERIMENTAL STUDY OF SLABBING FAILURE FOR DEEPBURIED MARBLE AT JINPING II HYDROPOWER STATION AND ITS INFLUENCES ON TBM EXCAVATION , 2010 .

[16]  P. K. Kaiser,et al.  Hoek-Brown parameters for predicting the depth of brittle failure around tunnels , 1999 .

[17]  T. R. Stacey,et al.  ROCKBURST MECHANISMS IN TUNNELS AND SHAFTS , 1994 .

[18]  Xibing Li,et al.  Experimental Study of Slabbing and Rockburst Induced by True-Triaxial Unloading and Local Dynamic Disturbance , 2016, Rock Mechanics and Rock Engineering.

[19]  C. Martin.  Brittle Rock Strength Failure: Laboratory And In Situ , 1995 .

[20]  Estimation of In-situ Compressive Strength of Rocks From In-situ Rock Stress Measurements In Highly Stressed Rock Structures , 1991 .

[21]  Mark S. Diederichs,et al.  The 2003 Canadian Geotechnical Colloquium: Mechanistic interpretation and practical application of damage and spalling prediction criteria for deep tunnelling , 2007 .

[22]  A. Dyskin,et al.  Crack growth under biaxial compression , 2002 .

[23]  M. Cai,et al.  Influence of intermediate principal stress on rock fracturing and strength near excavation boundaries : Insight from numerical modeling , 2008 .

[24]  T. R. Stacey.  A simple extension strain criterion for fracture of brittle rock , 1981 .

[25]  P. K. Kaiser,et al.  Support of underground excavations in hard rock , 1995 .

[26]  P. K. Kaiser,et al.  An interpretation of ground movements recorded during construction of the Donkin-Morien tunnel , 1991 .

[27]  Jimin Wang,et al.  Preliminary engineering application of microseismic monitoring technique to rockburst prediction in tunneling of Jinping II project , 2010 .

[28]  Chun’an Tang,et al.  Morphologic Interpretation of Rock Failure Mechanisms Under Uniaxial Compression Based on 3D Multiscale High-resolution Numerical Modeling , 2015, Rock Mechanics and Rock Engineering.

[29]  C. D. Martin,et al.  The strength of hard-rock pillars , 2000 .

[30]  A. Kidybiński,et al.  Bursting liability indices of coal , 1981 .

[31]  Hou Zhe-sheng,et al.  PRIMARY FAILURE TYPES AND THEIR FAILURE MECHANISMS OF DEEP BURIED AND INTACT MARBLE AT JINPING II HYDROPOWER STATION , 2011 .

[32]  A. Mazaira,et al.  Intense rockburst impacts in deep underground construction and their prevention1 , 2015 .

[33]  B. J. Carter.  Size and stress gradient effects on fracture around cavities , 1992 .

[34]  Ming Cai,et al.  Assessment of excavation damaged zone using a micromechanics model , 2005 .

[35]  Mark S. Diederichs,et al.  Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation , 2004 .