2D numerical simulation on excavation damaged zone induced by dynamic stress redistribution

The formation of an excavation damaged zone (EDZ) around an opening in a deep rock mass is associated with the dynamic stress redistribution that starts from transient release of high in situ stress to the final quasi-static stress state after the excavation. This study applies a theoretical analysis of stress redistribution due to transient unloading in surrounding rock under hydrostatic stress field, and develops a numerical elastodynamics model for finite element analysis. Coupling the theoretical and the numerical solutions, a general damage model for heterogeneous rock mass is proposed by taking the dynamic stress redistribution due to excavation into account. Finally, the dynamic stress redistribution, as well as the induced damage zone around the excavation under different lateral pressure coefficients is numerically simulated. The numerical result indicates that, the stress wave induced by the transient unloading will initially cause the damage only in the 1/3 radius vicinity of excavation perimeter. The damage zone may then develop further under the constant quasi-static far-field stress. Therefore, the EDZ development during deep excavation is closely dependent on in situ stress, rock strength and excavation method.

[1]  B. H G Brady,et al.  Rock Mechanics for underground mining: Third edition , 2006 .

[2]  Yingxin Zhou,et al.  Rock dynamics research related to cavern development for Ammunition storage , 1999 .

[3]  S. Timoshenko,et al.  Theory of elasticity , 1975 .

[4]  R. Paul Young,et al.  Acoustic emission and ultrasonic-velocity methods used to characterise the excavation disturbance associated with deep tunnels in hard rock , 1998 .

[5]  Jian Zhao,et al.  Advances in rock dynamics modelling, testing and engineering. , 2011 .

[6]  John P. Carter,et al.  SUDDEN EXCAVATION OF A LONG CIRCULAR TUNNEL IN ELASTIC GROUND , 1990 .

[7]  Chun’an Tang,et al.  Micromechanical Model for Simulating the Fracture Process of Rock , 2004 .

[8]  Peng Yan,et al.  Dynamic response of rock mass induced by the transient release of in-situ stress , 2012 .

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

[10]  S. Suknev.  Formation of tensile fractures in the stress concentration zone in gypsum , 2008 .

[11]  O. T. Bruhns,et al.  Simulating excavation damaged zone around a circular opening under hydromechanical conditions , 2008 .

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

[13]  Ming Cai,et al.  Influence of stress path on tunnel excavation response – Numerical tool selection and modeling strategy , 2008 .

[14]  R. S. Read,et al.  20 years of excavation response studies at AECL's Underground Research Laboratory , 2004 .

[15]  Wancheng Zhu,et al.  Numerical modeling on destress blasting in coal seam for enhancing gas drainage , 2013 .

[16]  V. Hajiabdolmajid,et al.  Modelling brittle failure of rock , 2002 .

[17]  Julius Miklowitz,et al.  Plane-Stress Unloading Waves Emanating From a Suddenly Punched Hole in a Stretched Elastic Plate , 1960 .

[18]  P. K. Kaiser,et al.  Quantification of rock mass damage in underground excavations from microseismic event monitoring , 2001 .

[19]  E. T. Brown,et al.  Rock Mechanics: For Underground Mining , 1985 .

[20]  N. Chandler,et al.  Excavation-induced damage studies at the Underground Research Laboratory , 2004 .

[21]  G. Bäckblom,et al.  Recent experiments in hard rocks to study the excavation response: Implications for the performance of a nuclear waste geological repository , 1999 .

[22]  E. Z. Lajtai.  Microscopic Fracture Processes in a Granite , 1998 .

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

[24]  Kun Du,et al.  Failure characteristics of high stress rock induced by impact disturbance under confining pressure unloading , 2012 .

[25]  M. A. Kayupov,et al.  Studies of the effect of dynamic processes during explosive break-out upon the roof of mining excavations , 1988 .