3D reconstruction method and connectivity rules of fracture networks generated under different mining layouts

In current research, a series of triaxial tests, which were employed to simulate three typical mining layouts (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruction techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension–shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of σ1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.

[1]  Ai Ting,et al.  Space–time evolution rules of acoustic emission location of unloaded coal sample at different loading rates , 2012 .

[2]  Brett Poulsen,et al.  Stress analysis of longwall top coal caving , 2010 .

[3]  Lg Tham,et al.  New strength criterion for rock with shear failure mode , 2001 .

[4]  Z. T. Bieniawski,et al.  Brittle fracture propagation in rock under compression , 1965 .

[5]  Hongwei Zhou,et al.  Application of fractal theory to top-coal caving , 2008 .

[6]  E. Z. Lajtai.  Brittle fracture in compression , 1974 .

[7]  Zhou Hongwei,et al.  Real-time evolution and connectivity of mined crack network , 2012 .

[8]  E. Z. Lajtai,et al.  Strength of Discontinuous Rocks in Direct Shear , 1969 .

[9]  Fan Jian-hua.  DETERMINING THREE-DIMENSIONAL CONNECTIVITY OF ROCK MASS DISCONTINUITY BY PROJECTION , 2005 .

[10]  N. Jones,et al.  Building solid models from boreholes and user-defined cross-sections , 2003 .

[11]  Heping Xie,et al.  Influence of different mining layouts on the mechanical properties of coal , 2012 .

[12]  Xiao Jian-xun.  Development of Research of Connectivity Rate of Discontinuities in Rock Mass and Application , 2006 .

[13]  Ai Ting,et al.  PRELIMINARY STUDY ON STRENGTH OF CRACKED ROCK SPECIMEN BASED ON FRACTURE MECHANICS , 2013 .

[14]  Dake Zhang.  SLIDING MODEL CONTROL BASED ON ACKERMANN'S FORMULA FOR SYSTEMS WITH BACKLASH-LIKE HYSTERESIS , 2005 .

[15]  Antonio Bobet,et al.  Modeling of Crack Initiation, Propagation and Coalescence in Uniaxial Compression , 2000 .

[16]  Hani S. Mitri,et al.  Numerical modelling of ore dilution in blasthole stoping , 2007 .

[17]  Zhang Yong,et al.  Mining-induced mechanical behavior in coal seams under different mining layouts , 2011 .

[18]  Heping Xie,et al.  Three-dimensional numerical analysis of deformation and failure during top coal caving , 1999 .