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Damage Mechanisms of Coal Pillars Induced by Blasting Construction in
Highway Tunnels Underlying Room-and-Pillar Mine Goafs
(1. China Railway (Liaoning) Benxi-Huanren Expressway Co., Ltd., Benxi 117000; 2. School of Infrastructure Engineering, Dalian
University of Technology, Dalian 116024; 3. China Railway Southwest Research Institute Co., Ltd., Chengdu 611731)
Abstract To investigate damage patterns of coal pillars during blasting construction of highway tunnels underlying room-and-pillar mine goafs, this study establishes a stress wave transmission model for inclined goaf areas based on stress wave energy distribution theory, analyzing spatial distribution characteristics and evolution trends of blast-induced stress wave energy transmitted to overlying coal pillars. Comparative analysis demonstrates strong consistency in damage spatial distribution patterns among theoretical calculations, numerical simulations, and field borehole inspection results. Through 20 sets of numerical simulations under different working conditions for the Changliangzi
Tunnel on the Benxi-Huanren Expressway crossing under goafs, the results indicate: (1) Coal pillar damage modes are predominantly controlled by geostress rather than goaf dip angle. Without considering geostress, pillars exhibit shear failure with tensile failure at crowns; with increasing geostress, damage mode transitions sequentially to splitting failure and then compressive-shear failure. (2) Under constant goaf dip angles, damage extents first decrease rapidly, then stabilize, and finally increase sharply with rising geostress. At identical geostress levels, damage extents progressively reduce with increasing dip angles. (3) Dual-index analysis (internal energy evolution and damage
rate) reveals that geostress inhibits pillar damage in room-and-pillar mine goafs above the tunnel, with suppression effects intensifying at steeper dip angles. When geostress reaches 8 MPa, all pillars except No.5 demonstrate inverse growth characteristics of the damage rate.
Abstract：
To investigate damage patterns of coal pillars during blasting construction of highway tunnels underlying room-and-pillar mine goafs, this study establishes a stress wave transmission model for inclined goaf areas based on stress wave energy distribution theory, analyzing spatial distribution characteristics and evolution trends of blast-induced stress wave energy transmitted to overlying coal pillars. Comparative analysis demonstrates strong consistency in damage spatial distribution patterns among theoretical calculations, numerical simulations, and field borehole inspection results. Through 20 sets of numerical simulations under different working conditions for the Changliangzi
Tunnel on the Benxi-Huanren Expressway crossing under goafs, the results indicate: (1) Coal pillar damage modes are predominantly controlled by geostress rather than goaf dip angle. Without considering geostress, pillars exhibit shear failure with tensile failure at crowns; with increasing geostress, damage mode transitions sequentially to splitting failure and then compressive-shear failure. (2) Under constant goaf dip angles, damage extents first decrease rapidly, then stabilize, and finally increase sharply with rising geostress. At identical geostress levels, damage extents progressively reduce with increasing dip angles. (3) Dual-index analysis (internal energy evolution and damage
rate) reveals that geostress inhibits pillar damage in room-and-pillar mine goafs above the tunnel, with suppression effects intensifying at steeper dip angles. When geostress reaches 8 MPa, all pillars except No.5 demonstrate inverse growth characteristics of the damage rate.
LIU Yang1 SHAO Zekai2 TIAN Haofan2 ZHANG Ruxi1 ZHENG Bo3 WANG Zhengzheng2
.Damage Mechanisms of Coal Pillars Induced by Blasting Construction in
Highway Tunnels Underlying Room-and-Pillar Mine Goafs[J] MODERN TUNNELLING TECHNOLOGY, 2025,V62(4): 132-144
2025, Vol. 62 