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Geomechanics and Engineering
  Volume 23, Number 2, October25 2020, pages 93-102
DOI: http://dx.doi.org/10.12989/gae.2020.23.2.093
 


Research on the support of larger broken gateway based on the combined arch theory
Hongyun Yang, Yanbao Liu, Yong Li, Ruikai Pan, Hui Wang, Feng Luo, Haiyang Wang and Shugang Cao

 
Abstract
    The excavation broken zones (EBZ) of gateways is a significant factor in determining the stability of man-made opening. The EBZ of 55 gateways with variety geological conditions were measured using Ground Penetrating Radar (GPR). The results found that the greatly depth of EBZ, the smallest is 1.5 m and the deepest is 3.5 m. Experimental investigations were carried out in the laboratory and in the coal mine fields for applying the combined arch support theory to large EBZ. The studies found that resin bolts with high tensile strength and good bond force could provide high pretension force with bolt extensible anchorage method in the field. Furthermore, the recently invented torque amplifier could greatly improve the bolt pretension force in poor lithology. The FLAC3D numerical simulation found that the main diffusion sphere of pretension force was only in the free segment zone of the surrounding rock. Further analysis found that the initial load-bearing zone thickness of the combined arch structure in large EBZ could be expressed by the free segment length of bolt. The using of high mechanical property bolts and steel with high pretension force will clearly putting forward the bolt length selection rule based on the combined arch support theory.
 
Key Words
    large EBZ; combined arch; high pretension force; extensible anchorage; initial load-bearing zone
 
Address
Hongyun Yang: 1.) State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing, 400074, China
2.) State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

Yanbao Liu: China Coal Technology Engineering Group Chongqing Research Institute, Chongqing 400039, China

Yong Li, Ruikai Pan, Hui Wang and Shugang Cao: State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China

Feng Luo: School of Mining and Geomatics, Hebei University of Engineering, Handan, Hebei, 056038, China

Haiyang Wang: State Key Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing Jiaotong University, Chongqing, 400074, China
 

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