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Table 2 The measured stress of the composite rock-bolt bearing structure and acceleration rate of surrounding rock displacement

From: Experimental studies on the effects of bolt parameters on the bearing characteristics of reinforced rock

Distance between bolts/mm Second stage Third stage Percentage of stress decrease (%)
Kinetic pressure coefficient range Peak stress/MPa Vertical closure acceleration rate of displacement/mm/MPa Kinetic pressure coefficient range Residual sress/MPa Vertical closure acceleration rate of displacement/mm/MPa
(a) Vertical stress at Sensor 1
No bolts 0.50–1.00 0.008 14.4 1.00–1.23 0.004 25.2 50.0
1000 0.50–1.24 0.018 12.6 1.24–1.47 0.010 20.4 44.4
800 0.50–1.95 0.049 7.2 1.95–2.42 0.029 14.9 40.8
600 0.50–2.66 0.069 7.2 2.66– 2.89 0.065 14.8 5.8
Distance between bolts/mm Second stage Third stage Percentage of stress decrease (%)
Kinetic pressure coefficient range Peak stress/MPa Rib convergence closure acceleration rate of displacement/mm/MPa Kinetic pressure coefficient range Residual sress/MPa Rib convergence closure acceleration rate of displacement/mm/MPa
(b) Vertical stress at Sensor 2
No bolts 0.50–1.00 0.114 12.0 1.00––1.23 0.052 15.2 54.4
1000 0.50–1.24 0.200 7.6 1.24–1.47 0.162 14.3 19.0
800 0.50–1.71 0.505 4.4 1.71–2.42 0.452 12.7 10.5
600 0.50–2.66 0.629 3.7 2.66–2.89 0.567 10.9 9.9
Distance between bolts/mm Second stage Third stage Percentage of stress decrease (%)
Kinetic pressure coefficient range Peak stress/MPa Vertical closure acceleration rate of displacement/mm/MPa Kinetic pressure coefficient range Residual sress/MPa Vertical closure acceleration rate of displacement/mm/MPa
(c) Horizontal stress at Sensor 1
No bolts 0.50–1.00 0.060 14.4 1.00–1.23 0.012 25.2 80.0
1000 0.50–1.24 0.080 12.6 1.24–1.47 0.040 20.4 50.0
800 0.50–1.95 0.150 7.2 1.95–2.42 0.100 14.9 33.3
600 0.50–2.19 0.187 6.7 2.19–2.89 0.157 10.7 16.0
Distance between bolts/mm Second stage Third stage Percentage of stress decrease (%)
Kinetic pressure coefficient range Peak stress/MPa Rib convergence closure acceleration rate of displacement/mm/MPa Kinetic pressure coefficient range Residual sress/MPa Rib convergence closure acceleration rate of displacement/mm/MPa
(d) Horizontal stress at Sensor 2
No bolts 0.50–1.00 0.009 12.0 1.00–1.23 0.006 15.2 33.3
1000 0.50–1.24 0.027 7.6 1.24–1.47 0.019 14.3 29.6
800 0.50–1.95 0.080 5.6 1.95–2.42 0.058 13.2 27.5
600 0.50–2.66 0.095 3.7 2.66–2.89 0.082 10.9 13.7
  1. (1)The peak stress is the maximum stress in the second stage; (2) The residual stress is the minimum stress in the third stage; (3) The percentage of stress decrease is the percentage of decrease from the peak to residual stress