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

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Table 5 The measured stress of the composite rock-bolt bearing structure and acceleration rate of surrounding rock displacement

Bolt diameter/mm	Second stage			Third stage			Percentage of stress decrease (%)
Bolt diameter/mm	Kinetic pressure coefficient range	Peak stress/MPa	Vertical closure acceleration rate of displacement/mm/MPa	Kinetic pressure coefficient range	Residual stress/MPa	Vertical closure acceleration rate of displacement/mm/MPa	Percentage of stress decrease (%)
(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
18	0.50–1.47	0.019	9.6	1.47–1.95	0.018	15.8	18.2
30	0.50–2.13	0.048	4.8	2.13–2.80	0.043	10.7	10.4

Bolt diameter/mm	Second stage			Third stage			Percentage of stress decrease (%)
Bolt diameter/mm	Kinetic pressure coefficient range	Peak stress/MPa	Rib convergence closure acceleration rate of displacement/mm/MPa	Kinetic pressure coefficient range	Residual stress/MPa	Rib convergence closure acceleration rate of displacement/mm/MPa	Percentage of stress decrease (%)
(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
18	0.50–1.71	0.461	6.7	1.71–1.95	0.353	14.6	23.4
30	0.50–2.35	0.622	3.9	2.35–2.80	0.587	10.6	5.6

Bolt diameter/mm	Second stage			Third stage			Percentage of stress decrease (%)
Bolt diameter/mm	Kinetic pressure coefficient range	Peak stress/MPa	Vertical closure acceleration rate of displacement/mm/MPa	Kinetic pressure coefficient range	Residual stress/MPa	Vertical closure acceleration rate of displacement/mm/MPa	Percentage of stress decrease (%)
(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
18	0.50–1.71	0.111	9.6	1.71–1.95	0.090	15.8	18.9
30	0.50–2.13	0.148	4.8	2.13–2.80	0.128	10.7	13.5

Bolt diameter/mm	Second stage			Third stage			Percentage of stress decrease (%)
Bolt diameter/mm	Kinetic pressure coefficient range	Peak stress/MPa	Rib convergence closure acceleration rate of displacement/mm/MPa	Kinetic pressure coefficient range	Residual stress/MPa	Rib convergence closure acceleration rate of displacement/mm/MPa	Percentage of stress decrease (%)
(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
18	0.50–1.71	0.024	6.7	1.71–1.95	0.022	14.6	8.3
30	0.50–2.13	0.058	3.9	2.13–2.80	0.056	10.6	3.4