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

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Table 3 The measured stress of the composite rock-bolt bearing structure and acceleration rate of surrounding rock displacement

Bolt length/mm	Second stage			Third stage
Bolt length/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
(a) Vertical stress at Sensor 1
No bolts	0.50–1.00	0.008	14.4	1.00–1.23	0.004	25.2
1600	0.50–1.47	0.019	8.5	1.47–1.95	0.018	15.0
1800	0.50–1.95	0.049	7.2	1.95–2.42	0.029	14.9
2000	0.50–1.95	0.062	6.8	1.95–2.58	0.057	10.8
2400	0.50–2.35	0.072	6.8	2.35–2.70	0.065	10.2

Bolt length/mm	Second stage			Third stage
Bolt length/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
(b) Vertical stress at Sensor 2
No bolts	0.50–1.00	0.114	12.0	1.00–1.23	0.052	15.2
1600	0.50–1.71	0.461	6.7	1.71–1.95	0.353	14.6
1800	0.50–1.71	0.505	4.4	1.71–2.42	0.452	12.7
2000	0.50–1.95	0.530	4.3	1.95–2.58	0.364	9.5
2400	0.50–1.95	0.536	4.3	1.95–2.70	0.365	6.8

Bolt length/mm	Second stage			Third stage
Bolt length/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
(c) Horizontal stress at Sensor 1
No bolts	0.50–1.00	0.060	14.4	1.00–1.23	0.012	25.2
1600	0.50–1.71	0.111	9.6	1.71–1.95	0.090	15.8
1800	0.50–1.95	0.150	7.2	1.95–2.42	0.100	14.9
2000	0.50–2.35	0.150	7.0	2.35–2.58	0.126	12.2
2400	0.50–2.35	0.152	6.8	2.35–2.70	0.133	10.2

Bolt length/mm	Second stage			Third stage
Bolt length/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
(d) Horizontal stress at Sensor 2
No bolts	0.50–1.00	0.009	12.0	1.00–1.23	0.006	15.2
1600	0.50–1.71	0.024	6.7	1.71–1.95	0.022	14.6
1800	0.50–1.95	0.080	5.6	1.95–2.42	0.058	13.2
2000	0.50–1.95	0.080	4.3	1.95–2.58	0.064	9.5
2400	0.50–2.35	0.086	4.3	2.35–2.70	0.075	8.9