Study on Pretightening Loss Effect of Bolt Support in Deep Soft Rock Roadway

Table 5

Calculation of pretightening force and loss of thread steel fine wire bolt.

Tightening torque (Nm)	Theoretical value (kN)	Pretightening force loss (kN)
		1#	2#	3#	4#	5#	6#	7#
100	30.34	6.94	4.04	6.94	7.44	6.44	10.34	5.84
125	37.93	9.13	4.73	7.73	10.63	8.23	13.03	5.73
150	45.52	13.82	7.52	10.42	13.82	11.42	17.72	10.02
175	53.10	20.90	8.20	13.10	20.90	16.50	20.90	9.20
200	60.69	19.19	9.49	15.29	21.19	17.29	19.19	11.89
225	68.28	21.98	12.18	18.08	21.98	23.88	23.38	15.08
250	75.86	29.56	14.86	24.66	23.16	24.66	26.56	20.26
275	83.45	31.75	18.05	29.35	32.25	26.35	30.25	25.35
300	91.03	30.03	20.23	33.43	39.43	27.13	32.93	30.53
325	98.62	34.22	20.52	37.62	34.72	31.02	34.22	35.72
350	106.21	33.51	26.71	40.31	35.41	36.91	37.41	40.31