Numerical Simulation of the Stress Field in Repeated Mining of Coal Seams Based on In Situ Stress Measurement

Table 3

Strength estimation and measured maximum principal stress in the roof and floor.

Rock formation	Lithology	Depth (m)	σci (MPa)	σ1m (MPa)	CRP (%)	GSI	mi	σcm (MPa)	σcm/σ1m	Em (GPa)
22# coal roof	Fine sandstone	402	28.87	13.81	90	90	21	14.11	1.02	25.68
	Fine sandstone	406	22.08	11.28	90	90	21	10.79	0.96	22.46
	Fine sandstone	406	24.31	10.77	90	90	21	11.89	1.10	23.57
22# coal floor	Medium sandstone	366	87.00	14.52	55	60	18	26.66	1.84	16.59
	Medium sandstone	355	170.55	16.79	55	60	18	52.27	3.11	17.78
	Medium sandstone	365	91.19	18.61	55	60	18	27.95	1.50	16.98
42# coal roof	Siltstone	400	51.27	17.27	98	80	21	25.07	1.45	40.27
	Siltstone	400	49.04	18.31	98	80	21	23.98	1.31	39.38
	Siltstone	400	54.61	18.99	98	80	21	26.70	1.41	41.56
	Fine sandstone	510	31.87	16.54	99	80	21	15.58	0.94	31.75
	Fine sandstone	510	33.50	13.51	99	80	21	16.38	1.21	32.55
	Fine sandstone	510	59.58	15.40	99	80	21	29.13	1.89	43.41
42# coal floor	Siltstone	470	40.90	14.15	89	75	18	16.50	1.17	26.97
	Siltstone	471	35.59	12.46	89	75	18	14.35	1.15	25.16
	Siltstone	471	21.52	12.46	89	75	18	8.68	0.70	19.56
52# down coal roof	Fine sandstone	532	172.27	18.81	73	60	21	52.80	2.81	17.78
	Fine sandstone	533	95.43	14.11	73	60	21	29.25	2.07	17.37
	Fine sandstone	533	148.65	11.09	73	60	21	45.56	4.11	17.78
	Fine sandstone	590	25.33	12.43	93	90	21	12.37	1.00	24.04
	Fine sandstone	590	42.27	15.62	93	90	21	20.68	1.32	31.09
	Fine sandstone	589	58.80	15.61	93	90	21	28.75	1.84	36.65
52# down coal floor	Medium sandstone	603	62.72	15.35	65	60	21	19.22	1.25	14.08
	Medium sandstone	603	136.11	15.22	65	60	21	41.71	2.74	17.78
	Medium sandstone	606	55.08	20.55	65	60	21	16.88	0.82	13.20