Experimental Study on Mudstone’s Strength Characteristics in Deep-Buried Coal-Measure Formation: A Case Study of Permian Longtan Formation

Table 2

Point load test results.

Group no.	Specimen no.	W (mm)	D (mm)	D′ (mm)	P (N)	A (mm^2)	De (mm)	Is (MPa)	F	Is(50) (MPa)	Mean value (MPa)
1	1a1	45.18	16.88	14.02	260	633.35	28.40	0.32	0.78	0.25	1.82
	1a2	52.64	16.96	11.81	3210	621.62	28.13	4.06	0.77	3.13
	1a3	49.79	5.72		1410	284.80	19.04	3.89	0.65	2.52
	1a4	51.55	13.20	9.98	1530	514.47	25.59	2.34	0.74	1.73
	1a5	54.46	18.54	15.04	860	819.08	32.29	0.82	0.82	0.68
	1a6	51.50	18.62		370	958.93	34.94	0.30	0.85	0.26
	1a7	48.69	15.65	11.12	5230	541.43	26.26	7.59	0.75	5.68
	1a8	49.96	15.51	11.84	4120	591.53	27.44	5.47	0.76	4.18
	1a9	47.36	28.01		258	1326.55	41.10	0.15	0.92	0.14
2	2a1	49.32	13.74	9.09	3830	448.32	23.89	6.71	0.72	4.81	1.60
	2a2	49.44	16.33		750	807.36	32.06	0.73	0.82	0.60
	2a3	50.54	10.14	5.43	310	274.43	18.69	0.89	0.64	0.57
	2a4	47.84	23.46	19.19	390	918.05	34.19	0.33	0.84	0.28
	2a5	47.03	26.61		2910	1251.47	39.92	1.83	0.90	1.65
	2a6	48.87	20.18	13.84	2340	676.36	29.35	2.72	0.79	2.14
	2a7	51.21	15.78		1310	808.09	32.08	1.27	0.82	1.04
	2a8	53.64	16.61	11.9	3740	638.32	28.51	4.60	0.78	3.57
3	3a1	52.55	20.73	16.73	3710	879.16	33.46	3.31	0.83	2.77	1.48
	3a2	53.50	16.37	10.3	1340	551.05	26.49	1.91	0.75	1.43
	3a3	48.76	18.60	12.69	4670	618.76	28.07	5.93	0.77	4.57
	3a4	53.27	25.08		780	1336.01	41.24	0.46	0.92	0.42
	3a5	49.83	21.31		1040	1061.88	36.77	0.77	0.87	0.67
	3a6	50.15	29.54		470	1481.43	43.43	0.25	0.94	0.23
	3a7	50.62	26.61		3910	1347.00	41.41	2.28	0.92	2.09
4	4a1	48.71	28.14	22.19	4340	1080.87	37.10	3.15	0.87	2.76	2.16
	4a2	49.92	24.46	20.14	3610	1005.39	35.78	2.82	0.86	2.43
	4a3	45.52	18.72	12.98	6010	590.85	27.43	7.99	0.76	6.10
	4a4	47.12	22.68		510	1068.68	36.89	0.37	0.87	0.33
	4a5	49.28	25.53	20.65	4230	1017.63	36.00	3.26	0.86	2.82
	4a6	45.08	34.14		1530	1539.03	44.27	0.78	0.95	0.74
	4a7	47.23	25.01		5200	1181.22	38.78	3.46	0.89	3.08
	4a8	48.18	32.83	27.45	2110	1322.54	41.04	1.25	0.91	1.15
5	5a1	46.83	19.82	16.77	5170	785.34	31.62	5.17	0.81	4.21	2.58
	5a2	52.11	21.01		450	1094.73	37.33	0.32	0.88	0.28
	5a3	42.25	26.67		5230	1126.81	37.88	3.65	0.88	3.22
	5a4	52.37	29.73	25.1	3640	1314.49	40.91	2.17	0.91	1.99
	5a5	49.50	21.27	16.77	5370	830.12	32.51	5.08	0.82	4.19
	5a6	48.62	17.46	13.87	1030	674.36	29.30	1.20	0.79	0.94
6	6a1	50.32	44.45		630	2236.50	53.36	0.22	1.03	0.23	2.05
	6a2	46.54	23.13	18.49	3420	860.52	33.10	3.12	0.83	2.59
	6a3	49.40	36.38	30.86	1570	1524.48	44.06	0.81	0.94	0.76
	6a4	48.31	28.68	21.61	7510	1043.98	36.46	5.65	0.87	4.90
	6a5	48.68	29.58	24.45	4560	1190.23	38.93	3.01	0.89	2.69
	6a6	51.51	42.85		9630	2206.99	53.01	3.43	1.03	3.52
	6a7	45.75	32.92		4010	1505.93	43.79	2.09	0.94	1.97
	6a8	54.37	18.22		1120	990.62	35.51	0.89	0.86	0.76