Strength and Microscopic Damage Mechanism of Yellow Sandstone with Holes under Freezing and Thawing

Table 2

List of test samples for compressive strength and microscopic analysis.

	Standard yellow sandstone		The hole diameter 6 mm		The hole diameter 8 mm		The hole diameter 10 mm		The hole diameter 12 mm
	Compression strength (MPa)	Average value (MPa)	Compression strength (MPa)	Average value (MPa)	Compression strength (MPa)	Average value (MPa)	Compression strength (MPa)	Average value (MPa)	Compression strength (MPa)	Average value (MPa)
0 times	61.75	60.07	53.46	51.33	46.32	49.95	46.62	45.34	41.96	37.86
0 times	60.20▲		51.13▲		48.62▲		46.19▲		36.38▲
0 times	58.26		49.32		54.92		43.23		35.23
5 times	56.22	54.89	50.23	48.60	49.82	47.48	45.07	43.20	40.72	37.59
5 times	55.73▲		48.62▲		47.06▲		42.87▲		36.17▲
5 times	52.73		46.96		45.56		41.65		35.88
10 times	52.67	51.38	51.08	47.68	43.02	41.46	41.06	38.90	32.51	30.55
10 times	50.89▲		46.62▲		41.16▲		39.37▲		31.12▲
10 times	50.59		45.33		40.21		36.23		28.03
20 times	51.54	48.07	46.26	44.88	41.55	39.26	32.58	31.03	29.23	27.07
20 times	46.56▲		45.27▲		39.01▲		31.29▲		27.86▲
20 times	46.12		43.12		37.23		29.23		24.13
40 times	43.23	41.3	39.26	38.64	36.71	34.83	31.15	29.79	20.09	19.04
40 times	42.35▲		39.03▲		34.03▲		30.01▲		20.03▲
40 times	38.32		37.63		33.75		28.21		17.02

▲, samples selected for microscopic analysis.