Experimental Evaluation of the Influences of Water on the Fracture Toughness of Mudstones with Bedding

Table 6

Mode II fracture toughness of Type B mudstone specimens for different soaking times.

Specimen number	Soaking time t (minutes)	Peak load Pcr (N)	Mode II fracture toughness KIIc (MPa m^0.5)		Degradation degree (%)
			Test value	Average value
BII0-1	0	2301.4 ± 0.01	0.251
BII0-2	0	2011.5 ± 0.01	0.222	0.269	0
BII0-3	0	3047.4 ± 0.01	0.334
BII50-1	50	2196.6 ± 0.01	0.240
BII50-2	50	2084.8 ± 0.01	0.228	0.255	−5.21
BII50-3	50	2719.2 ± 0.01	0.297
BII100-1	100	2394.8 ± 0.01	0.261
BII100-2	100	1812.2 ± 0.01	0.199	0.224	−16.73
BII100-3	100	1947.0 ± 0.01	0.212
BII200-1	200	2180.5 ± 0.01	0.238
BII200-2	200	2304.5 ± 0.01	0.243	0.203	−24.54
BII200-3	200	1177.5 ± 0.01	0.128
BII300-1	300	1885.4 ± 0.01	0.206
BII300-2	300	1912.9 ± 0.01	0.209	0.191	−29.00
BII300-3	300	1446.1 ± 0.01	0.158