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

Table 7

Mode II fracture toughness of Type C 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
CII0-1	0	2489.5 ± 0.01	0.272
CII0-2	0	2297.3 ± 0.01	0.251	0.255	0
CII0-3	0	2214.9 ± 0.01	0.242
CII50-1	50	2452.8 ± 0.01	0.268
CII50-2	50	2150.8 ± 0.01	0.235	0.247	−3.14
CII50-3	50	2178.3 ± 0.01	0.238
CII100-1	100	2022.7 ± 0.01	0.221
CII100-2	100	2077.6 ± 0.01	0.227	0.209	−18.04
CII100-3	100	1638.3 ± 0.01	0.179
CII200-1	200	1583.4 ± 0.01	0.173
CII200-2	200	1290.5 ± 0.01	0.141	0.150	−41.18
CII200-3	200	1244.7 ± 0.01	0.136
CII300-1	300	1052.5 ± 0.01	0.115
CII300-2	300	1080.0 ± 0.01	0.118	0.109	−57.25
CII300-3	300	860.3 ± 0.01	0.094