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

Table 4

Mode I fracture toughness of the Type C mudstone specimens for different soaking times.

Specimen number	Soaking time t (minutes)	Peak load Pcr (N)	Mode I fracture toughness KIc (MPa m^0.5)		Degradation degree (%)
			Test value	Average value
CI0-1	0	1711.8 ± 0.01	0.791
CI0-2	0	1487.6 ± 0.01	0.687	0.730	0
CI0-3	0	1540.2 ± 0.01	0.712
CI50-1	50	1329.2 ± 0.01	0.614
CI50-2	50	1289.0 ± 0.01	0.596	0.640	−13.33
CI50-3	50	1537.0 ± 0.01	0.710
CI100-1	100	1077.5 ± 0.01	0.498
CI100-2	100	1187.6 ± 0.01	0.548	0.508	−30.41
CI100-3	100	1033.6 ± 0.01	0.478
CI200-1	200	749.0 ± 0.01	0.346
CI200-2	200	670.0 ± 0.01	0.310	0.315	−56.85
CI200-3	200	625.9 ± 0.01	0.289
CI300-1	300	474.8 ± 0.01	0.219
CI300-2	300	501.2 ± 0.01	0.232	0.214	−70.68
CI300-3	300	413.3 ± 0.01	0.191