Relationship between Brittleness Index and Crack Initiation Stress Ratio for Different Rock Types

Table 2

Summary of mechanical parameters of gneiss samples.

No	σci (MPa)	σc (MPa)	σt (MPa)	α	σci/σc	Brittleness index
						B1	B2	B3	B4
P01	44.890	73.250	5.310	8.454	0.613	13.795	0.865	194.476	13.945
P02	41.260	68.740	6.086	6.780	0.600	11.295	0.837	209.169	14.463
P03	51.075	95.780	6.475	7.888	0.533	14.792	0.873	310.086	17.609
P04	35.250	68.130	4.343	8.117	0.517	15.689	0.880	147.928	12.163
P05	43.815	83.360	5.535	7.916	0.526	15.060	0.875	230.712	15.189
P06	40.230	79.630	5.226	7.699	0.505	15.238	0.877	208.058	14.424
P07	50.655	89.120	6.391	7.926	0.568	13.945	0.866	284.775	16.875
P08	41.625	99.600	5.551	7.499	0.418	17.943	0.894	276.439	16.626
P09	75.450	94.230	9.464	7.972	0.801	9.956	0.817	445.915	21.117
P10	44.010	72.400	5.658	7.779	0.608	12.797	0.855	204.803	14.311
P11	80.475	97.490	10.122	7.951	0.825	9.632	0.812	493.381	22.212
P12	70.725	103.530	8.769	8.066	0.683	11.807	0.844	453.908	21.305
P13	61.620	100.750	7.627	8.079	0.612	13.210	0.859	384.200	19.601