Experimental Study of Size Effects on the Deformation Strength and Failure Characteristics of Hard Rocks under True Triaxial Compression

Table 2

Test scheme and results of the size effect for two rocks under TTC.

Rock type	Size (mm^3)	σ3 (MPa)	σ2 (MPa)	σcd (MPa)	σp (MPa)	σcd/σp	ɛ3p (%)	ɛ2p (%)	θ (°)	A	Failure mode
BS granite	SL	5	5	144	202	0.71	−0.452	−0.452	74	201.82	Shear
			30	186	268	0.69	−0.512	−0.080	79	270.33	Shear
			60	193	295	0.65	−0.493	−0.006	80	294.79	Tension-shear
			90	197	308	0.64	−0.577	0.061	80	305.97	Tension-shear
	SM	5	5	150	203	0.74	−0.438	−0.438	73	201.82	Shear
			30	190	285	0.67	−0.602	−0.143	77	270.33	Shear
			60	205	300	0.68	−0.501	−0.006	81	294.79	Tension-shear
			90	204	313	0.65	−0.589	0.106	81	305.97	Tension-shear
	SS	5	5	151	205	0.74	−0.453	−0.453	72	201.82	Shear
			30	200	292	0.69	−0.718	−0.163	78	270.33	Shear
			60	212	311	0.68	−0.612	0.021	82	294.79	Tension-shear
			90	211	325	0.65	−0.608	0.052	81	305.97	Tension-shear
BHT basalt	SL	5	5	250	250	1.00	−0.168	−0.168	74	247.94	Tension-shear
			30	278	282	0.99	−0.185	−0.023	78	277.89	Tension-shear
			60	324	324	1.00	−0.186	0.010	78	318.65	Tension-shear
			90	341	350	0.97	−0.270	0.030	80	346.57	Tension-shear
	SM	5	5	261	261	1.00	−0.119	−0.119	75	265.25	Tension-shear
			30	286	296	0.97	−0.202	−0.100	79	277.89	Tension-shear
			60	339	339	1.00	−0.224	−0.019	79	318.65	Tension-shear
			90	353	358	0.99	−0.230	0.028	80	346.57	Tension-shear
	SS	5	5	274	284	0.96	−0.165	−0.165	75	265.25	Tension-shear
			30	329	334	0.99	−0.218	−0.073	78	277.89	Tension-shear
			60	362	366	0.99	−0.233	−0.032	80	318.65	Tension-shear
			90	367	386	0.95	−0.302	−0.029	88	346.57	Tension-shear