Mechanical Characteristics and Energy Evolution Laws for Red Bed Rock of Badong Formation under Different Stress Paths

Table 2

The mechanical parameters of b2 rocks under unloading conditions.

Specimen no.	σ3 (MPa)	(σ10/σc) (%)	σp (MPa)	σ30 (MPa)	σr (MPa)	β (°)
b2-3-1	2	90	81.6	0.122	15.142	75°01′
b2-3-2	4	95	100.432	0.500	11.261	73°30′
b2-3-3	8	80	101.662	0.252	21.223	73°
b2-3-4	16	95	206.419	5.013	51.605	73°

σ₁₀ is the axial stress when the unloading process starts; σ_c is the PS that corresponds to the loading test at the same confining pressure; σ₃₀ is the confining pressure when the rock specimen is destroyed.