Study on Energy Release of Surrounding Rock under the Multiple Unloading Disturbance during Tunnel Excavation

Table 3

Strength parameters of marble changing with plastic strain.

Signalment	(10^−3)	σci (MPa)	mb	s	a
Peak strength	0.00	140	3.0827	0.0357	0.50
Ductility section	1.20	90	3.0827	0.0357	0.50
Residual strength	2.30	40	3.8000	0	0.70