Study and Application on Stability Classification of Tunnel Surrounding Rock Based on Uncertainty Measure Theory

Table 1

Evaluation factors and grading standard.

Factors	Stability grade
	Stability; (I)	Relative stability; (II)	General stability; (III)	Instability; (IV)	Very instability; (V)
(1) Rock quality designation (RQD)/%	>90	75–90	50–75	25–50	<25
(2) Rock uniaxial compressive strength/MPa	>120	60–120	30–60	15–30	<15
(3) Rock mass integrity coefficient	>0.75	0.45–0.75	0.3–0.45	0.2-0.3	<0.2
(4) Strength coefficient of structural face	>0.8	0.6–0.8	0.4–0.6	0.2–0.4	<0.2
(5) Groundwater seepage (L/min·10 m)	<5	5–10	10–25	25–125	>125