Study on the Intelligent Evaluation System of Tunnel Frost Damage in Cold Regions Based on the Fuzzy Comprehensive Evaluation Model

Table 2

Membership function parameters of the positive quantitative index.

Positive quantitative index	I	II	III	IV
Air temperature outside the tunnel/°C	−5	−10	−15	−25
Driving density/(对/h)	2	4	6	8
Wind speed inside the tunnel/(m/s)	1	2	3	5
Void area length between surrounding rock and lining/m	3	5	10	20
Annual precipitation/mm	200	600	1600	2500
Blockage rate of the drainage pipe	0.2	0.5	0.8	0.9
Fracture rate of the surrounding rock	0.001	0.5	10	15