Rapid Assessment and Classification for Seismic Damage of Mountain Tunnel Based on Concentric Circle Method

Table 4

Discretized assessment index and description of lining damage.

Damage level	Seismic damage description	Discrete value
Extremely severe	Intensive crack or dislocation (l > 10 m,  mm); developing deformation; cracked vault lining is likely to fall; crushed vault lining range S > 3 m^2; extremely severe falling of secondary lining, even massive collapse to threaten traffic safety; inrushing groundwater	4
Severe	Crack or dislocation (5 m < l < 10 m, 5 mm <  w mm), cracked vault lining is likely to fall; crushed vault lining range 1 m^2 < S < 3 m^2; continuously inflowing groundwater	3
Moderate	Crack or dislocation (l < 5 m, 1 mm <  < 5 mm); small-scale lining peeling-off; crushed vault lining range S < 1 m^2; dripping groundwater	2
Slight	Crack or dislocation ( mm) but not further development; no crushed vault; slight seepage of groundwater	1
Undamaged	No cracks or crush; no groundwater seepage; no abnormal phenomenon	0

Note: L = length of crack,  = width of crack, and S = area of crushed range.