Risk Assessment of Shield Tunnel Construction in Karst Strata Based on Fuzzy Analytic Hierarchy Process and Cloud Model

Table 2

The risk level criteria.

Risk level	Risk acceptance criteria	Value	Standard cloud numerical characteristics
I	Negligible risk	[0, 0.25)	(0.125, 0.042, 0.01)
II	Strengthen monitoring and management	[0.25, 0.50)	(0.375, 0.042, 0.01)
III	Take measures to reduce risk	[0.50, 0.75)	(0.625, 0.042, 0.01)
IV	Unacceptable risk, rework the construction scheme	[0.75, 1)	(0.875, 0.042, 0.01)