Development and Application of an Industry Foundation Classes-Based Metro Protection Information Model

Table 3

Division of external project influence level.

Influence	Proximity
	Very close	close	Partly close	Not close
Strong influence (A)	Superfine level	Superfine level	Level 1	Level 2
Significant influence (B)	Superfine level	Level 1	Level 2	Level 3
General influence (C)	Level 1	Level 2	Level 3	Level 4
Lower influence (D)	Level 2	Level 3	Level 4	Below level 4

Note. If there exists soft underlying layer or soft interlayer in the surrounding geologic model of the metro structure, the influence level will be raised by one level.