Determination of the Installation Time of Secondary Liner during Excavation of Large Cross-Section Double-Arch Tunnels

Table 5

Safety factor of controlling points of initial support of different plans.

Plan	Internal force	Controlling points
		Plan 1	N	−746.6	−652.0	−599.3	−475.1	−662.0	−792.0
M	−8.0		−128.7	−45.4	−107.6	−160.8	37.0
K	3.2		1.3	2.7	1.5	1.0	2.4
Plan 2	N	−802.1	−588.3	−573.4	−420.4	−595.1	−840.5
	M	−10.4	−137.1	−52.5	−122.7	−176.8	40.1
	K	2.9	1.2	2.5	1.3	0.9	2.3
Plan 3	N	−644.4	−604.7	−542.1	−431.1	−580.1	−698.8
	M	−6.2	−110.2	−37.0	−87.8	−132.1	30.5
	K	3.7	1.5	3.1	1.9	1.2	2.8
Plan 4	N	−700.7	−541.2	−514.0	−374.9	−512.7	−749.0
	M	−8.3	−118.6	−44.3	−103.0	−148.5	33.8
	K	3.3	1.4	2.9	1.6	1.1	2.6

N : axial force, kN; M : bending moment, kN·m; and K : safety factor.