Mechanical and Deformation Characteristics and Optimization of Support Parameters for Superlarge-Span Tunnel: A Case Study from Laohushan Tunnel

Table 10

Internal force and safety factor of primary support under parameter 3.

Monitoring point	Position	Shotcrete axial force (kN)	Axial force of steel rib (kN)	Steel rib bending moment (kN·m)	Shotcrete safety factor	Steel rib tensile safety factor	Steel rib compression safety factor
0	Crown	510.9	111.4	−7.5	8.7	2.6	1.9
1	Crown deviated left 30°	1462.7	319.0	−3.9	3.3	19.2	2.5
2	Crown deviated right 30°	851.8	185.8	−2.2	5.4	39.7	4.3
3	Left haunch 60°	1845.0	402.3	−0.8	2.7		3.7
4	Right haunch 60°	1073.2	234.0	1.8	4.4		4.2
5	Left skewback	1356.7	295.8	−2.1	3.5		3.5
6	Right skewback foot	783.6	170.9	−4.5	5.8	5.8	2.8
7	Left side wall	189.8	41.4	0.4	22.8		22.8
8	Right side wall	16.1	3.5	0.4	265.4	46.8	39.5