Analysis of Pipe-Roof in Tunnel Exiting Portal by the Foundation Elastic Model

Table 1

Common sizes of steel pipe for pipe-roof.

Pipe-roof diameter (mm)	Thickness (mm)	Single pipe combined stiffness (N/m^2)
70	4.5	7.8 × 10^4
76	5	1.1 × 10^5
89	5	1.9 × 10^5
108	6	4.0 × 10^5
127	7	7.7 × 10^5
159	8	1.8 × 10^6
180	8	2.7 × 10^6
219	10	5.7 × 10^6
245	10	9.0 × 10^6
273	10	1.3 × 10^7