Research on Design Parameters and Fatigue Life of Tunnel Bottom Structure of Single-Track Ballasted Heavy-Haul Railway Tunnel with 40-Ton Axle Load

Table 1

Calculation conditions under different design parameters of tunnel foundation structure.

Influence factor	Grade of surrounding rock	Invert/floor thickness (cm)	Invert rise-span ratio
Specific parameters	II	10	1/5
	III	15	1/6
	IV	20	1/7
	V	30	1/8