Theoretical Study on Internal Forces of Primary Support of Tunnel by considering Time Effect

Table 3

Surrounding rock pressure.

Measuring point	Position θ (rad)	Surrounding rock pressure P (t) (kPa)
1	0.09	89.05 (exp (−0.001123t) − exp (−3.328t))
2	0.61	43.51 (exp (−0.01061t) − exp (−0.6016t))
3	0.50	20.15 (exp (−0.00316t) − exp (−0.5015t))