Effect of Subway Excavation with Different Support Pressures on Existing Utility Tunnel in Xi’an Loess

Table 4

Parameters of structures of metro tunnel.

Subject	(kN/m^3)	(MPa)		Layer (m)
Shield	463.84	2.10E + 05	0.30	0.04
Segment	25	2.84E + 04	0.20	0.3
Grouting (early)	23	0.9	0.30	—
Grouting (late)	23	400	0.2	—

“—” means that the grouting layer completely fills the gap at the shield tail, without a fixed thickness.