Safety Risk Analysis and Protective Control of Existing Pipelines Affected by Deep Pit Excavation in Metro Construction

Table 3

Summary of pipeline reinforcement measures.

Reinforcement measures		Effect on horizontal	Effect on horizontal	Economic cost	Reinforcement effect	Optimum parameters
The soil reinforcement at passive zone in the pit	Young’s modulus Es	Great	Great	High	General	Es = 60 MPa
	RS depth/RS width	Great	General		General	When Br = 3 m, Hr/Br = 2
The soil reinforcement underneath pipeline		Weak	Great	General	General	When Br = 3 m, Hr = 9 m
The soil reinforcement between pipeline and pit		Weak	Great	General	General	When Br = 1 m, Hr = 12 m
Bracing reinforcement	Position	Great	Great	Low	Great	At the same horizontal plane of underground pipeline
	Strut diameter	General	General	Low	General	d = 0.6 m
Diaphragm wall reinforcement	Thickness	General	General	High	General	Wall thickness is 800 mm
	Depth	Weak	Weak	High	Weak	Wall depth is 37.5 m