Physical Modeling of a Shallow-Buried Metro Tunnel in the Soft Loess Layer Using Similarity Theory

Table 4

Test condition of model test.

Working conditions	Excavation methods	Pre-reinforcement measures
Working condition 1	Two-step method	No reinforcement
Working condition 2	CRD-4 method	No reinforcement
Working condition 3	CRD-4 method	WSS grouting reinforcement
Working condition 4	CRD-4 method	Prelining reinforcement
Working condition 5	CRD-6 method	No reinforcement
Working condition 6	DSDM method	WSS grouting reinforcement