Key Techniques and Risk Management for the Application of the Pile-Beam-Arch (PBA) Excavation Method: A Case Study of the Zhongjie Subway Station

Table 1

Mechanical parameter of soil layer and supporting structure.

Name	ℎ (m)	𝐸 (Mpa)	𝑐 (kPa)	𝜑 (°)	𝛾 (kN/m)	𝜇
Miscellaneous fill	6.20	7.94	5	13	20.1	0.45
Silt sand	8.8	19.8	8.8	30.7	17.36	0.28
Medium sand	6.80	27.4	21.5	30.7	18.15	0.26
Coarse sand	4.4	27.4	21.5	34.7	18.15	0.26
Gravel sand	5.9	98	1.7	36.7	20.0	0.23
Primary lining	0.3	3000	/	/	25	0.25

𝛾: total unit weight; 𝐸: Young’s modulus, which is obtained from the in situ tests; ℎ: thickness of the soil layer; 𝜇: Poisson’s ratio of the soil.