Optimization Analysis of Deformation of Underlying Tunnel in Dewatering and Excavation of Phreatic Aquifer

Table 1

Physical performance parameters of rock and soil mass.

Layer	Soil type	Thickness (m)	Density (g·m^−3)	Compressive modulus (MPa)	Cohesion (KPa)	Internal friction (°)	Poisson ratio
①	Miscellaneous fill	3.93	1.76	4.12	—	—	0.38
②1	Silty fine sand	5.87	1.94	13.55	8	31.5	0.3
②2	Silty fine sand	4.93	1.93	15.02	6	32	0.28
③	Pebble	>50	2.2	19.3	10	41	0.18