Limit Drainage of Separated Tunnel Based on Ecological Groundwater Table: A Case Study

Table 1

Infiltration coefficient of precipitation in different strata.

Strata	Infiltration coefficient p
Silty clay	0.01∼0.02
Silt	0.02∼0.05
Mealy sand	0.05∼0.08
Fine sand	0.08∼0.12
Medium sand	0.12∼0.18
Coarse sand	0.18∼0.24
Round gravel (sand inclusion)	0.24∼0.30
Pebble (sand inclusion)	0.30∼0.35
Intact rock	0.01∼0.10
Relatively intact rock	0.10∼0.15
Relatively broken rock	0.15∼0.18
Broken rock	0.18∼0.20
Extremely broken rock	0.20∼0.25
Very weak karst development	0.01∼0.10
Weak karst development	0.10∼0.15
Karst medium development	0.15∼0.20
Karst development	0.20∼0.50