Evaluation of the Adaptability of an EPB TBM to Tunnelling through Highly Variable Composite Strata

Table 10

Correlation between the cutterhead opening ratio and the soil layer.

Geological stratification	Soil layer	ξ (%)
Diluvium	Cohesive soil	25–30
	Sandy soil	15–20
	Gravelly soil	20–25
	Interbedding of soft and hard soil	30–35
Alluvium	Cohesive soil	20–25
	Sandy soil	10–15
	Gravelly soil	15–20
	Interbedding of soft and hard soil	20–25