Tunnel Behaviour Caused by Basement Excavation in Clay

Table 1

Parameters of London Clay in the clay hypoplastic model [36].

Parameters	Physical meaning	Values
	Control the position of the isotropic normal compression line	1.375
	Control the slope of the isotropic normal compression line	0.11
	Control the slope of the isotropic unloading line	0.016
	The critical state friction angle	22.6°
	Control the shear stiffness	0.4
	Parameter controlling the initial (very-small-strain) shear; Modulus upon 180°strain path reversal and in the initial loading
	Parameter controlling the initial shear modulus upon 90°; Strain path reversal	4.5
	The size of the elastic range (in the strain space)	4.5
	Control the rate of degradation of the stiffness with strain	0.2
	Control the rate of degradation of the stiffness with strain	6