Viscoelastic Boundary Conditions for Multiple Excitation Sources in the Time Domain

Table 1

Parameters of the subway station and surrounding soil.

Boundary		Left	Right	Front	Back	Bottom
Input in the x direction	Stress term	z+	z-	x+	x+	x+
	Velocity and displacement term	x+	x+	-	-	x+
Input in the y direction	Stress term	z+	z-	-	-	y+
	Velocity and displacement term	y+	y+	-	-	y+
Input in the z direction	Stress term	x-	x+	y-	y+	z-
	Velocity and displacement term	z-	z-	z-	z-	z-

The letter “x+” in the table means that the corresponding term is in the positive x direction and other letters follow the same rule. The minus signs “-” means that there are no corresponding terms for these boundaries. Stress, velocity, and displacement terms are the third, second, and first term in (26), respectively.