Layered Grouting Technology Based on a Comprehensive Water-to-Cement Ratio for the Overlying Loess Stratum of Urban Shallow Tunnels

Table 2

Orthogonal test arrangement.

Test number	Factor 1	Factor 2	Factor 3	Factor 4
	()	P (MPa)	(%)	W : C
T-1	1 (1.4)	1 (1.5)	1 (9)	1 (0.8 : 1)
T-2	1 (1.4)	2 (2.0)	2 (15)	2 (1.0 : 1)
T-3	1 (1.4)	3 (2.5)	3 (21)	3 (1.2 : 1)
T-4	2 (1.6)	1 (1.5)	2 (15)	3 (1.2 : 1)
T-5	2 (1.6)	2 (2.0)	3 (21)	1 (0.8 : 1)
T-6	2 (1.6)	3 (2.5)	1 (9)	2 (1.0 : 1)
T-7	3 (1.8)	1 (1.5)	3 (21)	2 (1.0 : 1)
T-8	3 (1.8)	2 (2.0)	1 (9)	3 (1.2 : 1)
T-9	3 (1.8)	3 (2.5)	2 (15)	1 (0.8 : 1)