Effects of Construction Sequences and Volume Loss on Perpendicularly Crossing Tunnels

Table 1

Numerical analysis program.

Case	Description	C/D new tunnel	C/D existing tunnel
S1-gf	S1 (greenfield, i.e., without existing tunnel)	8.5	N/A
S2-gf	S2 (greenfield, i.e., without existing tunnel)	10.5	N/A
S1-vl	S1 (only volume loss, i.e., without weight loss)	8.5	10.5
S2-vl	S2 (only volume loss, i.e., without weight loss)	10.5	8.5
S1	New tunnel above existing tunnel	8.5	10.5
S2	New tunnel beneath existing tunnel	10.5	8.5