Ground Settlements due to Construction of Triplet Tunnels with Different Construction Arrangements

Table 5

Maximum settlements resulting from different twin arrangements.

Twin tunnels arrangement	Maximum settlement (mm)
Horizontal	−88.83
Vertical (top constructed first)	−77.03
Vertical (bottom constructed first)	−81.46
Skewed (top constructed first)	−81.27
Skewed (bottom constructed first)	−82.40