Experiments of Support Structure of Twin-Bore Highway Tunnels

Similar simulation tests were made to determine the reasonable structure and principle of supporting for twin-bore highway tunnels with four driveways excavated in classⅡsurrounding rock, and in-situ testing was carried out to prove and complement the experimental result in laboratory. The research results show that because stresses in the mid-partition of twin-bore highway tunnels become very complexly in the construction process, main attention shall be paid to preventing the mid-partition from turning over during the construction. In addition, rock bolts and shotcrete, instead of steel supports, should be taken as the main preliminary supporting of twin-bore highway tunnels with four driveways excavated in classⅡsurrounding rock. Finally, the principle of supporting was put forward for twin-bore highway tunnels with four driveways excavated in classes ⅠandⅡsurrounding rocks.