A Scale Model Test on Hydraulic Resistance of Tunnel Elements during Floating Transportation

The transportation of tunnel elements is one of the most important procedures of immersed tunnel construction. To investigate the hydraulic resistance of tunnel elements during transportation, hydrodynamic scale model tests of the were carried out in a towing tank for the tunnel element transportation under wave action. The test results show that the hydraulic resistance is linear to the square of towing speed basically. The drag coefficients of the element under different water depths and dragging angles are calculated. The dragging coefficient decreases with the increase of water depth, and increases with the increase of the dragging angle. Finally, the influence of the wave is also discussed for the tunnel dragged in the open sea.