Abstract:

Yellow River Crossing Tunnel on SouthtoNorth Water Diversion Project is the first tunnel in China where composite lining consisting of primary segment lining and prestressed insitucast reinforced concrete secondary lining is adopted. The diameter of the secondary lining of the tunnel is 7 m, while the thickness thereof is 45 cm, i.e., only 1/16 of the diameter thereof. Therefore, the prestressed insitucast reinforced concrete lining of the tunnel is thinner than that in normal cases. On the other hand, one single anchor cable of the prestressed insitucast reinforced concrete lining will undertake 2 250 kN tensioning force, i.e., the prestress is higher. Under these conditions, problems, such as cracks of the anchor tool channels, insufficient elongation of steel stands and jamming of embedded corrugated pipes, may occur. In the paper, solutions for these problems are studied by means of theoretical analysis and insitu tensioning tests. The paper can provide reference for similar projects in the future.

Key words: Yellow River Crossing Tunnel on SouthtoNorth Water Diversion Project, bonded circumferential anchor, prestressing, crack, anchor cable elongation value, corrugated pipe jamming