Water pressure test in the design of the tunnel in Yellow River crossing project of the mid-route of South-to-north water transfer project

Abstract

Yellow River crossing project of the mid-route of South-to-north water transfer project is the largest, the most complex and important, the symbolization of time limit for a project and the key project of the mid-route. Yellow River crossing project is the main part of the project, it is also the most difficult part of the project, the tunnels in Yellow River crossing project are double layout, located at the bottom of the Yellow River 40 m deep, 4.25 km long. Insidediameter of the tunnels is 7 m, outside diameter is 8.7 m. The tunnels not only need to bear external water pressure, earth pressure, but also take the internal water pressure of greater than 0.5 MPa, so, these tunnels are large pressure hydraulic tunnel. In order to ensure the seepage-proofing of the tunnel is effective, the water pressure test is essential in checking the water tightness of tunnel lining seams, and studying the permeability characteristics of the seepage control material within the fracture effect and the design for seepage control.