Abstract:

The primary support deformation of unsymmetricallypressured tunnels in Funiushan area is serious. As a result, study is carried out on deformation causes, main countermeasures and construction organization. The deformation of the primary support is analyzed in terms of geophysical prospecting, drilling, test, monitoring and numerical simulation; the analytical results are compared to actual conditions; and the original design of primary support parameters is regarded as the main causes of primary support cracks. Thus countermeasures, i.e. improvement of steel frame, adding systematic anchor bolts and grouting behind primary support, are adopted based on existing primary support technology; construction organization methods, i.e. short bench, short advance, rapid ring closure and timely inverted arch lining, are used. The primary support deformation has been successfully controlled and the construction safety of the tunnel has been guaranteed by adopting abovementioned technologies.

Key words: Mawan Tunnel, unsymmetrical pressure, primary support deformation, deformation analysis, parameter optimization