Abstract: In order to find out the relationship between liner structure deformation and the support parameters of long tunnel with large cross-section built in phillite stratum of meizo seismic area, the paper takes a dynamic deformation and inner forces field test of 5 different support types on the basis of new concept, combining with the actual three-stepped method adopted in Dujiashan tunnel of experimental section under construction, the variation of tunnel crown settlement, peripheral convergence displacement, ground surface settlement and structure inner forces under different excavation and support schemes are discussed. After analysis, some preliminary conclusions are drawn as follows. The strong strength and rigidity of scheme F5 is more suitable for thousand pieces rock tunnel construction. Then 3D elasticplastic finite element simulation of the construction process under 5 kinds of construction schemes is carried out; and the tunnel structure safety and surroundings rock stability during construction are evaluated by the comparative analyses of simulated tunnel deformation and support inner forces and those of field tested after excavation. The comprehensive analyses of field test and numerical simulation results show that there are only 2 (F4 and F5) support schemes are suitable for the tunnel excavations; and the tunnel deformation and structure inner forces are more reasonable of F5 scheme comparing to any other schemes. F5’s reasonableness and effectiveness are also certified by the successful application in practice. The above-mentioned support parameter determination technology and methods of tunnels built in soft rock can provide reference for similar projects.

Key words: phyllite tunnel, tunnel deformation, support optimization, field test, numerical simulation