Abstract: To investigate the advantages of earth pressure balance(EPB)/tunnel boring machine(TBM) dualmode shield tunneling in complex strata such as soil, soilrock combination strata, and longdistance hard rock, and the regularity of tunneling parameters and cutter consumption in various strata under dual modes, a case study is conducted on leftline excavation in the HuaideFuyong section of the Shenzhen metro. Then, the construction parameters from shield launching to mode conversion and construction completion period of tunnel excavation are collected, the parameter variations and tunneling efficiency of shield tunneling in different strata under the same mode and those in same strata under different mode are comparatively examined, and the parameter factor affecting construction efficiency is analyzed. It is concluded that: (1) Under EPB mode, the influence of soil pressure and cutter rotation speed on excavation parameters is significant. In soft soil layer, to guarantee the ground deformation within the design range, the soil pressure should be lowered as far as possible; in rock formation, the height of muck accumulation should be minimized, and the cutter rotation speed should be increased so as to improve the construction efficiency. (2) Under TBM mode, the excavation parameters are mainly affected by the degree of joint development of rock mass. The main parameters such as rotation speed and penetration degree should be adjusted in time to improve the construction efficiency. The cutting tool consumption locations and causes are analyzed when tunneling in hard rock formation with different geologies and modes, and the suggestion of reducing secondary abrasion of disc cutter induced by residue in the soil chamber is proposed to reduce the cutting tool consumption in fullface hard rock formation.

Key words: doublemode shield, earth pressure balance, tunnel boring machine, construction efficiency, tool consumption, driving performance