Abstract:

The project of pedestrian passageway on South Renmin Road crossing underneath Sichuan University in Chengdu is taken as an example to explore the adaptability of rectangular pipe jacking machine in sandy cobble strata. The key technologies of cutting and mucking system of the rectangular pipe jacking machine used in sandy cobble strata, i.e. composite cutterhead arrangement, resistance reduction of lower cutterhead, installation position of screw blades and structural form of gate, are studied. The study results show that: (1) The coplanar cutterhead arrangement adopted can decrease the phenomenon of cobble jamming induced by front and back cutterhead arrangement and avoid the shock of cobble to cutterhead, which shows superior adaptability to sandy cobble strata. (2) The fully and locally cutting of the big annulus of lower cutterhead is used to carry out structural improvement which can reduce the cutting torque by approximately 20%. (3) The mucking capacity of the screw conveyor can be improved by 3 times and the arc sealing gate can effectively seal the muck by designing a belttype doublescrew conveyor whose blades can stretch into soil chamber.

Key words: sandy cobble strata, rectangular pipe jacking machine, coplanar cutterhead arrangement, belttype doublescrew conveyor, mucking system