The utility model provides a subassembly is pour at tunnel slot moving die carrier's center, a serial communication port, the center is pour the subassembly and is fixed the central point who constructs (7) at M shape steel and put, it includes central gallows (1), a plurality of pneumatic cylinders (2), top lead screw (3), bottom lead screw (4) and tunnel center drainage pipe steel mould (5), a plurality of pneumatic cylinders (2) are fixed on central gallows (1), the bottom surface in central gallows (1) is fixed at tunnel center drainage pipe steel mould (5), the one end of top lead screw (3) is fixed on central gallows (1), the other end is fixed on M shape steel constructs central longeron (6) of (7), the one end of bottom lead screw (4) is fixed on central gallows (1), the other endis connected with tunnel center drainage pipe steel mould (5). The utility model discloses can appear central point that the steel constructs at M and put and once only pour a plurality of slots, reducible secondary track circuit drops into, effectively increases productivity and production efficiency.