Small-diameter center shaft driving Kelly TBM (tunnel boring machine)

The invention provides a small-diameter center shaft driving Kelly TBM (tunnel boring machine), which solves the problem that the TBM structure in the prior art cannot meet the requirements of small-diameter tunnel construction. The small-diameter center shaft driving Kelly TBM comprises a cutter disc, a shield, a steel arch installing device, a transmission shaft, an inner Kelly rack, an outer Kelly rack, a bracing shoe, a thrust cylinder, a main engine belt conveyor, a rear support, a driving box, a driving motor, a speed reducer, a main bearing, an adapter ring, a clamping oil cylinder and a clamping oil cylinder installing seat. The small-diameter center shaft driving Kelly TBM has the beneficial effects that the driving motor, the speed reducer and the driving box are backwards arranged at the tail of the inner Kelly rack, so that the length of the shield can be reduced, surrounding rocks can be timely supported, meanwhile the center of gravity of a main engine is shifted backwards, the stability of the main engine is facilitated, and the TBM is prevented from landing on the head; and the transmission shaft is located in the inner Kelly rack, and the main engine belt conveyor is arranged at the upper part of the outer Kelly rack, so that the sizes of the inner Kelly rack and the outer Kelly rack can be reduced, the operation space of the main engine area is enlarged, and the TBM structure is relatively compact so as to meet the requirements for excavation of small-diameter hard-rock channels.