Blind area excavation device of rectangular pipe-jacking heading machine

The invention provides a blind area excavation device of a rectangular pipe-jacking tunneling machine. The problems that in the excavation process of the rectangular pipe-jacking tunneling machine, a blind area cannot be excavated synchronously, blind area residues exist, the excavation face is uneven after blind area excavation, and a blind area soil layer in a high-viscosity area cannot be effectively smashed and shoveled away are solved. The tunnel boring machine comprises a tunnel boring machine shell and a plurality of tunnel boring machine wall breaking discs connected through a chain transmission mechanism, driving chain wheels rotationally connected with a tunnel boring machine body are arranged at the four corners of the front end of the tunnel boring machine body, the four driving chain wheels are symmetrically distributed in a rectangular shape, driving chains are wound around the driving chain wheels, and the rear ends of the driving chains are attached to the front end of the tunnel boring machin