The invention provides a large arch foot bench method based on a rigid
support system, and belongs to the technical field of
tunnel engineering. The large arch foot bench method based on the rigid
support system comprises the following steps that S1, an advance support is constructed on the outer side of a tunnel primary support; s2, an upper step is excavated; s3, constructing a tunnel primary support with a large arch
springing in an upper step range; s4, lagging behind the upper step for a certain distance, and excavating a lower step; s5, a lower step primary support in the lower step range is constructed; and S6, follow-up procedures are conducted according to a normal step construction method. The method combines the advantages of a
pipe-roofing underground excavation technology, a shallow-buried underground excavation method and a large-arch-foot bench method, construction can be organized according to the conventional bench method under a rigid
support system, a large-arch-foot tunnel primary support is arranged on an upper step, the influence on the upper step during excavation of a lower step can be obviously reduced, the implementation difficulty of the construction method is greatly reduced, the
operability is high, and the construction efficiency is high. And the construction safety and the construction efficiency are guaranteed, and remarkable economic and
social benefits are achieved.