Temporary steel support demolition construction method for large-section multi-pilot-tunnel tunnel

The invention discloses a temporary steel support demolition construction method for a large-section multi-pilot-tunnel tunnel. The method is divided into the demolition of a part above a middle plateand the demolition of a part under the middle part and concretely comprises the demolition of a first layer pilot tunnel, the demolition of a first transverse support, the demolition of a second vertical support and a second transverse support, the demolition of two sides of a third transverse support and a fourth transverse support and a fifth vertical support, the demolition of the third vertical support, the demolition of meshes and a section steel support in a third layer pilot tunnel, the demolition of the middle parts of the third transverse support and the fourth transverse support andthe demolition of remaining vertical and transverse supports. According to the method, the overlapping length and welding quality of a waterproof board at the connection position between a tunnel inverting arch and a side wal