Tunnel hard rock advance pilot tunnel expanding excavation construction method

The invention relates to the technical field of underground tunnel construction, in particular to a construction method for tunnel hard rock. An upper step excavation working face is sequentially divided into an advanced pilot tunnel milling excavation face and an expanding excavation face from left to right, and advanced pilot tunnel and expanding excavation parallel construction is adopted. By performing zoning operation on an excavation working face, parallel operation of advance pilot tunnel excavation and primary support can be achieved, the influence time of traditional upper step support is effectively avoided, and the overall construction progress of a tunnel is guaranteed; according to the tunnel hard rock advance pilot tunnel expanding excavation construction method, the expanding excavation face is excavated through drilling and the breaking hammer, the upper step milling amount is reduced, cutting tooth consumption is reduced, the comprehensive cost is low, dust is reduced, environmental protectio