Tunnel secondary lining with fabricated UHPC structure as bottom die and construction method of tunnel secondary lining

The invention relates to a tunnel secondary lining with a fabricated UHPC structure as a bottom die. The tunnel secondary lining comprises UHPC rib plate beam sections correspondingly assembled on a left side wall section, a right side wall section and a vault section of a tunnel pit, the fabricated UHPC structure is integrally formed to serve as the bottom die of the tunnel secondary lining, and the bottom die and a reinforcing mesh on the outer side of the secondary lining are poured into a whole. The performance of ultrahigh compressive strength, high crack resistance, impermeability, freezing and thawing resistance and high durability of UHPC is fully exerted, and the dimensional precision and quality of a prefabricated segment part can be guaranteed; the construction period can be shortened and the labor condition can be improved by adopting mechanical assembly in the tunnel; after being assembled into a ring, the formwork can be used as a dismantling-free formwork for pouring concrete and bear the dead