SUPPORT STRUCTURE FOR TUNNEL HAVING ULTRA-LARGE VARIABLE SECTION

Disclosed is a support structure for a tunnel having ultra-large variable section, the support structure comprising, along an annular shape of the tunnel, a vault (11) at a top portion, an inverted arch (12) at a bottom portion, side walls (13) and pilot tunnels outside of the side walls (13) at two sides, and also comprising, along a radial direction of the tunnel, a secondary lining (2) at an inner layer; pilot tunnel primary supports (42) are disposed outside the secondary linings of the two side walls (13); a boot-type large wall footing (41) is cast between the pilot tunnel primary support (42) and the secondary lining at the two side walls; a primary support (31) is disposed, along the radial direction of the tunnel, on an outer surface of a secondary lining of the vault (11) and a secondary lining (21) of the inverted arch; an inner layer primary support (32) is disposed between the secondary lining and the primary support (31) of the vault; the primary support (31) of the vault and the inner layer pri