An unfavorable geological body crossing tunnel casing bridge underground structure and a construction method thereof belong to the field of
tunnel engineering. The unfavorable geological body crossingtunnel casing bridge underground structure comprises a primary lining
system, a casing bridge structure and a second lining. The construction method comprises that
pipe pieces are embedded onto steeltube arches through grooves, the
steel tube arches are connected with first-type support piles through
diameter-variable connectors, grade beams are poured on the connecting parts of the first-type support piles, the
diameter-variable connectors and the
steel tube arch to form the primary lining
system; second-type support piles are between the grade beams on both sides of an excavated section, capping beams are poured at the tops of the second-type support piles, a layer of rubber
cushion is laid on the capping piles,
box girder inverted arches are hoisted onto the rubber
cushion to form a casing bridge structure; the primary lining
system and the casing bridge structure are connected in a poured mode through the
box girder inverted arches and prefabricated reinforcing bars of the gradebeams on both sides; the second lining is poured to form the unfavorable geological body crossing tunnel bridge casing underground structure. The unfavorable geological body crossing tunnel bridge casing underground structure and construction method thereof can cross unfavorable geological bodies such as
karst caves, underground rivers and soft ground, and meanwhile, can effectively transfer surrounding
rock pressure, reduce deformation of tunnels and ensure construction safety.