Method for installing large-tonnage ultra-wide steel box girder of cross-bank-slope cable-stayed bridge in navigation environment

The invention discloses a method for installing a large-tonnage ultra-wide steel box girder of a cross-bank-slope cable-stayed bridge in a navigation environment. Characterized in that; comprising the following steps; the method comprises the steps that 1, temporary piers A and B are constructed, and supports beside the piers are erected; 2, the guide beam is assembled, and then a beam erecting crane is assembled on the guide beam; 3, side span steel box girder incremental launching construction is carried out; 4, side span steel box girder falling construction is carried out; and 5, mid-span steel box girder single cantilever construction is carried out. The technical problems that side span beam transporting and beam hanging construction is difficult are solved, and occupation of an existing road is avoided; the technical blank of large-span, large-tonnage and ultra-wide steel box girder construction is filled up, and favorable reference is provided for construction of bridges of the same type in similar en