Underpinning method for existing continuous bridge

The invention discloses an underpinning method for an existing continuous bridge. The method comprises the following steps: supporting the bridge by using a concrete-filled steel tube arch and a new support below the existing bridge, arranging jacks on two sides of the new support, arranging skewbacks on skewbacks of the concrete-filled steel tube arch, adopting a cast-in-situ bored pile foundation below the skewbacks, and connecting the skewbacks by a prestressed concrete straining beam, connecting the concrete-filled steel tube arches through steel webs, jacking up the existing bridge through the jacks, enabling box girders to fall onto new supports through the jacks after piers of the existing bridge are cut, and transmitting bridge loads to the skewbacks through the concrete-filled steel tube arches and finally transmitting to the pile foundations. By adopting the method for underpinning the bridge, the influence on the existing bridge in the construction process can be effectively reduced, the settlement