Method for dismantling pier stud bent cap with upper structure reserved on viaduct

The invention relates to a method for dismantling a pier stud bent cap with an upper structure reserved on a viaduct. The method comprises the steps that A, a bridge deck is jacked; b, mounting an anti-overturning bag lifting device; c, a bent cap limiting protection device is installed; d, the pier column is separated from the bent cap; e, pier column cutting and dismantling are conducted, specifically, the pier column is divided into two half parts distributed in the transverse bridge direction to be dismantled alternately from top to bottom, and pier column cutting and dismantling specifically comprises the following steps that E1, a semi-cylinder on the inner side of the pier column is cut and dismantled for the first time; e2, cutting and removing a semi-cylinder on the outer side of the pier column for the first time; e3, the semi-cylinder on the inner side of the pier column is cut and dismantled again; e4, the semi-cylinder on the outer side of the pier column is cut and dismantled again, and the step