Duct piece dismantling method under shield first station-crossing condition

The invention belongs to the technical field of tunnel construction, and particularly relates to a duct piece dismantling method under the condition that a shield firstly passes through a station, which comprises the following specific steps of: erecting a frame body and excavating earthwork: erecting a support frame body in a shield tunnel by adopting I14 I-shaped steel, and after the support frame body is completely erected, excavating the earthwork; the segments are dismantled according to the principle that the segments are dismantled from top to bottom and are symmetrical with the center of the tunnel as the axis, dismantling operation is conducted from the two ends of a station to the middle in a combined mode through reserved holes, earthwork is excavated in a layered mode, segment assembling lines of the dismantled portions are exposed, and after excavation is completed, a walking type operation platform is arranged on the top of a middle plate; the first ring duct piece is dismantled through the adva