The invention discloses a shield segment dismantling process for a tunnel-first and
station-second construction method, and belongs to the technical field of
tunnel construction, and the shield segment dismantling process comprises the following steps: S1, excavating a
station foundation pit soil body to a steel support erection surface at a shield tunnel, and dismantling the upper half part of a shield segment affecting steel support erection; the steel supports at the shield tunnel are longitudinally arranged at intervals in the length direction of the shield tunnel; s2, steel supports are erected, and the soil body continues to be excavated downwards; and S3, after the
station foundation pit soil body is excavated to the bottoms of the shield segments, the remaining shield segments are sequentially dismantled from top to bottom. According to the method, only the upper half
pipe pieces locally influencing the supporting frame are removed, the whole-ring
pipe pieces which are not influenced are reserved, the remaining whole-ring
pipe pieces are used for guaranteeing overall stress, and the pipe pieces are removed after covering soil is excavated to the bottoms of the pipe pieces. Through the longitudinal integrity of the duct pieces, the safety of the foundation pit can be guaranteed when the constructed adjacent duct pieces in the station adopting the first-tunnel-later-station construction method are dismantled without additionally arranging a reinforcement measure in the duct pieces, and the investment is not increased and the construction period is not delayed.