The invention discloses a shield tunnel connection channel portal construction method based on mechanical excavation, and relates to the technical field of shield tunnel connection channel construction, and the shield tunnel connection channel portal construction method comprises the steps that a steel sleeve is installed at a connection channel portal, and portal sealing is achieved; a
glass fiber reinforced concrete pipe piece is pre-buried in the opening of the connection channel, and based on the multi-stage construction strategy, the
pipe jacking
machine entering and exiting construction task is executed in sequence; prefabricated jacking
pipe joints are adopted for channel tunneling and splicing, the size parameters of the jacking pipe joints meet the fireproof evacuation function requirement, and the jacking pipe joints are spliced in a staggered joint mode without wedge-shaped quantity; steel jacking pipe joints are arranged at the head end and the
tail end of the connecting channel, and arc-shaped
steel plates are pre-buried; and in the T-joint section where the transverse channel and the main tunnel intersect, an arc-shaped steel plate is adopted for
welding a tunnel portal connector, and an emergency grouting pipe is arranged on the arc-shaped steel plate, so that end-dividing grouting reinforcement is achieved. Reference is provided for shield tunnel connection channel mechanical method portal construction, the structural strength of a holing area is effectively improved, and the operation stability is improved.