Longitudinal separation type steel casing sinking and pulling-out construction method

The invention relates to the technical field of building equipment, and discloses a longitudinal separation type steel casing sinking and pulling-out construction method. The construction method comprises the following steps of assembling a steel casing, sinking the steel casing, pulling out the steel casing, upwards pulling out a connecting piece from a longitudinal operation cavity through a hoisting machine so as to separate flange strips, and correspondingly taking out a left half casing and a right half casing which are separated. According to the construction method, after a fishing spear penetrates through a fishing hole in the connecting piece, the hoisting machine is used for pulling the connecting piece out of the flange strips, so that the matched flange strips are separated, the separation of the left half casing and the right half casing is realized, the separated left half casing and right half casing are respectively pulled out upwards from soil, the resistance and the influence on a concrete p