PROBLEM TO BE SOLVED: To provide a cast-in-place construction method according to which a stabilizing liquid in an excavated hole is maintained in a good quality condition, and adhesion of mud cake to a hole wall at excavation is prevented or suppressed.
SOLUTION: The cast-in-place construction method is comprised of the following four steps. In the first step, a rod pipe 24 of an excavator 10 is driven for rotation and lowered, and excavation is carried out by a cutter head 26 arranged on a lower end of the rod pipe. In the second step, the stabilizing liquid is supplied from a lower opening of the rod pipe into the excavated hole 28. In the third step, the stabilizing liquid is supplied from the vicinity of a hole aperture of the excavated hole 28 to the excavated hole. In the fourth step, a suction port of a slurry lifting pump 60 is arranged in the excavated hole in a range of a predetermined height from a deepest bottom of the hole, and the slurry on the bottom of the excavated hole is recovered. According to the method, the above four steps are simultaneously carried out, and thereafter ready mixed-concrete is placed in the excavated hole. Therefore, according to the method, the stabilizing liquid in the excavated hole is maintained in a good quality condition.