To extremely effectively remove groundwater in a surface layer of the ground at a construction site, during the implementation of a deep well construction method.
A casing pipe 5 having water holes 6 is erected in a shaft 3 excavated in the ground at the construction site, and a sand filter layer 7 is formed in a gap between the outer peripheral surface of the casing pipe 5 and the inner peripheral surface of the shaft 3. Then a submersible pump 8 for pumping and draining groundwater infiltrating via the sand filter layer 7 into the casing pipe 5, is arranged at a lower end in the casing pipe 5. Further, a sealed space 15 is formed in the upper portion of the casing pipe 5, and the interior of the sealed space 15 is negatively pressurized by driving a vacuum pump 16, to thereby forcedly suck the groundwater in the surface layer of the ground at the construction site into the sealed space 15. In this manner, the groundwater is pumped and drained.
Higashio Masahiro
Torii Kazuhisa