ANCHOR DEVICE FOR PIPE BODY AND METHOD FOR PREVENTING PIPE BODY FROM BEING PULLED OUT

PROBLEM TO BE SOLVED: To provide an anchor device for a pipe body and a method for preventing the pipe body from being pulled out capable of more reliably preventing the pipe body inserted in a casing rod from being pulled out together with the casing rod when the casing rod is pulled out from the ground.SOLUTION: After inserting an outer pipe 15 into a casing rod installed in a borehole, water W is supplied into a cylinder 6 attached at a tip of the outer pipe 15 through a water injection pipe 12a which is connected to a back end of the cylinder 6. A piston 7 and a pressing member 3 are pushed forward by water pressure of the water W so that opening/closing blades 2 are opened toward a circumference direction of the cylinder 6 at the tip of the casing rod in the ground. When the piston 7 reaches to a prescribed position in the cylinder 6, the water W inside the cylinder 6 is flown outside through an enlarged diameter part 6a of the cylinder 6. After detecting a reduction in the water pressure inside the cylinder 6 due to outflow of water W by a water pressure sensor, the casing rod is pulled out to the ground.