| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a ground improvement device, which uses a portion of a flow channel of a multiple pipe for a flow channel of hole drilling water in drilling a hole in the ground, capable of surely switching the flow channels between when flowing the hole drilling water and when not flowing the same. <P>SOLUTION: A ground improvement device 1 comprises: an injection pipe 20 having an inner pipe flow channel 24a and an outer pipe flow channel 26a surrounding a periphery of the inner pipe flow channel 24a with a hole drilling bit 22 to drill the ground G at a lower end thereof; a lower nozzle 35 which is arranged on a side surface of a lower edge portion of the injection pipe 20 and injects a hardening material flowing in the inner pipe flow channel 24a as well as high pressure air flowing in the outer pipe flow channel 26a; a hole drilling water flow channel 29 communicating with the outer flow channel 26a to flow hole drilling water supplied to the hole drilling bit 22 when drilling the ground G; and a closing member 27 which is made of an elastic body with an inner space 27a thereof communicated with the inner flow channel 24a and closes the hole drilling water flow channel 29 by being expanded with supply of the hardening material into the inner space 27a. <P>COPYRIGHT: (C)2012,JPO&INPIT</p> |
