METHOD AND DEVICE FOR GROUND IMPROVEMENT

摘要

PROBLEM TO BE SOLVED: To sufficiently distribute an improvement material under an untreated layer without mixing the improvement material into the untreated layer when a ground under the untreated layer is improved leaving the untreated layer over an improved layer immediately below a ground surface. SOLUTION: A ground improvement device 1 comprises an extension arm 4 provided at the tip of an arm 3 of a back hoe 2 and a mixing and agitating machine 5 provided at the lower end of the extension arm 4. The mixing and agitating machine 5 includes an agitating chain 28 turning around a drive wheel 22 and guide wheels 23 and 24 and a plurality of agitating blades 29 provided on the chain 28. A lower delivery nozzle 37A delivering improvement material is provided under the mixing and agitating machine 5 near the guide wheels 23 and 24, and an upper delivery nozzle 37B delivering improvement material is provided over the mixing and agitating machine 5 near the drive wheel 22. The mixing and agitating machine 5 is moved while excavating by operating the agitating blades 29 until its upper end part 43 reaches an improved ground surface Z. Then, the improvement material is delivered from the delivery nozzles 37A and 37B by the operation of the agitating blades 29 so as to columnarly solidify the ground leaving an untreated layer over an improved layer immediately below a ground surface.