2010 年 59 巻 1 号 p. 32-37
This paper describes the outline newly developed mixing machine which is equipped with a cortra-rotational mixing head. The machine is a sort of the deep mixing stabilization apparatus. That is mixing head of this machine consists of a pair of basket -like mixing wings and a flat excavating & mixing head located at the end of rotary shaft. Outer and inner wings have the same shape, but those diameters are different. The diameter of former wing is Dmax = 2.5m and it has 4 small blades inside of wing. According to the inspection of the mixed situation with the three-dimensional motion in the model ground, it is ascertained that the kneading effect of the contra-rotational mixing head is so much higher in terms of mixing quality than the flat blades mixing head. The upper and lower mixing blade were connected mutually and formed the rigid basket-like mixing wing. It is remarkably proved that the contra-rotational mixing head with high rotary torque could install to the hard sandy soil layer of N = 30∼50. In case of ground PC piles were pre-installed beforehand, it was also proved that the contra-rotational mixing head can install to the ground with obstacle such as PC piles. Existing PC piles were crushed to a large number of pieces and homogeneously-premixed. As results of the investigation in actual work in several sites with existing PC piles, it was also ascertained that the coefficient of variation of the unconfined compressive strength of stabilized soil cement columns by the contra-rotational mixing head is smaller than that by flat blade mixing head.