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Onoda, Japan

Takeda T.,Onoda Chemico Co. | Sugiyama M.,Tokai University | Akaishi M.,Tokai University | Chang H.-W.,National Central University
Journal of GeoEngineering | Year: 2012

One-dimensional consolidation analysis is described for predicting the consolidation time curvesof clay exhibiting secondary compression during primary consolidation. The constitutive soil model isbased on the equation governing the secondary compression rate of the decrease in void ratio. This model uses four parameters, namely, Cc, C* c, Cα and c* v , that can be easily determined or assumed from incremental loading (IL) oedometric consolidation tests. In order to be certain of the correct proposed soil model, the consolidation time curves observed in oedometer specimens are compared againstthose predicted by the analysis. A satisfactory agreement between the computed behaviors and oedometer observations would indicate the correct assumption. In addition, it is shown that the void ratio rate (ės) due to secondary compression during primary consolidation varies by approximately 102~3 times as much as its final value before the application of the next loading increment. Source

Takeda T.,Onoda Chemico Co. | Sugiyama M.,Tokai University | Akaishi M.,Tokai University | Chang H.-W.,National Central University
Journal of GeoEngineering | Year: 2013

The finite difference analysis of one-dimensional consolidation of clays, exhibiting large amounts of secondary compression during primary consolidation, provide fairly good predictions of the consolidation-time curve for oedometer specimens with different heights. Some parameters including the initial rate of secondary compression defined by primary consolidation in this analysis have been assumed to avoid experimental difficulty. The trial and error calculation procedure was therefore used where the calculated consolidation-time curves fit the observed ones. Finally, it is emphasized that the assumption for unknown secondary compression behaviors during primary consolidation has a predominant influence on the consolidation-time curve. Source

Suzuki K.,Onoda Chemico Co. | Sattoh K.,Chuo University | Hara M.,Epo Column Association | Sato A.,Epo Column Association | And 3 more authors.
Zairyo/Journal of the Society of Materials Science, Japan | Year: 2010

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 D max=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. © 2010 The Society of Materials Science. Source

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