JPH0615766B2 - Excavation mixing agitator used for ground improvement - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is to inject a cement-based or lime-based solidifying material or the like in-situ on soft ground having insufficient supporting force for a building and having large deformability and permeability. The present invention relates to an excavation mixing agitator for improving the ground by mixing and agitating them with earth and sand.

[Conventional technology]

In the case of such ground improvement, it is important that the soil improvement material such as cement milk and the excavated soil are mixed and stirred uniformly over the entire improved ground. From this point, the tip of the insertion rod of the pit for excavation is A method of mixing and stirring by rotating a propeller-shaped stirring blade attached to is widely adopted.

In order to increase the mixing efficiency in the mixing and stirring using the stirring blade, the number of rotations of the stirring blade is increased, the mounting angle of the stirring blade is changed, and the size and shape of the stirring blade are changed. It has been effective enough.

[Problems to be solved by the invention]

However, in the conventional one-way stirring, the mixing / stirring state causes a co-rotation phenomenon in which the ground soil and the stirring blade rotate together, resulting in poor mixing with the cement milk and the cement milk being concentrated in the peripheral area, resulting in a mixed state. It lacks uniformity and it is difficult to obtain a sufficient solidified state.

Further, as described above, the conventional measures for improving the efficiency of mixing / stirring are inevitably large in size because the drive shaft of the stirring blade needs to be large, and further, when the enlarged stirring blade is used. In clay ground, clay adheres to the blades,
There is a problem that it is not possible to create a uniform mixed soil in which the earth and sand and the improving material satisfy a predetermined mixing ratio.

[Means for solving problems]

The present invention is composed of an inner shaft that rotates in opposite directions by a drive shaft and an outer steel pipe shaft that is shorter than the inner shaft. An improvement material slurry pouring hole is provided at the tip of the inner shaft, and a bottom surface is provided near the tip. In a drilling and mixing agitator used for ground improvement, which has a lower rotary blade with a bit for excavation attached to, and an upper rotary blade attached below the outer steel pipe axis,
The lower rotary vane and the upper rotary vane are formed so that their respective elevation angles are opposite to each other, and the inner shaft and the outer steel pipe shaft respectively have joint lengths corresponding to the depth of improvement depth as joint structures. It is characterized in that the height is adjustable.

〔Example〕

1 to 4 show an embodiment of a drill mixing mixer according to the present invention.

With reference to these figures, a drill mixing mixer 10 of the present invention
Is composed of an inner shaft 2 that rotates in opposite directions by a driving device 1 and an outer steel pipe shaft 3 that surrounds the inner shaft 2, and an excavating bit 5 having an improved material slurry pouring hole 4 at the tip of the inner shaft 2. The lower rotary vane 6 is integrally provided near the tip thereof. A bit 7 for excavation is attached to the lower surface of the lower rotary vane 6. Reference numeral 8 denotes an upper rotary blade attached below the outer steel pipe shaft 3.

As shown in FIG. 2, the lower rotary blade 6 attached to the inner shaft 2 and the upper rotary blade 8 attached to the outer steel pipe shaft 3 are set so that their elevation angles are opposite to each other. . Further, the distance between the upper rotary blade 8 and the lower rotary blade 6 depends on the size and the rotational speed of the lower rotary blade 6, but it is desirable that the direct influence of the stirring state by the lower rotary blade 6 continues. .

In addition, the upper rotary blade 8 has a function of adding the improving material by the lower rotary blade 6 to create a turbulent flow in the primary mixing layer to prevent co-rotation of earth and sand. The multi-stage structure is adopted, and the elevation angle of each blade and the number of rotary blades can be arbitrarily set.

Further, the length of the mixer / stirrer used for carrying out the present invention can be arbitrarily adjusted according to the floating of the improved soil. 3 and 4 show joint structures 9 for adjusting the lengths of the inner shaft 2 and the outer steel pipe shaft 3, respectively.
9 is shown. The joint structures 9 and 9 can change the lengths of the inner shaft 2 and the outer steel pipe shaft 3 and can cope with the improved depth.

FIG. 5 shows an outline of the present invention in which the mixing / stirring machine 10 shown in FIG.

Referring to the figure, as shown in (a),
The stirrer 10 is set, and while rotating the blades 6 and 8 in opposite directions, excavation is performed from the tip by the bit 7 at the lower end of the lower rotary blade 6, and the mixing stirrer 10 is set to the soil E as shown in (b). Let's go inside. Then, as shown in (c), after excavating to the planned depth, the improving material slurry is injected from the discharge port at the tip, and the lower rotary vane 6 and the upper rotary vane 8 rotate in reverse to prevent co-rotation of earth and sand and mix. After pulling up while stirring, mixing and stirring are repeated again as shown in (d), and the mixing and stirring machine 10 is pulled up as shown in (e) to complete the work.

By forming the above-mentioned reverse rotation layer, the mixing and stirring can be achieved in a short time, more uniformly, and with relatively small power.

〔Example〕

As shown in FIG. 1 above, using an excavator mixer having a lower rotating blade having a diameter of 450 mm and two counter rotating stirring blades,
The clay ground was improved while injecting cement and water as a 1: 1 ratio improver.

The following table shows the characteristics of the soil treated according to the above procedure in comparison with the conventional method in which mixing and stirring were performed by rotating a unidirectional blade under the same conditions.

The mixing / stirring point was divided into three parts according to the depth, and the variation in improvement at each point was examined.

[Effects of the Invention] In the excavating and mixing stirrer of the present invention, the co-rotation phenomenon of excavated earth and sand is prevented by forming the mixing / stirring layers that rotate in mutually opposite directions, and the improver and the mixing agent can be uniformly mixed over the entire excavated portion Therefore, not only the improvement effect can be improved, but also the amount of the mixture improving agent to be used can be small, and the effect that the construction can be performed particularly easily on the highly viscous ground.

[Brief description of drawings]

1 to 4 show an excavation mixing stirrer according to an embodiment of the present invention, and FIG. 5 is a diagram showing a use mode of the excavation mixing stirrer of the present invention.

Claims (1)

[Claims] 1. An inner shaft that rotates in opposite directions by a drive shaft, and an outer steel pipe shaft that is shorter than the inner shaft. An improvement material slurry pouring hole is provided at the tip of the inner shaft, and the improvement material slurry pouring hole is provided near the tip. An excavation mixing agitator used for ground improvement, which has a lower rotary blade with a bit for excavation mounted on the lower surface and an upper rotary blade mounted below the outer steel pipe axis, wherein the lower rotary blade and the upper rotary blade The excavation in which the elevation angles of the respective blades are formed in opposite directions, and the inner shaft and the outer steel pipe shaft are respectively formed as joint structures so that their lengths can be adjusted according to the depth of the improved depth. Mixing stirrer.