Multi-Rods Type Apparatus for Ground Improvement

This invention relates to a multi-rods type apparatus for ground improvement.

For the ground improvement work wherein a solidifixing agent is injected to be mixed with soil by means of agitating, a multi-rods type ground improvement apparatus is conventionally used, wherein excavation blades are fixed respectively to each end portion of plural rods, plural steps of agitating blades are fixed to the rods above the upperside of the excavation blades and the rods are connected with a link arm so as to be held at a spaced interval and to prevent rotation of the axes of the rods.

However, in a case where the aforementioned apparatus is used for a soil layer such as silt and mud which are sticky, there will occur such a phenomon that the dug soil deposited by the excavation blades rotates in coincident with the agitating blades, namely a corotating phenomenon, due to the viscosity of the soil. Therefore it is impossible to fully crush the clods and to get the soil well mixed with the solidifying agent for obtaining a good quality of ground.

This invention achieves solving of the above described defects, and provides a first multi-rods type of ground improvement apparatus and a second multi-rods type of ground improvement apparatus which prevent dug soil from corotating, to obtain a good quality of ground improvement.

In a first multi-rods type of ground improvement apparatus according to this invention, wherein excavation blades are fixed and injection openings for a solidifying agent are provided on each end portion of plural rods, plural steps of agitating blades are fixed to the rods above the upperside of the excavation blades and the injection openings, and at least one link arm is loosely mounted to connect the rods, said improvement is characterized in that a stationary corotating prevention wing is loosely mounted and connected to each rod between the excavating blade and the lowest positioned agitating blade, and both ends of the corotating prevention wing are extended in opposite directions from each center of each rod and from respective opposite sides of said plural rods such that each extended end of the corotating prevention wing is arranged to be the same length as that of the radius of the respective excavating blade (the length of the excavating blade plus the radius length of the rod).

Further, in a second multi-rods type of ground improvement apparatus, wherein pilot-heads are fixed respectively to the tip ends of plural rods, excavation blades are fixed to the rods and the rods are provided with injection openings for solidifier on an upper portion thereof, plural steps of agitating blades are fixed to the rods above the upperside of the excavation blades, and at least one link arm is loosely mounted to connect the rods said improvement is characterized in that a stationary corotating prevention wing is loosely mounted between the excavation blades and the lowest positioned agitating blades to connect the rods, both ends of the corotating prevention wing are extended in opposite directions from each center of each rod and from respective opposite sides of said plural rods such that each extended end of the corotating prevention wing is arranged to be the same length as that of the radius of the respective excavating blade (the length of the excavating blade plus the radius length of the rod).

Clods dug by the rotating and advancing excavation blades can be fully crushed between the excavation blades and the corotating prevention wing because the corotating prevention wing is kept still or stationary while the excavation blades are rotating. After that, the resultant crushed soil is further stirred by the agitating blades and sufficiently mixed with the solidifying agent.

FIG. 1 is a front view for showing an embodiment according to the present invention and

FIG. 2 is a front view for showing another embodiment according to the present invention.

Now, referring to the attached drawings, the disclosed enbodiments of this invention will be described.

FIG. 1 shows an embodiment of this invention, which is a two rods type apparatus for ground improvement. However, the number of rods is not limited to this type and more than two rods may be utilizable. In this embodiment, excavation blades 2 are fixed at the end portions of the two rods 1 and plural steps (three steps in the drawings) of agitating blades 3a, 3b and 3c are fixed is the rods above the upperside of the excavation blades 2. A single corotating prevention wing 4 is loosely mounted between each excavation blade 2 and each of the lowest agitating blades 3a to connect the rods 1. Both ends of the corotating prevention wing 4 are extended in opposite directions from each center of each rod 1 and from respective opposite sides of among said plural rods such that each extended end of the corotating prevention wing is arranged to be the same length as that of the radius of the excavating blade 2 (the length of the excavating blade plus the radius length of the rod). If both extended ends of the corotating prevention wing are longer than those of the excavation blades 2 each, end of the corotating prevention wing will collide with the side wall of the ground which is not excavated so that the excavating blades can not further advance into the earth. However, if the ends of the corotating prevention wing 4 are shorter than those of the excavation blades 2, clods excavated will run off through the ends of the corotating prevention wing and the ground side wall and will not be able to be fully crushed. Thus, in the ground improvement apparatus of this invention, the ends of the corotating prevention wing 4 are arranged to be equal with those of the excavation blades 2 fixed to both sides of the plural rods 1. Further, a link arm 5 is loosely mounted on the upperside of the corotating prevention wing 4, between the agitating blades 3b and 3c to connect the rods 1.

As described hereinafter, the corotating prevention wing 4 is kept still or stationary even if the rod 1 rotates, thereby preventing soil from corotating with the rod. The corotating prevention wing 4 also serves like the link arm 5 to hold the rods 1 to be spaced at a given interval together with preventing the axes of the rods from rotation. Further, there are provided injection openings 1a in the rods 1 in the vicinity of the excavation blades 2 fixed to each rod 1 (e.g., between the blades as shown in FIG. 1).

In use of the above mentioned apparatus according to this invention, clods excavated by the rotating and advancing excavation blades 2 are fully crushed between the excavation blades 2 because the corotating prevention wing 4 is kept still or stationary while the excavation blades 2 are rotating and the solidifying agent is injected from the injection openings 1a near the excavation blades 2. Thus, clods are prevented from rotating and the resultant crushed soil is further stirred by the agitating blades 3a, 3b and 3c, which are also rotating, and sufficiently mixed with solidifier the solidifying agent.

FIG. 2 shows another embodiment of this invention wherein pilot heads 6 are mounted to the tip ends of the rods 1 as shown in the ground improvement apparatus in FIG. 1. However, a ground improvement apparatus with three(3) or more rods may be applicable used.

By using the pilot head 6, excavating power can be improved and it enables smooth advancing into the ground. Other construction and effects are the same as described referring to FIG. 1. Therefore, the same numeral designates the same portion as in FIG. 1 and the description will be omitted.

As described above, clods dug by the excating blades 2 (or the pilot heads 6 in the second embodiment of this invention) are crushed between the corotating prevention wing 4 and the excavating blades, which are rotating so that soil is fully mixed and a good ground improvement is obtained. Further, since corotating prevention wing 4 also serves as a link arm, the number of the link arms 5 can be reduced.