JP3249702B2 - Ground improvement equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement apparatus used in a mixing method for forming a solidified body in a ground by stirring and mixing a solidified material and earth and sand at a current position.
More particularly, it relates to the stirring rod structure.

[0002]

2. Description of the Related Art For example, ground improvement of landfills, roads,
For soil improvement in land reclamation work, mixing method is mainly used to increase the soil strength by adding lime or cement-based chemical solidification material to the soil and solidifying it by forcible stirring and mixing. Has been adopted.

[0003] The above-mentioned mixed treatment method is relatively flexible in the shape and strength of the improved ground, can be applied to various grounds having different water depth conditions and ground conditions, and is economical. There are various advantages, such as a small amount of timber and a small amount of embankment associated with it, which has little effect on existing structures.In addition, it is a construction method suitable for ground improvement in urban areas because there is little vibration and noise during construction. Have.

[0004] Referring to FIG. 8, the structure of a stirring blade of a ground improvement apparatus used in the mixing method will be described. The stirring rod comprises an inner pipe 7 and an outer pipe 8 which rotate in opposite directions to each other. The excavating blade 2 has a structure in which stirring blades 3 and 3 are provided on the outer tube 8. The excavating blade 2 is provided with a tip excavating blade 4 having a small rotating diameter and a rotating shaft arranged at a predetermined distance above the excavating blade 4. The agitating / digging blade 5 having a large diameter is formed in a register mark shape including a left wing 5a and a right wing 5b in order to also have a function as a stirring blade. Further, the stirring blade 3 provided on the outer pipe 8 is also composed of two blades, a left blade 3a and a right blade 3b, similarly to the stirring and excavating blade 5, and the plurality of stirring blades 3, 3 are respectively arranged in the vertical direction. In general, they are separated from each other by a predetermined distance, and are arranged in a plurality of stages shifted by 90 degrees in a plane.

[0005]

In the case of such a ground improvement device, although it depends on the driving ability or the ground type,
When an excessive load is excessively applied to the stirring blade provided at the tip of the stirring rod due to stirring resistance, the rotation of the stirring rod (the outer tube or the inner tube) may jam (stop). In addition, when the diameter of the stirring blade is large, when the outer pipe diameter is large, and when the peripheral friction increases as the penetration depth of the rod increases, problems such as a decrease in penetration efficiency or pulling efficiency occur, and There were problems such as the excavated soil rising when the stirring rod was pulled up.

Accordingly, an object of the present invention is to prevent jamming of the rod shaft, improve excavation efficiency, and improve penetration and pulling of the stirring rod by simply making a simple change to the conventional stirring rod. An object of the present invention is to provide a ground improvement device that can be easily performed.

[0007]

In order to solve the above-mentioned problems, the present invention is provided with a stirring blade extending radially at a forward end of a rotating stirring rod, so that a solidified material and excavated soil are in-situ. In a ground improvement apparatus for forming an improved part by stirring and mixing, a forming area of the stirring blade is formed on an outer surface of the stirring rod.
At the proximal end side not exceeding a 3m than the biasing position, the helical protrusion width having a length of extension less than the protrusion width of the stirring blade
A continuous blade of 30 to 150 mm is provided at the tip of the stirring rod.
Side only, the proximal side is not formed, and
When the tip of the stirring rod reaches the lower end of the improved part
The formation range of the continuous blade sinks into the improved portion,
The component is configured to be located in the improved portion .

[0008] Further, the stirring rod is a rod having a double pipe structure comprising an inner pipe and an outer pipe, and the inner pipe and the outer pipe are rotated in opposite directions to each other so that the earth and sand do not co-rotate. Can be stirred and mixed.

[0009]

In the present invention, a spiral continuous blade is formed on the outer surface of the stirring rod, preferably on the base end side from the position where the stirring blade is attached. Therefore, the excavated soil above the stirring blade is temporarily lifted upward by the spiral continuous blade, and the rotational resistance applied to the stirring blade is reduced. As a result, jamming of the stirring rod is prevented. In addition, the excavated soil above the stirring blade is temporarily lifted upward by the spiral continuous blade, and the amount of excavated soil near the stirring blade is reduced, so that efficient mixing and stirring of the solidified material and the excavated soil can be performed.

[0010] Furthermore, since the penetration force of the stirring rod is increased by the rotation of the spiral continuous blade, the stirring rod can easily penetrate into the excavated soil. This is particularly effective when an excessive penetration resistance is applied to the outer tube, such as when a large diameter stirring blade is provided, when the outer tube diameter is large, or when the penetration depth is deep. In addition, when pulling up the outer tube while rotating the outer tube in the reverse direction, pulling up resistance and rotation resistance applied to the spiral continuous blade can be reduced, so that pulling up becomes easier. If the spiral continuous blade is formed over the entire length of the stirring rod when pulling up the stirring rod, the excavated earth and sand may be pulled up to the ground, but the spiral continuous blade is not formed on the upper part of the stirring rod. By leaving the portion, the pulling resistance and the rotation resistance can be reduced while the excavated earth and sand remains at the original position due to the resistance of the upper layer earth and sand.

On the other hand, in the case of the present invention, since it is only necessary to attach a helical continuous blade to the outer surface of the stirring rod of the existing ground improvement device, the manufacturing cost is low, the labor is not required, and the change can be made easily. It can be carried out.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on embodiments.
As shown in FIG. 1, a ground improvement device used in the mixing processing method includes a power swivel that is movable along the leader 21 on a leader 21 fixed in an upright state with respect to a base machine 23. 20 is mounted, and the stirring rod 1 is connected via a speed reducer.

The stirring rod 1 is a rod having a double pipe structure composed of an inner pipe 7 and an outer pipe 8. One of the inner pipe 7 and the outer pipe 8 is moved rightward by the speed change mechanism of the speed reducer. The other rotates in the forward and reverse directions such that the other rotates counterclockwise.

At the distal end of the stirring rod 1, as shown in FIG. 2, the inner pipe 7 is formed so as to protrude slightly ahead of the distal end of the outer pipe 8, and a cutting edge is provided at the distal end of the inner pipe 7. 2 are provided. The digging blade 2 is composed of a tip digging blade 4 fixed to the foremost portion and a stirring and digging blade 5 fixed above the tip digging blade 4. It consists of a pair of left digging blades 4a and right digging blades 4b provided symmetrically with respect to the center.
A plurality of excavating bits 10 are provided below the right excavating blades 4a and 4b. The left and right excavating blades 4a, 4b are formed so as to be inclined by a predetermined angle, and are mounted so that the cutting edges of the excavating bits 10, 10,... Enter the ground at a predetermined angle. In this case, the inclination angle of the left and right excavation blades 4a, 4b is desirably set to 80 to 90 °. A solidified material discharge port 9 is formed at the foremost portion of the inner pipe 7 so that a cement-based or lime-based powder or liquid solidified material is discharged.

Similarly, the agitating and digging blade 5 also includes a pair of left and right agitating and digging blades 5a and 5b provided symmetrically about the inner pipe 7. The stirring and excavating blades 5a, 5b are the excavating blades 4a,
4b is fixed at a position shifted from the mounting position of 4b by 90 degrees in a plane. A plurality of excavation bits 10 are provided below the both agitation and digging blades 5a and 5b, and the digging diameter of the agitation and digging blade 5 is substantially the same as that of a stirring blade 3A described later. Also, the left and right stirring and excavating blades 5a, 5b are formed to be inclined by a predetermined angle, respectively, similarly to the case of the distal excavating blade 4, and the cutting edges of the distal excavating bits 10, 10,. It is installed so as to enter at a predetermined angle. In this case, the inclination angle of the left and right stirring and excavating blades 5a and 5b is 40 to
It is desirable to set it to 50 °.

The tip excavation blade 4 and the stirring / excavation blade 5 are helically connected by a continuous blade 6 connecting them. As shown in FIG. 4, the continuous blade 6 includes a left continuous blade 6a that spirally connects an upper end side of the left excavation blade 4a and a lower end side of the left stirring and excavating blade 5a, and the right excavation blade 4b. The right side continuous blade 6b which spirally connects the upper end side of the bottom and the right side stirring / combining digging blade 5b in a spiral manner. The earth and sand dug up by the tip digging blade 4 is moved upward by the continuous blade 6 and further stirred. The portion that is agitated by the combined digging blade 5 and is located outside the tip digging blade 4 is firstly excavated by the agitated combined digging blade 5. In this case, the inclination angle of the continuous blade 6 is desirably set to 20 to 30 °.

On the other hand, near the end of the outer tube 8, stirring blades 3A to 3C are provided in a vertically arranged three-stage arrangement in the illustrated example. Each of the stirring blades 3A to 3C includes a pair of stirring blades 3a and 3b provided symmetrically with respect to the outer tube 8. Excavation bits 10 are provided at appropriate positions above the stirring blades 3a and 3b of these stirring blades 3B and 3C, and are used for excavation when the stirring rod 1 is lowered. Further, at least one of the stirring blades 3A to 3C, in the illustrated example, the stirring blade 3C is connected to the other stirring blades 3A, 3A, and 3C.
B is shorter than B. By doing so, the stirring performance on the shaft center side can be improved, and the resistance at the time of pulling up the stirring rod 1 can be reduced. Also,
The stirring blades 3a and 3b are formed so as to be inclined by a predetermined angle, and are mounted so that the cutting edge of the drill bit 10 enters the ground at a predetermined angle. in this case,
The inclination angle of the stirring blades 3a and 3b is 25 to 35.
° is desirable. In addition, each of the stirring blades 3A to 3C is
They are arranged so as to be shifted by 90 ° in plan view. In the present example, the example of the three-stage arrangement of the stirring blades is shown, but the one-stage arrangement or four or more stages may be arranged. Further, the number of stirring blades formed per stage may be, for example, three blades or four blades. The stirring blade 3
The drill bit 10 attached to a, 3b can be omitted.

In this embodiment, a plurality of vertical shearing auxiliary wings 11 are provided to the stirring blade 3A so as to shear the excavated soil in the vertical direction. This longitudinal shearing auxiliary wing 11
Is desirably formed to be as long as possible so as not to come into contact with the lower stirring and excavating blade 5 so as to secure a large shear surface. Usually, it is desirable that the length of the longitudinal shearing auxiliary wing 11 is at least 10 cm or more, preferably 20 cm or more. As shown in FIG. 6, it is desirable to form the end surface 11a of the longitudinal shearing auxiliary wing 11 on the rotation direction side into a blade shape to reduce the shear resistance. Further, as shown in FIG. 3, it is desirable that the longitudinal shearing auxiliary wings 11 are arranged on a plane such that the orientation direction is tangential. If it is arranged to be inclined with respect to the tangential direction, it will be subjected to a component force in the centripetal or centrifugal direction of the stirring rod 1 when shearing the excavated soil, causing the shaft to bend. As a result, the excavated soil can be effectively cut with almost no component force.

In the present embodiment, the vertical shearing auxiliary blade 11 is provided only for the lowermost stirring blade 3A, but may be provided for other stirring blades 3B and 3C. Further, it may be provided for a stirring blade arbitrarily selected among all the stirring blades 3A to 3C.

On the other hand, in the case of the present invention, a helical continuous blade 12 is formed on the outer surface of the outer tube 8, specifically, on the outer surface of the outer tube closer to the base end than the stirring blades 3A to 3C. I have. The spiral continuous blade 12 has a spiral shape corresponding to the direction of inclination of the stirring blades 3A to 3C provided on the outer tube 8, and when the stirring rod 1 rotates forward, the excavated soil is scraped upward and reversely rotates. In such a case, the excavated soil will be pushed downward. Further, if the projection width B of the spiral continuous blade 12 is too large, the movement of earth and sand is promoted.
It is preferable that the width is about 100 mm and the width is slightly extended from the outer tube surface. The pitch P is 200 to 600
mm, preferably about 300 to 500 mm.
The range of formation of the spiral continuous blade 12 is substantially the same as that of the stirring rod 1.
Can be formed over almost the entire length, but depending on the type of ground, the earth and sand may be pulled up to the ground at the time of lifting, so the upper portion of the stirring rod 1 may be left unformed. According to the test by the present inventors, the desired effect can be obtained only by forming the spiral continuous blade 12 in a range of 3 m on the upper side of the stirring blades 3A to 3C formed at the tip of the outer tube 8. Is known.

While the double-pipe type stirring blade structure in which the inner pipe 7 and the outer pipe 8 rotate in the forward and reverse directions has been described above, the present invention relates to a single-pipe rod-type stirring blade having no forward / reverse rotation mechanism. The same applies to wings.

Next, the improvement procedure by the above-described ground improvement apparatus will be described with reference to FIG. 7. As shown in FIG. 7 (A), after the excavating blade 2 at the tip of the stirring rod 1 is set at a predetermined position, the power swivel is set. The stirring rod 1 is made to penetrate by the drive of 20, and as shown in FIG. The penetration is performed without discharging the solidified material from the solidified material discharge port 9 at the tip.

Next, while the cement or lime-based liquid or powder solidified material is discharged from the discharge port 9 of the inner pipe 7 from the improvement start position, the ground is excavated with the excavating blade 2 at the tip, and the agitation is also performed. The excavated soil and the solidified material are agitated and mixed by the excavating blade 5 and the stirring blades 3A to 3C. In this case, the descending speed of the stirring rod 1 is 0.3 to 1.0 m / min.
It is good to make it to the extent and let it penetrate slowly.

When the stirring rod 1 reaches the supporting ground,
After the rotation direction of the inner tube 7 and the outer tube 8 is switched, the stirring rod 1 is pulled up. Also at the time of lifting, the excavated soil and the solidified material are slowly pulled up while being stirred and mixed by the stirring and excavating blade 5 and the stirring blade 3. The number of rotations of the stirring blade 3 and the digging blade 2 varies depending on the soil conditions of the soil to be improved, but the number of blade cutting per meter is 300 to 60.
It is desirable to set the number to zero. Here, the blade cutting frequency is the number of revolutions per 1 m of the improved portion of the stirring blade 3 and the excavating blade 2, and is a numerical value obtained by summing all the rotating speeds of the stirring blade 3 and the excavating blade 2 at the time of descent and ascending. Say.

[0025]

As described in detail above, according to the present invention, jamming of the stirring rod can be prevented, excavation efficiency can be improved, and the stirring rod can be improved by simply changing the conventional stirring rod. Can be easily penetrated and pulled up.

[Brief description of the drawings]

FIG. 1 is an overall side view of a ground improvement device.

FIG. 2 is an enlarged view of a tip portion of a stirring rod.

FIG. 3 is a view taken along line III-III in FIG. 2;

FIG. 4 is a view taken in the direction of arrows IV-IV in FIG. 2;

FIG. 5 is an enlarged side view of a main part of the outer tube.

FIG. 6 is a partial perspective view showing another example of a stirring blade for longitudinal shearing.

FIG. 7 is a process sequence diagram showing a ground improvement procedure.

FIG. 8 is a schematic view of a conventional stirring blade structure.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... stirring rod, 2 ... excavating blade, 3 ... stirring blade, 4 ... tip excavating blade, 5 ... stirring / excavating blade, 6 ... continuous blade, 7 ... inner tube, 8
... outer tube, 9 ... solidified material discharge port, 10 ... drill bit, 11 ...
Auxiliary wing for longitudinal shearing, 12 continuous spiral blade

Continuation of the front page (72) Inventor Norihiro Kojo 4-2-235 Kudankita, Chiyoda-ku, Tokyo Light Industry Co., Ltd. (72) Inventor Maki Naito 4-35, 2-93 Kudankita, Chiyoda-ku, Tokyo Light Industry (56) References JP-A-6-341138 (JP, A) JP-A-3-208910 (JP, A) JP-A-7-310315 (JP, A) JP-A-7-310314 (JP, A) A) JP-A-2-140321 (JP, A) JP-A-63-300109 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 3/12 102

Claims (2)

(57) [Claims] 1. A ground improvement device comprising a stirring blade extending radially at a forward portion of a rotating stirring rod, wherein a solidified material and excavated soil are stirred and mixed in situ to form an improved part. On the outer surface of the stirring rod, at the base end side where the formation range does not exceed 3 m from the mounting position of the stirring blade, a spiral protrusion width having a protrusion width smaller than the extension length of the stirring blade is 30.
The continuous blade of ~ 150 mm is formed only on the distal end side of the stirring rod, the base end side is not formed, and the continuous blade is formed in a state where the distal end of the stirring rod reaches the lower end of the improved portion. A ground improvement device, wherein a range is submerged in the improved portion, and the unformed portion is located in the improved portion. 2. The stirrer rod is a rod having a double tube structure comprising an inner tube and an outer tube, wherein the inner tube and the outer tube are rotatable in mutually opposite directions, and a stirring blade is provided on an outer surface of the outer tube. The ground improvement device according to claim 1, further comprising a spiral continuous blade.