JP2645322B2 - Construction method of soil cement composite pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a soil cement composite pile applied to construction-related foundation work.

[Prior Art] Conventional methods for forming a soil cement composite pile include, for example, the methods disclosed in JP-B-61-22089 and JP-A-62-197516. This method is shown in FIG. Stirring rod 1 while injecting infusion material such as cement milk into the ground
4b is forcibly stirred with soil to form a soil cement column 2 as shown in FIG. 4b. As shown in FIG. 4b to FIG. This is a method of press-fitting the empty tube 3.

As another conventional example, there is a method disclosed in Japanese Patent Publication No. 58-17849, which is shown in FIG.
With the auger head 1a, the ground is excavated to a predetermined depth while injecting a material having a low compressive strength after hardening, and then the auger head 1a is pulled up while stirring the ground soil and the hardened material to form a soil cement column 2, Next, as shown in FIG. 5b, while the hardened material of the soil cement column 2 is not yet hardened, the hollow pipe 3 is suspended in the borehole, and then the small-diameter auger head 1b is inserted into the hollow pipe and rotated. The hollow tube 3 and the auger head 1b are lowered to a predetermined depth, and as shown in FIG. 5c, the auger head 1b is inserted in advance of the hollow tube 3 and injected, and the root is hardened with high compressive strength after hardening. In this method, the lower end of the hollow tube 3 is solidified with a material, and the auger head 1b is pulled out while stirring the soil and the hardened material in the hollow tube 3 as shown in FIG. 5d.

[Problems to be Solved by the Invention] However, according to the conventional method for forming a soil cement composite pile, since a soil cement column is formed and a hollow tube is buried again, a soil cement column forming apparatus and a hollow management device are required. This requires complicated equipment, such as the necessity of equipment and the necessity of changing the setup, and there is a problem in terms of construction efficiency and construction cost. Further, even if the predetermined verticality of the soil cement column 2 formed as shown in FIG. 6 is not secured, or the predetermined verticality of the soil cement column 2 is secured as shown in FIG. It is difficult to install the hollow tube 3 to be buried at a predetermined verticality. Therefore, sufficient fogging cannot be secured, and there is a problem in structural strength or corrosion prevention. Furthermore, when the hollow pipe 3 is extended by welding to form a long pile due to poor construction efficiency, there is a problem that soil cement hardens during welding and burying becomes difficult. The present invention has been made to solve the problems described above.

[Means for Solving the Problems] A method for forming a soil cement composite pile according to the present invention includes:
In a hollow pipe such as a concrete pipe, at least one step, it is possible to expand and contract, and a rod having a lower end fitted with a drilling and stirring blade whose outer diameter is larger by a predetermined dimension than the outer diameter of the hollow pipe is inserted. A plurality of projecting blades projecting within the outer diameter of the expanded excavating stirring blade and divided into a plurality in the circumferential direction are fixed near the lower end of the hollow pipe, and the excavation is performed in advance of the lower end of the hollow pipe. While the stirring blade is expanded and the rod is rotated, a solidifying agent such as cement milk or cement is discharged from a nozzle near the tip of the rod, and the rod is fixed in the ground together with the non-rotating hollow tube. The invention according to claim 1, wherein the rod is advanced to a depth, and then the expanded excavating and stirring blade is contracted and pulled out from the hollow pipe. Feeding into the ground with the empty tube to the specified depth In the invention, the hollow tube is rotated in the opposite direction to the rod, and in the invention according to claim 2, the screw is provided at the tip of the rod, and the screw is In the invention according to claim 3, wherein the ground is excavated and stirred by the excavation stirring blade while being advanced into the ground, the invention according to claim 1, invention according to claim 2, invention according to claim 3, or invention according to claim 3, Arrange a plurality of solidifying material mixers,
The solidified material from the plurality of mixers is switched by a valve to supply the solidified material to the grout pump, or water is supplied to the grout pump through a valve instead of the solidified material, and the grout pump passes through the rod. The invention according to claim 4 is characterized in that different kinds of solidifying material or water are switched and discharged during feeding of the hollow tube from the nozzle near the rod tip.

[Operation] Since the soil cement columns are laid and the hollow pipes such as steel pipes and concrete are buried at the same time, the precision of laying the soil cement composite pile and the burial accuracy of the hollow pipes are maintained accurately. In particular, since the centering of the hollow pipe in the excavation hole is prevented by the projecting wing, accurate embedding is possible.

The earth mass in the earth and sand excavated and agitated by the excavation and agitating blade is mixed with a solidified material such as cement milk or a cemet system discharged from the nozzle to form soil cement. The soil mass in the soil cement hits the protruding wing near the lower end of the hollow pipe, and is broken down into small pieces.

In the case of the second aspect, the soil mass that rotates the projecting blade in the opposite direction to the excavating and stirring blade is finer.

In the case of the third aspect, since the screw at the tip of the rod is screwed into the ground like a cone and advanced, the propulsion is improved and the verticality is reliably maintained.

In the case of the fourth aspect, since the type of the solidified material ejected into the soil from the rod tip can be changed during excavation and stirring, the solidified material is required to have high solidification strength, for example, only at the upper and lower portions. A solidified material blended so as to increase the strength of the resin can be injected. Further, it is also possible to suppress the development of the strength and reduce the negative friction by, for example, discharging water or a solidifying material blended so that the strength after the solidification is reduced.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIGS. 1a to 1g are cross-sectional views showing an outline of a construction order according to an embodiment of the present invention.

First, as shown in FIG. 1a, the rod 10 is inserted into the hollow pipe 3 by inserting the drilling and stirring blade 11 from above in a closed state into the hollow pipe 3 such as a steel pipe or a concrete pipe. At a position where the blade 11 protrudes from the lower end of the hollow tube 3 by a predetermined distance (a distance at which the excavating and stirring blade 11 can expand), the blade is expanded and fixed in an enlarged state as shown in FIG. 1b. In this case, if the hollow tube 3 is set to the horizontal position and the rod 10 is inserted into the hollow tube 3 from the opposite side of the excavating and stirring blade 11, the excavating and stirring blade 11 can be inserted in an enlarged state. The use of a steel pipe having a projection provided on the outer surface of a hollow pipe increases the integrity with soil cement.

In addition, when a protrusion such as a reinforcing bar is fixed in the circumferential direction along the inner peripheral surface near the lower end portion of the hollow tube, the integrity of the soil cement and the inner surface of the hollow tube clogged inside the hollow tube is improved, The supporting force at the tip of the hollow tube can be further increased.

In the figure, reference numeral 10b denotes a position holding member fixed to the rod 10 and holding the positions of the rod 10 and the hollow tube 3, the outer periphery of which is in sliding contact with the inner periphery of the hollow tube 3.

As shown in FIGS. 2a and 2b, the lower end of the hollow pipe 3 has a protruding wing 3a (the
2a) and 3b (FIG. 2b) are divided in the circumferential direction and a plurality of them are fixed. 3a is a grooved member fixed laterally, 3b
Is fixed in the vertical direction, and may be a shape steel such as an angle or a steel plate. When the hollow tube 3 is a concrete tube,
The lower end may be head-wrapped with a ring-shaped iron plate and fixed thereto.

Next, as shown in FIG. 1c, while rotating the rod 10 in a state where the excavating and stirring blades 11 are enlarged, while discharging the cement milk or cement-based solidifying material from the nozzle 10a near the tip of the rod 10, the rod 10 At the same time, the hollow tube 3 is fed into the ground to a predetermined depth without rotation (FIG. 1d). At this time, the earth mass in the earth and sand excavated and agitated by the excavation and agitating blade 11 is mixed with a solidified material such as cement milk or cement discharged from the nozzle to form soil cement. The soil mass in the soil cement comes into contact with the projecting wings 3a (3b) at the lower end of the hollow pipe 3 and becomes finer, and is sufficiently stirred with the solidified material.

The second claim reduces the friction between the soil cement and the hollow tube when feeding the hollow tube 3 into the ground together with the rod 10, and ensures that the excavated earth mass hits the projecting wing 3a (3b) more strongly. When the hollow tube 3 is rotated in the opposite direction to the rod 10, when the hollow tube 3 is rotated in the opposite direction to the rod 10, the protruding wings 3 a (3 b) are strongly hit by the soil mass and the soil mass is finer. Be dropped off.

Since the protruding wings 3a (3b) protrude outward near the lower end of the hollow tube 3, when the hollow tube 3 is eccentric, it hits the wall of the borehole and is excavated in the soil cement column (drilled hole). Empty tube 3
Eccentricity is prevented, and the burying accuracy can be improved.

Next, as shown in FIG. 1e, the excavating and stirring blades 11 which have been expanded are reduced, and as shown in FIG. 1f, when they are pulled out from the hollow pipe 3, the inside of the soil cement column 2 is removed as shown in FIG. 1g. Hollow tube 3
Is buried, and the construction of the soil cement composite pile is completed.

With the passage of time during the construction, the solidification reaction of the cement-based solidification material generally starts early, leading to an increase in the friction between the soil cement and the hollow tube 3, so that a slow-hardening solidification material is used, A retarder may be added.

In the third claim, as shown in FIG. 3, a screw 10c is attached to the tip of the rod, and the screw 10c is advanced into the ground, and the ground is excavated by the excavation stirring blade 11, so that the verticality is reliably maintained. Dripping.

Next, a description will be given of a fourth aspect, the 1g view large solidified strength as shown in need synthetic pile lower A ₁ portion or portions of the lower A ₁ and the upper A ₂ are to increase the strength, the remaining B In order to reduce the strength of the part, the nozzle during feeding shown in FIG.
The type or composition of the solidified material to be discharged from 10a is changed and constructed. In this case, as shown in FIG. 8, two mixers for the solidified material are a mixer 13 and a mixer 14, and the mixed solidified material is switched by the switching valve 16 through the suction pipes 17a and 17b, and is switched by the grout pump 15. After passing through a delivery pipe 18 and passing through a swivel of a mechanical device (not shown) for forming a composite pile, the
Discharged into the soil from the nozzle 10a near the tip,
Mix and mix with soil at 1. By switching the switching valve 16, two types of solidified material, the solidified material entering the mixer 13 and the solidified material entering the mixer 14, can be selectively supplied during the feeding step shown in FIG. 1c. .

Further, when the portion B shown in FIG. 1g is a consolidation subsidence layer, in order to prevent negative friction, the nozzle 10a
Spouting water from the construction. In this case, the water suction pipe 19 is switched by the valve 19a, the solidified material is stopped, the water is supplied to the grout pump 15, and the water passes through the delivery pipe 18, passes through a swivel of a mechanical device (not shown) for forming a composite pile, and is connected to a rod. The water is discharged into the soil from the nozzle 10a near the tip of the rod 10, and the friction between the hollow tube and the consolidation subsidence layer in the portion B is reduced. Of course, the portion of the lower A ₁ and the upper A ₂ is construction by ejecting solidified material having strength.

[Effects of the Invention] According to the method of the present invention described in detail above, the following effects can be obtained.

Mixing and agitation of the solidified material and soil while excavating with the excavator and stirring blades, and at the same time feeding and burying the hollow pipes, two types of construction machines are required, one for building soil cement columns and one for burying hollow pipes. In addition to being able to perform construction with one unit, construction efficiency is good and construction cost can be reduced.

Since the construction of the soil cement column and the burial of the hollow pipe are performed simultaneously, the construction accuracy of the soil cement composite pile is reliably ensured.

Because of the rapid construction, the soil cement does not start to harden during construction, and it is not difficult to bury hollow pipe piles.

Since the protruding blades are provided at the lower end of the hollow pipe, the soil mass excavated by the excavating and stirring blades hits the ground and becomes finer, so that when mixed with the solidifying material, the strength increases.

Further, the area of the lower end of the hollow tube is increased by the protruding wings, and the tip support force is improved. In the case of the second aspect, when the projecting blade is rotated in the direction opposite to the excavating and stirring blade, the earth mass is finer and the strength of the soil cement is further increased.

Further, since the protruding wings protrude outward near the lower end of the hollow tube, the eccentricity of the hollow tube in the excavated soil cement column (drilling hole) is prevented, and the embedding accuracy is improved.

In the case of the third aspect, the screw at the tip of the rod is screwed into the ground and advanced from the excavation stirring blade, and the excavation hole is not bent.

In the case of the fourth aspect, since the type of the solidified material can be changed during excavation or water can be discharged into the ground instead of the solidified material, construction can be performed according to the condition of the ground, and negative friction is reduced. Construction is also possible.

[Brief description of the drawings]

1a, FIG. 1b, FIG. 1c, FIG. 1d, FIG. 1e, FIG. 1f, and FIG. 1g are cross-sectional views showing an outline of a working order of an embodiment of the present invention, FIG. 2a, FIG. The figure is a perspective view showing a state in which a projecting wing is attached to the lower part of the hollow tube, FIG. 3 is a front view of a rod provided with a screw at the tip of the rod, FIGS. 4a to 4c and FIGS.
Fig. 5d is a cross-sectional view showing the outline of the order of construction of the conventional method for forming a soil cement composite pile, Figs. 6 and 7 are cross-sectional views showing the drawbacks of the conventional method for forming a soil cement composite pile, and Figs.
The figure is a layout view of a solidifying material isostatic feeder capable of switching the type of solidifying material and water used in the embodiment of the present invention. 2 ... Soil cement column, 3 ... Hollow tube, 3a, 3b ... Protruding blade, 10 ... Rod, 10a ... Nozzle, 10b ... Position holding member, 10c ... Screw, 11 ... Drilling and stirring blade , 13,14… mixer, 15… grout pump, 16… switching valve, 17a, 17b… suction pipe, 18… delivery pipe, 19… water suction pipe, 19a… valve.

Continuation of the front page (72) Inventor Koichi Sato 2-6-3 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation (72) Inventor Tadashi Kimura 2-6-3, Otemachi, Chiyoda-ku, Tokyo Inside Nippon Steel Corporation (72) Inventor Shoichi Torizaki 2-6-3 Otemachi, Chiyoda-ku, Tokyo Nippon Steel Corporation Inside (72) Inventor Koichi Nagami 3-1 Nihonbashi Muromachi, Chuo-ku, Tokyo -3 Inside Kubota Iron Works Co., Ltd. (72) Inventor Mitsuru Otsuki 1-6 Shiohama, Ichikawa-shi, Chiba Prefecture Inside Kubota Iron Works Co., Ltd. (72) Inventor Kosei Fukuda 2-4-1 Akasaka, Minato-ku, Tokyo (56) References JP-A-58-521 (JP, A) JP-A-58-26116 (JP, A) JP-A-62-170614 (JP, A)

Claims (4)

(57) [Claims] An excavating and stirring blade which can be expanded and reduced in a hollow pipe such as a steel pipe or a concrete pipe in at least one step, and whose expanded outer diameter is larger than the outer diameter of the hollow pipe by a predetermined dimension. A projecting blade projecting within the expanded outer diameter of the excavating agitating blade, and divided into a plurality of pieces in the circumferential direction is fixedly mounted near the lower portion of the hollow tube. In a more advanced state, the excavating and stirring blades are expanded, and while rotating the rod, a solidifying material such as cement milk or cement is discharged from a nozzle near the tip of the rod, and the rod is not rotated. A method for constructing a soil cement composite pile, characterized in that the pile is fed into the ground together with the empty pipe to a predetermined depth, and then the expanded excavating and stirring blade is reduced and pulled out from the hollow pipe. 2. The soil according to claim 1, wherein when the rod is fed into the ground together with the hollow tube while rotating to a predetermined depth, the hollow tube is rotated in a direction opposite to that of the rod. How to make a cement composite pile. 3. The method according to (1) or (2), wherein a screw is provided at the tip of the rod, and the ground is excavated and agitated by an excavating agitating blade while the screw is advanced and penetrates into the ground. Construction method of soil cement composite pile. 4. A plurality of solidifying material mixers are arranged on the ground,
The solidified material from the plurality of mixers is switched by a valve to supply the solidified material to the grout pump, or water is supplied to the graft pump via a valve instead of the solidified material, and the grout pump passes through the rod and passes through the rod. Item (1), wherein a different kind of solidifying material or water is switched and discharged during feeding of the hollow tube from a nozzle near the rod tip.
Item (2) or (3), the method for forming a soil cement composite pile.