JPH0627405B2 - Ready-made pile burying method - Google Patents

Description

Description: [Industrial field of application] The present invention relates to a method for burying prefabricated piles used as a foundation for civil engineering and building structures.

[Conventional technology]

Various construction methods have been developed for the construction method of ready-made piles, and in particular, a pollution-free construction method that does not generate noise or vibration is required in the vicinity of urban areas or houses, and the construction methods described below are also proposed.

For example, as described in JP-B-58-4128, a part of the mud is attached to an earth auger while stirring the mud excavated while digging a hole with a diameter approximately equal to the outer diameter of the pile to the site where the pile is to be buried. The inner wall of the hole is squeezed into the inner wall of the hole by squeezing the inner wall of the hole with the kneading plate of the muddy soil, thereby making the inner wall of the hole firm, and thus providing the hole with the muddy water of a predetermined depth. There is a method of embedding a ready-made concrete pile in which after inserting the ready-made concrete pile into the hole, the pile is rotated and the push-in hardware provided at the lower end of the pile is bited into the support ground and locked.

Further, in Japanese Patent Laid-Open No. 56-6822, a hole having an enlarged diameter portion at the bottom and having a diameter larger than the pile diameter is pre-drilled while being filled with bentonite muddy water, and the excavated earth and sand in the hole is sucked and discharged. There is disclosed a prefabricated pile construction method in which concrete is poured into a portion, cement milk is poured onto the precast pile to deposit the prefabricated pile, and the tip of the prefabricated pile reaches the enlarged diameter portion.

[Problems to be Solved by the Invention]

However, the embedding method for ready-made concrete piles disclosed in Japanese Examined Patent Publication No. 58-4128 has the advantage that the amount of discharged soil is small, but when the piles are rotated and the tip is dug into a hard support ground. In addition, if the pile body is easily damaged and the pile is inserted so as not to break the pile, the tip of the pile often does not bite into the bottom of the hole, which may result in insufficient fixation of the pile tip. However, even if the diameter of the excavation hole is the same as the diameter of the pile, sufficient peripheral frictional force could not be expected.

The phenomenon that this peripheral frictional force cannot be expected is due to the fact that the embedding method for prefabricated concrete piles disclosed in Japanese Patent Publication No. 58-4128 mentioned above is subjected to enlarged tip digging, and the enlarged tip portion is filled with rooting liquid. The same applies even if the method is changed to fix the tip of the pile to the enlarged bulb part.

Further, in the method disclosed in Japanese Patent Laid-Open No. 56-6822, it is necessary to suction and discharge a large amount of excavated earth and sand, and it is not possible to expect sufficient peripheral frictional force between the pile and the hole wall. It was

The object of the present invention is to maintain the advantages of each conventional construction method, such as high pile support at the time of construction, large tip support force, small amount of soil discharge and low noise, while constructing long piles. It is possible to provide a construction method for ready-made piles that is possible and can be expected to have higher frictional force on the peripheral surface.

[Means for Solving the Problems]

This invention is a drilling rod having a plurality of stirring arms and leveling arms projecting from the side of a hollow drilling rod at required intervals in the longitudinal direction, and having a bit that can be expanded at the tip, while discharging water from the tip. While excavating a drill hole having a diameter larger than the pile diameter, the excavating soil is stirred with the excavating liquid by the stirring arm to form a slurry, the hole wall is smoothed by the leveling arm, and then water is watered at a predetermined depth. To cement milk,
Expand the above-mentioned tip bit, repeat the excavation rod while consolidating the root from the tip and discharging the cement milk, move up and down to build the expanded bulb part, then shrink the expanded bit and discharge the cement circumference fixed pile milk Pulling up the excavation rod while rotating, depositing the ready-made pile in the excavation hole filled with the mixed liquid of slurry excavated soil and pile circumference fixed cement milk,
The method for constructing a prefabricated pile is characterized in that the tip of the prefabricated pile is fixed to the enlarged bulb portion by hardening cement milk.

That is, according to the present invention, a hollow drilling rod having a drill bit capable of expanding at the tip is rotated, and a drill hole is drilled while discharging the drilling liquid of water from the tip. The diameter of the excavation hole is about 30 mm to 100 mm, preferably about 30 mm to 50 mm larger than the diameter of the existing ready-made pile to be sunk.

A plurality of agitating arms and leveling arms are provided in the longitudinal direction of the excavating rod, and at the same time as excavation, the agitating arm stirs and mixes the excavated soil with water to form a slurry, and at the tip of the leveling arm, excavates the excavated soil. Knead on the hole wall to solidify the hole wall. When excavating the sandy soil, which is highly collapsible, the excavating rod is rotated up and down to turn it into a slurry and mix the mud in the mud into the sandy soil. Therefore, inexpensive water can be used as the drilling fluid.

In order to prevent a suction phenomenon (boiling phenomenon of the ground due to suction) from occurring in the ground when the excavation rod is moved up and down during excavation, the leveling arm is, for example, a tenth arm.
As shown in FIG. 11 and FIG. 11, it is preferable to have a structure having a gap in the cross section of the drill hole so that the liquid in the drill hole can freely pass through the roller portion at the tip in the vertical direction.

Water is usually used as the drilling fluid, but bentonite or the like may be mixed depending on the ground and soil conditions.

The stirring arm may be of various shapes, such as a wing-shaped one, a rod-shaped one, or a blade piece provided at the tip.

The leveling arm is for kneading the excavated soil by pressing the hole wall by rotating the excavating rod, and is a drum-shaped one provided around the excavating rod, an arc-shaped one, or a cylinder or Those provided with an arcuate member can be used.

After excavating to a predetermined depth which becomes the support ground in this way, the bit is enlarged in the radial direction, and the excavation is performed while discharging the cement milk from the tip to construct the enlarged bulb.

For the excavation rod, one that can be enlarged and excavated, such as one in which the bit at the tip of the rod protrudes outward in the direction of the circle due to the resistance of the soil by reverse rotation, is used. The excavation rod is repeatedly moved up and down to perform excavation.

As an example, the diameter of the enlarged bulb portion is about 200 mm larger than the pile diameter, and the height is twice the pile diameter upward from the pile tip and about 1 m downward, and cement milk is injected as the root consolidation liquid.

Next, the excavation rod is rotated forward and the cement milk is discharged from the tip, and the excavation rod is pulled up.

As the pile circumference fixing liquid, for example, about 10% of the excavated volume of cement milk is used, and a mixed liquid of excavated soil and cement milk that has been slurried in the excavation hole is formed.

After this, the excavation rod is removed from the pile driver main body, and the ready-made pile is set and inserted into the excavation hole. In this case, the hole diameter of the excavation hole is larger than the diameter of the ready-made pile, and it can be sunk by the weight of the pile, but if it is difficult to sunk it, attach a blade-like push-in hardware etc. to the tip of the pile if necessary, Rotate the pile and push the tip of the pile to the position where it is about 1 m above the bottom of the hole. The pile can be rotated by removing the excavating rod and then fixing it by covering the pile head with a rotary cap or the like connected to the main body of the pile driver. In addition, the ready-made pile to be laid is preferably an open-ended pile with an open tip, and the excavated soil that has been slurried enters the pile, and the amount of discharged soil is small.

In this way, when the excavated soil is kneaded and solidified by the leveling arm and the tip of the ready-made pile is sunk to the position where it is embedded in the cement of the expanded bulb, the cement milk hardens and the tip is supported. The foundation pile with high strength and frictional force on the peripheral surface is completed.

〔Example〕

The present invention will be described in more detail below with reference to examples. First, the construction procedure of the examples will be described with reference to FIGS. 1 to 9.

First, as shown in FIG. 1, while discharging water from the tip,
The excavation rod 1 is rotated, and excavation is performed with the bit 2 at the tip. At this time, the stirring arm 3 stirs the excavated soil with water to form slurry water 5, and the leveling arm 4 having a roller at the tip solidifies the hole wall.

In this way, when the drill rod 1 reaches a predetermined depth,
As shown in FIGS. 2 and 3, the drill rod 1 is reversely rotated to expand the bit 2, and the drill rod is repeatedly moved up and down while ejecting the root compaction liquid cement milk 6 from the tip, and moved up and down to expand the bulb portion. Form 7.

Next, as shown in FIGS. 4 and 5, while the excavation rod 1 is rotated in the forward direction and pulled up, 10% of the volume of the cement milk excavated as the pile circumference fixing liquid 8 is discharged from the tip. At this time, the drill rod 1 mixes the muddy water 5 with the cement milk 8 fixed around the pile.

In addition, after injecting a predetermined amount of the pile circumference fixing cement milk 8, it can be pulled up while discharging water as necessary, so that the subsequent ready-made pile can be further laid down.

After the excavation rod 1 is pulled out, as shown in FIG. 6, the head portion of the prefabricated pile 9 is locked by the rotating cap 10, suspended in the excavation hole, and is sunk by its own weight.

The ready-made piles 9 are connected by supporting the lower piles by a pile holding device 11 as shown in FIG. 7 and welding the end fittings of the lower piles and the upper piles.

In this way, as shown in FIGS. 8 and 9, the prefabricated pile 9 is further sunk, and the tip of the prefabricated pile 9 is embedded into the enlarged bulb portion 7.

In addition, when it cannot be sunk by its own weight, the push-in metal fitting 12 is attached to the tip of the prefabricated pile 9 in advance, and the prefabricated pile 9 is rotated to push the pile tip to a position about 1 m above the bottom of the hole.

The construction procedure of the example is as described above, and in this example, the construction was performed under the following conditions. That is, the diameter of the pile used is 400 m
m, the diameter of the excavated hole is 450 mm, the diameter of the enlarged bulb is 600 mm, the depth is about 29 m, and the prefabricated pile is sunk up to 1 m from the bottom of the enlarged bulb, The tip of the pile was stopped in the cement layer of the enlarged bulb.

On the other hand, the diameter of the hole excavated as Comparative Example 1 is 40 times the diameter of the ready-made pile.
Excavation was carried out to a diameter substantially the same as 0 mm, and an enlarged bulb consolidation portion was formed similarly to the above-mentioned example to lay down ready-made piles.

Further, instead of the rod provided with the stirring arm and the leveling arm used in the example as Comparative Example 2, an excavating device substantially similar to that shown in Japanese Patent Laid-Open No. 56-6822 is used to excavate the excavated soil. While discharging to, the diameter of the hole is 450mm, the diameter of the enlarged bulb portion is 600mm, the depth is about 29m to form a drilling hole, cement milk is injected into the enlarged bulb portion, Cement milk is used as a pile circumference fixing liquid,
A ready-made pile with a diameter of 400 mm was sunk.

In order to measure the bearing capacity of the piles of Examples, Comparative Examples 1 and 2 which were laid down as described above, all of the piles were measured from the pile tip portion.
Strain gauges were embedded at 4 points in the circumferential direction at the point of 50 cm above and 1 m below the pile head portion during the pile forming, and a load test was performed after burying the pile. The stress generated in each cross section was calculated from the strain generated and The peripheral bearing capacity was calculated. The results are shown in Table 1.

As shown in Table 1, in Comparative Example 1 and Comparative Example 2, sufficient circumferential surface friction force cannot be expected.

As can be seen from Table 1, in this invention, it is clear that the peripheral surface supporting force is particularly high and the total supporting force is high.

〔The invention's effect〕

As shown in the examples, the present invention exhibits the following excellent effects.

Since the tip of the prefabricated pile is fixed by the expanded bulb in which cement milk is injected as the root consolidation liquid, the pile tip has a large bearing capacity.

The hole wall is leveled by the leveling arm to form an excavated hole with a uniform diameter, and the hole wall is strengthened by the leveling work, and soil collapse does not easily occur on the outer peripheral surface of the cement milk liquid fixed to the pile. Since it is larger than the diameter of the ready-made pile, the hole wall is not destroyed when the pile is sunk, and a synergistic effect with the pile-periphery-fixing cement milk liquid on the pile provides a higher peripheral surface supporting force than that of the conventional technology.

An excavating rod having a stirring arm and a leveling arm and having a bit that can be expanded at the tip, while excavating a drilling hole having a diameter larger than the pile diameter while discharging the drilling fluid from the tip, excavating soil with the stirring arm. Is mixed with cement milk to form a slurry, the hole wall is leveled by the leveling arm, and then water for excavation is switched to cement milk for root consolidation at a predetermined depth, and the tip bit is enlarged. , While discharging the cement milk for root consolidation from the tip, the excavating rod is repeated and moved up and down to build the enlarged bulb, so the conventional excavated soil is discharged to the ground to form the excavated hole, then There is no risk of the piles remaining high as in the conventional cement milk construction method in which cement milk is filled in the expanded excavation area.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 9 are longitudinal sectional views showing a construction procedure in an embodiment of the present invention, FIG. 10 is a transverse sectional view showing an example of a drill rod, and FIG. 11 is a front view thereof. It is a figure. DESCRIPTION OF SYMBOLS 1 ... Drilling rod, 2 ... Expandable bit, 3 ... Stirring arm, 4 ... Leveling arm, 5 ... Muddy water, 6 ... Rooting liquid, 7 ... Expanded bulb part, 8 ... Piling fixing liquid, 9 ... Ready-made pile 10 ... Rotating cap, 11 ... Pile holding device, 12 ... Push-in hardware.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tomio Shishido Inami Asahi Chemical Industry Co., Ltd. 106 Asaya Kasei Co., Ltd. Sakai-cho, Ibaraki Prefecture (72) Tomoyuki Hayakawa 1-8-3 Shinbashi, Minato-ku, Tokyo Japan Concrete Kogyo Co., Ltd. (72) Inventor Ikuo Ryoshima 1-8-3 Shimbashi, Minato-ku, Tokyo Nihon Concrete Industry Co., Ltd. (56) Reference JP-A-56-6822 (JP, A) JP-B-58 -4128 (JP, B2)

Claims (1)

[Claims] 1. A drilling rod having a plurality of agitating arms and leveling arms projecting from the side of a hollow drilling rod at required intervals in the longitudinal direction and having a bit that can be expanded at the tip, and water is discharged from the tip. While excavating a drill hole having a diameter larger than the pile diameter, while stirring the excavated soil with water by the stirring arm to form a slurry, the hole wall is leveled by the leveling arm, and then,
Water was changed to cement milk at a predetermined depth, the tip bit was enlarged, and the root rod was repeated while ejecting the cement milk from the tip to discharge the cement milk, and it was moved up and down to build an enlarged bulb portion, and subsequently expanded. Clamp the bit, fix the circumference of the pile, discharge the cement milk, and pull up the drill rod while rotating,
Characterized in that a ready-made pile is sunk in a drill hole filled with a mixed liquid of slurry excavated soil and pile-peripheral fixed cement milk, and the tip of the ready-made pile is fixed to an enlarged bulb portion by cement milk hardening. Ready-made pile burying method.