JP2006291455A - Construction method of foundation pile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve yield strength of a foundation pile, and to also improve resistance force to complicated extraction force acting on the foundation pile, in improving a means for strengthening the foundation pile by returning ground sediment removed on the ground in a hollow part of the driven foundation pile, when excavating a pile hole. <P>SOLUTION: When inserting the foundation pile 3, a ring-shaped wooden spacer 35 is installed on an outside surface of the foundation pile, and is suspended by a roller crane (not shown in Fig.), and is naturally dropped until a blocking-up plate 32 of its tip reaches the bottom in the pile hole, and a space (a) of about 20 cm is formed between a pile hole wall and a foundation pile side surface by lightly striking and stabilizing a bottom plate 32 to the pile hole bottom by a monkey fixture inserted via a through-hole of the pile. Qualitatively improved soil is inputted and filled in an inner hole (b) of the foundation pile and the space (a) formed by vertically inserting the foundation pile 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for constructing various foundation piles for civil engineering, particularly hollow foundation piles.

  Before placing the foundation pile into the ground, inject a bentonite-based ground improver and drill a pile hole with a spiral auger, earth drill, or all-casing, and then place a crawler boom in the pile hole. The foundation pile is driven using a suspended leader that is connected and held in a vertical position as a guide.

  The soil discharged when excavating this pile hole contains a considerable amount of bentonite. For this reason, the soil cannot be used as ordinary soil for land preparation, etc., and will be subject to various regulations as industrial waste, and the cost burden for the disposal will be quite large for contractors. Become.

  In addition, ground soil and sand discharged on the ground by excavation of this pile hole is returned to the hollow portion of the foundation pile after placement, thereby reducing the amount of residual soil.

  The applicant of the present application previously filled a foundation pile piled with modified soil obtained by adding and mixing hydrated and expansive quick lime with other cement-based additives into this waste soil in Patent Document 1. It was proposed to strengthen the foundation pile.

  Foundation piles of various buildings are required to have resistance to pulling force acting on the foundation pile as well as resistance to forces acting on the foundation pile in a complex manner.

However, although the previously proposed means for strengthening foundation piles contributes significantly to strengthening the strength of foundation piles, the tensile force is due to the gap between the foundation piles and the pile holes. In addition, the foundation pile has a low frictional force from the side, so that the resistance is insufficient.
JP-A-11-269874

  The present invention relates to the improvement of means for strengthening the foundation pile by returning the ground earth and sand excavated on the ground during excavation of the pile hole into the hollow portion of the foundation pile after placement, and the problem is In addition to improving the proof strength of the foundation pile, it is to improve the resistance to the complex pulling force acting on the foundation pile.

  The present invention, in advance, after excavating the pile hole, in the construction method of the foundation pile for placing the foundation pile in the pile hole, between the foundation pile and the pile hole wall to be placed in the pile hole, By forming a space that can be filled with the waste generated during excavation of the pile hole, and filling the space between the foundation pile and the pile hole wall with the waste generated during excavation of the pile hole together with the hollow portion of the foundation pile, The resistance of the side surface of the foundation pile is increased, and the resistance against the pulling force from above or the loading force from above is also increased.

  The space between the foundation pile and the pile hole wall is a pile hole having a diameter larger than the diameter of the foundation pile to be placed by any means such as an earth auger, all-casing, or earth drill method. Use a small-diameter foundation pile that is several tens of centimeters smaller, make the space between the pile hole walls of the foundation pile constant, attach a wooden or other spacer to the outer surface of the foundation pile, and hang it on a crawler crane. It can be formed by natural fall or light placement in parallel to the pile hole.

  And, at the lower tip of the foundation pile with a diameter smaller than that of the pile hole, a steel disk-like bottom plate having a diameter substantially the same as or slightly smaller than the pile hole diameter is attached and inserted into the pile hole. Insert a monken hammer through and tap the bottom plate to stabilize the foundation pile.

  With this bottom plate, the stability of the insertion foundation pile is increased, and the bottom of the pile hole is flattened and hammered to increase the degree of filling of the inner pile and outer space of the foundation pile for soil removal.

  By providing a steel rod or other protrusion on the bottom plate, the stability of the foundation pile inserted and driven can be increased.

  Furthermore, by providing a plurality of holes in the bottom plate, it is possible to assist the insertion of the foundation pile and to help remove the slime accumulated at the bottom of the pile hole.

  The present invention can be applied to foundation piles that use reinforcing bars for cast-in-place around which steel wires are wound, in addition to concrete and steel pipes that have been prepared in advance.

  At this time, a reinforcing steel cage is attached to the steel pipe to which the bottom plate is attached, a space is formed between the reinforcing steel cage and the pile hole, and improved soil including residual soil is filled between the reinforcing steel cage and the pile hole.

  The present invention increases the pull-out force as well as the proof stress by tightly filling the space formed between the hollow portion of the foundation pile inserted into the excavated pile hole and the foundation pile and the pile hole wall. A strong foundation pile can be formed.

  Moreover, even if it uses a small diameter foundation pile with respect to the conventional foundation pile, since it can pack inside, it can increase intensity | strength and can reduce a foundation pile constituent material, Therefore Material cost can be reduced.

  Furthermore, the amount of waste soil containing bentonite or cement introduced during excavation of the pile hole can be greatly reduced as industrial waste, which can contribute to improvement of environmental problems.

  Hereinafter, embodiments of the invention will be described by way of examples.

  This embodiment shows an example in which a steel pipe foundation pile is driven to the full depth.

  FIG. 1 shows a state in which a pile hole prior to foundation pile driving is excavated by a so-called all-casing method.

  In the figure, excavated soil B is discharged from the casing 1 while injecting bentonite for fixing the hole wall of the pile into the soil and swinging the casing 1 into the soil A.

After the lower end of the casing 1 reaches the soil support layer C, the sedimentation bucket 2 is lowered in the casing 1 and lowered to the bottom of the pile hole. After slime is precipitated in the bucket 2, the casing 2 is pulled up together to 1500 mm. Form a bore hole with an inner diameter.
FIG. 2 shows a steel pipe foundation pile 3 having a diameter of 1200 mm. The foundation pile 3 includes a foundation pile body 31 and a disk-like bottom plate 32 having an outer diameter slightly smaller than the inner diameter of the pile hole welded to the tip thereof. The bottom plate 32 includes a bottom of the pile hole. A hole 33 is formed to allow water accumulated in the upper surface to pass through the upper surface, and a steel material 34 for stabilizing the foundation pile is crossed and welded to the bottom of the bottom of the bottom of the pile hole.

  FIG. 3 shows a state where the foundation pile 3 shown in FIG. 2 is inserted into the pile hole. When the foundation pile 3 is inserted, a ring-shaped wooden spacer 35 is attached to the outer surface of the foundation pile, suspended on a crawler crane (not shown), and the bottom plate 32 for closing the tip reaches the bottom in the pile hole. The bottom plate 32 is lightly struck to the bottom of the pile hole and stabilized by the monken inserted through the through hole of the pile, and a space a of about 20 cm is formed between the pile hole wall and the side of the foundation pile.

  FIG. 4 shows a state where the soil a modified soil is put into the space a formed by vertically inserting the foundation pile 3 and the inner hole b of the foundation pile into the pile hole D formed in advance and filled. Indicates.

  The reforming and charging of the soil B can be performed by the apparatus disclosed in the above-mentioned Patent Document 1, and quick lime and cement are injected together with the soil. In this injection, since the space formed in the inner hole of the foundation pile and the outer surface of the foundation pile is closed by the bottom plate 32, a high filling degree can be obtained in the space.

  The foundation pile obtained in this way is reinforced by the modified soil filled in the foundation pile, and the surrounding area is firmly held by the modified soil filled in the pile hole. Therefore, it can be set as the foundation pile which has the proof stress excellent also with respect to the pressure and the tension | pulling force.

  The example which provides a cast-in-place pile in the pile hole shown in FIG. 1 formed in Example 1 is demonstrated with reference to FIGS.

  FIG. 5 shows a process for preparing a cast-in-place pile according to the present invention. In the figure, 4 is a steel pipe having a diameter slightly smaller than the inner diameter of the pile hole that forms a space of 30 mm to 50 mm between the inner wall of the pile hole and a length of about 2 m. Since the steel pipe 4 mainly has a function for stabilizing the bottom plate 32 at the bottom of the pile hole, the length corresponds to the entire depth of the pile hole as in the case of the first embodiment. It need not be length.

  5 is a reinforcing steel cage having an outer diameter that can form a gap of 150 mm to 200 mm between the inner wall surface of the steel pipe 4 when inserted into the steel pipe 4 with a smaller diameter than the inner diameter of the steel pipe 4. It is made longer than the depth. Further, the bottom plate 32 has an outer diameter slightly smaller than the inner diameter of the pile hole, as in the case of the first embodiment. The cast-in-place pile 6 is obtained by inserting the rebar cage 5 into the steel pipe 4 and then welding and integrating the tip thereof to the bottom plate 32 together with the tip of the steel pipe 4.

  FIG. 6 shows a procedure for providing the cast-in-place pile 6 prepared in this way in the pile hole formed by FIG. 1. The pile pile 6 settles in the pile hole, and the bottom plate 32 is stabilized at the bottom of the pile hole as shown in FIG. And the slurry at the time of excavation which remains in the bottom of the pile hole rises in the space formed between the inner wall of the pile hole and the bottom plate and the steel pipe by the load of the cast-in-place pile 6, and from the bottom surface of the pile hole Excluded, the bottom surface of the pile hole forms a stable surface with exposed solid soil.

  Then, by introducing the modified soil B into the inner and outer spaces of the reinforcing bar 5 of the cast-in-place pile 6, the space between the inner and outer sides of the cylindrical reinforcing bar 5 and the inner wall of the pile hole is further increased. It can be set as the foundation pile which is filled with the modified soil and has excellent proof force against external force, tensile force, and load.

  The present invention can be applied regardless of the material of the foundation pile and regardless of the excavation type of the pile hole.

The excavation state of the pile hole prior to the foundation pile placement is shown. Shows steel pipe foundation pile The state where the steel pipe foundation pile is inserted in the pile hole is shown. The space formed between the pile hole and the foundation pile and the inner hole of the foundation pile are filled with soil with improved soil quality. The procedure for preparing the cast-in-place is shown. The state where a cast-in-place pile is lightly inserted into the pile hole is shown. The state where the cast-in-place pile is inserted in the pile hole is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 2 Bucket 3 Foundation pile 31 Foundation pile main body 32 Bottom plate 33 Hole 34 Steel material 4 Steel pipe 5 Reinforcement cage 6 Cast-in-place pile

Claims (4)

After excavating a pile hole in advance, in the construction method of the foundation pile in which the foundation pile is placed in this pile hole,
Between the foundation pile to be placed in the pile hole and the pile hole wall, a space that can be filled with the soil discharged during excavation of the pile hole is formed,
Foundation pile construction method that increases the resistance to tensile force as well as the strength of the foundation pile by filling the hollow space of the foundation pile and the space between the foundation pile and the pile hole wall with the soil generated during excavation of the pile hole .   The construction method of the foundation pile of Claim 1 formed by making the space between the foundation pile and pile hole wall which are laid in a pile hole smaller than the diameter of the planned foundation pile as a foundation pile.   The foundation pile construction method according to claim 1, wherein the foundation pile to be placed in the pile hole is formed by attaching a disk-like bottom plate having a diameter substantially the same as or slightly smaller than the diameter of the pile hole at the lower end thereof. After excavating the pile hole in advance, in the construction method of the foundation pile to place the place pile in this pile hole,
Reinforcing bar cage in which the place pile is smaller than the inner diameter of the steel pipe inserted into the steel pipe having an outer diameter slightly smaller than the inner diameter of the pile hole and the inner surface of the steel pipe, The steel pipe and a bottom plate having an outer diameter slightly smaller than the inner diameter of the pile hole joined to the lower end of the reinforcing steel cage,
After tapping the bottom plate of the place pile and stabilizing the bottom plate of the place pile on the bottom surface of the pile hole,
A construction method of a foundation pile in which the space between the internal space of the place pile and the inner wall of the pile hole is reformed and filled with waste soil generated during excavation of the pile hole.

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