JP2019183495A - Construction method of cast-in-place concrete pile - Google Patents

Abstract

To provide a construction method of cast-in-place concrete piles capable of constructing efficiently and economically an expanded bottom pile consisting of multiple expanded bottom piles and connection piles by excavating excavation holes of expanded bottom piles and connection piles which are adjacent to each other with the same excavator.SOLUTION: Using a pile excavator 9, an excavation hole 10 of adjacent expanded bottom piles 1 is excavated at a predetermined interval so that at least shaft parts 2 of the adjacent expanded bottom piles 1 do not overlap. An excavator guide member 12 is inserted and installed in the excavation hole 10 of each expanded bottom pile 1. The ground G of a connection pile 8 between the excavation holes 10 of the adjacent expanded bottom piles 1 is excavated, and the excavation holes 10 of the adjacent expanded bottom piles 1 are communicated using the pile excavator 9 while guiding in the vertical direction with the excavator guide member 12 inserted and installed in the excavation hole 10 of each expanded bottom pile 1. Concrete is filled in a connected excavation hole which is composed of the excavation hole 10 of the adjacent expanded bottom pile 1 and the excavation hole 11 of the connection pile 8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for constructing a cast-in-place concrete pile.

  Conventionally, cast-in-place concrete bottom piles are often used as pile foundations in heavy buildings such as high-rise buildings.

  A cast-in-place concrete pile (cast-in-place concrete pile) has a shaft portion with a substantially constant diameter and a bottom portion in the shape of a truncated cone that is formed by expanding the tip of the shaft portion according to the required support force. The support strength can be significantly improved by providing an expanded bottom portion at the tip of the pile (see, for example, Patent Document 1).

  When constructing the cast-in-place concrete bottom pile, for example, an excavator is used to form an excavation hole having a substantially constant diameter from the ground surface while filling it with a stable liquid to a predetermined depth. Next, at the stage where a bottom-excavating machine (bottom-expanding machine such as a bottom-up bucket) connected to the tip of the rod is inserted and placed at the tip of the excavation hole, the rod is moved around the central axis while expanding the bottom-excavating excavator. Rotate to excavate the ground of the hole wall and widen the tip of the excavation hole. Then, reinforced rods are built into the expanded excavation hole, and concrete is laid to replace the stable liquid using a tremy pipe, and the pile head side is backfilled or a pile head foundation is constructed as necessary. The construction of cast-in-place concrete expanded piles is completed.

Japanese Patent No. 4120478

  Here, when constructing a plurality of expanded bottom piles 1, the pile interval between adjacent expanded bottom piles 1 is generally ensured to be equal to or greater than (shaft diameter (average diameter of shaft portion 2) + bottom expanded diameter (average diameter of bottom expanded portion 3)). .

  On the other hand, as shown in FIG. 3, there may be a portion where the interval between the pillars 5 of the building body 4 (= the interval between the piles 1) is narrower than the diameter of the expanded bottom. As shown in FIG. 4, the position of the adjacent expanded piles 1 is shifted in a plane (laterally) as shown in FIG. 4, or as shown in FIG. The bottom expansion part 3 of the bottom expansion pile 1 is shifted in the vertical direction (up and down) so that the bottom expansion part 3 does not overlap.

  However, if the adjacent expanded bottom piles 1 are shifted in plan, the positions of the pillars 5 of the building body 4 and the positions of the piles 1 are shifted, which causes a large moment in the expanded bottom pile 1 and this is processed. In order to do so, the base 7 needs to be thickened (FIG. 4).

  Moreover, if the bottom expanded part 3 of the adjacent bottom expanded pile 1 is shifted in the vertical direction, the lower pile 1 is excavated directly below the upper pile bottom 1a. Thus, there is a possibility that the supporting force of the upper pile 1 is insufficient, or the load P of the upper pile 1 is transmitted to the lower pile 1 and the supporting force of the lower pile 1 is insufficient (FIG. 5).

  On the other hand, as shown in FIG. 6, excavation holes are formed in adjacent expanded bottom piles (expanded pile portions) 1 at intervals at which the shaft portions 2 do not overlap, and the ground between adjacent expanded hole piles 1 is excavated. It is also conceivable that two expanded bottom piles (1) adjacent to each other are connected by a wall portion 14 and constructed as a single expanded bottom pile 1 (for example, see Patent Document 1).

  However, as shown in FIG. 7, when excavating the connection pile portion 8, the excavator 9 bends toward the excavation hole 10 side of the expanded pile portion (1) excavated in advance (excavation direction is shifted), There is a possibility that the ground G of the connecting pile portion 8 cannot be excavated appropriately.

  On the other hand, if the ground G of the connection pile part 8 between the excavation holes 10 of the adjacent expanded bottom pile parts (1) is excavated by a machine for constructing an underground continuous wall, the excavation hole is not bent and the connection pile part 8 Excavation work can be done.

  However, the excavator for the pile 1 (earth drill, etc.) and the excavator for the underground continuous wall (reverse, etc.) are different from each other, so it is necessary to put two kinds of large dedicated machines on site, Since the work using the wall excavator is expensive and requires a large area for the attached equipment, the total cost for constructing the pile 1 becomes very high. In addition, the space required for the construction becomes very large.

  In view of the above circumstances, the present invention makes it possible to excavate and form the excavation holes of adjacent bottom piles and connection piles with the same excavator, and efficiently and economically from a plurality of bottom expansion piles and connection piles. It aims at providing the construction method of the cast-in-place concrete pile which can construct the expanded bottom pile which becomes.

  In order to achieve the above object, the present invention provides the following means.

  A method for constructing a cast-in-place concrete pile according to the present invention is provided at a predetermined interval from a bottomed pile portion including a columnar shaft portion and a substantially truncated cone-shaped bottom expanded portion obtained by expanding a tip portion of the shaft portion. A cast-in-place concrete pile having a connecting pile portion for connecting the adjacent expanded bottom pile portions, wherein a pile excavator is used and at least the excavation holes of the adjacent expanded bottom pile portions are Excavation step for excavating bottom piles with a predetermined interval so that shaft portions of adjacent expanded bottom pile portions do not overlap, and excavator guides installed by inserting excavator guide members into the excavation holes of each of the expanded pile portions While being guided in the vertical direction by the excavator guide member inserted and installed in the excavation hole of each of the above-mentioned widened pile parts, using the excavator for piles, Excavating the ground of the connecting pile part to excavate the connecting pile part And forming concrete into the connection excavation hole comprising the excavation hole of the adjacent expanded bottom pile portion and the excavation hole of the connection pile portion. And a concrete placing process.

  In the method for constructing a cast-in-place concrete pile according to the present invention, one excavator guide member inserted into the excavation hole of one of the adjacent expanded bottom pile portions is an excavator for the pile on the surface facing the excavation hole of the other expanded bottom pile portion. The other excavator guide member inserted into the excavation hole of the other expanded bottom pile portion is formed with one guide surface for engaging the excavator for piles in the vertical direction by engaging the side surfaces of Preferably, the side of the pile excavator is engaged with the surface facing the excavation hole of the expanded bottom pile portion, and the other guide surface for guiding the pile excavator in the vertical direction is provided. .

  According to the construction method of the cast-in-place concrete pile of the present invention, it is possible to excavate and form the excavation holes of the adjacent expanded bottom pile portion and the connection pile portion with the same excavator, and a very large column axial force such as a high-rise building is suitable. It is possible to efficiently and economically construct a cast-in-place concrete bottom pile with a high bearing strength that can be supported on the ground.

In the construction method of the cast-in-place concrete pile which concerns on one Embodiment of this invention, it is a figure which shows the procedure which excavates the ground between adjacent bottom expanded pile parts. It is a figure which shows the cast-in-place concrete pile which concerns on one Embodiment of this invention. It is a figure which shows the case where the part where the space | interval of the pillar of a building main body (= space | interval of a pile) was narrower than an expanded bottom diameter produced. It is a figure which shows the state which shifted the position of the adjacent bottom expanded pile planarly. It is a figure which shows the state which shifted the bottom expanded part of the adjacent bottom expanded pile to the perpendicular direction. It is a figure which shows the state constructed by connecting two adjacent bottomed piles with a wall and constructing as one bottomed pile. It is a figure which shows the state in which the bending produced when excavating the ground between two adjacent expanded bottom pile parts.

  Hereinafter, with reference to FIG.1 and FIG.2, the construction method of the cast-in-place concrete pile which concerns on one Embodiment of this invention is demonstrated.

  In the construction method of the cast-in-place concrete pile of this embodiment, as shown to Fig.1 (a)-FIG.1 (c), using the conventional excavator 9 for piles, the cylindrical axial part of a substantially constant diameter 2 and the excavation hole 10 of the bottom expanded pile portion 1 composed of the substantially truncated cone-shaped bottom expanded portion 3 formed by expanding the tip portion of the shaft portion 2 is determined so that at least the shaft portion 2 of the adjacent expanded bottom pile portion 1 does not overlap. The preceding excavation is performed with an interval of (preceding excavation process). The pair of deepening piles 1 has a pair of excavation holes 10 so as to connect the central axis O1 of the shaft part 2 of each widening pile part 1 and the excavation holes 10 of the pair of adjacent deepening pile parts 1 in a subsequent process. Excavation is performed such that the central axis O1 of the excavation hole 11 of the connection pile portion 8 that excavates and forms the ground G between the excavation holes 10 is arranged on a straight line S1 in a plan view.

  At this stage, the excavator guide members 12 are inserted into the excavation holes 10 of the adjacent expanded bottom pile portions 1 (excavator guide member installation step).

  The excavator guide member 12 is formed using, for example, a reinforcing bar 12a and a steel plate 12b, and one excavator guide member 12 to be inserted into the excavation hole 10 of one adjacent bottomed pile portion 1 includes the other One guide surface 12c for guiding the excavator 9 for piles in the vertical direction is formed on the surface facing the excavation hole 10 of the expanded bottom pile portion 1, and the other is inserted into the excavation hole 10 of the other expanded bottom pile portion 1. In the excavator guide member 12, the other guide surface 12c for guiding the excavator 9 for piles in the vertical direction is formed on the surface facing the excavation hole 10 of the one expanded bottom pile portion 1.

  When these pair of excavator guide members 12 are inserted into the excavation holes 10 of one adjacent bottomed pile portion 1 and the other expanded bottom pile portion 1, the guide surfaces 12c of the pair of excavator guide members 12 are excavated for piles. Oppositely arranged with a predetermined interval according to the size and shape of the machine 9. In the present embodiment, the guide surface 12c of each excavator guide member 12 corresponds to a part of the concentric circle so as to correspond to the pile excavator 9 (the side surface of the pile excavator 9 is engaged) in a plan view. It is formed in a circular arc shape along.

  When a pair of excavator guide members 12 is inserted into the excavation holes 10 of the adjacent expanded bottom pile portions 1 and set in the stable liquid, the pile excavator guide members 12 (a pair of guide surfaces 12c) are used for piles. Excavating the ground G between the excavation holes 10 of the adjacent expanded bottom pile portions 1 (connected pile portion 8) while guiding them to the pair of guide surfaces 12c so as to insert the excavator 9 (connected pile portion excavating step) .

  At this time, the excavator 9 is guided by the guide surface 12c of the excavator guide member 12 and guided in the vertical direction. Thereby, even when excavating the ground G of the connection pile part 8 between the adjacent expanded bottom pile parts 1, a bending does not arise and excavating the ground G between the adjacent expanded bottom pile parts 1 suitably. Then, the excavation holes 10 of the pair of expanded bottom pile portions 1 can be connected by excavation holes 11 that become the connection pile portions 8.

  And the excavation hole 10 of the adjacent expanded bottom pile part 1 which consists of the axial part 2 and the bottom expanded part 3, and the excavation hole 11 of the connection pile part 8 which consists of the axial part 2 and the expanded bottom part 3 are formed in communication, and stable liquid The excavator guide member 12 is pulled out and removed from the connected excavation hole filled with the concrete, and the reinforcing bar is built and concrete is placed so as to replace the stable liquid using the tremy pipe (concrete placing step). Moreover, if necessary, the pile head side is backfilled or a pile head foundation is constructed, and the construction of the cast-in-place concrete pile 1 'is completed.

  As shown in FIG. 2, the cast-in-place concrete pile 1 ′ of the present embodiment constructed in this way includes three bottom-expanded piles 1, 8 composed of a shaft portion 2 and a bottom-extended portion 3. The central axes O1 and O2 of the shaft portions 2 of the piles 1 and 8 are arranged on the same straight line S1 in a plan view, and the shaft portions 2 of the adjacent expanded bottom piles 1 and 8 and a part of the expanded bottom portions 3 overlap each other. And built in an integrated form.

  In other words, the cast-in-place concrete pile 1 ′ of the present embodiment has one side 18 a and the other side 18 b of the side surface of the shaft connecting portion 18, in which the substantially cylindrical shaft portions 2 of the three bottom expanded piles 1 and 8 are integrated. The shaft connecting portion 18 extends from the upper end to the lower end, and is formed to have an arc concave and convex shape in which three convex arc surfaces 19 having a substantially constant diameter are connected in parallel. A conical concave / convex shape in which one conical surface 20a and the other surface 20b of the widened connecting portion 20 integrated with the widened bottom portion 3 are connected in parallel with three conical surfaces whose diameter gradually increases from the upper end to the lower end of the widened connecting portion 20. It is formed to exhibit.

  The cast-in-place concrete pile 1 ′ of the present embodiment formed as described above can realize a pile having high support strength by providing a large bottom area. Moreover, in addition to the one side 20a and the other surface 20b of the side surface of the widened connecting portion 20 being formed in a conical uneven shape, the one surface 18a and the other surface 18b of the side surface of the shaft connecting portion 18 are formed in an arc uneven shape. Thus, the frictional resistance of the pile 1 ′ can be greatly improved. From this point, it is possible to realize a pile 1 ′ having a higher support strength.

  In addition, what is necessary is just to determine the bottom area of each pile bottomed pile 1 and 8, and the bottom area total of the pile 1 'which consists of the axial connection part 18 and the bottom expansion connection part 20 with the required supporting force of the pile 1'.

  Therefore, in the construction method of the cast-in-place concrete pile according to the present embodiment, it is possible to construct the cast-in-place concrete pile 1 ′ that gives a necessary supporting force even when the pillar 5 of the building body 4 is close in design. Moreover, excavation of the adjacent bottom expanded pile part 1 and excavation of the connection pile part 8 can be performed using the excavator 9 for piles, such as the same Earl drill, without the excavation hole 10 bending.

  Therefore, according to the construction method of the cast-in-place concrete pile of this embodiment, the cast-in-place concrete pile 1 ′ having a high support strength capable of suitably supporting a very large column axial force such as a high-rise building is more efficient than the conventional method. It is possible to construct the system economically and economically.

  As mentioned above, although one Embodiment of the construction method of the cast-in-place concrete pile concerning this invention was described, this invention is not limited to said one Embodiment, It can change suitably in the range which does not deviate from the meaning. .

  For example, the excavator guide members 12 inserted and arranged in the excavation holes 10 of the adjacent expanded bottom pile portions 1 can excavate the connecting pile portion 8 by guiding the excavator 9 for piles in the vertical direction. For example, the shape and configuration are not necessarily limited as in the present embodiment.

  Moreover, the connection pile part 8 does not necessarily need to have a bottomed pile shape including the shaft part 2 and the bottom expanded part 3. That is, as long as a desired bearing strength can be obtained, the shaft portion 2 may be formed and configured.

1 Cast-in-place concrete pile (bottom pile, bottom pile)
1 'Cast-in-place concrete pile 1a Pile bottom 2 Shaft part 3 Expanded part 4 Building body 5 Column 7 Foundation 8 Linked pile part 9 Excavator 10 Excavated hole in expanded pile part 11 Excavated hole in coupled pile part Excavator guide member 12a Reinforcing bar 12b Steel plate 12c Guide surface 14 Wall 18 Axis connecting portion 18a One surface 18b Other surface 19 Convex arc surface 20 Expanded connecting portion 20a One surface 20b Other surface G Ground O1 Central axis O2 Central axis P Load S1 Straight line

Claims (2)

A connection that connects a columnar shaft portion and an expanded bottom pile portion that is formed by expanding a tip portion of the shaft portion and a substantially truncated cone shape, and the adjacent expanded bottom pile portions that are provided at a predetermined interval. A method of constructing a cast-in-place concrete pile with a pile portion,
Using an excavator for piles, an expanded bottom pile excavation step for excavating the excavation hole of the adjacent expanded bottom pile portion at a predetermined interval so that at least the shaft portion of the adjacent expanded bottom pile portion does not overlap;
An excavator guide member installation step for inserting and installing an excavator guide member in the excavation hole of each of the above-mentioned expanded pile parts,
While guiding in the vertical direction with the excavator guide member inserted and installed in the excavation hole of each expanded bottom pile portion, using the excavator for piles, the connection pile portion between the excavation holes of the adjacent expanded bottom pile portions Excavating the ground to form an excavation hole of the connection pile portion, and connecting the excavation hole of the adjacent expanded bottom pile portion, a connection pile portion excavation step;
A method for constructing a cast-in-place concrete pile, comprising: a concrete placing step for placing concrete in a connected excavation hole including an excavation hole in the adjacent expanded bottom pile portion and an excavation hole in the connection pile portion. In the construction method of the cast-in-place concrete pile of Claim 1,
One excavator guide member to be inserted into the excavation hole of one of the adjacent expanded bottom piles is such that the side of the excavator for the pile is engaged with the surface facing the excavation hole of the other expanded bottom pile, and the excavator for the pile Is formed with one guide surface for guiding in the vertical direction,
The other excavator guide member to be inserted into the excavation hole of the other expanded pile part is engaged with the side facing the excavation hole of the one expanded bottom pile part so that the side of the excavator for the pile engages the vertical excavator for the pile. A method for constructing a cast-in-place concrete pile, characterized in that it is provided with the other guide surface for guiding in the direction.

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