JP2880348B2 - Pile head treatment method for cast-in-place concrete pile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile head treatment method for cast-in-place concrete piles, and more particularly to a pile head treatment method for crushing and removing excess concrete by hydration and expansion of a static crushing agent. It is about.

[0002]

2. Description of the Related Art Generally, a so-called cast-in-place concrete pile is used as a foundation pile for building a building, a bridge, or the like, in which a pile hole is excavated at a site, and fresh concrete is poured into the pile hole to form a pile. Has been conventionally employed. In the above-mentioned construction method, it is necessary to crush and remove the defective concrete in the extra pile head of the cast-in-place concrete pile.
However, the conventional method of crushing and removing using a breaker or the like has a problem that the environment is deteriorated due to noise, vibration, or the like given to the neighborhood.

[0003] As a crushing and removing method free from problems such as noise and vibration, a pile head treatment method using a static crushing agent that generates heat and expands due to hydration is known. In this method, as shown in FIGS. 9 and 10, the first containers 1a filled with the static crushing agent are attached to the main bars 2a. A plurality of second containers 1b filled with the static crushing agent are vertically attached to the main reinforcing bars 2 at intervals along the circumferential direction of the reinforcing bar cage 2 with binding wires 3.

In this state, the cage 2 is inserted into the pile hole 4, and the first and second containers 1a and 1b are immersed in the stable liquid at the time of excavation which has been filled in the pile hole 4 in advance. The moisture in the liquid is brought into contact with the static crushing agent in the containers 1a and 1b to expand the crushing agent and cast and cure the concrete, and thereafter the pile head of the cast-in-place concrete crushed by the expansion of the crushing agent. The raised portion 5 is to be removed. The first containers 1a are for causing a crack at the boundary between the pile main body 6 and the pile head extra portion 5 to separate the pile head extra portion 5 from the pile main body 6. The crushing agent of the second containers 1b is crushed so as to divide the pile head extra portion 5, thereby facilitating removal of the pile head extra portion 5.

[0005]

However, in the pile head processing method shown in FIGS. 9 and 10, the pile diameter is 15 mm.
The extra pile portion 5 can be crushed and removed with sufficient accuracy up to about 00 mm. However, when the diameter is larger than about 1600 mm, the crushing action of the crushing agent does not function sufficiently, and the accuracy of the cracks deteriorates. It becomes difficult to crush and remove accurately.

Conventionally, to solve such a problem,
11 and 12 when the pile diameter is about 1600 mm or more.
As shown in FIG. 9 and FIG.
In the same manner as in the example shown in FIG. 1, a first container 1a filled with a static crushing agent is attached, and rebars 7 are assembled between the main rebars 2 and 2, and the first containers 1a.
The first container 1a is further provided near the center of the pile hole 4 inside the
Are attached to form the first containers 1a into a double ring shape. In addition, the rebars 8 are assembled above the rebars 7 in the same manner as the rebars 7. The upper and lower ends of the second container 1 b are fixed to the rebars 7 and the rebars 8. Second container 1
The arrangement position of b ... is set inside the pile pit compared to the conventional case. Then, the extra pile portion 5 is crushed and removed in the same manner as described above.

However, in this case, when the concrete is poured, the tremee pipe is placed in the first container 1a near the center.
, And if they do, the container 1a may come off the reinforcing bars 7, and the crushing effect may not be obtained.

In the above-described method, the lower ends of the second containers 1b are fixed by the reinforcing bars 7 for fixing the inner first containers 1a.
Are at substantially the same level as the lower end of the first container 1a, and the first container 1a and the second container 1b expand substantially in the same manner. Before a crack is formed between the pile main body 6 and the pile head extra portion 5, the crushing agent of the second container 1b.
Harmful cracks could occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for forming a tremee pipe into a first container 1a even in a pile head treatment of a cast-in-place concrete pile having a pile diameter of 1600 mm or more. An object of the present invention is to provide a pile head treatment method for a cast-in-place concrete pile that can accurately crush and remove the excess embossed portion 5 without contact, and does not cause a crack on the pile body 6 side.

[0010]

According to the pile head treatment method of the cast-in-place concrete pile according to the present invention, first, the static crushing agent is filled in first and second permeable containers, and the first container is filled with the static crushing agent. The cross-sectional area is larger than the cross-sectional area of the second container;
The first container is mounted along the circumferential direction at a position corresponding to the lower end portion of the extra pile head portion of the concrete on the inner peripheral side peripheral portion of the rebar cage, and at least double in the radial direction of the pile hole. And a plurality of the second containers are circumferentially spaced from each other at a position above the first container in an extra portion of the pile head of the concrete on the inner peripheral side peripheral portion of the reinforcing bar cage. Each of the first and second containers was vertically filled and mounted at least twice in the radial direction of the pile hole, and then the reinforced cage was inserted into the pile hole to fill the first and second containers in advance. The solution to the above-mentioned problem was to bring the concrete into contact with the stabilizing liquid and then to cast concrete into the pile hole.

[0011]

According to the above arrangement, by arranging the first container and the second container at least doubly in the radial direction, it is possible to cope with the pile head treatment of the cast-in-place concrete pile of 1600 mm or more. . Then, the first container and the second container are attached to the inner peripheral portion of the reinforcing bar cage, thereby preventing contact with the tremy tube. Further, by increasing the cross-sectional area of the first container filled with the crushing agent to be larger than the cross-sectional area of the second container, the capacity of the crushing agent in the first container is increased to reduce the expansion amount of the first container. By making the amount of expansion larger than that of the second container, it is possible to make the first container crack earlier than the second container crack.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 8 are drawings for explaining a pile head treatment method for a cast-in-place concrete pile according to this embodiment. The pile head treatment method shown in these drawings is particularly effective for a pile diameter of 1600 mm or more. Is suitably adopted in the case of

The pile head processing method according to this embodiment is based on the following: After the cast-in-place concrete that forms the pile, the pile upper end portion (pile head extra portion 5) that is extra-filled so as not to leave the slime in the pile. Is crushed with a static crushing agent. And
In the pile head processing method of this embodiment, first, the pile hole 4 is excavated in the presence of the stabilizing liquid as in the conventional method. Further, as a stabilizer for preventing the peripheral wall of the pile hole 4 from collapsing at the time of excavating the pile hole, a bentonite solution or a solution obtained by adding a CMC or a dispersant to a bentonite solution is used.

Next, the first and second containers 10 and 11 shown in FIGS. 1 and 2 are filled with a static crushing agent. Here, filling the static crushing agent means filling the inside of the container with the static crushing agent. The first and second containers 1
Numerals 0 and 11 are tubular having water permeability. In addition,
The water-permeable first and second containers 10 and 11 may be entirely formed of a permeable material such as paper, or may be formed of a part of the peripheral wall or opening of the container from a mesh that does not allow the crushing agent to fall off. A net formed from such a net can be used.

That is, in such a container, the container itself has water permeability (water permeability), or the water is easily passed through the net portion, so that the container becomes a water-permeable container. And the container filled with the static crushing agent by such a configuration easily absorbs moisture when it comes into contact with the stabilizing liquid as described later, and contacts the granular static crushing agent with the water. It has become.

In the present embodiment, the first container and the second container 1 are formed by covering the openings at both ends of the container with a net.
0 and 11. The cross-sectional area of the first containers 10 is larger than the cross-sectional area of the second containers 11. By increasing the cross-sectional area of the first containers 10 in this manner, the expansion amount of the static crushing agent filled in the first containers 10 can be reduced by the static amount filled in the second containers 11. It is larger than the swelling amount of the crushing agent.

The static crushing agent is composed of a swelling crushing agent which is exothermic and expands due to hydration of calcium oxide or the like, and to which a known retarder or the like is added. Here, the reason why the retarder is added is that by appropriately adjusting the type and amount of the retarder, the time required for the hydration expansion pressure of the static crushing agent to be exhibited can be adjusted to a desired time.

Incidentally, as such a static crushing agent, one which has been molded into granules in advance is used. Here, the granulation of the static crushing agent is performed by providing a gap of an appropriate size between each particle so that the stable liquid in the pile hole 4 can sufficiently contact each particle as described later. In order to

As a method of molding the static crushing agent into granules, a method of continuously granulating dry powder of the static crushing agent at a high pressure into a strong almond-like briquette by a briquetting machine, A method in which a dry powder of a crushing agent is compression-molded into a plate shape by a smooth roll using a compacting machine, and then crushed and granulated is preferably employed. Of course, other dry compression molding methods can also be employed. In addition, the size of the granules of the static crushing agent may be at least as large as that at least a void is formed between the particles so that water can easily enter, and for example, those having a particle size distribution shown in Table 1 below Is preferred.

[0020]

[Table 1]

Then, the first and second containers 10 and 11 filled with the static crushing agent are attached to the reinforcing bar cage 2 serving as a reinforcing bar for the pile. The rebar basket 2 has a plurality of main bars 2a arranged in parallel on the circumference, and these main bars 2a are fixed by a number of ring-shaped hoop bars 2b.

The first and second containers 10, 11
First, as shown in FIG. 2,
First and second fittings 12 and 13 are attached to the main reinforcement 2a of the reinforcing rod cage 2.
, And the first and second containers 10 and 11 are attached to the main bar via the first and second attachments 12 and 13.

The first fitting 12 is shown in FIGS.
As shown in the figure, a base 12a extending along the main muscle 2a
And an extension 12b extending horizontally from the base 12a. The base 12a is attached to the main bar 2a by a binding wire or welding.

The extension 12b has two rectangular through-holes 12c, 12c arranged in the longitudinal direction. These through holes 12c, 12c
Are formed so as to penetrate at right angles and horizontally with respect to the length direction of the extending portion 12b. The first fixture 12 is adapted to attach the first container 12 to the main reinforcement 2a by inserting and fitting the first container 12 into these through holes 12c. The lower surface of the extension 12b is tapered so that the tip of the extension 12b becomes thinner. A substantially semicircular concave portion 12d for fitting with the main bar 2a is formed at the rear end of the extending portion 12b.

As shown in FIG. 2, the first mounting member 12 has the extending portion 12b arranged so as to face the center of the reinforcing bar 2 and the first mounting member 12 is spaced apart in the circumferential direction. Several are arranged at the height. Also, the first fixture 12
The height of the extension portion 12b is the pile main body 6 and the pile head extra portion 5
The height of the border has been.

The first container 10 is inserted into the through hole 12c of the first fixture 12 in a state of being formed in an arc shape in advance. Then, the plurality of arc-shaped first containers 10 are connected to the first mounting members 12.
The two through-holes 12c are respectively inserted, and are doubly arranged along the circumferential direction on the inner peripheral edge of the reinforcing bar cage 2. That is, the first containers 10 are arranged in a double ring shape at the inner peripheral edge of the rebar basket 2.

The second attachment 13 is attached to the main bar 2a so as to extend horizontally from the main bar 2a. Also,
The second fixture 13 has two pieces arranged along the length direction thereof.
Rectangular through holes 13a, 13a are formed. These through holes 13a, 13a are formed so as to penetrate the second mounting member 13 vertically and vertically. These through holes 1
By inserting and fitting the second containers 11 and 11 into the 3a and 13a, respectively, the second containers 11 and 11 are
a. A substantially semicircular recess 13b for fitting with the main bar 2a is formed at the rear end of the second mounting member 13. Further, the left and right side surfaces of the second attachment 13 are tapered such that the second attachment 13 becomes thinner toward the tip.

As shown in FIG. 2, the second mounting member 13 is vertically moved above one of the main reinforcing bars 2a with its tip directed toward the center of the rebar cage 2 as shown in FIG. 2
A plurality is attached at a time and at intervals in the circumferential direction. The upper and lower ends of the second containers 11 are inserted into the through holes 13a of the two second mounting members 13 attached to one main bar 2a and fitted. Thus, the main muscle 2a is
Mounted vertically along the length of the. Also, the second
Are mounted in the radial direction of the reinforcing cage 2 doubly.

That is, the second containers 11 are reinforced cages 2
In the inner peripheral edge portion, a plurality of pairs are vertically arranged at intervals in the circumferential direction. The lower end of the second container 11 is located above the position where the first container 10 is attached. The main reinforcing bar 2a is provided with a main reinforcing bar above the first fixture 12 as shown in FIGS. 5 and 8, that is, at a position corresponding to the pile head margin 5 so that concrete does not adhere to the main reinforcing bar. A covering main bar trimming member 15 is attached.

Next, the reinforcing rod cage 2 is inserted into the pile hole 4 in which the stabilizing liquid has been placed, and is immersed. Then, the stabilizing liquid permeates into the first and second containers 10 and 11 and comes into contact with the granular static crushing agent, and the static crushing agent starts to expand. At this time, the water level of the stable liquid in the pile hole 4 is low, and the first and second containers 1
Even when 0 and 11 are not completely immersed in the stabilizing liquid, as will be described later, the water level of the stabilizing liquid rises when replacing the concrete with the stabilizing liquid, and the first and second containers 10 and 11 are placed in the stabilizing liquid. Can be immersed.

Then, concrete is poured while replacing the stabilizing liquid with concrete, and after the placement is completed, the concrete is cured until the concrete develops its strength. Then, during this time, since the expansion of the static crushing agent has been completed, when digging up the soil and performing root cutting, the excess embankment concrete is crushed at a preset position by the expansion force of the static crushing agent .

At this time, the cross-sectional area of the first containers 10 is larger than the cross-sectional area of the second containers 11 and the amount of expansion of the first containers 10 is larger than that of the second containers 11. Of the boundary between the pile body 6 and the pile head extra portion 5 formed by the first containers 10... This can be done before cracks are formed.

As described above, the first and second containers 10 and 11 are provided in a radially double manner at the inner peripheral side edge portion of the reinforcing bar cage 2 so as to be cast in place having a diameter of 1600 mm or more. Also in the concrete pile, the pile head extra portion 5 can be crushed, and the first and second piles can be crushed.
Of the first and second containers 10 and 11 in contact with the tremy pipe for placing concrete in the pile hole 4 by the presence of the containers 10 and 11 on the inner peripheral side of the rebar cage 2. Can be prevented.

The lower end of the second container 11 is located above the first container 10, and the crack at the boundary between the pile main body 6 and the pile head extra portion 5 formed by the first container 10 is better. Since the second container 11 can be formed before the crack formed in the extra pile 5 by the second container 11, the crack in the pile main body 6 and the extra pile head 5 causes the crack by the second container 11 to reach the pile main body 6 side. Can be prevented. That is, it is possible to prevent a harmful crack from being formed on the pile main body 6 side. Hereinafter, the results of the pile head processing performed based on the above-described example will be described as Example 1 and Example 2, but the present invention is not limited to Example 1 and Example 2. (Example 1) In the cast-in-place concrete pile shown in FIG. 1 and FIG.
0 mm, the depth d of the excess concrete was 800 mm, and the width W of the cover concrete was 150 mm, and the work was performed as follows.

First, the B-tube (first container 10) and the M-tube (second container 11) of NEW-CAB (trade name; manufactured by Sumitomo Cement Co., Ltd.) are connected to the first and second tubes as described above. It was attached to the main reinforcement 2a of the reinforcing rod cage 2 using the attachments 12 and 13. The B pipe 10 and the M pipe 11 are filled with CAB (trade name; manufactured by Sumitomo Cement Co., Ltd.) which is a kind of static crushing agent. In addition, what was previously molded into granules is used as the CAB. The B pipe 10 and the M pipe 1
No. 1 covers the openings at both ends thereof with a net so that the static crushing agent does not fall out of the inside of the tube and that water easily penetrates into the tube.

Next, the rebar cage 2 is inserted into the pile hole 4,
After submerging the B pipe 10 and the M pipe 11 in the stabilizing solution, concrete was poured. When the soil was dug up after 10 days, cracks of a gap of 1 cm to 2 cm occurred along the boundary between the pile main body 6 and the pile head extra portion 5, and
The pile head extra part 5 is approximately 7 in the pile head extra part 5.
Cracks were generated that would result in splitting. Further, the crack generated in the pile head excess portion 5 did not reach the pile main body 6 side. (Example 2) In the cast-in-place concrete pile shown in FIGS. 1 and 2, the pile diameter L of the cast-in-place concrete pile was set to 230.
0 mm, the depth d of the excess concrete was 900 mm, and the width W of the cover concrete was 100 mm.

First, the B-tube 10 and the M-tube 11 of NEW-CAB (trade name; manufactured by Sumitomo Cement Co., Ltd.) are connected to the rebar basket 2 by using the first and second fittings 13 and 14 as described above. Attached to main bar 2a. The B pipe 10 and the M pipe 11 are filled with CAB (trade name; manufactured by Sumitomo Cement Co., Ltd.) which is a kind of static crushing agent. The CAB
What was previously molded into granules is used. Also,
The B tube 10 and the M tube 11 cover both ends of the opening with a net so that the static crushing agent does not fall out of the tube,
Water was easily penetrated into the tube.

Next, the rebar cage is inserted into the pile hole 4 and B
After submerging the pipe 10 and the M pipe 11 in the stabilizing solution, concrete was poured. When the soil was excavated after elapse of 10 days, a crack having a gap of 1 cm to 2 cm was generated along the boundary between the pile main body 6 and the pile head extra portion 5, and the pile Cracks were generated so that the head portion 5 was roughly divided into six. Further, the crack generated in the pile head excess portion 5 did not reach the pile main body 6 side.

[0039]

As described in detail above, according to the pile head treatment method of the cast-in-place concrete pile of the present invention,
By providing the container and the second container at least in the radial direction at the inner peripheral edge of the rebar cage at least in a radial direction, a tremy pipe for placing concrete in the pile hole is provided in the first and second containers. Without contact, even for a concrete pile having a pile diameter of 1600 mm or more, the pile head can be treated. In addition, by attaching the lower end of the second container above the first container and making the cross-sectional area of the first container larger than the cross-sectional area of the second container, a crack is generated on the pile body side by the static crushing material. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a plan view showing the inside of a pile hole for explaining a pile head processing method of a cast-in-place concrete pile according to the embodiment.

FIG. 2 is a side sectional view of the inside of the pile hole.

FIG. 3 is a side view showing a first fixture supporting a first container in the pile head processing method.

FIG. 4 is a plan view showing the first attachment.

FIG. 5 is a side view showing a state where the first attachment is attached to a main bar.

FIG. 6 is a side view showing a second fixture supporting a second container in the pile head processing method.

FIG. 7 is a plan view showing the second attachment.

FIG. 8 is a side view showing a state where the second attachment is attached to a main bar.

FIG. 9 is a plan view showing the inside of a pile hole for explaining the conventional technique.

FIG. 10 is a side sectional view showing the inside of the pile hole.

FIG. 11 is a plan view showing the inside of a pile hole for describing a problem to be solved by the above invention.

FIG. 12 is a side sectional view showing the inside of the pile hole.

[Explanation of symbols]

 2 Reinforcing cage 2a Main reinforcement 4 Pile hole 5 Extra pile head 10 First container 11 Second container

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-59721 (JP, A) JP-A-3-1799991 (JP, A) JP-A-2-266018 (JP, A) 22811 (JP, B2) Japanese Patent Publication No. 61-45012 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) E02D 5/34

Claims (1)

(57) [Claims] [Claim 1] A cylindrical reinforced cage having a static crushing agent previously inserted thereinto is inserted into a pile hole filled with a stable liquid during excavation, and then concrete is poured into the pile hole. In a pile head treatment method for a cast-in-place concrete pile that is crushed by the hydration and expansion action of a static crushing agent, first, the static crushing agent is filled into first and second permeable containers, and the first The cross-sectional area of the container is larger than the cross-sectional area of the second container, and the first container corresponds to the lower end portion of the extra pile portion of the concrete pile head on the inner peripheral edge of the reinforcing bar cage. At a position where the pile is attached along the circumferential direction and at least doubly in the radial direction of the pile hole, and the plurality of second containers are attached to the inner periphery of the reinforcing rod cage at the periphery of the concrete pile head. At a position above the first container of the heap portion, Are mounted vertically at intervals along the direction and at least doubly mounted in the radial direction of the pile hole, and then the reinforcing cage is inserted into the pile hole, and the first and second containers are previously placed in the pile hole. A pile head treatment method for cast-in-place concrete piles, which comprises bringing concrete into contact with a stable liquid filled in the pile and then placing concrete into the pile hole.