JPS6223128B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cast-in-place pile construction method among pile foundation construction methods.

When constructing a concrete structure, there are various methods for installing piles underground.

For example, there is a ready-made pile method in which pre-manufactured piles are driven into the ground, and a method in which reinforced concrete piles are constructed by drilling holes in the ground and pouring concrete directly into the holes.

The present invention relates to an improvement of the latter method.

Next, this conventional construction method will be explained.

(b) After excavating the specified ground, fill it with bentonite liquid.

(b) Next, after inserting the reinforcing bar cage a, lower the tremie pipe to the bottom of the hole and press-fit the fresh concrete e.

(c) The press-fitted fresh concrete e fills the entire hole while pushing up the bentonite liquid from the bottom of the hole.

As described above, an underground pile as shown in FIG. 10 is constructed, and generally speaking, the larger the diameter of the underground pile, the better the stability of the structure above it.

Therefore, in the conventional method, concrete is poured thoroughly into the entire hole which is drilled to a large diameter.

However, as seen in existing hollow piles, even if the area around the center axis of the pile is hollow, it can still withstand sufficient strength for practical use.

Under these circumstances, there has been a desire for an underground pile driving method that reduces the amount of concrete around the central axis of the pile.

On the other hand, in the known hollow cast-in-place pile construction method, a reinforcing bar cage is first inserted into a vertical pile, and a flexible hollow body is installed inside the reinforcing bar cage.

Next, fluid is forced into the hollow body, and after the concrete has been placed and hardened, the fluid is removed and the hollow body is then removed.

There is also a method of installing the hollow body while pressurizing fluid into the hollow body.

Note that instead of injecting fluid into the hollow body, there is a method in which a formwork or the like is installed inside the hollow body, and the formwork or the like is removed after concrete is poured and hardened.

The present invention has been made in response to the above-mentioned demands, and it is possible to construct concrete piles that require much less concrete to be cast compared to conventional piles, even if they are large-diameter piles with good stability for the upper structure. To provide a hollow cast-in-place pile construction method that can be used to construct piles, eliminate work steps, and facilitate work.

Next, an example of the reinforcing bar cage A used in the present invention will be described based on the drawings. (FIG. 1) The reinforcing bar cage of the present invention is composed of a tubular cage 1 and a plurality of hollow bodies 2 located within the tubular cage.

(a) Tube basket The tube basket 1 is made by arranging a plurality of vertical members 11, which serve as main reinforcements, in parallel in a vertical direction in a circumferential manner.

A tube made of vertical members 11 is then bundled together at several locations with annular link bars 12.

(b) Hollow body The hollow body 2 is a hollow cylinder made of a thin iron plate, resin material, paper, etc., and the upper and lower ends of the cylinder part 23 are closed with lids 21.

Its cross-sectional diameter is slightly smaller than the diameter of the tubular basket 1.

Further, the upper and lower lids 21 may have a conical shape, for example, and in that case, the cylindrical portion 23 is closed with the apex thereof directed in the vertical direction.

Furthermore, a small hole 22 is made near the apex.

The diameter of the small hole 22 is such that coarse aggregate in the fresh concrete E (FIG. 4) does not flow into the hollow body 2.

A diamond striation 13 (FIG. 6) that crosses the annular link strut 12 penetrates the wall surface of the hollow body 2 and fixes the hollow body 2 to the tubular cage 1.

In addition, the hole through which the diamond reinforcement 13 penetrates the wall surface of the hollow body 2 is formed so that the coarse aggregate of the ready-mixed concrete E is inserted into the hollow body 2.
Any diameter is sufficient as long as it does not flow inside.

In other words, the bentonite liquid C in the hole may flow into the hollow body 2 through the hole, so there is no need for any special work to plug the hole, and it takes time and effort to attach the hollow body 2 to the barrel 1. do not.

Next, a method of using the above-mentioned reinforcing bar cage A will be explained.

(a) Drilling a hole (Fig. 2) Drilling a hole to a predetermined depth using a drilling machine B while filling bentonite liquid C.

(b) Inserting reinforcing bar cage (Fig. 3) Insert reinforcing bar cage A into the hole filled with bentonite liquid C to the bottom of the hole.

At this time, the bentonite liquid C is poured into the small hole 2 of the hollow body 2.
2 into the hollow body 2 and fills the inside of the hollow body 2. (Fig. 6) (c) Fresh concrete press-in (Fig. 4) The tremie pipe D is lowered to the bottom of the hole filled with bentonite liquid C, and the fresh concrete E is press-fitted.

The press-fitted fresh concrete E pushes up the bentonite liquid C and fills the hole.

At this time, since the small holes 22 of the hollow body 2 are of a size that does not allow the coarse aggregate in the fresh concrete E to flow in, the inside of the hollow body 2 remains filled with the bentonite liquid C, and the hollow body 2 remains filled with the bentonite liquid C. Concrete E is stable within tube cage 1 without any buoyancy acting on it.

Through the above steps, it is possible to construct a concrete pile using fresh concrete E, which has a hollow body 2 filled with bentonite liquid C inside the pile. (Fig. 5) (d) Other Embodiment 1 (Fig. 7) The cross-sectional shape of the hollow body 2 surrounded by the link bars 12 and the vertical members 11 is not only circular as in this embodiment, but also as shown in Fig. 7 1. Other shapes such as 5 rectangles, 5 triangles, 2, 3, 4 are also possible.

(E) Other Example 2 (Fig. 8) In this example, a plurality of hollow bodies 2 were installed in the canopy 1, but as shown in Fig. 8, an integral cylinder extending almost the entire length of the pile was 2, fill the inside with bentonite liquid C and fill the hole with fresh concrete E.
It is also possible to satisfy the following.

(F) Other Embodiment 3 (Fig. 9) The direction of the lid 21 of the hollow body 2 does not necessarily depend on the direction of the cylindrical part 2.
There is no need for the apex to face the outside of the cylindrical part 3, and there is no problem even if one of the vertices faces the inside of the cylindrical part 23; It is fine as long as it is blocked.

Since the present invention is as explained above, the following effects can be expected.

(a) The small holes in the hollow body allow bentonite liquid to flow in, but not ready-mixed concrete.

Therefore, the constructed concrete pile has a hollow body inside which is still filled with the bentonite liquid during construction.

Therefore, the amount of concrete to be press-fitted can be reduced by the capacity of the hollow body, resulting in a cost reduction.

(b) Even large-diameter piles that can maintain good stability for the structure above have a hollow body filled with bentonite liquid inside, so large-diameter piles that require the entire pile to be densely cast in concrete. It is possible to dramatically reduce the amount of concrete compared to the conventional method.

(c) The device of the present invention allows bentonite liquid to flow into the hollow body through a small hole formed in the hollow body.

Therefore, the air inside the hollow body is excluded and the bentonite liquid becomes a weight.

Therefore, when a hollow body is installed in a hole filled with bentonite liquid, the hollow body can be easily installed without being subjected to resistance due to buoyancy.

Furthermore, even if fresh concrete is press-fitted into the hole, buoyancy does not occur because bentonite liquid remains inside the hollow body.

Therefore, the hollow body can be reliably fixed in a predetermined position.

(d) If a hollow body with air still existing inside is installed in a hole filled with bentonite liquid, the hollow body may be deformed by lateral pressure.

In the device of the present invention, since the bentonite liquid flows into the hollow body, the pressure inside and outside the hollow body becomes equal.

Therefore, since no lateral pressure is applied to the hollow body, there is no risk of deformation, and the hollow body can be reliably installed.

(e) The device of the present invention allows bentonite liquid to flow into the hollow body.

Therefore, the diameter of the hole through which the diamond wire penetrates the wall surface of the hollow body may be such that coarse aggregate of fresh concrete does not flow into the hollow body.

In other words, since the bentonite liquid in the hole may flow into the hollow body through the hole, there is no need to perform any special work to close the hole, and no effort is required to attach the hollow body to the cylinder cage.

(F) A hollow body can be attached to the tube cage and inserted into the hole as a whole.

Furthermore, the bentonite liquid naturally flows into the hollow body through the small holes in the hollow body, and the bentonite liquid may remain in the hollow body, so there is no need to inject or drain the bentonite liquid.

Furthermore, there is no need to remove the hollow body.

Therefore, the number of work steps can be reduced compared to the conventional method, and the work can be performed easily.

(g) Since bentonite liquid requires special disposal treatment, it is desirable to minimize the amount of waste to avoid complicating the work.

In conventional devices, when a hollow body is installed in a hole filled with bentonite liquid, the bentonite liquid overflows out of the hole by the volume of the hollow body, so the bentonite liquid overflows out of the hole using a pump etc. from the upper opening of the hollow body. The amount of bentonite liquid to be disposed of must be reduced by injecting it into a hollow body.

However, in the device of the present invention, simply by placing the hollow body in the hole, the bentonite liquid in the hole naturally flows into the hollow body, so there is no need to inject it from the upper opening of the hollow body using a pump or the like.

Therefore, the work can be simplified.

[Brief explanation of the drawing]

Fig. 1: Perspective view of the reinforcing bar cage of the present invention, Nos. 2 to 6
Figure: Explanatory diagram of the construction method, Figure 7. 1-5: Cross-sectional view of reinforcing bar cages having hollow bodies with different cross-sectional shapes, Figures 8-
Figure 9: An explanatory diagram of another embodiment; Figure 10: An explanatory diagram of a conventional concrete pile. DESCRIPTION OF SYMBOLS 1... Tube basket, 2... Hollow body, 11... Vertical member, 12... Link line, 21... Lid body, 22... Small hole, 23... Cylindrical part,
A...Rebar cage, B...Drilling machine, C...Bentonite liquid,
D...Tremy pipe, E...Ready-mixed concrete.

Claims (1)

[Claims] 1. In the hollow cast-in-place pile construction method in which a hollow body is provided inside the hole, bentonite liquid flows into a cylindrical cage made of a plurality of vertical members, but the coarse aggregate in the concrete is Hollow-in-place casting is a method in which a reinforcing steel cage, in which a hollow body with upper and lower lids with a small hole that does not allow water to flow in is placed, is inserted into a hole filled with bentonite liquid, and then concrete is poured. Pile method.