JPH04238913A - Non-reinforced in-situ concrete pile and its manufacture - Google Patents

Abstract

PURPOSE:To effectively and efficiently construct a non-reinforced in-situ concrete pile by a method in which a earthquake-proof reinforcing part is connected to a concrete pile containing a dispersed steel reinforcing fiber for the portion from the upper end to a necessary depth portion of the pile. CONSTITUTION:A concrete pile 2 containing a uniformly dispersed steel reinforcing fiber 3 is formed. An earthquake-proof reinforcing part 4 is connected to the pile 2 for the portion from the upper end to a necessary depth portion for lateral vibration of the pile 2 to form a non-reinforced in-situ concrete pile 1. As the reinforcing part 4, round or angular steel tubes, H-, I-, or grooved shape steels, and reinforcing bar cage may be selectively used. The lowering of the operating efficiency with insertion of reinforcing bars can thus be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cast-in-place concrete pile and a method for constructing the same.

0002

[Prior Art] Conventionally, as cast-in-place concrete piles,
It is generally known that a reinforcing bar cage having a length extending over the entire length of the pile is buried inside the pile, thereby imparting strength to the pile, particularly earthquake resistance. However, in order to construct conventional cast-in-place concrete piles with reinforced steel, a vertical hole is first dug in the ground while injecting bentonite liquid, then a long reinforcing bar cage is erected inside the vertical hole, and then a vertical hole is placed in the vertical hole. The method used is to pour concrete, but since it takes time to erect the reinforcing steel cages, the soil in the bentonite solution settles to the bottom of the vertical hole, and if fresh concrete is poured as it is,
Since the strength of the lower end of the resulting concrete pile is significantly reduced, extra work is required to discharge the settled earth and sand out of the hole using an air lift before concrete pouring, and the required work area must be prepared for assembling the reinforcing cage. Not only that, but the number of specialized reinforcing bar workers has been decreasing in recent years, and it is very difficult to recruit the necessary number of specialized reinforcing bar workers.Furthermore, when the length of concrete piles is changed, the length of reinforcing bar cages must be adjusted accordingly. There were many problems associated with reinforcing steel cages, such as the fact that increasing and decreasing the number of cages was extremely time-consuming.

0003

Problem to be Solved by the Invention The first invention of the present application aims to provide a cast-in-place concrete pile without reinforcing bars that does not require the conventional reinforcing cage and has sufficient strength. An object of the present invention is to efficiently and effectively construct a cast-in-place concrete pile without reinforcement according to the first invention.

0004

[Means for Solving the Problems] In order to solve the above problems, the first invention of the present application provides a pile made of fiber-reinforced concrete containing reinforcing fibers in a uniformly dispersed state, the fiber-reinforced concrete pile comprising: proposed an unreinforced cast-in-place concrete pile to which seismic reinforcing material with a length extending from its upper end to the required depth for reinforcement against lateral shake earthquakes was proposed, and the present application No. 2
The invention involves drilling a vertical hole in the ground by injecting a hole wall collapse prevention liquid, pouring ready-mixed concrete in which reinforcing fibers are dispersed and mixed into the excavated vertical hole, and before pouring the ready-mixed concrete, Or, after pouring and before the concrete hardens, insert seismic reinforcing material into the vertical hole with a length extending from the top end of the fiber-reinforced concrete pile to be constructed to the depth required for reinforcement against a lateral shake earthquake;
We propose a method for constructing non-reinforced cast-in-place concrete piles in which the seismic reinforcing material is combined with the fiber-reinforced concrete piles by concrete hardening.

[0005] The above-mentioned "reinforcing fibers" in the present invention include metal fibers such as steel, aluminum alloy, and copper alloy, synthetic fibers such as nylon, polypropylene, and polyester, or glass fibers, rock fibers, slag fibers, and other various fibers. The thickness, length, content, etc. of the fibers are selected appropriately depending on the properties and purpose of the fibers, and the shapes can be processed into various shapes such as straight lines, curves, waves, and spirals. be. In addition, various other reinforcing materials such as cylindrical or rectangular steel pipes, H-shaped, I-shaped, channel-shaped steel shapes, reinforcing steel cages, etc. are selectively used as the above-mentioned "seismic reinforcement material". As the method for "excavating a vertical hole in the ground" in the second invention of the present application, an earth drill method, a Benoto method, a reverse circulation method, an earth auger method, etc. are used as appropriate.

[0006]

[Example] Unreinforced cast-in-place concrete pile (1) in Figure 1
The pile body (2) is made of steel fiber reinforced concrete containing steel fibers in a uniformly dispersed state, and the steel fibers (3)...
As an example, as shown in FIG. 2, it has a shape in which wave-shaped bent parts are continuous on both sides of a straight part, and in this example, the thickness is about 0.2
~0.6 mm and a length of approximately 20 to 50 mm, and a cylindrical seismic reinforcement is installed on the outer peripheral surface of the pile body in the range from the upper end of the pile body (2) to the depth that requires reinforcement against lateral shake earthquakes. A steel pipe (4) is covered with the pile body (2) in a connected state. (5) is a spiral protrusion protruding from the inner peripheral surface of the reinforcing steel pipe (4), thereby strengthening the connection with the pile body (2). According to experiments, the mechanical properties of the unreinforced cast-in-place concrete pile made of steel fiber-reinforced concrete in this example are: a marked improvement in tensile strength and toughness, a marked increase in crack strength, and Excellent impact resistance, fatigue failure is 200 times compared to 20,000 times for reinforced concrete piles.
The strength against side-to-side earthquakes has been further improved by adding seismic reinforced steel pipes.

Another embodiment (1a) of FIG. 3 has a pile body (2a) made of concrete reinforced with continuous chevron-shaped nylon fibers (3a) as shown in FIG. This is an example in which an earthquake-reinforced H-shaped steel (4a) is buried in a bonded state at the axial center position inside the pile main body up to a depth that requires reinforcement.

Next, an embodiment of a method for constructing a cast-in-place concrete pile without reinforcement will be described. As an example, the method for constructing the unreinforced cast-in-place concrete pile (1) in Figure 1 is as shown in Figure 5 (A). While drilling a vertical hole in the ground using the excavation bucket (10), bentonite liquid is injected into the vertical hole to prevent collapse of the hole wall. H) is excavated. The vertical hole (H) is filled with bentonite liquid in which excavated soil is suspended. Next, (C) As shown in the figure, insert the tremie tube (11) into the vertical hole (H).
Then, as shown in the figure (D), from the lower end of the opening of the tremie pipe (11), the ready-mixed concrete (12) mixed with steel fibers in a dispersed state is pushed out into the vertical hole (H). The tremie pipe (11) is gradually pulled up, and the steel fiber mixed ready-mixed concrete (12) is sufficiently poured into the vertical hole (H) as shown in the figure (E). At the time of pouring the fresh concrete, the excavated soil in the bentonite liquid is not yet settled and is in a suspended state, so the soil will not be concentrated at the bottom of the fresh concrete. next(
F) Ready-mixed concrete (12
) is hardened, an earthquake-reinforced steel pipe ( 4) is press-fitted, and the reinforcing steel pipe (4) is positioned so that the upper end of the reinforcing steel pipe (4) almost coincides with the upper end of the vertical hole (H) opening, and waits for the fresh concrete (12) to harden. When the fresh concrete hardens, the unreinforced cast-in-place concrete pile (1) shown in FIG. 1 is obtained.

As another example of the method for constructing cast-in-place concrete piles without reinforcement, vertical holes (H) are excavated in steps (A) and (B) in the example of FIG.
) into the predetermined position of the vertical hole (H), then (C) inserting the tremie pipe (11), (D), (E) pouring the steel fiber mixed concrete (12), and In some cases, concrete is hardened and cast-in-place concrete piles without reinforcement are constructed. Steel fiber mixed ready-mixed concrete in this example (12)
When pouring concrete into the vertical hole (H), the earth and sand in the bentonite solution has not yet settled to the bottom of the hole, so it is unlikely that the earth and sand will be concentrated at the bottom of the poured concrete. .

0010

Effects of the Invention The unreinforced cast-in-place concrete pile of the first invention of the present application has superior mechanical properties compared to conventional cast-in-place concrete piles with reinforcing steel, and has sufficient strength against side-to-side earthquakes due to the seismic reinforcement. Moreover, since the conventional rebar cages can be removed, there is no need for a work space for assembling the rebar cages, there is no need to hire specialized rebar workers, and the length of concrete piles can be reduced. Its utility value is extremely high, as changes can be made immediately without any problems.

[0011] The method for constructing unreinforced cast-in-place concrete piles according to the second invention of the present application can omit the time-consuming step of constructing a reinforcing cage in the conventional construction method, so it is possible to inject a hole wall collapse prevention liquid and drill a vertical hole. After that, pouring of ready-mixed concrete into the vertical hole can be started without waiting for a long time, and thereby the ready-mixed concrete can be placed before the earth and sand in the hole wall collapse prevention liquid settles to the bottom of the vertical hole. This eliminates the conventional extra work of draining settled earth and sand out of the hole before pouring fresh concrete, making it possible to build piles with extremely high work efficiency.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a cast-in-place concrete pile without reinforcement.

FIG. 2 is an enlarged front view of reinforcing steel fibers.

FIG. 3 is a longitudinal sectional view of another embodiment.

FIG. 4 is an enlarged front view of reinforcing nylon fibers.

[Fig. 5] (A), (B), (C), (D), (E), (
F) is a schematic cross-sectional view showing the steps of a cast-in-place concrete pile construction method without reinforcement.

[Explanation of symbols]

1, 1a Unreinforced cast-in-place concrete piles 2, 2a
Pile body 3 Reinforcing steel fiber 3a Reinforcing nylon fiber 4 Earthquake reinforcement steel pipe 4a Earthquake reinforcement H-shaped steel H Vertical hole 12 Steel fiber mixed ready-mixed concrete

Claims (2)

[Claims] Claim 1: A pile made of fiber-reinforced concrete containing reinforcing fibers in a uniformly dispersed state, the fiber-reinforced concrete pile having a length extending from its upper end to a depth necessary for reinforcement against a lateral shake earthquake. Non-reinforced cast-in-place concrete piles with seismic reinforcement. [Claim 2] A vertical hole is excavated in the ground by injecting a hole wall collapse prevention liquid, and ready-mixed concrete mixed with reinforcing fibers is poured into the excavated vertical hole, and the ready-mixed concrete is poured. Before or after pouring and before the concrete hardens, seismic reinforcing material with a length extending from the top end of the fiber-reinforced concrete pile to be constructed to the depth required for reinforcement against a lateral shake earthquake is inserted into the vertical hole, and the concrete hardens. A method for constructing a non-reinforced cast-in-place concrete pile, which comprises combining the seismic reinforcing material with the fiber-reinforced concrete pile.