JPH05222723A - Forming method for foundation pile - Google Patents

Abstract

PURPOSE:To increase frictional resistance force in horizontal direction and vertical direction so as to increase supporting force by forming a concrete pile in one body with wing pieces, and pressing and fitting a part of each wing piece in the ground so as to construct a foundation pile. CONSTITUTION:The insides of wing pieces 10, 11, 12, 13 are received in a steel pipe casing 4, and these are hung down into a drilled hole 3. When the steel pipe casing 4 is reached to the bottom, a hydraulic device 7 is operated so as to move pistons 7A outward in the radial direction and press all the wing pieces outward. Hereby, the knife-like outside end parts 10B, 11B, 12B, 13B are pressed in the inner wall of the drilled hole 3. Next, when all the wing pieces are perfectly drawn out of slits 4A, 4B, 4C, 4D, the pistons 7A are retreated and separated from them. Next, the steel pipe casing 4 is rotated on the opposite side of the projecting direction of pins 10A, 11A, 12A, 13A, detached from the through holes of piece parts 5A, 5B, 5C, 5D, and all the wing pieces 10-13 are disengaged from the piece parts 5A-5D. Finally, after the steel pipe casing 4 is pulled up, concrete is placed in the drilled hole 3 so as to form a foundation pile.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a foundation pile, in which concrete is placed in an excavated hole to construct a foundation pile of cast-in-place concrete pile.

[0002]

2. Description of the Related Art Generally, in a method of constructing a foundation pile, first, an excavation hole is excavated in the ground. The drill hole is formed by supplying water by a water feed pump into a vertically driven casing pipe, by an earth drill in a waterless drill, or by another drilling machine. After completion of this excavation,
A rebar cage is arranged in the excavation hole with a predetermined distance from the inner wall of the excavation hole.

Next, a tremie pipe is inserted to the bottom of the excavation hole to perform hole bottom treatment, and then the mud water accumulated in the excavation hole is drained by an underwater pump. Then, concrete is placed in the excavation hole through the tremie pipe, and the casing pipe is pulled out to complete the construction of the foundation pile.

In this way, when constructing a foundation pile of cast-in-place concrete pile, the ultimate bearing capacity of the ground, the allowable bearing capacity and the allowable bearing capacity of the ground, and the ultimate bearing capacity, the allowable bearing capacity and the allowable bearing strength of the pile are determined. Considering this, it is necessary to design the foundation pile.

The ultimate bearing capacity, allowable bearing capacity, and allowable bearing capacity of the ground are as shown in FIGS. 14 to 17, respectively.
Distribution of frictional resistance F2 to F5 on the pile surface according to the type of strata
Difference occurs. Here, P is vertical load, Rp is transfer stress, and St1, St2 and St3 are soft clay layer, upper sand layer and intermediate sand layer, respectively.

On the other hand, the supporting force of the foundation pile is composed of the peripheral frictional force of the support layer and the supporting force of the pile tip. When the bearing capacity of the foundation pile is, for example, in the vertical direction (pile axial direction), considering the load surface of the pile, the tip of the pile is considered to penetrate into the soil layer as the foundation sinks, as shown in FIG. Therefore, the equivalent load surface is considered to be above the pile tip surface. Conventionally, the acting surface S of the load is a surface (L / 3) which is above the tip of the pile by ⅓ of the pile length L, but this shows the distribution of the peripheral resistance acting on the pile on the peripheral surface of the pile. Diagonal line F1
This is because the triangular shape is assumed as shown in, and the action surface of the resultant force of the peripheral resistance is considered.

[0007]

In the conventional method of constructing a foundation pile, when designing the foundation pile, if the pile length is short, the friction resistance against the load from the direction perpendicular to the pile axis (horizontal direction) is obtained. Since the force is small, the pile rotates or moves as a rigid body. For this reason, it is necessary to increase the frictional resistance force in order to fully exhibit the performance as a foundation pile.

Further, when the pile length is long, there is a problem that an extremely large bending stress is applied to the foundation pile due to a load from a direction (horizontal direction) perpendicular to the pile axis. Therefore, when designing a foundation pile, there is a problem that a larger foundation pile must be built in consideration of the bearing capacity of the foundation pile.

The present invention has been made in view of the above problems, and it is possible to increase the horizontal and vertical frictional resistance of the foundation pile to increase the supporting force and to stabilize the foundation pile upper structure. It provides a method of constructing a foundation pile that can be done.

[0010]

In the method of constructing a foundation pile according to the present invention, a cylindrical casing having therein a wing piece that can be expanded outward by a press-fitting means can be lifted out into an excavation hole. After suspending and holding a part of the wing piece by press fitting into the hole wall, the press fitting means and the tubular casing are separated from the wing piece and lifted out of the excavation hole, and concrete is placed in the excavation hole. The foundation piles were constructed.

[0011]

In the method of constructing a foundation pile according to the present invention, when the foundation pile is constructed, the concrete pile and the wing piece are integrally molded, and a part of the wing piece is press-fitted into the ground to be fitted in the horizontal direction. And increase the vertical friction resistance to increase the bearing capacity of the foundation pile.

[0012]

The present invention will be described below with reference to the illustrated embodiments.
FIG. 1 is a vertical cross-sectional view showing an apparatus used for carrying out an embodiment method of the present invention, FIG. 2 is a cross-sectional view of an essential part of FIG. 1, and FIGS. 3 and 4 are respectively a foundation pile of this embodiment. It is a longitudinal section showing a process of construction.

As shown in FIG. 1, an excavation machine (not shown) excavates an excavation hole 3 in the ground 2. Drill hole 3
Inside, the steel pipe casing 4 as a tubular casing is suspended by a suspension means (not shown). An annular member 5 is fitted to a predetermined position on the outer periphery of the steel pipe casing 4, and the annular member 5 has a top portion 5 having a through hole formed in the circumferential direction.
A, 5B, 5C and 5D (four in this embodiment) are formed so as to project at a predetermined interval. Further, the steel pipe casing 4 is formed with slits 4A, 4B, 4C and 4D below the top portions 5A, 5B, 5C and 5D.

A hydraulic device support mechanism 6 is provided inside the steel pipe casing 4, and is lifted up and down integrally with the steel pipe casing 4 by a suspension means (not shown). The hydraulic device support mechanism 6 is provided with a hydraulic device 7 such as a hydraulic jack as a press-fitting means at a predetermined position. The hydraulic device 7 is a piston 7
The piston 7A is provided with A and is moved in the radial direction by a control device (not shown).

By the way, in the top portions 5A, 5B, 5C and 5D of the steel pipe casing 4, as shown in FIG. 5, wing pieces 10, 11, 12 and 13 formed of triangular plate bodies are provided with pins 10A and 11A. , 12A, 13A, respectively, so as to be rotatable and removable. Wings 10,
One of the lower inner sides of 11, 12, 13 is detachably attached to the piston 7A of the hydraulic device 7 (see FIGS. 6 and 7). Furthermore, the outer ends 1 of the wings 10, 11, 12, 13
0B, 11B, 12B and 13B are sharply formed in a knife shape over a predetermined region.

For this reason, when suspending the steel pipe casing 4 in the excavation hole 3, first, the blade pieces 10, 11, 12, 13 are first suspended.
The pins 10A, 11A, 12A, 13A of the top 5A,
Inserted into the through holes 5B, 5C, 5D, the wing pieces 10, 11,
The inside of 12, 13 is attached to the piston 7A of the hydraulic device 7. Then, the hydraulic device 7 is operated to retract the piston 7A toward the center of the steel pipe casing 4, and the wing pieces 10, 1
After accommodating 1, 12, 13 in the steel pipe casing 4 from the slits 4A, 4B, 4C, 4D, the steel pipe casing 4 is suspended in the excavation hole 3.

Next, the process of constructing the foundation pile will be described while describing the operation. The inside of the wing pieces 10, 11, 12, and 13 is housed in the steel pipe casing 4, and the steel pipe casing 4 is suspended in the excavation hole 3 (see FIG. 3). The steel pipe casing 4 is adapted to rotate by a suspension means (not shown). When the steel pipe casing 4 reaches the bottom, the hydraulic device 7 is operated to move the piston 7A outward in the radial direction, and
Press 0, 11, 12, 13 outwards (see FIG. 4). The knife-shaped outer ends 10B, 11B, 12B, 13B of the blade pieces 10, 11, 12, 13 are press-fitted into the hole wall of the drill hole 3 in accordance with the advancement of the piston 7A.

The wing pieces 10, 11, 12 and 13 have predetermined areas press-fitted into the ground 2 so that the slits 4A, 4B, 4C and 4 are formed.
When the piston 7A retreats completely from D, it is separated from the piston 7A. Next, the steel pipe casing 4 is attached to the pins 10A, 11A, 12 by a suspension means (not shown).
A, 13A is rotated in the direction opposite to the protruding direction, and pin 10
A, 11A, 12A, 13A is the top portion 5A, 5B, 5
The winglets 10, 11, 12, 1 disengage from the C and 5D through holes.
3 is disengaged from the top portions 5A, 5B, 5C and 5D.

At this time, the winglets 10, 11, 12, 13
Is held in a state in which a predetermined area is fitted in the ground 2 and a part of which is exposed from the hole wall of the excavation hole 3. And
The steel pipe casing 4 is lifted to the outside of the excavation hole 3 by a suspension means (not shown).

Finally, concrete is poured into the excavation hole 3 to complete the foundation pile construction (see FIG. 12). In the above embodiment, the winglets 10, 11, 12, 13 have two stages, but the number of stages is not limited to this, and may be one stage, or multiple stages of two or more stages depending on the type of formation. You may comprise.

FIG. 8 is an explanatory view showing an apparatus used for carrying out the method of another embodiment of the present invention, and shows an example in the case of the excavation hole 53 having a short pile length. The wing pieces 20, 21, 22, 23 are formed vertically according to the pile length. An annular member 35 is fitted in the vicinity of the lower end of the steel pipe casing 34, and a hydraulic device support mechanism 36 is extended below the steel pipe casing 34. The hydraulic device support mechanism 36 is provided with a plurality of hydraulic devices 37 at predetermined positions so as to apply a desired pressing force in accordance with the press-fitted areas of the blades 20, 21, 22, 23.

FIG. 10 is an explanatory view showing an apparatus used for carrying out the method of another embodiment of the present invention, and shows an example in which it is applied to the tip bottom expanding part of the bottom expanding pile 63 or the like. Wings 40, 41, 4
2 and 43 are formed wide according to the tip bottom expanded portion 63A. An annular member 75 is fitted near the lower end of the steel pipe casing 74, and a hydraulic device support mechanism 76 is extended below the steel pipe casing 34. Hydraulic device support mechanism 76
Is provided with a hydraulic device 77 at a predetermined position, and the blade 40,
A desired pressurizing force is applied in accordance with the press-fitted area of the tip bottom expanded portion 63A of 41, 42, 43.

[0023]

As described above, according to the present invention, when the foundation pile is built, the concrete pile and the wing piece are integrally molded, and part of the wing piece is fitted into the ground, so that the horizontal direction and The frictional resistance in the vertical direction can be increased to increase the supporting force of the foundation pile, and the upper structure of the foundation pile can be stabilized. Moreover, since the wing pieces can bear the horizontal load and the frictional resistance, the horizontal cross-section of the foundation pile can be reduced in diameter to further reduce the size of the foundation pile, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an apparatus used for carrying out a method according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part of FIG.

FIG. 3 is a vertical sectional view showing a process of constructing a foundation pile.

FIG. 4 is a vertical sectional view showing a process of constructing a foundation pile.

5 is a perspective view of a main part of FIG. 1. FIG.

FIG. 6 is an explanatory diagram showing the operation of the hydraulic device.

FIG. 7 is an explanatory diagram showing the operation of the hydraulic device.

FIG. 8 is a vertical cross-sectional view showing an apparatus used for carrying out the method of another embodiment of the present invention.

9 is a cross-sectional view of the main part of FIG.

FIG. 10 is a vertical cross-sectional view showing an apparatus used for carrying out a method according to another embodiment of the present invention.

11 is a cross-sectional view of the main part of FIG.

FIG. 12 is an explanatory diagram showing a state in which the foundation pile has been completely built.

FIG. 13 is an explanatory diagram showing the distribution of the peripheral surface resistance acting on a general pile on the peripheral surface of the pile.

FIG. 14 is an explanatory diagram showing the distribution of frictional resistance on the pile peripheral surface according to the type of formation.

FIG. 15 is an explanatory diagram showing the distribution of frictional resistance on the pile peripheral surface according to the type of stratum.

FIG. 16 is an explanatory diagram showing the distribution of frictional resistance on the peripheral surface of the pile according to the type of formation.

FIG. 17 is an explanatory diagram showing the distribution of frictional resistance on the peripheral surface of the pile according to the type of formation.

[Explanation of symbols]

 3, 53, 63 Excavation holes 4, 34, 74 Steel pipe casing (cylindrical casing) 7, 37, 77 Hydraulic system (press-fitting means) 10-13, 20-23, 40-43 Wing piece

Claims (1)

[Claims] 1. A tubular casing, in which a wing piece that can be expanded outward by a press-fitting means is housed, is suspended so that it can be lifted out into an excavation hole, and a part of the wing piece is hung by the press-fitting means. After being press-fitted and held in the hole wall, the press-fitting means and the tubular casing are separated from the blade pieces and lifted out of the excavation hole, and concrete is placed in the excavation hole to construct a foundation pile. How to build foundation piles.