KR101334393B1 - Pre-boring method for micro pile - Google Patents

Abstract

The present invention relates to a pre-boring construction method for a small diameter foundation pile, and more particularly, to excavating a buried hole in the ground, and to put the expansion bit into the buried hole, reaming by the expansion bit Forming a partial expansion in the inner wall of the buried hole, embedding a small diameter foundation pile through the buried hole, and placing and curing concrete in the buried hole.
Therefore, when the small diameter foundation pile is installed on the soft ground, the present invention partially forms the expansion hole in the inner wall of the buried hole by using the expansion bit, and when the concrete is placed through the buried hole, the concrete is filled in the expansion hole so that the shear protrusion And the expansion and shear projections thus formed function as shear keys to increase the shear resistance between the ground and the concrete, so that when compressive and / or tensile forces are applied to the small diameter foundation pile from the structure, at the interface between the ground and the concrete The purpose of this study is to propose a preboring method for a small diameter foundation pile file that can improve structural stability by preventing slip or separation.

Description

PRE-BORING METHOD FOR MICRO PILE}

The present invention relates to a method for pre-boring a small diameter foundation pile for supporting a structure by a composite action of concrete embedded in the buried hole, which is embedded in the ground through a buried hole formed in the ground. Digging a buried hole, inserting an expansion bit into the buried hole, forming a partial expansion in the inner wall of the buried hole through boring by the expansion bit, and embedding a foundation pile through the buried hole. And pouring concrete into the buried hole and curing.

Conventionally, when constructing a foundation pile for the construction of a building or structure, inject concrete into the buried hole to integrate the foundation pile and concrete, and compressive and / or tensile forces applied from the structure by shear resistance between the ground and the concrete. In particular, when the foundation pile is installed in the soft ground, the compressive and / or tensile force is applied to the foundation pile from the structure because sufficient shear resistance cannot be secured at the interface between the ground and concrete due to the characteristics of the soft ground. There was a problem that can not prevent the separation of the ground and concrete.

Therefore, in the present invention, when the foundation pile is installed on the soft ground, the expansion of the buried hole is partially formed by using the expansion bit, and when the concrete is placed through the buried hole, the concrete is filled in the expansion hole and the shear protrusion is formed. The expansion and shear projections thus formed function as shear keys to increase the shear resistance between the ground and the concrete, so that when compressive and / or tensile forces are applied to the foundation pile from the structure, slip at the interface between the ground and concrete, It is characterized by improving the structural stability by preventing the separation phenomenon.

In general, when a building or a structure is erected, a foundation work is performed to reinforce the ground to support the upper structure according to the condition of the ground or the load of the structure.

If the ground contacted to the structure, such as a hard ground, has sufficient rigidity to support it, the foundation work can be carried out directly on it, but in the case of a soft ground that is not, the pile is embedded or piled to prevent ground subsidence. After the designated construction to improve the reinforcement of the ground, the foundation will be carried out on it.

At this time, the file to be constructed on the soft ground is divided into steel pipe file, PC file, PHC file, etc. according to the material,

In addition, according to the shape and use, it is divided into a steel sheet pile, tubular pile, H- section steel pile, etc., The tubular pile is generally used in the soft ground as described above.

In addition, when the basic reinforcement work for the expansion and reconstruction of an existing building or the basic reinforcement work for a narrow area where large excavation equipment cannot be used, the micro file, which is a small diameter file, is used.

The micropile is usually a file having a diameter of 250 mm or less, and can support a large load by small diameter drilling using small equipment, compared to a general tubular pile, and can be drilled on any type of ground because of its small diameter. There is an advantage that can be constructed at any angle from to horizontal.

The micropile is inserted into a pile hole drilled to a predetermined diameter and length, and then installed through a process of integrating the micropile with the ground by filling a filler such as concrete or grout material.

On the other hand, the support force of the micropile is determined by the tip bearing force of the tip portion in contact with the ground and the frictional force generated between the outer peripheral surface of the micropile and the inner wall of the ground.

In this case, when the compressive force is applied to the micropile from the structure, the tip of the microil is embedded in the ground, and the tip of the concrete or the crowded material integrated with the microil is supported by the ground, so that the compressive force from the structure is to some extent. It can secure resistance.

However, in the case of soft ground, slippage and separation occur at the interface between ground and concrete, because the tensile force applied from the structure must be resisted only by friction between the ground and concrete.

Hereinafter, the present invention will be described in detail. However, the "small diameter basic file" expressed below refers to a microfile.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems,

In case of installing small diameter foundation pile on the soft ground, partly expand the inner wall of the buried hole by using the expansion bit, and when the concrete is placed through the buried hole, the concrete is filled in the expansion hole and the shear projection is formed. The formed expansion and shear projections function as shear keys to increase the shear resistance between the ground and concrete,

When compressive and / or tensile force is applied to the small-diameter foundation piles from the structure, one purpose is to improve the structural stability by preventing slip or separation at the interface between the ground and concrete.

In another aspect, the present invention comprises a pile main body is a pile body embedded in the ground through the buried hole, and the wing member connected to the pile main body, arranged to be spaced apart from each other,

In particular, the wing member enlarges the acupressure area by the concrete to increase the binding force between the small-diameter foundation pile and the concrete, whereby the small-diameter foundation pile is efficiently applied when the compressive and / or tensile force is applied to the small-diameter foundation pile from the structure. Resistance to maximize shear performance,

In addition, when the concrete is being poured while the pile body is embedded in the buried hole, the wing member performs the function of a spacer supporting the pile body in the buried hole. Another object is to improve the convenience and installation performance of the installation work can be prevented from tilting or tilting.

In addition, the present invention is provided with a first reinforcing material connected to the wing member, and a second reinforcing material connected to the first reinforcing material arranged in the vertical direction is provided to increase the adhesion performance of the small diameter foundation pile and concrete of the small diameter foundation pile It is another object to reinforce shear performance.

In addition, the present invention is that the wing member is made of a multi-layer structure, the wing members of each layer arranged up and down are arranged in a mutually staggered form,

It is another object of the present invention to upgrade the shear performance by the wing members by reinforcing the wing members arranged up and down on the shear weak areas formed between the wing members of each layer.

Furthermore, the present invention increases the adhesion strength between the wing member and the concrete by introducing a shear connecting member in the form of a perfobond rib as the wing member, and in particular, concrete flows into the through hole of the perforbond rib to form a dowel. It is another object of the present invention to resist shear force in the vertical direction and to prevent separation from concrete, that is, material separation in the horizontal direction.

In addition, the present invention is to extend the acupressure region by the concrete by introducing a wave-shaped shear connector to the wing member, in particular in the vertical direction applied from the structure by expanding the vertical acupressure region by the concrete between the bone and bone of the wing member Another object is to improve shear performance by more effectively resisting compressive and / or tensile forces.

The pre boring method of the small diameter foundation pile according to the present invention

(a) digging a buried hole in the ground;

(b) inserting an expansion bit into the buried hole and forming partial expansion in the inner wall of the buried hole by reaming by the expansion bit;

(c) embedding a small diameter foundation pile through the buried hole; And

(d) pouring concrete into the buried hole, curing step is made, including,

The concrete is filled in the expansion formed in the step (b) is characterized in that to increase the shear resistance between the ground and the concrete.

Pre-boring construction method of a small diameter foundation pile according to the present invention is the pile body embedded in the buried hole; And a pile connected to the pile body and spaced apart from each other, thereby increasing shear performance by synthesizing with the concrete, and functioning as a spacer for supporting the pile body in the buried hole when the concrete is poured. It characterized in that it comprises a; wing member provided.

The annular first reinforcement is connected to the wing member according to the present invention,

A second reinforcement is connected to the first reinforcement and arranged in a vertical direction.

The wing member according to the invention is composed of a multi-layer structure,

The wing members of each layer arranged up and down are characterized in that they are arranged in a staggered form.

The wing member according to the present invention is characterized by increasing the dowel performance of concrete as a shear connector in the form of perfobond ribs.

The wing member according to the invention is characterized in that to increase the acupressure resistance by the concrete in the form of wave shear connector.

The pre boring construction method of the small diameter foundation pile according to the present invention is to install concrete through the buried hole after forming a partial expansion in the buried hole inner wall using the expansion bit when installing the small diameter foundation pile in the soft ground When the expansion is filled with concrete to form shear projections, the expansion and shear projections thus formed as a shear key to increase the shear resistance between the ground and concrete,

When compressive and / or tensile forces are applied to the small diameter foundation piles from the structure, structural stability can be improved by preventing slip or separation at the interface between the ground and concrete.

In another aspect, the present invention comprises a pile main body is a pile body embedded in the ground through the buried hole, and the wing member connected to the pile main body, arranged to be spaced apart from each other,

In particular, the wing member enlarges the acupressure area by the concrete to increase the binding force between the small-diameter foundation pile and the concrete, whereby the small-diameter foundation pile is efficiently applied when the compressive and / or tensile force is applied to the small-diameter foundation pile from the structure. Resistance to maximize shear performance,

In addition, when the concrete is being poured while the pile body is embedded in the buried hole, the wing member performs the function of a spacer supporting the pile body in the buried hole. It can be prevented from being tilted or tilted, so that the convenience of installation work and the construction performance can be improved.

In addition, the present invention is provided with a first reinforcing material connected to the wing member, and a second reinforcing material connected to the first reinforcing material arranged in the vertical direction is provided to increase the adhesion performance of the small diameter foundation pile and concrete of the small diameter foundation pile It is possible to reinforce shear performance.

In addition, the present invention is that the wing member is made of a multi-layer structure, the wing members of each layer arranged up and down are arranged in a mutually staggered form,

It is possible to upgrade the shear performance by the wing member by reinforcing the wing members arranged up and down mutually reinforcing the shear weak portion formed between the wing members of each layer.

Furthermore, the present invention increases the adhesion strength between the wing member and the concrete by introducing a shear connection member in the form of a perfobond rib as the wing member, and in particular, concrete flows into the through-hole of the perforbond rib to form a dowel. As a result, the shear force in the vertical direction can be resisted, and in the horizontal direction, separation from the concrete, that is, material separation can be prevented.

In addition, the present invention is to extend the acupressure region by the concrete by introducing a wave-shaped shear connector to the wing member, in particular in the vertical direction applied from the structure by expanding the vertical acupressure region by the concrete between the bone and bone of the wing member By more effectively resisting compressive and / or tensile forces, shearing performance can be improved.

1 is a flowchart showing a pre boring construction method of a small diameter foundation pile according to the present invention,
2 and 3 is a process chart showing a small diameter foundation pile construction method according to the present invention,
4 is a perspective view showing a small diameter foundation pile according to the present invention,
Figure 5 is a perspective view showing another embodiment of the wing member of the small diameter foundation pile according to the present invention,
Figure 6 is a perspective view showing another embodiment of the wing member of the small diameter foundation pile according to the present invention.

Hereinafter, a small diameter foundation pile construction method according to the present invention will be described with reference to the accompanying drawings.

As shown in Figures 1 to 5 small diameter foundation pile construction method according to the present invention

(a) digging a buried hole 1 in the ground G;

(b) Inserting the expansion bit 3 into the buried hole 1, and forming a partial expansion 5 in the inner wall of the buried hole 1 through reaming by the expansion bit 3 Making;

(c) embedding a small diameter foundation pile (FP) in the embedding hole (1); And

(d) placing concrete (C) in the buried hole (1), curing step is made, including.

As shown in Figure 1 to Figure 3 in the pre-boring construction method of a small diameter foundation pile according to the present invention, step (a) (S100) is

It is a process of forming the buried hole 1 by drilling a hole in the ground G with an excavator.

Although the depth and diameter of the buried hole (1) in step (a) (S100) varies depending on the ground conditions at the construction site,

In the present invention, the diameter of the buried hole (1) is approximately 200mm to 250mm in diameter, is excavated to a depth of 20m or more is formed so as to embed a small diameter micropile.

As shown in Figures 1 to 3 in the small diameter basic pile construction method according to the present invention, step (b) (S200) is

The expansion bit 3 is injected into the embedding hole 1, and a partial expansion 5 is formed in the inner wall of the embedding hole 1 by reaming by the expansion bit 3.

In the step (b) (S200), the expansion bit 3 is inserted into the buried hole 1 and descends, and when the expansion bit 30 is stopped at a predetermined position, the bit is rotated by the centrifugal force. As it opens, the inner wall surface of the buried hole 1 is excavated by the rotational force to form an expansion hole 5 having an annular groove shape.

In this state, the expansion bit 3 is lowered again to rotate another bit in the stopped state at the position where the expansion 5 is formed, thereby forming another expansion 5.

This operation is repeated to form a plurality of expansion holes (5) in the inner wall (1),

When the reaming operation by the expansion bit 3 is completed, the expansion bit 3 is lifted and discharged to the buried hole 1.

As shown in FIG. 2B, the shape of the expansion hole 5 formed by the expansion bit 3 may be a variety of shapes such as a polygonal shape, a 'c' shape, a trapezoidal shape, or a semi-elliptic shape. It is possible to be formed in the form.

As shown in Figure 1 to Figure 3 in the pre-boring construction method of a small diameter foundation pile according to the present invention, step (c) (S300) is

The small-diameter foundation pile FP is inserted into the embedding hole 1, press-fitted and embedded in the ground.

In the step (c) (S300), the small diameter base pile FP is as shown in Figs.

Pile body 10 is embedded in the ground (G) through the buried hole (1); And connected to the pile body 10, arranged to be spaced apart from each other, to increase the shear performance by the synthesis action with the concrete (C), when placing the concrete (C), in the buried hole (1) And a shear connector having a function as a spacer for supporting the pile body 10.

In general, the ground (G) to excavate the small diameter foundation pile (FP) to form a buried hole (1) of a constant depth,

In this case, in the case of the micropile, the depth of the buried hole 1 is excavated about 20m or more, and the diameter is about 200mm to about 250mm.

Hereinafter, as described above, the structure is supported by the synthesis of the small diameter foundation pile (FP) and concrete (C),

With reference to the accompanying drawings, the core technical idea according to the present invention for improving the shearing performance by increasing the binding force between the small diameter base pile (FP) and concrete (C) will be described in more detail.

As shown in Figure 4 to Figure 6 in the small diameter base file according to the present invention, the pile body 10 is

It is inserted in the embedding hole 1, press-fits the tip, and is embedded in the ground G.

The pile body 10 is composed of a steel bar of about 65mm to 75mm in diameter,

At this time, in the case of the pile body 10, in particular, the micro-pile as described above, the cross-sectional area of the tip portion is formed in a very narrow cylindrical shape, and when the compressive force is received by the structure, the tip bearing force is not very large, The tip of the pile FP may be caused to sink into the ground (G).

On the contrary, when the tensile force is applied upward to the pile body 10, the binding force between the outer circumferential surface of the boring pile body 10 and the concrete C is weak and sufficient shearing performance cannot be guaranteed, so that the pile powder rises or is pulled upward. Problems may arise.

Therefore, in the present invention, the wing body 20 to increase the shear performance of the pile body 10 and the concrete (C) so that the pile body 10 having a small diameter, that is, the micropile can more stably support the structure. Introduced,

This will be described in more detail below.

4 to 6, the wing member 20 according to the present invention is

It is connected to the outer circumferential surface of the pile body 10, arranged to be spaced apart from each other to increase the shearing performance of the small diameter foundation pile (FP) through the synthesis action with the concrete (C) filled through the buried hole (1).

The wing member 20 is composed of a multi-layer structure arranged in multiple stages in the vertical direction on the outer peripheral surface of the pile body 10,

Each layer is provided with a plurality of wing members 20, which is shown in the accompanying drawings that three wing members 20 are provided for each layer.

This is because when the small diameter foundation pile FP is a small diameter micro pile, since the diameter of the buried hole 1 is narrow, too many wing members 20 are provided.

It is difficult to inject the buried holes 1 into the concrete C and the grout material having a particle size of a predetermined size, and to completely fill the buried holes 1 without supply even if it is compacted.

Therefore, the wing member 20 is preferably to be provided with an appropriate number to fill the buried hole (1) without voids through the injection and compaction of concrete (C), grout material.

In particular, the wing member 20 according to the present invention by expanding the pressure area by the concrete (C) by ensuring a sufficient contact area with the concrete (C),

This can increase the resistance to the compressive force and / or tensile force applied from the structure it is possible to ensure the structural stability by improving the shear performance of the small diameter foundation pile (FP).

In the wing member 20 having a multi-layer structure, as shown in FIGS. 4 and 5 (A), the wing members 20 of each layer are arranged on the same line up and down, respectively, or FIGS. 4 to 6 ( It can be arranged in a staggered form as shown in B).

However, as shown in FIGS. 4 and 5 (A), when the wing members 20 of each layer are arranged in the same line up and down, shear weak areas are generated between the wing members 20 of each layer.

In this case, while the wing member 20 of each layer is arranged in the same line up and down, shear weak spots are formed at the same position,

4 to 6 (b), when the wing members 20 of each layer are arranged in a staggered form up and down, the wing members 20 located above and below each other to compensate for the shear weak areas between each other, reinforcement It is more advantageous to improve the shear performance.

Furthermore, in order to strengthen the adhesion between the wing member 20 and the concrete (C) in the small diameter foundation pile (FP) according to the present invention

An annular first reinforcement 30 is connected to the wing member 20, and is provided with a second reinforcement 40 connected to the first reinforcement 30 and arranged in a vertical direction.

The first reinforcing material 30 may be connected to both the upper or lower or upper and lower portions of the wing member 20, or may be connected to the side of the wing member 20,

In addition, the second reinforcing material 40 is vertically connected to the second reinforcing member connected to the wing member 20 of each layer.

At this time, the first reinforcing material 30 is the wing member 20, and the second reinforcing material 40 is welded to the first reinforcing material 30, respectively,

The first reinforcing material 30 serves as a connecting material for connecting the second reinforcing material (40).

The first and second reinforcing members 40 are wing members for filling the voids of concrete (C) or grout material as described above when the small diameter foundation pile FP according to the present invention is a small diameter micro pile. Introduced to compensate for the limitation of the number of installation and the shape of (20)

Through this, by supplementing the limitations as described above serves to reinforce the shear performance between the small diameter foundation pile (FP) and concrete (C).

Furthermore, the wing member 20 according to the present invention can be manufactured in various forms,

Hereinafter, various embodiments of the wing member 20 and features thereof will be described in more detail.

First, as shown in FIG. 5, the wing member 20 according to the present invention is a shear connector 21 in the form of a perfobond rib.

It is available in flat or 'Y' or 'a' shaped perforbond ribs.

As shown in FIG. 5A, the through-hole ribs have through holes 21a formed therein.

The buried hole 1 is filled with concrete (C) or grout material flows into the through hole (21a) to form a dowel (dowel) to resist shear force in the vertical direction, concrete (C in the horizontal direction) ) And the separation, that is, the material separation phenomenon can be blocked to increase the shear performance and adhesion to the concrete (C).

In addition, as shown in (B) of Figure 5 is shown in Figure 4 (B), the wing members 20 of each layer are arranged in a staggered up and down shape, the wing members 20 located in the upper and lower sides are shear weak areas between each other. By supplementing and reinforcing, it is possible to improve the shear performance.

Next, as shown in FIG. 6, the wing member 20 according to the present invention has a wave-like shear connector 23.

As shown in (A) of FIG. 6, the vertical pressure resistance by the concrete C between the valleys and the valleys of the shear thermal binder 23 is increased so that the vertical compressive force and / or tensile force applied from the structure is applied. It has the feature to double the shearing performance by making it more effective.

6 (B) is also shown as another modification of the shear connector 23 in the form of a wave

In this case, the shear connector is formed in a wave form in the vertical direction, and the shear connector arranged vertically is bent in different directions and arranged to cross each other.

This has the advantages of the wave type shear connector and the advantages of the cross type shear connector.

In addition, the through hole 23a is formed in the shear connection member 23 in FIG. 6B so that the buried hole 1 is filled with concrete C, or grout flows into the through hole 23a to form a dowel ( It is also desirable to form a dowel) to resist shear forces in the vertical direction and to separate the concrete (C) from the horizontal direction, that is, to prevent material separation, thereby increasing shear performance and adhesion to the concrete (C). .

Furthermore, although not shown in the accompanying drawings, through-holes are provided in the wing member in the form of a flat plate or a straight plate of FIG. 4, or the shear connecting member in the form of a wave in FIG. It is also preferable to form a dowel by the concrete to give a more improved shear performance.

In addition, although not shown in the accompanying drawings, when the reinforcing bars are reinforced in the through-holes, the dowel performance of the concrete is enhanced by the reinforcing bars, and also has a direct influence on the stiffness change that appears from the yield load.

In addition, depending on the reinforcement amount of the reinforcing bar can be improved the shear resistance capacity and ductility action by the shear friction.

As shown in Figures 4 to 6, the classification according to the shape of the wing member has the following differences in shear strength, fabrication convenience and field workability.

First, in terms of shear strength, the wing member of the 'Y' shaped perforbond rib type is the most excellent, and the shear strength decreases in the order of the wave member and the direct wing member.

This is because the wing member of the 'Y'-shaped perforbond rib type has increased shear strength compared to the other two types of wing members due to the acupressure resistance and the dowel performance of the concrete by the through hole.

Next, in terms of ease of manufacture, the simplest form of wing member is the easiest to manufacture, and the relatively complicated 'Y' shaped perforbond rib-shaped wing member, or the wave-shaped wing member is a straight plate-shaped wing The workability is inferior to that of the member.

In addition, in terms of field workability, the simplest form of the wing member has the best shape, and the relatively complex form of the 'Y' shaped perforbond rib wing member or the wave form wing member is relatively straight plate wing member. Poor construction property

And as the shape of the wing member is simplified, it can be seen that the ease of manufacture or excellent field workability,

In particular, when installing micro piles with small diameters in terms of field workability, buried holes are also small in diameter, so the more complicated the shape of the wing member is, the more difficult it is to completely fill the buried holes during concrete pouring. Do.

Meanwhile, the wing member 20 according to the present invention performs a function as a spacer for supporting the pile body 10 in the buried hole 1.

This is inserted into the buried hole (1), the pile body (10) embedded in the ground (G) is inclined to one side or inclined to one side by the injection pressure of the concrete (C) or grout material injected into the buried hole (1) The phenomenon can be prevented.

That is, the outer surface of the wing member 20 is arranged close to the inner wall of the buried hole (1) to restrict and support the movement of the pile body 10, the concrete (C) is injected into the buried hole (1) B, the pile body 10 is prevented from flowing even in the injection pressure of the grout material, thereby ensuring the ease of installation of the small-diameter foundation pile FP, thereby improving the construction performance.

Furthermore, the formation position of the expansion is preferably provided between the wing members arranged up and down as shown in FIG.

This is because when the expansion is formed at the position where the wing members of each layer are provided, the thickness of the concrete may be reduced by the wing members, thereby reducing the shear capacity.

Therefore, it is preferable to form the expansion between the wing members arranged up and down to ensure sufficient thickness of the concrete.

As shown in Figures 1 to 3 in the small diameter basic pile construction method according to the present invention, step (d) (S400) is

Concrete (C) is poured into the buried hole (1), and curing is a step of integrating the small diameter foundation pile (FP) and concrete (C).

In the step (d) (S400), the concrete (C) is poured into the buried hole (1) while the small-diameter foundation pile (FP) is embedded in the ground (G) in the step (c) (S300). When the concrete (C) is filled in the expansion hole 5 and cured, an annular shear projection 7 corresponding to the expansion hole 5 is formed.

The expansion (5) and the shear projections 7 according to the present invention is to perform a function as a shear key between the ground (G) and concrete (C),

This is because when the small diameter foundation pile (FP) is installed in the soft ground, the shear resistance between the ground (G) and the concrete (C) is weak due to the characteristics of the soft ground, and the compressive and / or tensile force is applied to the small diameter foundation pile from the structure. At this interface, slip may occur,

As a result, the phenomenon in which the ground G and the concrete C are separated can be prevented from occurring.

That is, the expansion (5) and the shear projections (7) increase the shear resistance between the ground (G) and concrete (C) when the compression and / or tensile force is applied to the small diameter foundation pile (FP) from the structure (5) and the shear projections (7) can be prevented to prevent the slip from occurring at the interface between the ground (G) and concrete (C),

This prevents the ground (G) and the concrete (C) to be separated to improve the structural stability.

In this case, the tip of the small diameter foundation pile (FP) is embedded in the ground (G), and the concrete (C) tip integrated with the small diameter foundation pile (FP) is applied from the structure by being supported by the ground (G). It can secure some resistance against losing compressive force,

The tensile force applied from the structure must be resisted only by friction between the ground (G) and concrete (C).

By introducing the expansion (5) and shear projections (7) according to the present invention by increasing the shear resistance between the ground (G) and concrete (C) by maximizing the resistance to the tensile force between the ground (G) and concrete (C) Slip or separation can be prevented more completely.

On the other hand, the ground is usually composed of hard ground near the surface, the soft ground is often located at the bottom,

In such a ground structure, the wing member does not need to be disposed in the hard ground, but in the soft ground, it is preferable to arrange the wing member so that shear performance can be achieved through a compounding action with a small diameter foundation pile and concrete.

In addition, the expansion and shear projections are to increase the shear resistance at the interface between the ground and the concrete, it is preferable to be placed on the hard ground as described above to increase the resistance between the ground and the concrete.

In the above description with reference to the accompanying drawings pre-boring construction method of the present invention the small diameter base piles, mainly described in a specific shape and direction, the present invention can be variously modified and changed by those skilled in the art, such variations and modifications Should be construed as being included in the scope of the invention.

FP: Foundation file G: Ground
C: concrete
1: buried hole 3: expansion bit
5: expansion 7: shear projection
10: File body
20: wing member 21: shear connection member of the shape of perforbond rib
21a: through hole 23: wave type shear connector
23a: through hole
30: first reinforcing material
40: second reinforcing material
S100: (a) Step S200: (b)
S300: (c) Step S400: (d)

Claims (6)

(a) digging a buried hole in the ground;

(b) inserting an expansion bit into the buried hole and forming a partial expansion (5) in the inner wall of the buried hole through reaming by the expansion bit;

(c) inserting a small diameter base file through the buried hole,
The small diameter base file,
A pile body 10 inserted into the buried hole 1; And
It is made to include a wing member 20 is arranged spaced apart from each other connected to the pile body,
The annular first reinforcement 30 is connected to the wing member,
It is connected to the first reinforcing material 30, and further provided with a second reinforcing material 40 arranged in a vertical direction,
The wing member 20 is composed of a multi-layer structure, the wing member of each layer disposed up and down is characterized in that the configuration is arranged in a mutually staggered form,

(d) placing and curing concrete in the buried hole; comprising, the wing member 20 connected to the outer circumferential surface of the pile body 10 is the pile in the buried hole when the concrete is placed It has a function as a spacer for supporting the main body, characterized in that the shear performance is increased by the composite action of the wing member 20 and the concrete connected to the outer peripheral surface of the pile body 10,

The pre-boring method of the small diameter foundation pile, characterized in that the concrete is filled into the expansion (5) formed in the step (b) to increase the shear resistance between the ground and the concrete.
delete delete delete The method of claim 1,
The wing member 20 is a pre-boring method for the small diameter foundation pile, characterized in that to increase the performance of the dowel (Dowel) of concrete as a shear connection material in the form of perfobond ribs (perfobond rib).
The method of claim 1,
The wing member 20 is a pre-boring method of the small diameter foundation pile, characterized in that to increase the acupressure resistance by the concrete in the form of wave shear connector.

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