WO2009072824A1

WO2009072824A1 - Foundation structure using micro pile and method for forming the same

Info

Publication number: WO2009072824A1
Application number: PCT/KR2008/007175
Authority: WO
Inventors: Sun Guen Lee
Original assignee: Metro T & C Co., Ltd
Priority date: 2007-12-04
Filing date: 2008-12-04
Publication date: 2009-06-11
Also published as: US20100247245A1; CN101918642A; KR100873060B1

Abstract

A foundation structure using a micro pile and a method of forming the same. A cover steel plate is disposed at an upper end of the micro pile, and has a micro pile hole. The micro pile is connected with others in series thanks to the use of two through eight protrusions formed on a lower end thereof. Grout or concrete is injected into a hollow channel of the micro pile, and enhances a conglomerating force between the micro pile and the ground abutting the micro pile to thereby strengthen the force supporting the ground in the vertical and horizontal directions.

Description

[DESCRIPTION] [invention Title]

FOUNDATION STRUCTURE USING MICRO PILE AND METHOD FOR FORMING THE SAME [Technical Field]

The present invention relates, in general, to a foundation structure using a micro pile and a method of forming the same, and more particularly, to a foundation structure using a micro pile and a method of forming the same, in which a cover steel plate is disposed at an upper end of the micro pile, and has a micro pile hole, in which the micro pile is connected with others in series thanks to the use of two through eight protrusions formed on a lower end thereof, and in which grout or concrete is injected into a hollow channel of the micro pile, and enhances a conglomerating force between the micro pile and the ground abutting the micro pile to thereby form a vertical and horizontal supporting force.

[Background Art] A micro pile generally refers to a pile having a small diameter (less than 300 mm). A foundation structure using this micro pile occupies a small space, but it can support great load. As such, this foundation structure is mainly applied to locations into which large-size equipment cannot enter due to spatial restrictions. FIG. 1 is a cross-sectional view illustrating a conventional foundation structure using a micro pile.

As illustrated, the foundation structure is configured of a pipe 10 inserted into a hole drilled in foundation ground, that is, the ground making up the foundation, and a micro pile 20 inserted into the pipe 10. Cement milk or mortar is injected into a space between the pipe 10 and the micro pile

20, and then is cured in the space.

In the case in which the hole is deep, numerous micro piles

20 are connected by connectors 30. Generally, spacers 40 are used in order to maintain a uniform interval between an inner circumference of the pipe 10 and an outer circumference of the micro pile 20.

A support plate 50 is coupled at an upper portion of the micro pile 20 by double nuts 60a and 60b. This structure is penetrated into foundation concrete 70, and serves to transmit the load of an upper structure to the foundation ground.

Meanwhile, the foundation ground can be divided into a soft bed 2 composed of clay, sand, etc. and a support bed 3 composed of rock. Assuming that there is no pipe 10, the cement milk or mortar injected into the drilled hole 1 will run out through pores of the soft bed 2. The chance of this happening in the support bed 3 is very slim. As such, the pipe 10 is configured to penetrate only into the soft bed 2. On the assumption that a section of the soft bed 2 (ranging from the ground surface to line a-a) into which the micro pile 20 penetrates cannot exert strength, that section is referred to as a free field A. Further, on the assumption that a section of the support bed 3 (ranging from line a-a to line b-b) into which the micro pile 20 penetrates can exert actual strength as a foundational structure, that section is referred to as an anchorage field B.

Since it is the support bed 3 that has strength capable of resisting the load of the upper portion, a lower end of the micro pile 20 is required to penetrate the support bed 3 to a predetermined depth in order to ensure the stability of the entire structure. At this time, the depth of the anchorage field B generally must range from between 4 and 5 m.

However, in the case in which the soft bed 2 of the foundation ground is excessively deep, the total length of the micro piles 20 becomes excessive in order to penetrate up to the depth of the anchorage field B. As such, a plan for solving this problem is urgently required. [Disclosure] [Technical Problem]

Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a foundation structure using a micro pile and a method of forming the same, in which grout or concrete is injected into a hollow channel in a micro pile, and in which the grout or concrete is discharged and cured through discharge holes formed in the micro pile, so that a conglomerating force between the micro pile and the ground can be enhanced, and so that force for supporting the ground in vertical and horizontal directions can be strengthened to reinforce the ground and thus to prevent the ground from collapsing.

[Technical Solution] In order to achieve the above object, according to one aspect of the present invention, there is provided a foundation structure using a micro pile. A cover steel plate is fitted around an upper end of the micro pile and includes a micro pile hole. Bolt holes spaced apart from the micro pile hole by a predetermined distance are formed in the cover steel plate, and bolts are inserted into the bolt holes via and through washers and each have a length equal to a distance from the upper end of the micro pile to intermediate discharge holes of the micro pile. An upper joint is formed with two through eight cylinders on the upper end of the micro pile, and a lower joint is formed with two through eight protrusions on a lower end of the micro pile so as to be engaged with the upper joint. The lower joint has half the length of the upper joint, and the micro pile is connected with others in series so as to reinforce the ground. Grout or concrete is injected into a hollow channel of the micro pile, discharged through the intermediate discharge holes and the joint discharge holes, and penetrates into the ground abutting the micro pile such that the micro pile is conglomerated with the ground. Here, the micro pile may include pile upper and lower screw threads of a predetermined length at the upper and lower ends thereof.

Further, the joint discharge holes may include spaces defined by engagement between the lower joint and the upper joint.

According to another aspect of the present invention, there is provided a foundation structure using a micro pile. A cover steel plate is fitted around an upper end of the micro pile and includes a micro pile hole. Nut holes spaced apart from the micro pile hole by a predetermined distance are formed in the cover steel plate, and T-shaped nuts are screwed onto protrusions of an upper joint inserted into the nut holes of the cover steel plate. The upper joint is formed with two through eight cylinders on the upper end of the micro pile, and a lower joint is formed with two through eight protrusions on a lower end of the micro pile so as to be engaged with the upper joint. The lower joint has half the length of the upper joint, and the micro pile is connected with others in series so as to reinforce ground. Grout or concrete is injected into a hollow channel of the micro pile, discharged to the intermediate discharge holes and the joint discharge holes, and penetrates into the ground abutting the micro pile such that the micro pile is conglomerated with the ground. Here, the micro pile may include pile upper and lower screw threads of a predetermined length at the upper and lower ends thereof.

[Advantageous Effects]

According to embodiments of the present invention, the foundation structure using a micro pile and the method of forming the same are configured to inject the grout or concrete into the hollow channel in the micro pile, and to allow the grout or concrete to be discharged and cured through discharge holes formed in the micro pile, so that a conglomerating force between the micro pile and the ground can be enhanced, and so that force for supporting the ground in vertical and horizontal directions can be strengthened to reinforce the ground and thus to prevent the ground from collapsing.

Further, the micro pile is fixed and stabilized by a layer of the grout or concrete discharged into the ground through the respective discharge holes thereof. [Description of Drawings]

FIG. 1 is a cross-sectional view illustrating a conventional foundation structure using a micro pile.

FIG. 2 is a top plan view illustrating a foundation structure using a micro pile according to a first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a foundation structure using a micro pile according to a first embodiment of the present invention. FIGS. 4 through 6 illustrate a foundation structure using a micro pi]e according to a first embodiment of the present invention in a top plan, cross-sectional and top plan view, respectively. description of symbols of the main parts in the drawings> 31: bolt 32: washer

33: T-shaped nut 51: pile upper screw threads 52: intermediate discharge hole 53: pile lower screw threads 54: lower joint 55: upper joint 56: joint discharge hole 300: cover steel plate 500: micro pile 1000: hollow channel

200: floor slab 3000: metal bar

5000: grout or concrete

[Best Mode] Reference will now be made in greater detail to an exemplary embodiment of the invention with reference to the accompanying drawings.

FIG. 2 is a top plan view illustrating a foundation structure using a micro pile according to a first embodiment of the present invention, and FIG. 3 is a cross-sectional view illustrating a foundation structure using a micro pile according to a first embodiment of the present invention.

FIGS. 2 and 3 illustrate a foundation structure using a micro pile according to a first embodiment of the present invention in a top plan and cross-sectional view, respectively .

As illustrated in FIGS. 2 and 3, the foundation structure using a micro pile according to a first embodiment of the present invention is configured so that the micro pile 500 further reinforces and supports the load of the ground under a floor slab 2000, in which metal bars are embedded. The micro pile 500 has a hollow channel 1000, into which grout or concrete 5000 can be injected, from an upper end to a lower end thereof. When injected into the hollow channel 1000, the grout or concrete 5000 is discharged into the ground abutting the micro pile 500 through intermediate discharge holes 52 between the upper and lower ends of the micro pile and joint discharge holes 56 at the upper and lower ends of the micro pile. Here, the micro pile 500 is inserted into a cover steel plate 300 at the upper end thereof. The cover steel plate

300 is provided with a micro pile hole 1000, and bolt holes spaced apart from the micro pile hole 1000 by a predetermined distance. At this time, bolts 31 are inserted into the bolt holes via and through washers 32. Further, each bolt 31 has a length similar to that between the upper end of the micro pile 500 and the intermediate discharge hole 52. Each washer

32 includes an ordinary circular or quadrilateral washer. Here, the foundation structure using a micro pile is constructed in such a manner that the micro pile 500 is separated from the bolts 31 in order to reinforce a wide range of ground, thereby distributing the load of the ground.

The micro pile 500 and the bolts 31 are inserted into the single cover steel plate 300.

Further, the micro pile 500 is provided with pile upper and lower screw threads 51 and 53 of a predetermined length at upper and lower portions thereof so as to be more easily constructed. As the micro pile 500 rotates to move into the ground, the pile upper and lower screw threads 51 and 53 serve as drill bits.

Besides, when constructed, the micro pile 500 is connected with others in sequence, and then moves into the ground until an optimal supporting force acts on the ground. At this time, the connection between the upper and lower micro piles 500 is made by engagement between a lower joint 54 of the upper micro pile and an upper joint 55 of the lower micro pile so as to form the joint discharge holes 56.

To this end, the upper joint 55 is provided with two through eight cylinders on the upper end of the micro pile 500. Here, the cylinders may have screw threads.

Further, the lower joint 54 is provided with two through eight protrusions in the lower end of the micro pile 500 so as to be engaged with the upper joint 55. Here, preferably, the lower joint 54 is half as long as the upper joint 55.

Here, it is apparent that the joint discharge holes 56 are spaces defined by engagement between the lower joint 54 and the upper joint 55.

The grout or concrete 5000 is injected into the hollow channel 1000 of the micro pile 500, and then is discharged to the intermediate and joint discharge holes 52 and 56. As a result, the grout or concrete 5000 penetrates into the ground abutting the micro pile 500, so that the micro pile 500 is conglomerated with the ground and the floor slab 2000. The upper and lower piles 500 are conglomerated with the ground by the grout or concrete 5000 discharged through the joint discharge holes 56.

Then, the grout or concrete 5000 is poured up to an upper surface of the floor slab such that the upper end of the micro pile 500, cover steel plate 300, washers 32 and bolts 31 are not exposed to the outside. <Second Embodiment>

FIGS. 4 through 6 illustrate a foundation structure using a micro pile according to a first embodiment of the present invention in a top plan, cross-sectional and top plan view, respectively .

As illustrated in FIGS. 4 though 6, the foundation structure using a micro pile according to a second embodiment of the present invention is configured so that the micro pile 500 further reinforces and supports the load of ground under a floor slab 2000, in which metal bars are embedded. The micro pile 500 has a hollow channel 1000, into which grout or concrete 5000 can be injected, from an upper end to a lower end thereof. When injected into the hollow channel 1000, the grout or concrete 5000 is discharged into the ground abutting the micro pile 500 through intermediate discharge holes 52 between the upper and lower ends of the micro pile and joint discharge holes 56 at the upper and lower ends of the micro pile. Here, the micro pile 500 is provided with an upper joint 55 having two through eight cylinders on the upper end thereof. At this time, the cylinders may have screw threads.

The micro pile 500 is inserted into a cover steel plate 300 at the upper end thereof. The cover steel plate 300 is provided with a micro pile hole 1000, and approaches the micro pile 500 such that the micro pile hole 1000 is aligned with the hollow channel 1000 of the micro pile. At this time, the cover steel plate is provided with nut holes spaced apart from the micro pile hole 1000 by a predetermined distance. T-shaped nuts can be inserted into the nut holes of the cover steel plate 300. Thus, the T-shaped nuts can be screwed onto the upper joint 55 of the micro pile through the nut holes of the cover steel plate 300.

Each T-shaped nut is designed to have a grip at the upper end of a hollow cylinder such that a user can directly grasp and turn it. The hollow cylinder is provided with female screw threads .

In addition, when constructed, the micro pile 500 is connected with others in sequence, and then moves into the ground until an optimal supporting force acts on the ground. At this time, the connection between the upper and lower micro piles 500 is made by engagement between a lower joint 54 of the upper micro pile and an upper joint 55 of the lower micro pile so as to form the joint discharge holes 56. To this end, the upper joint 55 is provided with two through eight cylinders on the upper end of the micro pile 500. Here, the cylinders may have screw threads.

The grout or concrete 5000 is injected into the hollow channel 1000 of the micro pile 500, and then is discharged to the intermediate and joint discharge holes 52 and 56. As a result, the grout or concrete 5000 is penetrated into the ground abutting the micro pile 500, so that the micro pile 500 is conglomerated with the ground and the floor slab 2000. The upper and lower piles 500 are conglomerated with the ground by the grout or concrete 5000 discharged through the joint discharge holes 56. Then, the grout or concrete 5000 is poured up to an upper surface of the floor slab such that the upper end of the micro pile 500, cover steel plate 300, and T-shaped nuts 33 are not exposed to the outside.

Now, a method of forming the foundation structure using a micro pile according to the present invention will be described below in detail.

First, the ground is excavated to a width and depth between 50 cm and 500 cm.

Then, drilling work for burying a pipe in the ground is carried out. The drilling work is for burying the pipe in the ground in advance so as to be able to insert a hollow pipe into the ground and then to easily insert the micro pile

500 through the hollow pipe.

The micro piles 500 are inserted into the ground through the hollow pipe one by one.

To this end, the micro piles 500 are connected in such a manner that the upper joint 55 of the first micro pile 500 is engaged with the lower joint 54 of the second micro pile 500.

Then, the micro piles 500 are connected and inserted into the ground until an optimal supporting force acts on the ground, and then the hollow pipe buried by the drilling work is removed.

The cover steel plate 300 is installed on the upper end of the uppermost micro pile 500. At this time, the cover steel plate 300 approaches the micro pile 500 such that the micro pile hole thereof is aligned with the hollow channel 100 of the micro pile 500. Then, the T-shaped nuts are screwed onto the protrusions of the upper joint 55 inserted into the nut holes of the cover steel plate. Subsequently, the grout or concrete 500 is injected into the hollow channel 1000. At this time, the grout or concrete 500 is deposited from the lower end of the lowermost micro pile 500 due to its weight, and penetrates into the ground through the angled holes, i.e. the intermediate and joint discharge holes 52 and 56, of each micro pile 500 by injection pressure. It is apparent that, as the grout or concrete 500 cures, the micro piles 500 become conglomerated with the ground. Further, it is apparent that the cured grout or concrete 5000 reinforces the horizontal supporting force .

Finally, the grout or concrete 5000 is poured up to the surface of the ground such that the upper end of the micro pile 500, cover steel plate 300, and T-shaped nuts 33 are not exposed to the outside. Although the invention has been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the appended claims and their equivalents.

[industrial Applicability]

The micro pile generally refers to a pile having a small diameter (less than 300 mm). A foundation structure using this micro pile occupies a small space, but it can support a great load. As such, this foundation structure is mainly applied to locations in which large-size equipment cannot enter due to spatial restrictions. In the foundation structure using a micro pile and the method of forming the same, the cover steel plate having the micro pile hole is disposed at the upper end of the micro pile, and the micro pile is connected with others in series thanks to the use of two through eight protrusions formed on the lower end thereof. Further, the grout or concrete is injected into the hollow channel of the micro pile, and enhances a conglomerating force between the micro pile and the ground abutting the micro pile to thereby strengthen the force supporting the ground in the vertical and horizontal directions. Thus, the foundation structure using a micro pile and the method of forming the same can be readily applied to existing and new constructions.

Claims

[CLAIMS] [Claim l]

A foundation structure using a micro pile, in which: a cover steel plate including a micro pile hole is fitted around an upper end of the micro pile; bolt holes formed in the cover steel plate are spaced apart from the micro pile hole by a predetermined distance, into which bolt holes are inserted bolts via and through washers, wherein each bolt has a length equal to a distance from the upper end of the micro pile to intermediate discharge holes of the micro pile; an upper joint is formed with two through eight cylinders on the upper end of the micro pile, and a lower joint is formed with two through eight protrusions on a lower end of the micro pile so as to be engaged with the upper joint; the lower joint has half a length of the upper joint, and the micro pile is connected with others in series so as to reinforce ground; and grout or concrete is injected into a hollow channel of the micro pile, discharged through the intermediate discharge holes and joint discharge holes, and penetrates into the ground abutting the micro pile such that the micro pile becomes conglomerated with the ground.

[Claim 2] The foundation structure as set forth in claim 1 , wherein the micro pile includes pile upper and lower screw threads of a predetermined length at the upper and lower ends thereof.

[Claim 3]

The foundation structure as set forth in claim 1, wherein the joint discharge holes are spaces defined by engagement between the lower joint and the upper joint.

[Claim 4]

A foundation structure using a micro pile, in which: a cover steel plate including a micro pile hole is fitted around an upper end of the micro pile; nut holes are formed in the cover steel plate spaced apart from the micro pile hole by a predetermined distance, and T- shaped nuts are screwed onto protrusions of an upper joint inserted into the nut holes of the cover steel plate; the upper joint is formed with two through eight cylinders on the upper end of the micro pile, and a lower joint is formed with two through eight protrusions on a lower end of the micro pile so as to be engaged with the upper joint; the lower joint has half a length of the upper joint, and the micro pile is connected with others in series so as to reinforce ground; and grout or concrete is injected into a hollow channel of the micro pile, discharged through the intermediate discharge holes and joint discharge holes, and penetrates into the ground abutting the micro pile such that the micro pile becomes conglomerated with the ground.

[Claim 5]

The foundation structure as set forth in claim 4 , wherein the micro pile includes pile upper and lower screw threads of a predetermined length at the upper and lower ends thereof.

[Claim 6]

The foundation structure as set forth in claim 4, wherein the joint discharge holes are spaces defined by engagement between the lower joint and the upper joint.