KR102234544B1 - Leading-edge extension type micropile device for reinforcing structures - Google Patents

Abstract

A micro-pile device for structure reinforcement comprises: a micro-pile (10) inserted into a drilling hole (3) formed in the ground; and a front end support unit (30) having a plate (31) which supports a bottom end part (11) of the micro-pile (10) on an upper surface thereof, surface-contacts with a floor of the drilling hole (3) on a lower surface thereof, and has a trapezoid cross-section, of which an upper edge is longer than a lower edge, disposed to be spaced from a wall surface of the drilling hole (3) and having a wedge (33) protruding from the plate (31) to a lower side to penetrate the floor of the drilling hole (3).

Description

Structure reinforcement micropile device {LEADING-EDGE EXTENSION TYPE MICROPILE DEVICE FOR REINFORCING STRUCTURES}

The present invention relates to a micropile method, and more particularly, to a micropile apparatus for reinforcing structures.

In general, when reinforcing the foundation in consideration of seismic resistance for existing buildings or structures (hereinafter referred to as'structures'), if it is difficult to enter large equipment, construction with small equipment is not recommended. Small diameter piles with a diameter of 300 mm or less are used as possible, and such a small diameter pile is called a micropile. In particular, micropiles of 75mm or less are often used in consideration of the economics of construction.

Micropile is usually installed by forming a perforated hole in the ground consisting of a soft layer such as a soil layer or sediment layer and a rock layer that is a supporting layer below it, inserting the micropile into the hole, and then filling the cement grout material. Steel pipes (casings) are generally installed in the soft layer to prevent the walls of the perforated holes from collapsing.

These microfiles generally have the following problems.

First, the cross-sectional area of the tip portion is small, so that the bearing force of the tip portion is not large, and when a compressive load (buckling load) is applied due to this, the load is concentrated on the tip portion and the micropile digs into the ground, causing settlement.

Second, when a compressive load is applied, the micropile may be bent due to weak resistance of the wall of the perforated hole in the soft layer. The steel pipe installed in the soft layer only serves to prevent the perforated hole wall from collapsing, so it cannot withstand a large compressive load.

Third, when a pull-out load (tensile load) is applied to the micropile, the friction between the micropile and the wall of the perforated hole may be weak, resulting in a problem that the micropile is pulled out.

Fourth, a slurry such as sand or rock debris accumulates on the bottom of the perforated hole, so that the supporting force of the micropile can be reduced.

In order to solve this problem, various techniques have been proposed in the prior art. For example, Korean Patent No. 10-0956879 (hereinafter referred to as “prior art 1”), Korean Patent No. 10-1182802 (hereinafter referred to as “prior art 2”), and Korean Patent No. 10-1359488 (hereinafter referred to as “prior art 2”). Prior Art 3'), Korean Patent No. 10-1181543 (hereinafter referred to as'prior art 4'), and the like.

Prior Art 1 focuses on the distribution of compressive loads, Prior Art 2 focuses on improving the bearing capacity for tensile and compressive loads, and Prior Art 3 focuses on distributing compressive loads and preventing settling. 4 focuses on improving the bearing capacity for tensile and compressive loads and preventing settling, and both have limitations in that there is no consideration for buckling prevention and slurry discharge in the soft layer.

A first object of the present invention is to provide a micropile device for reinforcing structures in which the slurry accumulated on the bottom of the perforated hole can be easily discharged while preventing the subsidence of the ground.

A second object of the present invention is to provide a micropile device for reinforcing structures capable of preventing the micropile from bending even when a compressive load is applied in a soft layer.

In order to achieve the above object, according to the present invention, the micropile 10 inserted into the perforated hole 3 formed in the ground; And the end portion 11 of the micropile 10 is supported on its upper surface, and the bottom surface is in surface contact with the bottom of the perforated hole 3, and the upper side is arranged to be spaced apart from the wall surface of the perforated hole 3, and the upper side is the lower side. Includes; a plate 31 having a longer trapezoidal cross section, and a tip support portion 30 including a wedge 33 protruding downward from the plate 31 and penetrating the bottom of the perforated hole 3. A micropile device for reinforcing structures is provided.

The plate 31 has a circular planar shape, the diameter of the upper surface is 90% or less of the diameter of the perforated hole 3, the diameter of the lower surface is greater than the diameter of the micropile 10, the micro It is preferable that the side inclination angle of the plate 31 with respect to the axis of the pile 10 is 45° or more.

The structure reinforcing micropile device further includes a buckling reinforcement part 60 installed on the soft layer 1 of the ground, and the buckling reinforcement part 60 is the micropile 10 at the top of the soft layer 1 And an upper support member 61 that is screwed with, and a lower support member 62 that is screwed with the micropile 10 under the soft layer 1, and the upper support member 61 and the lower support member A plurality of buckling support bars 63 connecting the 62 may be included.

According to the present invention, it is possible to easily discharge the slurry accumulated on the bottom of the perforated hole upward while preventing the subsidence of the ground.

In addition, it is possible to prevent the micropile from bending even when a compressive load is applied in the soft layer.

1 is a schematic diagram of a micropile apparatus for reinforcing structures according to a first embodiment of the present invention.
2 is a schematic perspective view of the tip support portion 30 in FIG. 1.
3 is a schematic cross-sectional view of the pressing plate 50 in FIG. 1.

Prior to the detailed description of the present invention, main terms used in the present specification are first defined.

In'top' and'bottom','top' and'bottom','top' and'bottom','top' and'bottom', etc.,'top' and'bottom' are not based on the direction of gravity. It is a concept according to the depth direction or length direction of the formed hole.

The'tip part' of the micropile refers to a part of the micropile to which the link part according to the present invention is coupled as a part of the ground corresponding to the rock layer, which is a support layer.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a micropile device for reinforcing structures according to a first embodiment of the present invention.

As shown, the micropile device for reinforcing a structure according to the first embodiment (hereinafter, also abbreviated as a'micropile device') includes a micropile 10, a moving ring 20, and a tip support part 30. Wow, it is configured to include a link portion 40 and a pressing plate (50). The micropile device may further include a buckling reinforcement part 60.

The micropile 10 is a member that is inserted into a perforated hole 3 formed in the ground consisting of a soft layer 1 such as a soil layer or a sediment layer, and a rock layer 2 that is a support layer below it, and is integrated with the cement grout material to provide a supporting force. Male threads are formed on the outer circumferential surface of the micropile 10. A steel pipe 4 may be installed in the soft layer 1, and a gap maintaining member (not shown) for maintaining a gap between the steel pipe 4 and the micropile 10 may be installed in the micropile 10. When a plurality of micropiles 10 are installed, the plurality of micropiles 10 are coupled by a coupler 5.

The moving ring 20 is screwed with an upper portion of the tip of the micropile 10 to move in the axial direction of the micropile 10 according to the rotation of the micropile 10. Female threads are formed on the inner circumferential surface of the moving ring 20 for screwing with the micropile 10.

The hinge part 21 is coupled to the lower surface of the moving ring 20. The hinge part 21 may be fixedly coupled to the moving ring 20 by welding or the like, or may be slidably coupled. Sliding coupling may be achieved by, for example, a coupling groove formed on the lower surface of the movable ring 20 and a coupling protrusion formed on the hinge portion 21. When the moving ring 20 and the hinge part 21 are fixedly coupled, as will be described later, when the pressing plate 50 contacts the wall surface of the perforated hole 3, it is moved and pressed in contact. When the movable ring 20 and the hinge part 21 are slidably coupled, as will be described later, when the pressing plate 50 contact-presses the wall surface of the perforated hole 3, it is contact-pressed in place.

2 is a schematic perspective view of the tip support portion 30.

As shown, the tip support part 30 supports the distal end 11 of the micropile 10 at its upper surface so as to be capable of idling, and the plate 31 in surface contact with the bottom of the perforated hole 3 at the lower surface thereof. , It includes a wedge 33 protruding from the lower surface of the plate 31 and penetrating into the bottom of the perforated hole 3.

In order to support the distal end 11 of the micropile 10 so as to be idle, a receiving groove 32 for accommodating the distal end 11 of the micropile 10 is formed in the center of the upper surface of the plate 31.

It is preferable that the plate 31 has a trapezoidal cross section whose upper side is longer than that of the lower side. It is preferable that the plate 31 has a circular planar shape, the diameter of the upper surface is preferably 90% or less of the diameter of the perforated hole 3, and the diameter of the lower surface is preferably not less than the diameter of the micropile 10, and , It is preferable that the side inclination angle of the plate 31 with respect to the axis of the micropile 10 is 45° or more. The numerical values here are to include errors in a typical range for manufacturing or construction.

This shape and numerical limitation takes into account the function of preventing the tip support part 30 from sinking to the bottom of the perforated hole 3 and the function of discharging the slurry at the bottom of the perforated hole 3 to the top of the tip support part 30. will be. That is, if the diameter of the upper surface of the plate 31 is larger than 90% of the diameter of the perforated hole 3, it is difficult to secure a space for discharging the slurry, and the diameter of the lower surface is smaller than the diameter of the micropile 10 or the plate 31 If the lateral inclination angle of) is less than 45°, it is considered that there is a risk of sinking.

According to this configuration, the subsidence of the micropile can be prevented by the wide contact surface combining the inclined side and the lower surface of the plate 31, and the floor through the space between the inclined surface of the plate 31 and the wall surface of the perforated hole 3 The slurry of the plate 31 can move upward.

In the present embodiment, an example in which the upper surface of the plate 31 has a circular planar shape has been described, but is not limited thereto, and may have a polygonal planar shape according to design or construction needs.

The wedge 33 protruding from the lower surface of the plate 31 penetrates into the bottom of the perforated hole 3 and functions to prevent the tip support 30 from rotating accordingly when the micropile 10 rotates.

In the present embodiment, an example in which four wings are arranged radially symmetrically as a configuration of the wedge 33 is described, but the number of wings is not limited thereto, and the number of wings may be two or four or more, and in addition to the wings, various types of wedges Can be used.

As shown in FIG. 1, a hinge portion 34 is coupled to the upper surface of the tip support portion 30. The tip support portion 30 and the hinge portion 34 may be coupled in the same manner as the coupling method of the movable ring 20 and the hinge portion 21 described above.

The link unit 40 includes an upper link 41 and a lower link 42. The upper link 41 is hinge-coupled with the hinge portion 21 of the moving ring 20 at its upper end, and is link-coupled with the upper end of the lower link 42 at its lower end. The lower link 42 is link-coupled with the lower end of the upper link 41 at its upper end, and hinge-coupled with the hinge portion 34 of the tip support portion 30 at the lower end thereof. Herein, "link coupling" includes a case in which the upper link 41 and the lower link 42 are directly link-coupled, as well as a case in which the link is indirectly coupled through the intermediate link 43 to be described later. Further, the upper link 41 and the lower link 42 are hinged to the upper and lower portions of the pressing plate 50 to be described later, so that the pressing plate 50 also functions as the intermediate link 43.

The link part 40 contracts downward and expands (expands) radially when the moving ring 20 moves downward by the rotation of the micropile 10 while being supported by the tip support part 30 at the bottom thereof. . Conversely, when the moving ring 20 moves upward, the link portion 40 also expands upward and contracts radially.

According to this embodiment, the number of the link units 40 is preferably three, but is not necessarily limited thereto, and may be two or four or more according to design or construction needs. It is preferable that the plurality of link portions 40 are arranged radially symmetrically.

The pressing plate 50 is installed at a portion where the upper link 41 and the lower link 42 of each link unit 40 are linked to each other, and the wall surface of the perforated hole 3 is formed by radial expansion of the link unit 40. Contact pressure.

3 is a schematic cross-sectional view of the pressing plate 50. As shown, the pressing plate 50 has an arc-shaped cross section of the same radius of curvature as the radius of curvature of the perforated hole 3. With this configuration, the contact area between the pressing plate 50 and the wall of the perforated hole 3 can be increased, and thus, reinforcing force for the wall of the perforated hole 3 can be increased. In order to further increase the contact area, it is preferable that the plurality of pressing plates 50 are disposed adjacent to each other in the initial state in which the link portion 40 is inserted into the perforated hole 3. Here, the "same" of the radius of curvature does not mean completely the same, but is a concept including errors in general manufacturing and construction.

A wedge 51 may be installed on the outer circumferential surface of the pressing plate 50. In this case, since the area of the outer circumferential surface of the pressing plate 50 is wide, there is an advantage that a plurality of wedges 51 can be installed. According to this configuration, it is possible to further increase the reinforcing force of the pressing plate 50 to the wall of the perforated hole 3.

Each corner of the pressing plate 50 is preferably rounded so as not to scratch the wall surface when the pressing plate 50 moves while in contact with the wall surface of the perforated hole 3. In this case, the rounding treatment does not necessarily have to be performed on all corners, but may be performed on only some corners according to constructional necessity.

Buckling reinforcement part 60, as shown in Figure 1, the upper support member 61 screwed with the micropile 10 at the top of the soft layer 1, and the micropile ( 10) and a lower support member 62 that is screwed together, and a plurality of buckling support bars 63 connecting the upper support member 61 and the lower support member 62.

Male threads are formed at the upper and lower ends of the buckling support bar 63, and the buckling support bar 63 is fixed to the upper support member 61 and the lower support member 62 by nuts 64, respectively.

The operation of the micropile device for reinforcing structures according to the present embodiment having such a configuration will be described as follows.

First, as shown in FIG. 1, the micropile 10, the moving ring 20, the tip support part 30, the link part 40, the pressing plate 50, and the buckling reinforcement part ( The assembly of 60) is inserted into the perforated hole (3). At this time, it is preferable that the pressing plate 50 is inserted in a state where the central axis of the micropile 10 and the central axis of the perforated hole 3 coincide with each other in a lightly contacted or slightly spaced state. This state may be secured by expanding the link part 40 radially to some extent in advance, or secured in the maximum contraction state of the link part 40 in which the upper link 41 and the lower link 42 are arranged in a straight line. It could be. This state corresponds to the "initial state" described above. Here, the "match" between the central axis and the central axis does not mean a complete coincidence, but is a concept including general manufacturing and construction errors. According to this configuration, there is an advantage that the pressing plate 50 can replace the role of a conventional space holding member.

Next, by perforating the micropile 10, the wedge 33 of the tip support 30 is in contact with the bottom of the perforated hole 3, while the lower surface of the plate 31 of the tip support 30 is in contact with the bottom of the perforated hole 3 (3) Let it penetrate into the floor.

Next, the micropile 10 is rotated. As the micropile 10 rotates, the moving ring 20 moves downward and the link portion 40 expands radially. When the micropile 10 is continuously rotated, the pressing plate 50 strongly contacts and compresses the wall of the perforated hole 3, thereby providing a reinforcing force to the wall of the perforated hole 3.

Although the present invention has been described in detail through the embodiments and the accompanying drawings, the technical idea of the present invention is determined by the matters described in the claims, and various modifications within the scope not departing from the scope of the technical idea of the present invention There may be examples and equal examples.

Although reference numerals are given to elements described in the claims, this is only for convenience of understanding, and is not intended to limit the scope of the present invention.

1: the fragile layer
2: bedrock
3: perforated hole
4: steel pipe
5: coupler
10: microfile
11: distal
20: moving ring
21: hinge part
30: tip support
31: plate
32: receiving groove
33: wedge
34: hinge part
40: link part
41: upper link
42: lower link
43: intermediate link
50: pressure plate
51: wedge
60: buckling reinforcement part
61: upper support member
62: lower support member
63: buckling support bar
64: nut

Claims (3)

Micropile 10 inserted into the perforated hole 3 formed in the ground; And
The top surface of the micropile 10 is supported by the end portion 11 of the micropile 10, and the bottom surface is in contact with the bottom of the perforated hole 3, and the upper side is arranged to be spaced apart from the wall surface of the perforated hole 3, and the upper side is greater than the lower side. Including; a plate 31 having a long trapezoidal cross section, and a tip support portion 30 including a wedge 33 protruding downward from the plate 31 and penetrating into the bottom of the perforated hole 3,
The plate 31 has a circular planar shape, the diameter of the upper surface is 90% or less of the diameter of the perforated hole 3, the diameter of the lower surface is greater than the diameter of the micropile 10, and the micro Micropile apparatus for reinforcing structures, characterized in that the side inclination angle of the plate (31) with respect to the axis of the pile (10) is 45° or more. delete The method of claim 1,
It further includes; a buckling reinforcement part 60 installed in the soft layer 1 of the ground,
The buckling reinforcing part 60 includes an upper support member 61 screwed with the micropile 10 on the upper side of the soft layer 1, and the micropile 10 and screwed on the lower side of the soft layer 1 And a plurality of buckling support bars (63) connecting the lower support member (62) to be coupled, and the upper support member (61) and the lower support member (62).

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