KR101984692B1 - Constructing method and apparatus for pre-tension micro pile - Google Patents

Abstract

The present invention relates to a construction method and an apparatus for pre-tensioning a micropile and, more specifically, to a construction method and an apparatus for pre-tensioning a micropile which can maximize tensile force by filling/hardening grouting after tensioning a pile, namely a steel bar installed on the ground. The construction method for pre-tensioning a micropile comprises: a step of forming a bore hole on the ground; a step of inserting a steel bar with an expansion member mounted on a lower portion thereof into the bore hole; a step where the expansion member infiltrates into an inner wall of the bore hole to be fixed while deploying outwards; a step of holding and tensioning an upper portion of the steel bar and then fixing the upper portion of the steel bar; and a step of filling grouting in the bore hole. The steel bar is tensioned before the grouting is filled, and the grouting is filled in the bore hole to be hardened while the steel bar is tensioned.

Description

TECHNICAL FIELD [0001] The present invention relates to a pre-tensioning method and a pre-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for tensioning a microfiber, and more particularly, to a method of tensioning a microfiber, which is capable of maximizing a tensile force And more particularly, to a method of applying tension to a microfiber and a tensioning device.

In general, the bearing capacity of the foundation is determined by the strength of the foundation, the size of the foundation and the penetration of the foundation. It is important to extend the foundation of the foundation when the strength of the foundation is insufficient.

However, if the load transferred to the foundation is very large, the penetration of the foundation must increase considerably, so that the entire foundation must be inserted deeply, which leads to an increase in construction costs.

Therefore, in this case, we use the pile method to penetrate steel, concrete, and wood, which have high stiffness, deep into the ground so that the base is supported in the hard core.

The pile method should be easy to penetrate in the middle soil layer and the supporting force of the tip of the pile should be sure.

However, in the same area as the river basin, it is impossible to insert the pile due to the impact, and because of the scouring effect, the site pile method is used to pre-drill the concrete using auger equipment.

There is a micro pile method used in the ground in this field pile method.

Micro Pile is a small pile drill that is pierced to a certain depth in the ground, assembles and installs piles and reinforcing bars, and grouted to low pressure (7 ~ 20 bar) using a pump. To be installed by installing a small diameter pile shaft.

In the above-described construction method using a micro pile, the bearing force due to the main surface friction is increased and the frictional resistance effect around the pile larger than the actual pore size is obtained.

In addition, since the tip end portion has a definite support effect, the supporting force also increases.

Because of this characteristic, microfiles are installed in sandy soil with higher frictional resistance than clayey soil.

In addition, by using small-scale drilling equipment, it is possible to reduce vibration and noise compared to type construction or large-diameter drilled pile, so that it is highly utilized as a foundation pile of a downtown foundation or a foundation area of a plant, and there is an advantage of easy construction in the ground.

A method of constructing the above micro file is as follows. Conventionally, the micro file is installed and then grouting is performed to cure the micro file.

When an external force due to an earthquake or the like acts in the state where the microfiber (steel bar) is installed, a tension is applied to the hardened grouting material and the microfiber (steel bar), and the microfiber (steel bar) is contracted or relaxed, And it can not sufficiently cope with damage of the upper structure (foundation bottom concrete) and the like.

Patent Document 1: JP-A-10-2016-0087190

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a grouting material in which a micropile inserted in a perforation hole is previously tensioned and then a grouting material is filled / cured, A tensioning method and a tensioning device for a microfiber which can minimize the re-stretching of the microfiles while minimizing the damage of the placed and hardened grouting material by external tensile stress, There is a purpose.

According to an aspect of the present invention, there is provided a method of tensioning a microfiber sheet, the method comprising: forming a perforation hole in the ground; Inserting a steel bar having an extension member at its lower portion into the perforation hole; Fixing the lower portion of the steel rod to the perforation hole while being infiltrated into the inner wall of the perforated hole while the extending member is deployed outwardly; Holding an upper portion of the steel rod and fixing the upper portion of the steel rod after tension; And filling the grooved material with the grouting material, wherein the steel rod is pulled before the grouting material is filled, and the grouting material is filled in the hole when the steel rod is pulled, do.

By extending the steel bar downward, the expanding member is expanded while being bent in the outward direction, and is penetrated and fixed to the inner wall of the perforation hole.

Or forming a perforation hole on the surface; Inserting a steel bar into the perforation hole; Injecting a lower grouting material into the perforation hole to form a bulb at a lower portion of the steel rod, and fixing the lower portion of the steel rod to the perforation hole by the bulb; Holding an upper portion of the steel rod and fixing the upper portion of the steel rod after tension; And filling the perforation hole with an upper grouting material, wherein the steel rod is tensioned before filling the upper grouting material in a state where the steel rod is fixed to the perforation hole by the bulb, The upper grouting material is filled in the perforation hole and hardened.

At this time, a packer is mounted on the periphery of the steel bar, the filler is inserted into the packer so that the packer is brought into close contact with the inner wall of the perforation hole, and then the lower grouting material is injected into the perforation hole to form the bulb.

The lower end of the steel rod is fixed to the perforation hole, and the steel rod is pulled upward to fix the upper portion of the steel rod to a support plate provided on the ground, thereby fixing the steel rod in a tensioned state.

Wherein the support plate is provided with a tension member for applying a force in a direction opposite to the perforation hole so that the upper end of the steel rod is coupled to the tension member so that the steel bar is tensioned in a direction opposite to the perforation hole by a force acting on the tension member And then the steel rod is fixed to the support plate in a tensioned state.

The tension member includes a compressed spring, and the elastic bar pulls the steel rod in a direction opposite to the perforation hole by an elastic restoring force of the compressed spring.

Wherein the tension member is mounted in a compressed state with the spring releasing the compression of the compressed spring after coupling the steel rod to the tension member so that the steel rod is tensioned in the opposite direction of the perforation hole by the resilient restoring force of the spring, .

The tensile member includes a cylinder, and pulls the steel rod in a direction opposite to the perforation hole by a force to extend the cylinder.

And tensioning the steel bar by the tension member to fix the steel bar to the support plate, and then removing the tension member.

According to another aspect of the present invention, there is provided a microfiber tensioning apparatus comprising: a support plate having a first through hole in contact with a surface of a hole formed therein and communicating with the hole; A tension member disposed on the support plate and formed with a second through hole communicating with the first through hole and generating a pushing force in a direction opposite to the support plate; A rigid rod penetrating the first through hole and the second through hole and inserted and disposed in the perforation hole; An extension member mounted on a lower portion of the steel bar and extending in an outward direction and penetrating an inner wall of the hole to fix the lower portion of the steel bar to the hole; A first engaging member for engaging an upper portion of the steel bar to the support plate; And a second engaging member for engaging an upper portion of the steel bar to the tension member, wherein the upper end of the steel bar is fixed to the upper end of the steel bar by the second engaging member, And is coupled to the tension member and is pulled in a direction opposite to the support plate.

Or a support plate having a first through hole in contact with a surface of the substrate on which the perforation hole is formed and communicating with the perforation hole; A tension member disposed on the support plate and formed with a second through hole communicating with the first through hole and generating a pushing force in a direction opposite to the support plate; A rigid rod penetrating the first through hole and the second through hole and inserted and disposed in the perforation hole; A packer mounted around a lower end of the steel bar and expanded by a filler injected into the inside of the steel bar and closely attached to the inner wall of the perforation hole; A first engaging member for engaging an upper portion of the steel bar to the support plate; And a second engaging member for engaging an upper portion of the steel bar with the tension member, wherein the steel bar is fixed to the perforation hole by a bulb formed at a lower portion of the packer, And is coupled to the tension member by a coupling member and is pulled in a direction opposite to the support plate.

Wherein the first engaging member and the second engaging member are made of a nut and the outer circumferential surface of the steel rod is formed with a thread to which the first engaging member and the second engaging member are screwed, And the second engagement member are engaged with the support plate and the tension member, respectively.

The tension member includes: an upper fixed plate disposed on the support plate and having the second through hole; And a spring for generating a force pushing the upper fixing plate in an upward direction with respect to the supporting plate, wherein the spring is mounted in a compressed state to generate a force for pushing the upper fixing plate in a direction opposite to the supporting plate.

The tension member may further include a locking member for holding the spring in a compressed state. When the locking member is released, the spring elastically restores to push the upper fixing plate upward.

The tension member includes: an upper fixed plate disposed on the support plate and having the second through hole; And a cylinder for generating a force for pushing the upper fixing plate in an upward direction with respect to the supporting plate, wherein the cylinder is extended to generate a force for pushing the upper fixing plate in a direction opposite to the supporting plate.

As described above, according to the present invention, there is provided the following effect according to the pre-tensioning method and the pre-tensioning apparatus of the micro pile.

Since the micropile is pre-tensioned and filled with the grouting material to cure, a prestress is added inside the hardened grouting material bonded to the lower end of the steel rod, thereby minimizing the damage of the hardened grouting material by the external tensile stress .

In particular, since the whole steel bar is stretched and then the grouting material is filled in the entire perforation hole to be cured, a prestress acts on the entire portion of the grouting material, and a large tensile force can be obtained.

Therefore, a large tensile force acts on the entire steel bar inserted into the ground, so that the tensile force of the steel bar is reduced and the loosening thereof can be delayed, thereby minimizing the work of reinforcement of the steel bar.

1 is a perspective view of a pre-tensioning device of a microfiber according to a first embodiment of the present invention, Fig.
FIGS. 2 and 3 are flowcharts of a method of pre-tensioning a microfiber according to a first embodiment of the present invention,
FIG. 4 is a flowchart showing a part of the method of tensioning a microfiber according to a modification of the first embodiment of the present invention,
5 is a partial flow chart of a method of predicting a microfiber according to another modification of the first embodiment of the present invention,
6 is a cross-sectional view of a state in which construction is completed by a pre-tensioning method of a microfiber according to the first embodiment of the present invention,
FIGS. 7 and 8 are flowcharts of a method of pre-tensioning a microfiber according to a second embodiment of the present invention,
Fig. 9 is a cross-sectional structural view of a state in which construction is completed by a pre-tensioning method of a microfiber according to a second embodiment of the present invention; Fig.

First Embodiment

FIG. 1 is a perspective view of a pre-tensioning device of a microfiber according to a first embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of a microfabrication method according to a first embodiment of the present invention Fig. 4 is a flowchart showing a part of the microfabrication method according to a modification of the first embodiment of the present invention, Fig. 5 is a flowchart showing a microfabrication method according to another modification of the first embodiment of the present invention, Fig. And FIG. 6 is a cross-sectional view of a state in which construction is completed by a pre-tensioning method of a microfiber according to the first embodiment of the present invention.

1 to 3, the microfiber tensioning device of the present invention comprises a support plate 10, a tension member 20, a steel bar 30, an extension member 40, A first engaging member 50, a second engaging member 60, and the like.

The support plate 10 has a substantially flat plate shape. The lower surface of the support plate 10 is in contact with the ground, and the first through hole 15 is formed in the center.

The tension member 20 is disposed at an upper portion of the support plate 10 and has a second through hole 25 communicating with the first through hole 15, Pushing forces are generated.

In this embodiment, the tension member 20 includes a lower fixing plate, an upper fixing plate 21, and a spring 22.

The lower fixing plate is coupled to the upper surface of the support plate 10.

The upper fixing plate 21 is spaced apart from the upper portion of the lower fixing plate.

The spring 22 is disposed between the lower fixing plate and the upper fixing plate 21 to generate a force to push the upper fixing plate 21 upward against the lower fixing plate or the supporting plate 10.

The tension member 20 may be formed of only the upper fixing plate 21 and the spring 22 without the lower fixing plate.

At this time, the lower end of the spring 22 is held in contact with the support plate 10.

The upper fixing plate (21) is provided with a second through hole (25) communicating with the first through hole (15).

The spring 22 is mounted in a compressed state to generate a force to push the upper fixing plate 21 in the direction opposite to the supporting plate 10 by an elastic restoring force.

The tension member 20 may include a lower fixing plate, an upper fixing plate 21 and a cylinder 23, as shown in FIG.

The cylinder (23) generates a force to push the upper fixing plate (21) in the direction opposite to the supporting plate (10) by the pneumatic pressure or the hydraulic pressure supplied from the outside.

The steel bar 30, that is, the micro pile is formed in a long bar shape and is disposed to pass through the first through hole 15 and the second through hole 25. [

The steel bar 30 is inserted into the perforation hole 70 formed on the ground.

The extension member 40 is mounted on the lower portion of the steel bar 30 and is expanded outward by an external force.

The extension member 40 may have a variety of structures known in the art.

In the present embodiment, the extension member 40 has a structure that is expanded while bending outwardly due to a blow applied from the outside.

The extension member 40 is infiltrated into the inner wall of the perforation hole 70 while being expanded in the outward direction so that the lower portion of the steel bar 30 is fixed to the perforation hole 70.

The first engaging member 50 serves to engage the upper portion of the steel bar 30 with the support plate 10.

The second engaging member 60 serves to connect the upper portion of the steel bar 30 to the upper fixing plate 21 in detail.

If the first and second engagement members 50 and 60 are coupled to the steel bar 30 and are capable of coupling the steel bar 30 to the support plate 10 and the tension member 20, , And various known conventional structures.

In the present embodiment, threads are formed on the outer peripheral surface of the steel bar 30.

The first engaging member 50 and the second engaging member 60 are formed of a nut that is screwed to a thread formed on the outer peripheral surface of the steel bar 30.

At this time, the maximum diameter of the first engaging member 50 and the second engaging member 60 of the nut is larger than the diameters of the first through holes 15 and the second through holes 25, respectively .

The first engaging member 50 and the second engaging member 60 engaged with the steel bar 30 at the upper portion of the support plate 10 and the upper fixing plate 21 are respectively supported by the support plate 10 and the upper fixing plate 21, (21), thereby being coupled to the support plate (10) and the upper fixing plate (21).

The steel bar 30 coupled by the tension member 20 by the second engaging member 60 is tensioned by the spring 22 or the cylinder 23 and then pulled by the first engaging member 50, And is in a tensioned state.

At this time, the lower portion of the steel bar 30 is infiltrated into the inner wall of the perforation hole 70 by the extending member 40 and fixed to the ground.

A construction method using the micro pile cactus apparatus of the present invention having the above-described structure is as follows.

As shown in FIG. 2 (a), the microfabrication method of the present invention first forms a perforation hole 70 on the ground.

Then, as shown in FIG. 2 (b), the steel bar 30 having the extension member 40 mounted thereon is inserted into the perforation hole 70.

Thereafter, as shown in FIG. 2 (c), the steel bar 30 is driven downward so that the expanding member 40 is expanded while being bent in the outward direction.

As the expanding member 40 is bent outwardly, the expanded portion of the expanding member 40 penetrates the inner wall of the perforation hole 70 and is fixed.

When the extension member 40 is expanded and infiltrated into the inner wall of the perforation hole 70, the lower portion of the steel bar 30 to which the expansion member 40 is coupled is fixed to the perforation hole 90 .

3 and 4, when the lower portion of the steel bar 30 is fixed to the perforation hole 90 by the extension member 40, the upper portion of the steel bar 30 is held on the ground, And then the upper portion of the steel bar 30 is fixed.

It is preferable to use the tensile member 20 as shown in the drawing of the present embodiment, although it is possible to pull the steel bar 30 by pulling it upwards by referring to a separate tensioner.

In this embodiment, the support plate 10 is provided on the ground, and the steel bar 30 is pulled upward by using the tension member 20 to pull up the upper portion of the steel bar 30 to the support plate 10 ).

Since the lower end of the steel bar 30 is fixed by penetrating the inner wall of the perforation hole 70 when the steel bar 30 is pulled upward, Is pulled out without going upwards.

When the tension member 20 includes the spring 22, the support plate 10 and the tension member 20 are installed on the upper portion of the perforation hole 70 as shown in FIG. 3 (a) do.

The first engaging member 50 is fastened to the upper portion of the steel bar 30 such that the first engaging member 50 is disposed on the upper portion of the support plate 10.

At this time, the first engaging member 50 is not in contact with the support plate 10 but is spaced apart.

The steel bar 30 protrudes out through a first through hole 15 formed in the support plate 10 and a second through hole 25 formed in the tension member 20.

The second engaging member 60 is fastened to the upper portion of the steel bar 30 in a state in which the spring 22 constituting the tension member 20 is compressed as shown in FIG. 3 (b).

Then, the second engaging member 60 is fixed to the upper surface of the upper fixing plate 21 while being in contact with the steel bar 30.

When the external force compressing the spring 22 is removed, the upper fixing plate 21 constituting the tension member 20 is moved upward in the direction opposite to the support plate 10 by the resilient restoring force of the spring 22 At this time, the upper fixing plate 21 is caught by the second engaging member 60 and is not lifted to tension the steel bar 30.

That is, the force of the tensile member 20 causes the steel bar 30 to be pulled in the direction opposite to the perforation hole 70.

At this time, since the lower portion of the steel bar 30 penetrates and is fixed to the inner wall of the perforation hole 70, the tension member 20 holds the steel bar 30 in the upward direction The steel rods 30 are not separated from the perforation holes 70.

When the steel bar 30 is pulled as described above, the first engaging member 50 is tightly fixed to the support plate 10 as shown in FIG. 3 (c).

As a result, the steel bar 30 is in a state of being fixed by the first engaging member 50 and the support plate 10 in a tensioned state.

When the tension member 20 includes the cylinder 23, the support plate 10 and the tension member 20 are installed on the upper portion of the perforation hole 70 as shown in FIG. 4 (a) .

The first engaging member 50 is fastened to the steel bar 30 so that the first engaging member 50 is disposed on the upper surface of the support plate 10.

At this time, the first engaging member 50 is not in contact with the support plate 10 but is spaced apart.

The steel bar 30 protrudes out through a first through hole 15 formed in the support plate 10 and a second through hole 25 formed in the tension member 20.

At this time, the cylinder 23 is shrunk.

The second engaging member 60 is fixed to the upper surface of the upper fixing plate 21 in a state where the second engaging member 60 is fastened to the upper portion of the steel bar 30, as shown in FIG. 4 (b).

Thereafter, as shown in FIG. 4 (c), hydraulic or pneumatic pressure is applied to the cylinder 23 to extend the length of the cylinder 23.

The upper fixing plate 21 constituting the tension member 20 tries to rise in a direction opposite to the supporting plate 10 due to a force to increase the length of the cylinder 23, Is not caught by the second engaging member 60 but is not lifted and pulls the steel bar 30.

That is, the force of the tensile member 20 causes the steel bar 30 to be pulled in the direction opposite to the perforation hole 70.

At this time, since the lower portion of the steel bar 30 penetrates and is fixed to the inner wall of the perforation hole 70, the tension member 20 holds the steel bar 30 in the upward direction The steel rods 30 are not separated from the perforation holes 70.

When the steel bar 30 is pulled as described above, the first engaging member 50 is fastened and fixed to the support plate 10.

As a result, the steel bar 30 is in a state of being fixed by the first engaging member 50 and the support plate 10 in a tensioned state.

The tension member 20 may be constructed and configured as shown in FIG.

The tension member (20) comprises a compressed spring (22).

As shown in Fig. 5 (a), after the support plate 10 is installed, the first engagement member is fastened to the steel rod.

At this time, the first engaging member 50 is not in contact with the support plate 10 but is spaced apart.

Thereafter, the tension member 20 mounted with the spring 22 in a compressed state is installed on the upper side of the support plate 10.

At this time, the tension member 20 includes a locking member 27 for keeping the spring 22 in a compressed state.

The locking member 27 interconnects the upper fixing plate 21 and the lower fixing plate 26 so as not to spread apart.

A separate link is provided to each of the upper and lower fixing plates 21 and 26 and each link is connected with a locking member 27 made of a pin so that the locking member 27 is fixed to the upper fixing plate 26. [ (21) and the lower fixing plate (26).

The spring 22 disposed between the upper fixing plate 21 and the lower fixing plate 26 is compressed while the locking member 27 connects the upper fixing plate 21 and the lower fixing plate 26 have.

5 (a), the locking member 27 connects the upper fixing plate 21 and the lower fixing plate 26, so that the spring 22 is in a compressed state.

5 (b), the second engaging member 60 is fastened to the upper portion of the steel bar 30 when the support plate 10 and the tension member 20 are installed.

Then, the second engaging member 60 is fixed to the upper surface of the upper fixing plate 21 while being in contact with the steel bar 30.

Thereafter, the locking member 27 is released.

In this embodiment, since the locking member 27 is formed of a pin or the like, when the pin fixing the upper fixing plate 21 and the lower fixing plate 26 is removed, the locking member 27 is released.

When the locking member 27 which has kept the compressed state of the spring 22 is released, the spring 22 pushes the upper fixing plate 21 upward while generating the elastic restoring force.

At this time, the upper fixing plate 21 is caught by the second engaging member 60 and is not lifted to tension the steel bar 30.

That is, the force of the tensile member 20 causes the steel bar 30 to be pulled in the direction opposite to the perforation hole 70.

At this time, since the lower portion of the steel bar 30 penetrates and is fixed to the inner wall of the perforation hole 70, the tension member 20 holds the steel bar 30 in the upward direction The steel rods 30 are not separated from the perforation holes 70.

When the steel bar 30 is tensioned as described above, the first engaging member 50 is fastened and fixed to the support plate 10 as shown in FIG. 5 (c).

As a result, the steel bar 30 is in a state of being fixed by the first engaging member 50 and the support plate 10 in a tensioned state.

6, the second engaging member 60 and the tension member 20 are removed to use the second engaging member 60 and the tension member 20 for the other steel rods.

Even when the second engagement member 60 and the tension member 20 are removed, since the steel bar 30 is fixed in a state of being tensioned by the first engagement member 50 and the support plate 10, Is not released.

Thereafter, the perforation hole 70 is filled with a grouting material 80 to be cured.

When the grouting material 80 is hardened and becomes a bulb, the steel rod 30 is present in the grouting material 80 in a stretched state.

That is, since the grouting material 80 is not cured after the grouting material 80 is cured, but the grouting material 80 is cured after the steel rod 30 is tensioned, 30 are present inside the bulb formed by the grouting material 80 in a tensioned state.

Therefore, the hardened grouting material 80, that is, the entire bulb, acts on the entirety of the prestress by the steel bar 30, that is, the compressive force in advance.

Therefore, even if external tensile stress is applied to the cured grouting material 80, since the cured grouting material 80 is previously subjected to the compressive force by the steel rod 30 that has been pre-tensioned, It is possible to minimize the damage of the grouting material 80 due to the external tensile stress.

That is, the prestress acts on the grouting material 80 due to the tensile force of the steel rods 30, so that the external tensile stress acting on the grouting material 80 can be more effectively canceled even in the external environment of the soft clay in the ground have.

Particularly, since the steel rods 30, that is, the micro pile is entirely stretched, the grouting material 80 is filled in the entire perforation holes 70 to be cured, so that the prestress acts on the entire section of the grouting material 80, It is possible to have a larger tensile force than the conventional one.

Therefore, a large tensile force acts on the entire steel rods 30, so that the tensile force of the steel rods is reduced and the loosening of the steel rods is delayed, thereby minimizing the work of re-welding the steel rods 30.

Second Embodiment

FIGS. 7 and 8 are flow charts of a method of pre-tensioning microfiles according to a second embodiment of the present invention, and FIG. 9 is a view showing a method of prefolding the microfiles according to the second embodiment of the present invention Fig. 2 is a cross-sectional view showing a state in which construction is completed by the present invention.

The microfiber tensioning device of the second embodiment has no expansion member as compared with the first embodiment and has the packer 35 as a component.

The packer 35 is formed in the shape of a closed bag and mounted around the lower end of the steel bar 30.

When the filling material is injected into the inside of the packer 35 through a hose or the like, the packing 35 is expanded and is brought into close contact with the inner wall of the perforation hole 70.

When the packer 35 is expanded and brought into close contact with the inner wall of the perforation hole 70, the upper portion and the lower portion of the packer 35 are separated.

A hose passing through the packer 35 is mounted on the inside of the packer 35 so that the grouting material is injected into the lower part of the packer 35 as described later.

Other configurations are the same as those in the first embodiment, so a detailed description thereof will be omitted.

Hereinafter, a construction method using the microfiber cactus apparatus of the present invention having the above-described structure will be described.

7 (a), the perforation hole 70 is formed on the ground surface, and the steel bar 30, on which the packer 35 is mounted as shown in FIG. 7 (b), is inserted into the perforation hole 70).

Thereafter, as shown in FIG. 7 (c), the filler is injected into the interior of the packer 35 through the hose.

Then, the packer 35 is expanded and is brought into close contact with the inner wall of the perforation hole 70.

When the packer 35 is inflated and brought into close contact with the inner wall of the perforation hole 70, the upper and lower portions of the perforation hole 70 are separated by the packer 35.

After the packer 35 has been inflated, the lower grouting material 81 is injected into the perforation hole 70 existing in the lower portion of the packer 35 as shown in FIG. 7 (d).

At this time, the lower grouting material 81 can be injected into the lower part of the packer 35 through the hose passing through the packer 35. When the lower grouting material 81 is hardened, Thereby forming a bulb 81 that is coupled to the bulb.

The bottom of the steel bar 30 is fixed to the perforation hole 70 by the bulb 81 and the packer 35.

The bulb 81 may be formed by inserting the steel bar 30 into the perforation hole 70 without the packer 35 and injecting the grouting material into only the lower part of the perforation hole 70 and curing it.

However, by mounting the packer 35, the packer 35 can be brought into close contact with the inner wall of the perforation hole 70 to increase the fixing force, and the packer 35, which is mounted at a specific position of the steel bar 30, The amount of the lower grouting material injected into the lower portion of the packer 35 can be made constant by virtue of the fact that the size of the bulb 81 is substantially the same.

When the lower end of the steel bar 30 is fixed to the perforation hole 70 by the bulb 81 or the like as described above, And the upper portion of the steel bar 30 is fixed.

At this time, the tensile member 20 may use not only the structure shown in FIG. 8 but also the structures shown in FIGS. 3 to 4 of the first embodiment.

Since a specific method of holding the upper portion of the steel bar 30 by using the tension member 20 and pulling the upper portion of the steel bar 30 upward and fixing the upper portion of the steel bar 30 is the same as that of the first embodiment, It is omitted.

The second engaging member 60 and the tension member 20 are removed and the upper grouting material 82 is inserted into the perforation hole 70 as shown in FIG. And then cured.

Other details are the same as in the first embodiment, and therefore, a detailed description thereof will be omitted.

The pre-tensioning method and the pre-tensioning apparatus of the microfile according to the present invention are not limited to the above-described embodiments, but can be variously modified and practiced within the scope of the technical idea of the present invention.

10: support plate, 15: first through hole,
A lower fixing plate, a locking member, and a locking member. The locking member includes a locking member,
35: packer, 40: extension member, 50: first engagement member, 60: second engagement member,
70: perforation hole, 80: grouting material, 81: lower grouting material (bulb), 82: upper grouting material.

Claims (16)

Forming a perforation hole in the ground;
Inserting a steel bar having an extension member at its lower portion into the perforation hole;
Fixing the lower portion of the steel rod to the perforation hole while being infiltrated into the inner wall of the perforated hole while the extending member is deployed outwardly;
Holding an upper portion of the steel rod and fixing the upper portion of the steel rod after tension;
Stretching the steel rod, filling the hole with a grouting material to cure the steel rod,
The steel rod is tensioned upward in a state in which the expanding member is expanded while being bent in the outward direction to penetrate the inner wall of the perforation hole to fix the lower portion of the steel rod to the perforation hole, The upper end of the steel bar is fixed to a support plate provided on the lower end of the steel bar so that the steel bar is fixed in a tensioned state,
And a tension member for applying a force in a direction opposite to the perforation hole is mounted on the support plate,
Wherein the tension member comprises a compressed spring, the spring is mounted in a compressed state,
After the upper portion of the steel rod is coupled to the tension member, the compression spring is released to compress the spring so that the steel rod is pulled in the direction opposite to the perforation hole by the elastic restoring force of the spring, And a fixing step of fixing the micro pile to the surface of the micro pile.
delete delete delete delete delete delete delete delete delete A support plate having a through hole in contact with a surface of the hole formed with the through hole and communicating with the through hole;
A tension member disposed on the support plate and formed with a second through hole communicating with the first through hole and generating a pushing force in a direction opposite to the support plate;
A steel bar passing through the first through hole and the second through hole, the steel bar being inserted into the through hole and having a thread formed on an outer circumferential surface thereof;
An extension member mounted on a lower portion of the steel bar and bent toward the outer side by hitting the steel bar in a downward direction to penetrate the inner wall of the hole to fix the lower portion of the steel bar to the hole;
A first engaging member formed of a nut and screwed on the upper portion of the steel bar and engaged with the support plate to engage the upper portion of the steel bar with the support plate;
And a second engaging member screwed on the upper portion of the steel bar and engaged with the tension member to engage the upper portion of the steel bar with the tension member,
The tension member
A lower fixed plate disposed above the support plate;
An upper fixing plate disposed on an upper portion of the lower fixing plate, the upper fixing plate having the second through hole formed therein and having an upper surface held in contact with a lower surface of the second coupling member;
A spring disposed between the lower fixing plate and the upper fixing plate in a compressed state to generate a force pressing the upper fixing plate upward with respect to the lower fixing plate;
And a locking member for connecting the lower fixing plate and the upper fixing plate to each other to prevent the spring from being held in a compressed state,
When the locking member is released while the lower end of the steel rod is fixed to the perforation hole by the extension member, the spring that has been compressed is elastically restored, and the upper fixing plate is pushed upward, The second joining member pulls the steel bar in a direction opposite to the lower fixed plate, and after the steel bar is pulled, the first joining member is brought into contact with the support plate so that the steel rod is fixed by the first engagement member and the support plate Of the microfiber. ≪ RTI ID = 0.0 > 11. < / RTI >
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