KR102287362B1 - Reinforcement method fot tip of PHC pile using loe fluidity mortar - Google Patents

Abstract

An expansion reinforcement method for the tip of a PHC pile using low-mobility mortar according to the present invention comprises: a pile installation step for inserting a PHC pile (2) having a hollow part (1) formed therein into the ground; a drilling step for, after preparing a drilling machine (40) equipped with a rod (41) having a drilling bit (42) at the bottom, inserting the rod (41) of the drilling machine (40) through the hollow part (1) of the PHC pile (2) inserted in the ground to form a lower drilling hole (50) drilled to a predetermined depth from the bottom of the PHC pile (2); an injection step for separating the rod (41) from the drilling machine (40), connecting an injection device (60) to the rod (41), and pressure-injecting a low-mobility grout material having a slump value of 50 mm or less in a non-discharge manner through the injection device (60) to form a cylindrical bulb (70) under the PHC pile (2); and a rod pull-out step for pulling out the rod (41). According to the present invention, the tip of a PHC pile can be smoothly expanded and reinforced without providing a separate tip reinforcing tool of a steel material on the PHC pile.

Description

{Reinforcement method fot tip of PHC pile using loe fluidity mortar}

The present invention relates to a method of expanding and reinforcing the tip of a PHC pile, in particular, by press-injecting low-flow mortar into the PHC pile in a non-discharge type to form cylindrical bulbs around and below the tip of the PHC pile, and also to remove the soil around the periphery. It relates to a method of expanding and reinforcing the tip of a PHC pile using a low-flow mortar, which is strengthened by compression to increase the density of the surrounding ground.

In the case of installing a pre-made pile such as a concrete pile or a steel pile in the ground to reinforce the ground in the prior art, if the ground at the tip of the pile is soft, the tip bearing capacity of the pile is also low, so the bearing capacity that the unit pile can bear is also Since it is small, there is a problem in that the installation cost of piles increases as the number of piles installed or the depth of piles must be increased in order to support the required design load.

On the other hand, in recent years, in order to increase the tip bearing capacity of the pile, the site where the pile is to be installed is excavated in advance, and a grouting material such as concrete, mortar or soil cement is injected into the tip of the excavation hole to form a bulb, and the pile is installed thereon. The file method is used.

As such, as one method of forming a grouting bulb at the tip of the excavation hole, an expandable cutter blade is mounted on the excavation bit, the ground is first excavated to a predetermined depth with the excavation bit, and then the cutter blade is expanded and rotated to rotate the excavation hole. A method (DCM method, deep cement mixing method) is used to form an extended cutting part around the tip and inject a grouting material here.

However, the equipment installed to apply this method is made of very large equipment because paste injection, air supply, and rotation of the stirring blade must all be done, and the expandable cutter blade maintains a very complex structure and high strength. Should be.

Recently, "composite pile construction method in which enlarged bulbs are formed" (Korean Patent Publication No. 10-2185255, Patent Document 1) has been published.

In the case of Patent Document 1, after inserting the pile body into the drilling hole, a solidified body is formed in the space between the pile and the drilling hole, and the pile body is fixed to the inner wall of the drilling hole by frictional force through the solidified body during construction. A method of forming an enlarged bulb in the lower part of the pile by high-pressure injection of the injection material through the jet cruising equipment through the hollow of the main body is disclosed.

In Patent Document 1, ultra-high pressure compressed air crushes the ground around the tip of the pile, and in this process, a large amount of slime is generated, which requires a separate treatment process and cost for the slime.

In addition, in the case of this method, when the aquifer is present, the construction effect is not only reduced, but there is also a problem in that the construction cost is increased because the unit cement is excessively input by high-pressure spraying.

Moreover, the ground under the PHC pile becomes weak due to high-pressure spraying, and there is a risk of displacement due to disturbance of the original ground around the PHC pile before the sprayed paste hardens. There are also problems that arise.

In particular, in order to perform jet grouting in the same method as in Patent Document 1, the lower end of the pile is in an open state, and as a result, cement paste is injected at high pressure from the bottom of the pile to form a hollow part of the pile and a bulb at the bottom thereof. If the perimeter of the side of the pile is not fixed to the wall of the drilling hole because all parts are in a soft state, the pile will flow during construction. There is also a problem in that the air lengthens because it has to proceed to

Accordingly, in reinforcing the PHC pile by forming an enlarged bulb through mortar injection at the tip of the PHC pile, it is necessary to minimize the disturbance of the original ground during construction to prevent the deformation of the PHC pile and to develop a construction method that can be constructed even with small equipment. I would say

KR 10-2185255 (2020.11.25)

The method for reinforcing the tip of a PHC pile using a low-flow mortar of the present invention is to solve the problems occurring in the prior art as described above, and the PHC pile smoothly without having a reinforcing mechanism made of a separate steel material for the PHC pile. It is intended to be able to expand and reinforce the tip of the

More specifically, in consideration of the use of agitation blades for ground improvement in ground improvement methods such as the JSP method or the DCM method or the disturbance of the ground due to high-pressure air injection, a low-fluidity mortar such as a rice cake is used. It is intended to suppress ground disturbance around PHC piles by press-injection in a non-discharge type.

In addition, since the cement paste is non-discharge type press-injection around the tip of the PHC pile, the soil around the tip of the PHC pile is compressed and strengthened to increase the density of the surrounding ground. It is intended to ensure excellent tip bearing capacity without

In addition, a sealed tip shoe is mounted at the bottom of the PHC pile, and the perforation bit penetrates the tip shoe and excavates the ground, thereby minimizing the pressure caused by the injection of the injection material from flowing into the hollow part through the hollow part of the PHC pile. This is to keep the density high.

The present invention provides a pile installation step of inserting a PHC file (2) having a hollow part (1) formed therein in order to solve the above problems; After preparing a perforator 40 equipped with a rod 41 equipped with a perforating bit 42 at the bottom, the rod 41 of the perforator 40 through the hollow portion 1 of the PHC file 2 inserted in the ground ) by inserting the PHC file (2) to a predetermined depth from the bottom of the drilling step to form a lower drilling hole (50) and; After separating the rod 41 from the perforator 40 and connecting the injection device 60 to the rod 41, a low-fluidity injection material having a slump value of 50 mm or less is poured through the injection device 60. An injection step of forming a cylindrical bulb 70 in the lower portion of the PHC pile (2) by press-injection in an ejection type; and a rod drawing step of drawing the rod 41 .

In the above configuration, the PHC pile (2) is equipped with a tip shoe (3) at the lower end, and the drilling step is performed by passing the tip shoe (3) through the punching bit (42). .

In addition, the punching bit 42 is formed in the form of an empty tube inside so that the injection material can be discharged at the bottom, and an upper inclined portion 42a that expands downward from the point connected to the rod 41 is formed, A lower inclined portion 42b, which is gradually reduced in diameter from the lower end of the upper inclined portion 42a, is formed, so that in the rod drawing step, the upper inclined portion is formed in the hole 3a of the tip shoe 3 penetrated in the drilling step. It is characterized in that the rod 41 is drawn while the (42a) is supported.

In addition, the outer diameter of the perforated bit 42 is made larger than the outer diameter of the rod 41, and the rod 41 has a structure in which an upper pipe 41a and a lower pipe 41b are detachably connected, In the rod drawing step, the upper tube 41a is separated from the lower tube 41b, only the upper tube 41a is drawn out, and the lower tube 41b is embedded in the bulb together with the perforated bit 42. do.

In addition, the pile installation step includes a casing installation step of inserting and constructing the casing 10 in the ground while excavating the ground using the auger 20; an auger drawing step of injecting the cement paste 30 into the casing 10 while drawing the auger 20; a file insertion step of inserting the PHC file (2) into the casing (10); It proceeds to a casing drawing step of drawing the casing (10), and the drilling step and the injection step are performed before the complete hardening of the cement paste (30).

At this time, in the casing installation step, the ogre 20 is inserted to a depth of the lower drilling hole 50 by design, which is lower than the lower position of the PHC pile 2 by design.

In addition, the PHC pile (2) is targeted to the ground when the insertion depth is higher than the bedrock layer, and the PHC pile (2) is characterized in that it is inserted to a lower depth than the bedrock layer.

In addition, in the drilling step, the perforation bit 42 is made to reach the rock layer under the PHC pile 2, or by drilling to a certain depth from the rock layer, the bulb 70 formed by the injection step is from the rock layer to the PHC pile It is characterized in that it is made to support (2).

In addition, the low-fluidity injection material is characterized in that cement, stone dust, and soil are mixed with water.

According to the present invention, it is possible to smoothly expand and reinforce the tip of the PHC pile without having a separate steel tip reinforcement mechanism for the PHC pile.

More specifically, in consideration of the use of agitation blades for ground improvement in ground improvement methods such as the JSP method or the DCM method or the disturbance of the ground due to high-pressure air injection, a low-fluidity mortar such as a rice cake is used. It is possible to suppress the ground disturbance around the PHC pile by press-injection in a non-discharge type.

In addition, since the cement paste is non-discharge type press-injection around the tip of the PHC pile, the soil around the tip of the PHC pile is compressed and strengthened to increase the density of the surrounding ground. It is possible to secure excellent tip bearing capacity without

In addition, a sealed tip shoe is mounted at the bottom of the PHC pile, and the perforation bit penetrates the tip shoe and excavates the ground, thereby minimizing the pressure caused by the injection of the injection material from flowing into the hollow part through the hollow part of the PHC pile. The density can be maintained high.

1 is a cross-sectional flow chart showing a file installation step in the present invention.
Figure 2 is a cross-sectional flow chart showing the state in which the drilling step, the injection step, the rod drawing step in the present invention is in progress.
Figure 3 is a cross-sectional flow chart showing in more detail the state in which the drilling step, the injection step, and the rod drawing step are in progress in the present invention.
Figure 4 is a cross-sectional flow chart showing a case of integrating the lower tube of the rod and the bulb in the present invention.
Figure 5 is a view specifically showing that the drilling, injection step is made in the present invention.
Figure 6 is a cross-sectional flow chart showing the state of construction so as to connect the bulb to the bedrock layer in the present invention.

Hereinafter, a method of expanding and reinforcing the tip of a PHC pile using the low-flow mortar of the present invention will be described in detail with reference to the accompanying drawings.

The method of expanding and reinforcing the tip of the PHC pile using the low-flow mortar of the present invention is largely composed of a pile installation step, a drilling step, an injection step, and a rod drawing step.

1. File installation step

The PHC file (2) having the hollow part (1) formed therein is inserted into the ground.

There is a method of driving the pile by inserting the PHC pile (2) into the ground, but if the pile is driven in soft ground such as a landfill, the ground is pushed as much as the volume of the pile, so the pile is broken, floated up, or pushed after the pile construction. etc. occur.

Therefore, the method of inserting the casing and inserting the pile into the casing is appropriate for pile construction.

Accordingly, the pile installation step is preferably composed of a casing installation step, an ogre drawing step, a pile insertion step, and a casing drawing step.

The casing installation step consists of inserting and constructing the casing 10 in the ground while excavating the ground using the auger 20, and the auger drawing step drawing the auger 20 while drawing the auger 20 while drawing the cement paste inside the casing 10 ( 30) is injected.

At this time, before the ogre is pulled out, the soil inside the casing 10 is drained to form a space for the PHC pile 2 to be inserted into the casing 10 .

The installation of the casing 10 proceeds using the driving equipment.

Usually, the maximum insertion depth of the casing 10 through one driving device is 30 ~ 35m, and when two driving devices are connected, the casing can be installed up to approximately 60m.

Therefore, the installation of the casing 10 can be installed up to 60m by connecting one or two driving equipment.

At this time, it is not suitable to connect the three driving equipment because the construction cost increases enormously.

If the depth of the bedrock (rock layer) is located at about 70m, the PHC pile (2) must be driven up to the bedrock. After inserting the PHC pile (2) inside, it is sufficient to expand and reinforce the tip of the PHC pile (2) to secure the tip support force.

At this time, in the casing installation step, the ogre 20 may be excavated to a lower position than the lower end position of the PHC pile 2 by design.

This is to be excavated to the depth of the lower drilling hole 50 to be described later so as to correspond to the bulb position in the design.

However, in the case where the lower drilling hole 50 has a depth exceeding 60 m from the surface of the strata, the perforator 40 used for forming the bulb 70 to be described later is utilized.

The pile insertion step proceeding after installation of the casing proceeds by inserting the PHC pile (2) into the casing (10) using equipment such as a crane, and the casing extraction step is to draw out the casing (10). proceeds

At this time, it is preferable to draw the casing 10 while injecting the cement paste 30 .

After the casing 10 is drawn out, the head of the PHC pile 2 can be arranged.

In addition, it is preferable that the PHC pile (2) is equipped with a non-open tip shoe (3) at the lower end.

The reason why the tip shoe 3 is mounted is that the soil or injection material is pushed into the PHC pile 2 by the pressure generated during bulb formation due to forced press-in from the bottom of the PHC pile 2 to minimize the interference with bulb formation. to do

At this time, in the drilling step, the rod 41 of the perforator 40 and the perforating bit 42 must pass inside the hollow 1 of the PHC pile 2, and the inner surface of the tip shoe 3 has the perforated bit It is preferable that the incision line 3c is formed through a punching device or the like so that the 42 can easily break through the tip shoe 3 .

Here, the cut-off line 3c means forming a groove or forming a fine hole on the surface of the tip shoe 3, and the position may be the center, and the punching bit 42 is in contact. It will be said that it may be formed in a circle along the point.

The above-described process is preferably performed on the ground when the depth into which the PHC pile 2 is inserted is higher than the bedrock layer, and the PHC pile 2 is preferably inserted and constructed at a depth lower than the bedrock layer.

2. Perforation step

After preparing a small perforator 40 equipped with a rod 41 equipped with a perforating bit 42 at the bottom as shown in FIGS. 2 and 5, the hollow part 1 of the PHC file 2 inserted into the ground ) is inserted through the rod 41 of the perforator 40, the PHC file 2 is drilled to a predetermined depth from the bottom to form a lower perforation hole (50).

At this time, excavation is performed through the perforation bit 42, but it is preferable to minimize or eliminate the topcoat.

In addition, the injection material can be supplied through the rod 41 without pulling out the rod 41. In this case, the punched bit 42 connected to the rod 41 has a hollow inside so that the injection material can be discharged at the bottom. It is preferable to consist

The punching bit 42 may have the same outer diameter as the rod 41, and may be configured to have a wedge-shaped sawtooth shape while the lower end is formed flat or to be made of a sharp cutting edge.

Alternatively, the lower end may be formed in a shape that gradually becomes sharper.

At this time, if the PHC file 2 is equipped with a tip shoe 3 at the bottom, the drilling step is performed by passing the tip shoe 3 through the punching bit 42 .

3 shows a state in which a hole 3a is formed in the tip shoe 3 along the penetration of the tip shoe 3 .

However, when the bottom of the perforated bit 42 is made flat, the above-described shape may be relatively difficult to penetrate the tip shoe 3 .

In order to solve this problem, the tip shoe 3 is preferably formed in a pointed shape at the lower end.

However, when taking a shape that becomes sharper toward the lower end, the area excavated and stirred by the perforation bit 42 is excessively small, so there is a problem that a very high injection pressure is required when injecting the injection material.

Therefore, it is preferable that the drill bit 42 excavates the ground with an appropriate area.

Accordingly, the outer diameter of the perforated bit 42 is preferably made larger than the rod 41, and the tip portion thereof is preferably formed in a pointed shape.

However, in this case, when the punching bit 42 passes through the tip shoe 3, the periphery of the hole 3a is opened downward and the raised portion 3b is easily formed.

By the way, after penetrating the tip shoe 3 with the punching bit 42 and continuing to excavate, the lower drilling hole 50 is formed, and then the rod 41 is moved upward while starting to supply the injection material using the rod 41. When the later rod 41 is to be drawn out, the upward movement of the punching bit 42 is not easy due to the raised portion 3b formed during the drilling.

In order to solve this problem, as shown in FIG. 3 , an upper inclined portion 42a extending downward from the point connected to the rod 41 is formed, and downward from the lower end of the upper inclined portion 42a. A lower inclined portion 42b that is gradually reduced in diameter may be formed.

In this case, in the rod drawing step, the rod 41 can be smoothly drawn while the upper inclined portion 42a is supported on the raised portion 3b around the hole 3a of the tip shoe 3 which is penetrated in the drilling step. do.

In addition, in a state in which the injection material is being injected while the upper inclined portion 43a is supported by the raised portion 3b, the introduction of the injection material into the hollow portion 1 through the hole 3a is significantly suppressed. The bulb 70 is formed from a distance from the bottom of the PHC pile 2, and gradually comes to a point as close as possible to the PHC pile 2 and flows into the hollow part 1 through the hole 3a when formed. As a result, it is possible to minimize the phenomenon that the compression of the surrounding ground is not performed smoothly.

At the lower left end of FIG. 3 , a state in which the injection material is supplied in a state in which the upper inclined portion 43a is supported by the raised portion 3b is shown.

After forming the bulb 70 while compressing the surrounding ground in the lower left state of FIG. 3, the rod 41 is moved upward to supply a certain amount of injection material in the state where the punching bit 42 is located inside the hollow part 1 When the injection material is filled to a certain height inside the hollow part 1, it will be cured and then hardened.

In this case, the bulb 70 at the bottom of the PHC pile 2 and the injection material filled in the hollow part 1 connect the lower part of the PHC pile 2 and the bulb 70 integrally after curing is completed.

The drilling step configured as described above may be performed after the cement paste 30 injected at the time of construction of the PHC pile 2 is completely hardened, but considering that the bulb 70 is integrated into the lower part of the PHC pile 2, the injected Construction before complete curing of the cement paste 30 is more preferable in terms of construction convenience, but integration.

In the present invention, without spraying high-pressure air like jet grouting, the low-fluidity injection material is press-fitted in a state in which the hollow part 1 is maximally sealed using the tip shoe 3, so the lower part of the PHC pile 2 Since the ground is excessively soft and the flow of the PHC pile 2 does not occur well during construction, construction can be performed before the complete hardening of the injected cement paste 30 .

On the other hand, the drilling step may be configured to allow the drilling bit 42 to reach the rock layer below the PHC pile 2 or to drill to the inside of the rock layer as shown in FIG. 6 .

In this case, the bulb 70 serves to support the PHC pile 2 from the ground.

3. Injection step

After separating the rod 41 from the perforator 40 and connecting the injection device 60 to the rod 41, a low-fluidity injection material having a slump value of 50 mm or less is poured through the injection device 60. A cylindrical bulb 70 is formed in the lower part of the PHC pile 2 by press-injection in an ejection type.

5 shows an injection facility for supplying a low-fluidity injection material.

First, in the state in which the injection material 65 is stocked, the injection material 65 is mixed and prepared in the factory type injection plant 66 or the vehicle-mounted injection plant 67 .

Such a plant is pipe-connected to the injection pump 62 at the construction site, and the injection pump 62 is connected to a lift device 64 called a drawing jack key through a high-pressure injection hose 61 .

The lifting device 64 is connected to the rod 41 and is configured to move the rod 41 upward or downward.

Reference numeral '63' in the drawing indicates the generator 63 for the operation of the input pump 62.

This injection step is also preferably made before the cement paste 30 injected when the PHC pile 2 is installed is completely hardened, as described above.

This allows the bulb 70, the PHC pile 2 and the injection materials to be completely integrated.

As shown in FIG. 6 in the drilling step, when the drilling bit 42 is configured to reach the bedrock layer below the PHC pile 2 or to drill to the inside of the bedrock layer, as shown in the right diagram of FIG. 6 , the bedrock layer The bulb 70 is formed from the connection point with (4), and the bulb 70 serves to support the PHC pile 2 from the bedrock layer (4).

In order to play this role, the low-fluidity injection material is composed by mixing cement, stone dust, and soil with an appropriate amount of water, unlike conventional injection materials. It can be made to support the pile (2).

The mixing ratio of cement, stone dust, and soil for this purpose may consist of 100 to 200 parts by weight of stone dust and 100 to 200 parts by weight of soil based on 100 parts by weight of cement, and water is adjusted to an appropriate amount to satisfy low fluidity.

4. Rod drawing step

When the supply of the injection material is completed, the process is finished by drawing the rod 41 from the hollow part 1 of the PHC pile 2 using the lift device 64 .

When the above process is performed, as shown on the right side of FIG. 2 , the cylindrical bulb 70 is formed alone or in layers at the lower part of the PHC pile 2 .

In the drawing of the rod 41 , the start bit 42 and the lower part of the rod 41 are positioned in the lower part of the hollow part 1 , and integration with the bulb 70 can be made better.

For this purpose, as shown in FIG. 4, the rod 41 has a structure in which an upper pipe 41a and a lower pipe 41b are detachably connected, and in the rod drawing step, the upper pipe 41a is connected to the lower pipe. Separated from (41b), only the upper tube (41a) is drawn out, and the lower tube (41b) may be configured to be embedded in the bulb (70) together with the perforated bit (42).

The upper pipe (41a) and the lower pipe (41b) may be connected to each other in a fitting manner and fixed and separated from each other by inserting a fixing pin (41c) in the fitting portion.

In this case, the coupling between the bulb 70 and the PHC pile 2 can be achieved through the rod 41 and the drill bit 42 embedded in the injection material in addition to the injection material injected into the hollow part 1 and hardened. .

In particular, as described above, when the outer diameter of the start bit 42 is larger than the outer diameter of the rod 41 and the upper inclined portion 42a and the lower inclined portion 42b are formed, the rod 41 as shown in the right diagram of FIG. ) During the drawing operation, only the upper pipe 41a is separated and drawn, and the lower pipe 41b and the drill bit 42 are not drawn. no difficulties arise.

In the present invention, it was assumed that the lower bulb 70 was formed at the parent site where the PHC pile 2 was previously constructed, and the allowable tip bearing capacity was calculated.

As a result, it was confirmed that the tip bearing capacity before reinforcement of 1,178 kN can be improved up to 2,029 kN.

Therefore, when the process according to the present invention is applied, the small perforator 40 and the injection device 60 are used to excavate up to the rock layer with an auger without the need for more than two driving equipment in the soft ground where the rock layer is located deeply. By forming the bulb 70 in the lower part of the PHC pile 2 without need, it is possible to secure the tip support force.

1: hollow part 2: PHC file
3: tip shoe 3a: hole
3b: raised portion 3c: incision line
4: bedrock layer 10: casing
20: Ogre 30: Paste
40: perforator 41: rod
41a: upper tube 41b: lower tube
41c: fixing pin 42: punched bit
42a: upper inclined portion 42b: lower inclined portion
50: lower drilling hole 60: injection device
61: high pressure injection hose 62: injection pump
63: generator 64: lift device
65: injection material 66: factory type injection plant
67: vehicle-mounted injection plant 70: bulb

Claims (9)

In the method of expanding and reinforcing the tip of the PHC pile,
A pile installation step of inserting the PHC file (2) having a hollow part (1) formed therein into the ground;
After preparing a perforator 40 equipped with a rod 41 equipped with a perforating bit 42 at the bottom, the rod 41 of the perforator 40 through the hollow portion 1 of the PHC file 2 inserted in the ground ) by inserting the PHC file (2) from the bottom to a predetermined depth, a drilling step of forming a lower drilling hole (50);
After separating the rod 41 from the perforator 40 and connecting the injection device 60 to the rod 41, a low-fluidity injection material having a slump value of 50 mm or less is used through the injection device 60. An injection step of forming a cylindrical bulb 70 in the lower portion of the PHC pile (2) by press-injecting the discharge type;
and a rod drawing step of drawing the rod 41,

The PHC file (2) is equipped with a tip shoe (3) at the bottom,
The drilling step is performed by passing the tip shoe 3 through the drilling bit 42,

The outer diameter of the punching bit 42 is made larger than the outer diameter of the rod 41,
The rod 41 has a structure in which an upper pipe 41a and a lower pipe 41b are detachably connected,
In the rod drawing step, the upper tube 41a is separated from the lower tube 41b, only the upper tube 41a is drawn out, and the lower tube 41b is embedded in the bulb together with the perforated bit 42. doing,
A method of expanding and reinforcing the tip of a PHC pile using low-flow mortar.
delete delete delete The method of claim 1,
The file installation step is
a casing installation step of inserting and constructing the casing 10 in the ground while excavating the ground using the auger 20;
an auger drawing step of injecting the cement paste 30 into the casing 10 while drawing the auger 20;
a file insertion step of inserting the PHC file (2) into the casing (10);
It proceeds to; a casing drawing step of drawing the casing (10),

The drilling step and the injection step are characterized in that before the complete curing of the cement paste (30),
A method of expanding and reinforcing the tip of PHC piles using low-flow mortar.
6. The method of claim 5,
In the casing installation step, the auger 20 is designed to be inserted to the depth of the lower drilling hole 50 by design, which is lower than the lower position of the PHC pile 2 by design,
A method of expanding and reinforcing the tip of PHC piles using low-flow mortar.
The method of claim 1,
It is characterized in that the PHC pile (2) is inserted into the ground when the depth is higher than the bedrock layer, and the PHC pile (2) is inserted and constructed to a lower depth than the bedrock layer,
A method of expanding and reinforcing the tip of PHC piles using low-flow mortar.
The method of claim 1,
The drilling step is
Let the drill bit 42 reach the rock layer below the PHC pile 2, or drill to a certain depth from the rock layer,
characterized in that the bulb 70 formed by the injection step is made to support the PHC pile (2) from the bedrock layer,
A method of expanding and reinforcing the tip of PHC piles using low-flow mortar.
9. The method of claim 8,
The low-fluidity injection material is characterized in that it is prepared by mixing cement, stone dust, and soil with water,
A method of expanding and reinforcing the tip of PHC piles using low-flow mortar.

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