KR20120123952A - Expansion device for end of file - Google Patents

Abstract

PURPOSE: An extension device for the head of a pile is provided to reduce construction time and costs by reducing the length of a pile. CONSTITUTION: An extension device for the head of a pile comprises multiple extension grooves(110), extension portions, and extension wings(130). The extension grooves are formed along the circumference of the bottom end of a pile(100). The extension portions are formed between the extension grooves. The extension wings are formed in the inner side of the extension portions. One surface of each extension wing is fixed to each extension portion, and the other surface is inclined.

Description

Pile tip extension {EXPANSION DEVICE FOR END OF FILE}

The present invention relates to a pile for increasing the tip bearing capacity, and more particularly, to a tip expansion device of the pile that can increase the tip area by increasing the tip area by extending the tip using the tip device of the pile.

A pile is a structure that installs even a tip support layer that can secure bearing capacity when the ground subsidence and the bearing capacity of the ground are outside the allowable range when the structure is constructed on the soft ground.

Piles are generally divided into tip support piles and friction piles. However, this is difficult to distinguish clearly. That is, when the celebration is small, the friction pile is supported by the surrounding friction, and when the celebration is large, it is mainly supported by the tip bearing force. However, most of the piles are installed in soft or loose layers, so the friction of the main surface is not large, and most of them are secured by the tip bearing capacity.

The engineering method of calculating the bearing capacity of the pile is as follows.

(1) hydrostatic formula

Ultimate support = tip support + principal friction

Allowable bearing capacity

(2) Increase in ultimate bearing capacity (applied safety factor 3)

Increased bearing capacity by increasing tip area of pile Pile diameter D = 40 cm D = 44 cm D = 45 cm D = 46 cm Ultimate bearing capacity (ton) 188 228 240 249 Allowable bearing capacity (ton) 63 76 80 83 % Increase 17.0 21.0 24.0

(3) converted to N

Based on D = 40cm, N value that can secure 188 tons of ultimate bearing capacity when the tip area is increased by the extension part is inverted.

Convert N value of tip strata to inverse Pile diameter D = 40 cm D = 44 cm D = 45 cm D = 46 cm Ultimate bearing capacity (ton) 188 228 240 249 Reference N inch 50 50 50 50 N value equivalent 50 41 39 38

As shown, the tip bearing pile has a larger allowable bearing capacity as the tip area of the pile increases, so that the tip area is increased in construction, stability and economy.

Recently, after the insert having the same diameter as the body in the drilling hole to extend the cross-sectional area of the tip, there is no problem in the workability, the technology for the pile to increase the end bearing capacity is being researched and developed.

For example, the Republic of Korea Patent Application No. 2009-0040096 (see Figure 1) consists of the tip of the pile in the tapered form, attached to the expansion wedge, the expansion wedge after the insertion of the pile, the area of the pile tip is expanded A pile configured to be disclosed is disclosed.

This prior art has the following problems.

In the prior art, the use of a separate structure, such as an expansion wedge, the structure is complicated, there is a problem in that the cost of manufacturing cost increases and the manufacturing time is long, which is disadvantageous in economics.

However, the present invention is not only very advantageous in terms of economy and workability due to the simple manufacturing method and structure, but also in the case of small quantity, it is possible to manufacture on site, and in many cases, it is possible to manufacture a factory for mass production.

The present invention has been made to solve the conventional problems as described above, the object of the present invention is to install a tip expansion device using a conventional steel pipe at the tip of the pile after inserting the tip into the drilling hole hammer or other The objective is to provide a pile that can increase the tip bearing capacity by increasing the tip area by simply extending the tip extension device with the equipment (ie all equipment capable of extending the tip).

In general, the pile to be constructed is the same diameter, that is, the area of the pile head and the tip portion. However, the pile using the tip extension device is a pile that increases the tip bearing capacity (ie, the allowable bearing capacity) by increasing the tip area when only the head and the tip are constructed on the same site, thereby increasing the tip area. The tip can be shorter in construction time than the same general pile, reducing the construction period and cost (see Table 2).

As shown in Table 2, when the diameter is 40cm, the N value should be 50 or more to secure the ultimate bearing capacity of 188 tons, but when the tip is extended by the tip extension device, the N value is 38.

That is, the maximum allowable bearing force can be obtained even if the depth of drilling is shortened.

In addition, there is an advantage that can be used by connecting the end expansion device to both the steel pipe pile and PHC pile, and since the production of the end expansion device is simple, no special technology is required, and the manufacturing cost and production period are greatly reduced.

(1) Tip extension method

To extend the tip of the pile, make several extension grooves in the steel pipe pile by a certain length, and then manufacture an extension device by welding the extension blades (triangle or trapezoidal iron plate) between the expansion groove and the expansion groove. Insert the produced pile into the drilling hole and use the hammer for the steel pipe pile, and for the PHC pile, make the tip extension device with the larger diameter steel pipe and insert the PHC pile inside the tip extension device to the PHC pile. Apply a load to extend the tip to increase the tip area.

Therefore, in the case of piles of the same diameter, the size of the tip expansion device is larger than the steel pipe pile, that is, the tip area becomes larger, so that the allowable bearing capacity of the PHC pile is larger.

1) Steel pipe pile

In the case of steel pipe piles, the tip extension device can be manufactured directly on the tip of the steel pipe pile.In this case, the method of extending the tip is to insert the pile into the perforated hole, and then insert the hammer into the steel pipe and prefabricate and weld it. When the load is applied to the blade, the expansion groove opens and the area of the tip portion increases.

2) PHC Pile (High Strength Concrete Pile)

In the case of PHC pile, the tip expansion device is made of steel pipe larger than the outer diameter of PHC pile, and the finished product is made by inserting PHC pile into the steel pipe. Use it to extend the tip as the expansion groove opens.

3) Manufacture of tip extension device

The tip expansion unit can be factory manufactured and field manufactured as required.

In particular, if the length of the support is different and the number of constructions is different because the tip support layer is irregular, it may take a lot of time to manufacture the tip extension device at the site, which may affect the construction period. It is very effective to shorten the construction period by connecting piles by construction length in the field.

(2) Construction method

1) Steel pipe pile

-Drill more than the pile diameter by the predetermined length at the position where the pile is to be constructed.

-Insert the manufactured tip extension pile.

-Put the hammer inside the steel pipe and apply the load to extend the tip.

-In case of increasing friction, fill the inside of the hole with soil. Inject CEMENT MILK to the outside.

-If tip bearing capacity is sufficient, fill the inside and outside of the hole with soil around the site.

2) PHC stake

-The extension tip is made of steel pipe larger than the outer diameter of PHC pile.

-Make a pile by inserting PHC pile into the manufactured extension tip.

-Drill more than the pile diameter by the predetermined length at the position where the pile is to be constructed.

-Insert the manufactured tip extension pile.

-Use PHC as a substitute for HAMMER to extend the tip.

-In case of increasing principal friction, inject CEMENT MILK into the hole.

-If tip bearing capacity is sufficient, fill the hole with soil around the site.

In the present invention as described above has the following effects.

1) Material supply is easy because it uses steel pipes used in the market.

2) The production method is simple and mass production is possible.

3) Expandable wing is easy to manufacture because it uses steel plate.

4) Easy to make expansion groove.

5) Since the tip support layer is a rigid support layer, when the tip extension part is extended with a hammer or a PHC pile, the maximum extension diameter extends only to the wall of the drilled hole, so that the extension part is not destroyed even if a large load for expansion is applied. That is, the maximum diameter of the expansion device does not become larger than the maximum drilling diameter.

6) If the tip extension is extended, the tip area is increased and the allowable bearing capacity is increased.

7) As the allowable bearing capacity increases, the construction length of the pile can be shortened, which reduces the cost and construction period. In other words, the drilling length is shortened, so the drilling length and material cost are reduced.

8) Both steel pipe pile and PHC pile can be used.

9) The material cost of piles is cheaper than that of steel pipe piles, so it is possible to save construction cost by using PHC piles in strata not affected by corrosion. However, if corrosion is concerned, the cost of construction may increase slightly because the tip expansion device uses thicker steel pipes and extension wings.

10) It is very effective because the tip area is increased even when it is installed in the strata where the load capacity of the structure does not need to be large.

11) Effective for clay soft ground. In other words, the effect of the sub-friction can be replaced to some extent by the increase in the tip bearing capacity.

12) The VE effect is very large.

13) If the pile is inserted inside the drilled hole, even if the verticality drops, applying a load to extend the tip will cause the pile to be naturally located in the center of the drilled hole because the extension will no longer open on the wall, increasing the verticality.

14) If the CEMENT MILK is injected after the construction is completed, the allowable bearing capacity can be increased because the frictional force increases, which increases the stability and economy.

15) During drilling, settlement is caused by the SLIME remaining at the tip. However, since the tip extension part is installed on the base plate through the SLIME part by the force applied to extend the tip when the tip expansion pile is extended, additional settlement by SLIME can be prevented after completion of construction. In addition, since the inside of the tip extension part is empty, SLIME processing is not a problem after completion of drilling.

1 is a cross-sectional view showing the tip expansion pile according to the prior art.
Figure 2 is a perspective view showing a specific embodiment of the tip expansion device for a steel pipe pile according to the present invention.
Figure 3 is a cross-sectional view showing a specific embodiment of the tip expansion device for a steel pipe pile according to the present invention.
Figure 4a to 4d is a construction flowchart showing the construction method of the tip expansion device for steel pipe piles according to the present invention.
Figure 5 is a perspective view showing a specific embodiment of the tip expansion device for a concrete pile according to the present invention.
Figure 6 is a cross-sectional view showing a specific embodiment of the tip expansion device for a concrete pile according to the present invention.
7A to 7C are plan views illustrating various embodiments of an extension part applied to the tip extension device according to the present invention.

The present invention is to achieve the object as described above, the present invention is formed integrally with the steel pipe pile at the lower end of the steel pipe pile of the hollow steel pipe form; A plurality of expansion grooves are formed in the longitudinal direction along the outer periphery of the lower end, and a plurality of expansion portions divided into the expansion grooves are formed; One side is fixed to the inner side of the expansion portion and the other side is configured to include an expansion blade of the plate member extending to the center of the steel pipe to the inclined surface: the inclined surface of the expansion blade is formed to be wider from the upper end to the lower end It includes the tip expansion device of the pile.

And the present invention is formed in the form of a circular steel pipe having a diameter that can be inserted into the bottom of the concrete pile of the circular rod shape: a plurality of expansion grooves are formed in the longitudinal direction along the outer periphery of the lower portion, the expansion grooves Forming a plurality of distinct extensions; One side is fixed to the inner side of the expansion portion and the other side is configured to include an extension blade of the plate member extending to the center to the inclined surface: the inclined surface of the expansion blade, the pile is formed so as to become wider from the top to the bottom It includes a tip extension device.

In this case, the extension blade is formed in a triangle or trapezoidal shape, the inclined surface of the extension blade may be formed in a straight line or curve.

In addition, the extension blade may be fixed to the inner surface of the extension by welding.

And the expansion groove may be formed at intervals to equally divide the steel pipe.

In addition, two or more said extension blades may be formed in the inner surface of each location of the said extension part.

Hereinafter, with reference to the accompanying drawings a specific embodiment of the tip expansion device according to the present invention as described above will be described in detail.

The tip expansion device according to the present invention will be described by dividing the embodiment to be applied to the steel pipe pile and PHC pile (hereinafter referred to collectively as 'concrete pile' regardless of strength), and first to explain the tip expansion device for steel pipe pile Shall be.

Figure 2 is a perspective view showing a specific embodiment of the tip expansion device for a steel pipe pile according to the present invention, Figure 3 is a cross-sectional view showing a specific embodiment of the tip expansion device for a steel pipe pile according to the present invention.

As shown in these drawings, the tip expansion device 140 for the steel pipe pile according to the present invention is formed integrally with the steel pipe pile 100 in the lower steel pipe pile. In addition, a plurality of expansion grooves 110 are formed along the outer circumference of the lower end of the lower end of the steel pipe pile tip expansion device 140. Expansion portions 120 are formed between the expansion grooves 110 by the expansion grooves 110.

The expansion groove 110 is formed by a predetermined length in the longitudinal direction of the tip expansion device 140 for the steel pipe pile, the length of the expansion groove 110 is formed differently depending on the required size of the expansion unit 120 do.

2 and 3, four expansion grooves 110 are formed, and an example in which four expansion portions 120 are formed is illustrated. However, the number of the expansion grooves 110 and the expansion portions 120 may vary depending on site conditions. Each may be formed differently (ie, six, eight, etc.).

On the other hand, as shown in Figure 3, the inner side of the expansion portion 120 of the tip expansion device 140 for steel pipe piles, the expansion blade 130 is formed.

The extension wing 130 is one side is fixed to the expansion unit 120 and the other side (pile center side) is a plate-shaped member formed as an inclined surface, is formed to have a slope that is wider from the upper end to the lower end.

At this time, the extension blade 130 is fixed by welding to the inner surface of the extension portion 120.

On the other hand, the extension blade 130 may be configured in a variety of forms, as shown in Figure 3, may be formed in a trapezoidal shape of the upper portion is narrow, the lower portion is wide, or may be formed in a triangular shape. However, the steel pipe pile 100 has an inclined surface toward the lower end, the inclined surface when the vertical load is applied to the inclined surface, the steel pipe pile 100 from the top to the lower portion so that the partial force is generated in the outward direction of the steel pipe pile (100) It is the same to have the inclination direction adjacent to the central part of.

In addition, the inclined surface may be formed as a straight inclined surface, it may be formed in a curved surface.

Hereinafter, the construction method of the tip expansion device for a steel pipe pile according to the present invention with reference to Figure 4a to 4d will be described in detail.

In order to construct the basic construction using the tip expansion device for steel pipe piles according to the present invention, first, as shown in Figure 4a, the hole to insert the pile into the ground is drilled. At this time, the drilling hole is drilled to correspond to the diameter after the expansion is expanded.

Then, as shown in Figure 4b, the steel pipe pile equipped with a tip expansion device for a steel pipe pile according to the present invention is inserted into the drilling hole.

And as shown in Figure 4c, using a hammer 200 to apply a load to the inside of the steel pipe pile (100). At this time, as the loading method of the hammer, various known loading methods may be used according to the site conditions as well as the hammer.

When the hammer 200 is driven into the tip expansion device 140 for the steel pipe pile through the steel pipe pile 100, the hammer 200 extends 130 at the bottom of the tip expansion device 140 for the steel pipe pile. ) The load in the vertical direction is transmitted to the inclined surface.

Therefore, the load by the hammer 200 generates a horizontal force toward the outside of the tip expansion device 140 for the steel pipe pile to the expansion blade 130 and the expansion portion 120 by the horizontal force is the steel pipe pile It will be opened in the outward direction of the distal end expansion device 140.

As shown in FIG. 4D, when the expansion part 120 is expanded, the tip part of the tip expansion pile 140 is expanded (that is, the tip area of the pile is increased), and the steel pipe pile 100 is expanded. The leading bearing capacity of is increased.

Then, as shown in Figure 4e, depending on the construction conditions to fill the cement mortar or soil between the outer circumferential surface of the steel pipe pile and the perforation hole. Of course, a filler such as cement mortar may also be filled inside the steel pipe pile 100.

Next, the tip expansion device for concrete piles according to the present invention will be described.

5 is a perspective view showing a specific embodiment of the front end expansion device for a concrete pile according to the present invention, Figure 6 is a cross-sectional view showing a specific embodiment of the front end expansion device for a concrete pile according to the present invention.

As shown in these figures, the tip expansion device 400 for concrete piles according to the present invention is formed to be inserted into the concrete pile (300).

The concrete pile 300 is a concrete round rod-shaped concrete piles, generally PHC piles using high-strength concrete is used.

And the tip expansion device 400 for the concrete pile is formed of a circular steel pipe having a diameter that can be inserted into the lower end of the concrete pile (300).

At this time, a plurality of extension grooves 410 in the longitudinal direction are formed on the lower outer circumferential surface of the front end expansion device 400 for the concrete pile, thereby forming an extension 420 between the expansion grooves 410.

On the other hand, the expansion blade 430 is formed in the expansion portion 420 inside the tip expansion device 400 for the concrete piles. The expansion blade 430 is to have the same shape as the expansion blade 130 of the above-described expansion device for the steel pipe pile. Figure 6 shows the expansion wing 430 formed in a triangular shape.

Looking at the construction method of the tip expansion device for the concrete piles, the tip expansion device 400 for the concrete pile is inserted into the bottom of the concrete pile 300 is inserted into the drilling hole, the head of the concrete pile 300 Load the load.

At this time, the loading method can be applied to a variety of known methods, for example, in place of the hammer can be loaded by driving the expansion blade to the weight of the concrete pile (300).

When a load is applied to the head of the concrete pile 300, the load is transmitted to the inclined surface of the expansion blade 430 inside the tip expansion device 400 for the concrete pile.

Therefore, a horizontal force is generated on the expansion blade 430 toward the outside of the expansion cap 400, and the expansion part 420 is opened in the outward direction of the tip expansion device for the steel pipe pile by the horizontal force.

Hereinafter, various embodiments of the extension that can be applied to the tip expansion device according to the present invention will be described.

7A to 7C show various embodiments of the extension part applied to the tip extension device according to the present invention in a plan view.

As shown in FIG. 7A, four extension portions 120 are formed by dividing steel pipes into four portions, and one expansion wing 130 is formed on an inner surface of the expansion portion 120.

On the other hand, the expansion unit 120 shown in Figure 7b is formed of four by dividing the steel pipe into four, the inner side of the expansion unit 120 is formed with two expansion wings 130, respectively. In this case, expansion is possible in a more stable form than the extension shown in FIG. 7A.

In addition, the expansion part 120 illustrated in FIG. 7C is formed by dividing the steel pipe into six equal parts, and one expansion wing 130 is formed on the inner surface of the expansion part 120.

Of course, the form of the expansion portion is not limited to the form shown in Figs. 7A to 7C, it is possible to form N expansion portions by dividing the steel pipe into N equal parts.

In addition, as many extension blades as necessary may be formed inside the extension part.

It is to be understood that the invention is not limited to the disclosed embodiment, but is capable of many modifications and variations within the scope of the appended claims. It is self-evident.

The present invention relates to a tip expansion device that extends the tip end of the pile to increase the end support force, according to the present invention, there is an advantage that can provide a tip expansion device that is relatively simple in structure and easy to manufacture and construct.

100: steel pipe pile 110: expansion groove
120: expansion unit 130: expansion wing
140: tip expansion device for steel pipe pile 200: hammer
300: concrete pile 400: tip expansion device for concrete pile

Claims (6)

An inner part of which is integrally formed with the steel pipe pile at a lower end of the steel pipe pile having a hollow steel pipe shape;
A plurality of expansion grooves are formed in the longitudinal direction along the outer periphery of the lower end, and a plurality of expansion portions divided into the expansion grooves are formed;
One side is fixed to the inner side of the expansion portion and the other side comprises an expansion blade of the plate member extending to the center of the steel pipe to the inclined surface:
The inclined surface of the expansion blade,
End expansion device of the pile, characterized in that the width is formed from the top to the bottom wider.
It is formed in the form of a round steel pipe with a diameter that can be inserted into the bottom of the concrete pile in the form of a round rod:
A plurality of expansion grooves are formed in the longitudinal direction along the outer periphery of the lower end to form a plurality of expansion portions divided into the expansion grooves;
One side is fixed to the inner side of the expansion portion and the other side comprises an extension wing of the plate member extending to the center with an inclined surface:
The inclined surface of the expansion blade,
Tip expansion device of the pile, characterized in that the width is formed from the top to the bottom wider.
The method according to claim 1 or 2,
The expansion wing,
Formed in the shape of a triangle or trapezoid,
The inclined surface of the expansion blade is a front end expansion device of the pile, characterized in that formed in a straight or curved.
The method of claim 3, wherein
The expansion wing,
Tip expansion type pile, characterized in that fixed to the inner surface of the expansion by welding.
The method of claim 4, wherein
The expansion groove,
Tip expansion type, characterized in that the steel pipe is formed at equal intervals or unevenly divided intervals.
The method of claim 5, wherein
The expansion wing,
Tip expansion type, characterized in that at least one formed between the expansion groove inner side surface expansion groove.

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