KR20110087175A - From first of all excavation reclamation methodof phc pickets will improve and the method will be able to the method - Google Patents

Abstract

PURPOSE: A construction method for improving the supporting force of PHC pile is provided to increase supporting force by minimizing a slime which is the most serious problem. CONSTITUTION: A construction method for improving the supporting force of PHC pile comprises : a step of forming a perforation hole(100) on the location, in which a pile foundation is installed, after removing slime from the lower part of the perforation hole ; a step of inserting a PHC pile in the perforation hole ; a step of punching the bedrock in a fixed depth by using an excavator of small diameter ; a step of installing an air hole on the center of the PHV pile and removing slime ; a step of inserting a pipe the center part of the pipe and injecting cement paste into the center part ; and a step of injecting cement paste into the surrounding the PHC pile.

Description

{From first of all excavation reclamation methodof PHC pickets will improve and the method will be able to the method}

The present invention relates to a pre-drilling embedding method of the pile foundation construction method, and proposes a method for the pile foundation to function as a foundation more stably and efficiently.

More specifically, the present invention relates to a method for increasing the bearing capacity of the rock on which the pile is supported and the slime (50) lowered in the drilling tool (100) generated during pre-excavation.

In general, in order to construct buildings, foundation works are performed to prevent settlement of the ground. The most commonly used among these foundation works is the method of installing pile foundations.

However, due to the trend of urbanization, high-rise, large-scale and heavy weight of building foundations to install pile foundations, the low vibration / noise method is required due to the strengthening of environmental requirements and regulatory standards for pile foundation construction. have.

If the pile foundation method is classified according to the construction method, it can be classified into anti-punching method, embedding method and on-site casting method. Type method is a method that has been traditionally used to hit the pile directly on the ground. The embedding method is a method developed to solve the problem of noise and vibration generated during the construction of the type pile, and it is a method of drilling the location where the pile is to be installed and plowing the ground after entering the pile, which includes SIP (soil-cement injected precast pile ) Method, SAIP (special auger SIP) method, SDA (seperated doughnut auger) method, and quick-break method.

Since the noise and vibration regulation law was announced in 1994 and the construction of urban structures increased, the demand for pre-drilling embedding method began to increase as the low vibration / noise method was required due to the strengthening of environmental requirements and regulatory standards for pile construction. Recently, it is used in most sites except for special cases such as coastal areas where there are no complaints caused by noise and vibration in driving.

However, in the pre-excavation embedding method, when the drill tool 100 is drilled, the slime 50 generated under the drill tool 100 becomes a problem.

Representatively, when the pile is built into the drilling tool 100, the pile is settled in the slime 50. When the load is applied after the pile construction, the pile may press the slime 50 to sink the pile, which acts as a dangerous factor for the stability of the building. . The slime 50 is a sediment that is piled up or adhered to the bottom surface of the drilling tool 100 by being mixed with water and the soil and stone pieces generated while digging the ground, and cast concrete on the drilling tool 100 without removing it. When the pile is installed, the bearing capacity of the pile is weakened, which in turn causes the lower foundation of the building to become poor. Such weakening of the bearing capacity of the cast-in-place pile is the thicker the thickness of the slime (50), the length of the cast pile The shorter it gets, the bigger it gets. In addition, when the cement paste 700 is injected after drilling, the cement paste 700 may be mixed with the slime 50, and a mixing ratio error may occur. Problems such as the cement paste 700 may not be tightly filled due to the degree of error and irregularities may occur.

Meanwhile, in the buried method, the drilling tool 100 drills the foundation rock, enters the pile, and injects cement paste 700 to fill the pile foundation tightly, and the cement paste 700 leaks out between the pores or joints between the rocks. It can weaken the bearing capacity of pile foundations.

The problem to be solved by the present invention is to provide a PHC pile 300 that can increase the bearing capacity while reducing the amount of settlement by minimizing the slime (50) is the biggest problem of the embedded pile.

In order to solve the above technical problem, the present invention removes the slime 50 by installing a small diameter air hole (500) in the PHC pile (300), and grouts and cuts the pores of the base arm with a small diameter punching machine (500). Stabilize the ground so that the PHC pile 300 is efficiently and stably constructed.

According to the present invention, the following effects can be expected.

First, when designing the PHC pile 300, because the slime (50) to see the low N value of the ground with a safe value, because the slime (50) is removed to determine the N value appropriately to design the PHC pile 300 efficiently The construction cost can be reduced.

Second, when designing the PHC pile 300, the N value of the ground is lowered with a safe value due to the ground subsidence, and since the ground is stabilized, the PHC pile 300 can be efficiently designed by appropriately setting the N value, thereby reducing construction costs. do.

1 is generally a construction method for installing the PHC pile 300.
2 shows that the PHC pile 300 is settled due to the slime 50 at the lower part of the drilling tool 100.
3 shows that the cement paste 700 leaks into the pores of the bedrock below the drilling tool 100.
4 shows the insertion of a tube 500 into the central space of the PHC pile 300 to remove the slime 50 and grout the joints and pores of the rock.
5 shows that the pipe 500 is installed in the central space of the PHC pile 300.
6 shows a fixing device 600 that can be installed under the PHC pile 300 to fix the pipe 500 and increase the tip bearing capacity.

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

Figure 1 shows a general method for constructing the PHC pile 300 in the pre-excavation buried method.

In Figure 2 shows the problem when not removing the slime 50 after the drilling operation in the position of the pile foundation,

3 illustrates a problem when the construction of the PHC pile 300 is made in the state where reinforcement is not made in the base arm supported by the PHC pile 300.

The following is the design formula when designing pile foundation.

Ru = 40NAP + 1 / 5NsAs + NcAc / 2

<Symbol>

Ru: ultimate bearing capacity of the pile (t)

qd: Ultimate bearing capacity of piling ground of pile (t / m2)

Ap: Tip area of pile (m2)

U: perimeter of pile (m)

l: length of the pile in the ground (m)

fs: Pile frictional force (t / m2)

N: n value of tip ground of pile

Ns: N-value average of sand layer to pile tip

As: U x ls

Nc: N-value average of clay layer to pile tip

Ac: U x LC

h: depth of penetration of the pile into the support layer (m)

c: cohesion of the ground (t /)

2 to 3, when designing the PHC pile 300 is designed to set the N value of the tip ground lower than the actual to control these variables.

Therefore, by minimizing these variables to increase the N value of the design ground, the small diameter PHC pile 300 can be used at the same load can reduce the construction cost.

4 is a method for minimizing the above parameters by installing an air hole 500 or a small diameter boring machine 500 in the central space formed in the PHC pile 300 in the method of removing the slime 50 and drilling the rock. To show. After forming the drilling tool 100 to the base rock at the position where the pile foundation is installed with the drilling machine 500, and after the PHC pile 300 is inserted into the formed drilling tool 100, the small space into the center of the PHC pile 300 After inserting the aperture puncher 500 to drill the rock layer to a certain depth, the air hole 500 is installed in the space of the center to remove the slime 50, and from between the joints and the pores of the rock bed layer below the drill hole 100. Cement paste 700 is injected.

6 illustrates a method used in the case of covering the cap on the lower portion of the pile to increase the tip support of the PHC pile 300 in the construction of the method of FIG.

When the PHC pile 300 is entered into the drilling tool 100, a space is formed between the drilling tool 100 and the PHC stake 300 face surface, and since the space is formed in a circular shape, an air hole 500 or a small diameter drilling machine ( If the 500 is installed, the pipe 500 may move during construction, which may make it difficult to work. Therefore, the apparatus of FIG. 6 is installed on the lower surface of the PHC pile 300, and the air hole 500 or the small diameter boring machine 500 is fixed to the apparatus of FIG.

In addition, by using the device of Figure 6 can increase the cross-section of the pile in the design to obtain the pile can further improve the performance of the PHC pile 300. It is natural that the number of pipes 500 that can be installed in the apparatus in FIG. 6 is adjusted according to circumstances.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, the present invention is not limited to the above-described exemplary embodiments, and various modifications, additions and substitutions may be made without departing from the scope of the present invention. And the scope of the present invention is defined by the appended claims.

10: soil ground
20: Rock bed
50: Slime
100: drilling tool
300: PHC stake
500: pipe (air hole or small diameter boring machine)
600: fixing device for reinforcing tip bearing capacity
700: cement paste

Claims (5)

In the construction method of the PHC pile 300 to remove the slime (50) in the lower part of the drilling tool 100, to improve the bearing capacity of the bedrock,
(a) pre-excavating a position where the pile foundation is installed to form a drilling tool 100; (b) entering the PHC pile 300 into the drilling tool 100; (c) perforating the bedrock to a predetermined depth by installing a small diameter perforator 500 as a space formed in the center of the built-in PHC pile 300; (d) installing an air hole 500 to a space formed in the center of the built-in PHC pile 300 and removing the slime 50; (e) injecting the cement paste 700 into the boring hole 100 of the rock by inserting the tube 500 into the space formed in the center of the built PHC pile 300; (f) the built PHC pile 300 Injecting the cement paste 700 around the space formed in the center of the center and the PHC pile 300; Construction method of the PHC pile 300, comprising a
The method of claim 1,
Construction method of the PHC pile 300 by selecting only one of the steps of excavating with a small diameter punching machine 500 and removing the slime 50 with the air hole (500)
The method of claim 1, wherein
Method of installing and installing an air hole 500 or a small diameter boring machine 500 between the gap between the drilling tool 100 and the PHC pile 300, not the central space of the PHC pile 300
In claim 3,
PHC pile 300 in order to facilitate the installation of the air hole 500 or the small diameter boring machine 500 between the gap between the drilling hole 100 and the PHC pile 300, not the central space of the PHC pile 300 PHC pile installed with auxiliary device to fix the pipe (500)
In claim 4,
PHC pile construction method for designing a device 600 that can fix the pipe 500 in the lower PHC pile 300 as a structure to improve the tip bearing capacity

Images