JP3163420B2 - Construction method of pile with high frictional force - Google Patents

Abstract

A method of constructing high-friction piles in the ground is provided, wherein the amount of excavated soil from prebored holes can be reduced, and the total number of piles which must be set for a pile foundation can be reduced. An auger is utilized which comprises an elongated shaft (1) and a helical blade (2, 3) extending around the shaft (1) and projecting radially from the periphery of the shaft (1). The shaft comprises a first helical blade (2) along the length of the main portion thereof with an inclination angle in the positive direction of rotation and at least one second helical blade (3) only along the top portion of the shaft (1) with an inclination angle in the opposite or reverse direction as that of the first helical blade (2). When drilling such an auger into the ground, the agitated soil is thrust sideways into the ground so that a plastic zone (A) is formed around the hole up to a prescribed range. Next, a hardening agent (4) is poured into the hole, and then a support or reinforcement material (5) is inserted into the hardening agent (4) before the hardening agent (4) hardens completely. The support material (5) and the plastic zone (A) surrounding the hole form together a monolithic pile. <IMAGE>

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for constructing a pile having a high frictional force.

[0002]

2. Description of the Related Art Pile foundations using existing piles such as concrete piles and steel pipes are constructed by two types of methods. In other words, there are a driving method in which the existing pile is driven directly into the ground, and an embedding method in which a hole is formed in the ground and the existing pile is inserted into the hole.

[0003]

Among them, the embedding method has many features. However, since it is necessary to discharge earth and sand larger than the pile capacity by drilling, residual soil is generated. There is a problem that the processing is costly.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned conventional problems, and has a high friction, which can reduce the amount of excavated soil left over and the amount of piles driven. It is an object of the present invention to provide a method for constructing a pile having strength.

[0005]

In order to achieve the above object, a method of constructing a pile having a high frictional force according to the present invention uses an auger provided with an arc plate around a stirring blade and a spiral blade. This auger forms a hole by spreading the earth and sand around the ground, forming a plastic area in a certain area around the hole wall of the formed hole, and then pouring a hardening agent into the hole. Before the hardening agent is hardened, a support member is inserted into the inside thereof, and the support member and the plastic region around the hole wall are integrated to form a pile, which is characterized by a construction method of a pile having a high frictional force. is there.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for constructing a pile having a high frictional force according to the present invention will be described below with reference to the drawings.

<A> Auger to be used. In constructing the pile of the present invention, an auger as shown in FIG. 2 is used. That is, except for the upper position of the rotating shaft 1,
A spiral blade 2 having an inclination in the normal rotation direction is provided around the rotation shaft 1 over substantially the entire length. The forward spiral wing 2 has the same structure as a normal auger wing for excavation.

<B> Reverse spiral wings. On the other hand, a spiral blade 3 having an inclination in a direction opposite to the inclination of the forward spiral blade 2 is provided above the rotating shaft 1. By providing the reverse spiral wing 3 especially on the upper part of the rotating shaft 1, it is possible to prevent the forward rotation spiral wing 2 of the auger from raising the drilling earth and sand. However, since the amount of excavated earth and sand once increases, in some cases, a penetrating pipe 31 penetrating vertically may be attached to a part of the reverse spiral wing 3.
This reverse spiral wing 3 can be provided double as shown in FIG. Alternatively, as shown in FIG.
The structure which attaches the outer wall 32 to the outer periphery of can also be adopted. In such a case, a penetrating pipe 31 penetrating vertically may be attached to a part of the reverse spiral wing 3.

<C> Preventing the excavated soil from rising. When the auger as described above is placed on the ground and the rotating shaft 1 is rotated, the ground can be bored by the forward spiral wing 2 occupying the main part. However, since the reverse spiral blade 3 is provided on the upper part of the forward spiral blade 1, all or part of the earth and sand that has risen due to the rotation of the forward spiral blade 1 is prevented from rising by the reverse spiral blade 3. . As a result, the excavated earth and sand can be pushed back and pushed into the surrounding earth and sand without being discharged to the outside. In some cases, a bentonite solution or the like is mixed simultaneously with the drilling.

<D> Formation of a plastic region. Originally, earth and sand equivalent to the volume of the rotating shaft 1 and the spiral blades 2 and 3 should be discharged to form a cavity. However, by preventing the discharge of the earth and sand, that volume of earth and sand is spread to the surroundings. In this way, the soil is spread to the surroundings, thereby compressing the surrounding soil and reducing the gap between the soil particles (the sum of the pore water and air in the soil particles). Thus, the plastic region A can be formed in a certain range.

<E> Setting of plastic region. As the plastic region A formed around the hole wall, the region is determined using the shear elastic constant of the ground and the adhesive force as factors.
For example, the range of the plastic region A can be calculated by the following formula (Equation 1).

(Equation 1)

<F> Injection of a curing agent and a support member. While maintaining the plastic region A under the above conditions, the hardener 4 such as mortar is injected into the holes. Then, before the curing agent 4 is completely cured, the support member 5 is inserted therein. The support member 5 is, for example, H steel. The amount of the hardener 4 to be charged is determined by the amount of the hardener 4 when the support member 5 is inserted.
Is set to such an amount as to reach the upper part of the hole, the hardener 4 does not overflow to the outside of the hole. When the hardening agent 4 is hardened, a pile in which the support member 5 and the plastic region A around the hole wall are integrated can be formed.

[0013]

As described above, the method of constructing a pile having a high frictional force according to the present invention, as described above, pushes a certain range into the plastic region by pushing the drilled soil around the hole wall with almost no discharge. In this method, the hardening agent 4 is poured into the inside, and the supporting member 5 is charged. Therefore, the following effects can be obtained. <B> Since the ground around the pile is compacted and improved to a dense state, a certain range of the plastic region A set around the pile can be used as the range of the pile. Therefore, the number of piles to be piled can be significantly reduced as compared with the conventional method, and the construction cost can be reduced. <B> The amount of discharged earth and sand is extremely small, and most of it is pushed into the surrounding earth and sand. Therefore, the amount of residual soil treatment is small and economical.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a pile having a high frictional force with a surrounding plastic region.

FIG. 2 is an explanatory view of an auger for constructing a friction pile according to the present invention.

FIG. 3 is an explanatory view of another embodiment of the auger.

Continuation of the front page (56) References JP-A-8-13972 (JP, A) JP-A-5-247923 (JP, A) JP-A-8-269970 (JP, A) JP-A-7-901 (JP) , B2) (58) Field surveyed (Int. Cl. ⁷ , DB name) E02D 5/34 E02D 3/12 101 E21B 7/00

Claims (2)

(57) [Claims] 1. A spiral blade having a forward rotation inclination and a reverse rotation inclination spiral blade are provided around a rotation axis, and the spiral blade having a reverse rotation inclination is provided with a rotation shaft. By using the auger provided on the upper part of the auger, a part of the rise of drilling soil by the forward spiral wing of this auger is blocked by the reverse spiral wing, so that the hole is formed while pushing the drilling soil around. A plastic region is formed in a certain range around the hole wall of the formed hole, and then a hardener is injected into the hole, and before the hardener is hardened, a support member is inserted into the inside thereof, A method for constructing a pile with high frictional force, which comprises integrating a plastic region around the hole wall to form a pile. 2. A plastic region formed around the hole wall is determined by using the shear elastic constant of the ground forming the hole and the adhesive force as factors, and the plastic region is integrated with a support member to form a pile. The method for constructing a pile having a high frictional force according to claim 1, which is configured.