KR20210010138A - Helical pile - Google Patents

Abstract

The present invention relates to a helical pile with improved penetrability, which adjusts a vertical interval of helixes coupled to an outer circumferential surface of a pile shaft to improve the rotational penetrability of the helical pile so as to easily rotate and penetrate into a designed depth, thereby securing stable bearing power and shortening construction time. The helical pile with improved penetrability comprises: a hollow pile shaft; and at least two helixes spirally coupled to the outer circumferential surface of the pile shaft so as to be vertically spaced apart from each other. A distance (d) between the upper and lower helixes is determined such that the upper helix penetrates through a path formed under the ground in accordance with rotational penetration of the lower helix.

Description

Helical pile with improved penetration

The present invention improves the rotational penetration of the helical pile by adjusting the vertical gap of the helix coupled to the outer circumferential surface of the pile shaft, so that it is easily rotated to the depth of design to secure a stable support, and the construction time can be shortened. It is about a helical file that improves entry.

A helical pile is a small-diameter steel pipe pile with a helix (20, helix) attached to a hollow pile shaft (10), a small steel pipe, and is compressed or compressed by acupressure at the top and bottom of the helix and the frictional force on the main surface of the pile shaft. It exhibits a support force against tensile force (Fig. 1).

These helical piles are penetrated into the ground by rotation, and the ground disturbance is small, noise and vibration are small, and the construction speed is fast due to the non-topography. Accordingly, it is widely used in Korea to reinforce the existing foundation and support solar power facilities.

When the helix constituting the helical pile is formed in a spiral of the same curvature over the entire rotation length and the helix face is formed horizontally in all cross sections, the path formed in the ground by the lower blade of the helix when the helical pile penetrates the rotation It is possible to minimize the rotational penetration resistance by digging into the ground in a downward continuous manner as the rear part passes continuously.

However, in general, the helix is manufactured to form a spiral by cutting the plate into a donut-shaped circle with a hole in the center so that the shaft can be coupled, cutting one side of the plate in and out, and then spreading the cut left and right plates vertically.

In the case of manufacturing a helix by spreading the cut surface of the plate vertically as described above, the left and right sides of the helix bend obliquely and the curvature of the helix is inconsistent with each other depending on the position.

In this way, if the cross section of the helix is formed to be inclined and the curvature of each cross section is inconsistent, the surface resistance of the helix increases when the helical pile penetrates the ground, and ground disturbance occurs, which causes the bearing capacity to decrease.

In addition, when a plurality of helixes are provided on the outer peripheral surface of the pile shaft, the upper and lower helixes are usually 3 times the outer diameter of the helix to prevent the shadow effect that the lower helix is repeatedly affected by the load acting on the upper helix. Place them apart from each other so that they are ideal. Since the spacing between these helixes is determined by considering only the shadow effect, each helix is rotated into the ground independently of each other.

Accordingly, as the number of helixes increases, there is a problem that the penetration resistance increases.

On the other hand, the helical pile completes the pile penetration by determining whether or not it has penetrated into sufficiently hard ground by the torque value of the penetration equipment during rotation penetration. However, if the torque value rises due to the penetration resistance of the helix itself as above, it may be mistaken that the pile has reached the design depth, and the pile insert work may be completed.

In this case, the N-value of the ground to which the helical pile is inserted is insufficient, so that the supporting force cannot be exhibited as much as the design.

KR 10-1191286 B1

In order to solve the above problems, the present invention improves the rotational penetration of the helical pile so that the rotational penetration of the helical pile is easily possible to the design depth, thereby securing a stable support and reducing the construction time. I want to provide a file.

The present invention according to a preferred embodiment is composed of a hollow pile shaft and a helix screwed to the outer circumferential surface of the pile shaft so that at least two or more are spaced apart vertically, but the distance (d) between the upper and lower helixes is the rotation of the lower helix It provides a helical pile for improving penetration, characterized in that the upper helix is determined to pass through the passage formed in the ground according to the penetration.

The present invention according to another preferred embodiment provides a helical pile for improving penetration, characterized in that the plane angles of the lower start ends of each helix are configured to be different from each other.

The present invention according to another preferred embodiment provides a helical pile for improving penetration, characterized in that the grout injection hole is formed in the upper rear position of the helix in the pile shaft.

The present invention according to another preferred embodiment provides a helical pile for improving penetration, characterized in that the helix is configured to become thinner toward the outside in cross section.

The present invention according to another preferred embodiment provides a helical pile with improved penetration, characterized in that the lower portion of the helix is formed in a wedge shape whose thickness becomes thinner toward the start end.

The present invention according to another preferred embodiment provides a helical pile with improved penetration, characterized in that a welding groove is formed in a lower portion of the inner end of the helix coupled to the pile shaft.

The present invention according to another preferred embodiment provides a helical pile with improved penetration, characterized in that a guide hole having a sharp center bottom is provided at a lower end of the pile shaft.

According to the present invention, the vertical gap between the plurality of helixes coupled to the outer circumferential surface of the pile shaft is determined so that the upper helix passes through the passage formed in the ground according to the rotational penetration of the lower helix.

Accordingly, by improving the rotational penetration of the helical pile, it is possible to easily rotate the penetration to the design depth, thereby securing a stable support force and providing a helical pile with improved penetration that can shorten the construction time.

1 is a front view showing a conventional helical pile.
Fig. 2 is a perspective view showing a helical pile with improved penetration of the present invention.
Fig. 3 is a diagram showing a relationship between a spacing between helixes and a pitch.
4 is a cross-sectional view showing an arrangement of upper and lower helixes.
5 is a perspective view showing the location of grout injection holes.
6 is a perspective view showing an embodiment of a helix.
7 is a cross-sectional perspective view showing a part of the helix shown in FIG. 6;
8 is a front view showing another embodiment of a helix.
9 is a bottom perspective view of the helix shown in FIG. 8;
10 is a cross-sectional perspective view showing a cross-section of a lower starting end of a helix.
11 is a cross-sectional view showing a detail of a coupling between a helix and a pile shaft.

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

Fig. 2 is a perspective view showing a helical pile with improved penetration of the present invention, and Fig. 3 is a view showing a relationship between a pitch and a spacing between helixes.

As shown in FIGS. 2 and 3, the helical pile for improving penetration of the present invention is a helix screwed to the outer peripheral surface of the pile shaft 1 so that at least two or more of the hollow pile shaft 1 and at least two are separated vertically. It consists of (2), wherein the gap (d) between the upper and lower helixes (2) is determined so that the upper helix (2) penetrates the passage (4) formed in the ground according to the rotational penetration of the lower helix (2). do.

An object of the present invention is to provide a helical pile with improved penetration, which can secure a stable support and shorten construction time by improving the rotational penetration of a helical pile so that rotational penetration is easily possible up to the design depth.

The pile shaft 1 exerts a supporting force by the frictional force on the main surface, and may be composed of a high-strength steel pipe with a hollow formed therein.

The helix 2 is welded to the outer peripheral surface of the pile shaft 1 in a spiral manner.

The helix 2 resists compressive or tensile loads by acupressure on the lower or upper surface.

The helix 2 may be formed in a closed ring shape on a projected area, and may be configured to rotate the pile shaft 1 by 360° or more to support the load of the ground.

The helix 2 is configured to be horizontal over the entire length of the spiral rotation of the helix 2, that is, to form a cross section orthogonal to the pile shaft 1 and to have a constant curvature. Accordingly, after the lower end of the helix 2 is rotated and penetrated while cutting the ground, the rear portion of the helix 2 is penetrated along the space cut at the lower end, so that penetration resistance can be minimized.

The helix 2 is preferably manufactured by casting so that the same curvature can be formed for each cross section.

Since the helix 2 is attached to the pile shaft 1 by welding, a weldable cast steel can be used.

The plurality of helixes 2 coupled to the outer circumferential surface of the pile shaft 1 are provided in the same rotation direction.

The helix 2 is coupled vertically to the pile shaft 1 so as to be spaced apart from each other. In the present invention, the upper helix 2 is formed along the passage 4 formed in the ground while the lower helix 2 is rotated and penetrated. Determine the distance between the upper and lower helixes (2) so that they can enter the ground.

For example, when the upper and lower helixes 2 have the same planar phase, that is, the lower start point of the helix 2 is the same, the distance d between the upper and lower helixes 2 is It is configured to be n times the pitch of the helix 2 (p, the vertical distance when the helix rotates one spiral rotation).

Accordingly, even if the number of helixes 2 increases, penetration resistance can be minimized.

As shown in FIGS. 2 and 3, a guide hole 3 having a sharp central lower end may be provided at the lower end of the pile shaft 1.

As shown in FIG. 1, the conventional helical pile is sharply formed by cutting the lower end of the shaft at an angle.

However, since the tip formed in this way touches the ground and the intrusion part is out of the center of the pile, eccentricity occurs when the helical pile rotates, thereby generating flow in the helical pile.

Therefore, in order to prevent such a flow, a guide hole 3 having a sharp central lower end may be mounted at the lower end of the pile shaft 1.

4 is a cross-sectional view showing an arrangement of upper and lower helixes.

As shown in FIGS. 2 and 4, each of the helixes 2 may be configured to have different plane angles of the lower starting ends.

Even if the upper helix 2 shares the passage 4 formed in the ground by the lower helix 2 and penetrates, the upper and lower helix 2 is separated from each other, so the empty wall of the passage 4 is perfectly maintained. It is difficult. Accordingly, when the upper helix 2 penetrates, an increase in penetration resistance generated when the lower helix 2 cuts the ground is inevitable.

However, in general, in the helical pile, the upper and lower helixes 2 are in the same phase, that is, the lower start ends of the upper and lower helixes 2 (ground cutting part of the lower helix) are joined at the same angle in the plane.

Therefore, the greatest resistance force always acts on the start end side of the lower part of the helix (2), and this resistance force acts eccentrically on one side based on the helical pile. Therefore, there is a problem in that the rotation of the helical pile is hindered, the intrusion of the helical pile is not easy, and ground disturbance increases.

Therefore, in the present invention, by disposing the upper and lower helixes 2 in different phases, the resistance force during rotational penetration is prevented from acting eccentrically to the helical pile.

Accordingly, the helical pile rotates in place to facilitate rotational penetration, and vibration and ground disturbance of the helical pile can be minimized.

For example, the positions of the lower start ends of the upper and lower helixes 2 may be configured to be symmetrical in plan view.

That is, as shown in (a) and (b) of Fig. 4, the upper and lower helixes 2 have a phase difference of 180° from each other, so that the lower start end of the helix 2 is the pile shaft 1 It can be formed alternately from left to right.

In addition, when there are three helixes 2, they may be configured to have a phase difference of 120° to each other to minimize eccentricity due to penetration resistance (not shown).

At this time, when the phase difference between the upper and lower helixes 2 is 180°, the distance between the upper and lower helixes 2 is maintained at (n+1/2) times the pitch of the helixes 2, and formed by the lower helixes 2 The underground passage 4 can be made to be shared by the upper helix 2.

5 is a perspective view showing the location of the grout injection hole.

As shown in FIG. 5, a grout injection hole 11 may be formed in the pile shaft 1 at a position behind the upper end of the helix 2.

As described above, after passing through the lower helix 2, the underground passage 4 formed by the lower helix 2 may be narrowed or closed due to the load of the upper ground and the inflow disturbance of the surrounding ground.

In order to prevent this, a grout injection hole 11 may be formed in the pile shaft 1 at the upper rear position of the helix 2.

Accordingly, when the pile rotation penetrates, the grout material can be injected into the passage 4 formed by the helix 2 from the immediate room of the helix 2 after passing through the helix 2, so that the empty wall of the passage 4 can be maintained. Do.

In addition, as a result, the helix 2 on the top can easily enter, thereby minimizing rotational penetration resistance.

6 is a perspective view showing an embodiment of the helix, and FIG. 7 is a cross-sectional perspective view showing a part of the helix shown in FIG. 6.

As shown in FIGS. 6 and 7, the helix 2 may be configured to have a thinner thickness toward the outside in cross section.

Conventionally, since the helix is manufactured by cutting a plate, it is common to have a rectangular shape having the same thickness on the inside and outside of the helix.

However, such a rectangular cross section has a large torque resistance during pile rotation.

In addition, the helix 2 is coupled in a cantilever structure having one end coupled to the side of the pile shaft 1 in cross section. Accordingly, when a load is applied to the surface of the helix 2, the moment at the side of the pile shaft 1 is large and the moment decreases toward the outside.

Therefore, the helix 2 does not have to form a cross section with the same thickness over the entire cross section.

Therefore, in the present invention, by configuring the helix 2 to be thinner toward the outside in cross section, it is possible to reduce the torque resistance and to save the amount of steel material.

8 is a front view showing another embodiment of the helix, FIG. 9 is a bottom perspective view of the helix shown in FIG. 8, and FIG. 10 is a cross-sectional perspective view showing a cross section of a lower starting end of the helix.

8 to 10, the lower portion of the helix 2 may be formed in a wedge shape whose thickness decreases toward the start end.

During rotation of the helical pile, when a large stone exists in front of the start end of the lower part of the helix 2, the lower front surface of the helix 2 may be caught by the stone, making rotation penetration difficult.

Therefore, when there is an obstacle such as a large stone in front of the lower end of the helix 2, the start end of the lower part of the helix 2 is wedge-shaped so that the obstacle can be pushed upward or downward by the rotation of the helix 2 Can be formed.

To this end, the bottom surface of the helix 2 may be cut into a flat surface 21 to form a wedge shape (FIGS. 9 and 10).

In this case, due to the curvature of the helix 2, the lower end forms an arc shape.

Accordingly, it is preferable that the upper end of the helix 2 is formed in an inwardly concave arc shape to correspond to the lower arc shape, thereby forming a closed ring shape in plan view.

11 is a cross-sectional view showing a detail of a coupling between a helix and a pile shaft.

As shown in FIG. 11, a welding groove 22 may be formed at a lower portion of an inner end of the helix 2 coupled to the pile shaft 1.

In the conventional helical pile, when the helix is coupled to the pile shaft, the helix is joined to the pile shaft in a T-shape, and the pile shaft and the helix surface are joined by fillet welding.

However, fillet welding has a limit in bending resistance because it cannot guarantee the bending performance beyond the thickness of the pile shaft, which is the base material, even if the welding bead is sufficiently secured.

Accordingly, in the present invention, in order to secure a stable bending performance against a load acting upward on the helix during use, a welding groove 22 may be formed at the lower portion of the inner end of the helix 2 to enable penetration welding. .

As shown in FIG. 11, a welding bead may be filled in the welding groove 22 in the lower portion where the tensile stress acts largely due to the bending moment during use, and penetration welding may be performed.

And it is possible to weld (W) by fillet welding without a separate welding groove on the upper part where the compressive force acts mainly.

1: pile shaft
11: grout injection hole
2: helix
21: flat surface
22: welding groove
3: guide sphere
4: passage
W: welding

Claims (7)

Consisting of a hollow pile shaft (1) and a helix (2) screwed to the outer circumferential surface of the pile shaft (1) so that at least two or more are spaced apart,
The gap (d) between the upper and lower helixes (2) is determined so that the upper helix (2) passes through the passage (4) formed in the ground according to the rotational penetration of the lower helix (2).
In claim 1,
Each of the helixes (2) is a helical pile with improved penetration, characterized in that the planar angle of the lower start end is configured to be different from each other.
In claim 1,
In the pile shaft (1), a grout injection hole (11) is formed in the upper rear position of the helix (2).
In claim 1,
The helix (2) is a helical pile with improved penetration, characterized in that the thickness is configured to become thinner toward the outside in cross section.
In claim 1,
The lower portion of the helix (2) is a helical pile with improved penetration, characterized in that formed in a wedge shape whose thickness becomes thinner toward the start end.
In claim 1,
A helical pile with improved penetration, characterized in that a welding groove (22) is formed at a lower portion of the inner end of the helix (2) coupled to the pile shaft (1).
In paragraph 1
Penetration-enhancing helical pile, characterized in that a guide hole (3) having a sharp central lower end is provided at the lower end of the pile shaft (1).

Images