JPH07305349A - Device for preventing tendon from rising together with ground anchor and method for construction - Google Patents

Abstract

PURPOSE:To prevent a tendon from rising together with a ground anchor as a casing pipe is pulled out. CONSTITUTION:This device for preventing a tendon from rising together with a ground anchor comprises a cylindrical portion 11 for connection to the anchored end 3 of a tendon 2 and a wing 12 projected from the outer periphery of the cylindrical portion 11, inclined from the end of the cylindrical portion 11 to an anchor head 4 and in a direction in which it gradually extends away from the center of the anchored end 3, and given a restoring force in that direction. The wing 12 is enlarged more than the bore of a casing pipe 5 by the restoring force and resists the force of drawing out toward the anchor head 4, while abutting the wall of a hole drilled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supply prevention device and a construction method used for constructing a permanent or temporary ground anchor.

[0002]

2. Description of the Related Art Ground anchors are constructed by inserting a casing pipe into a target ground and making a hole, then injecting grout material into the casing pipe, and before hardening the anchor tendon. Insert
This is performed by pulling out the casing pipe and fixing the fixing portion of the tendon in the grout material. However, when pulling out the casing pipe, the tendon may be pulled up together with the casing pipe due to friction between the casing pipe and the tendon. It is difficult to recover if the tendon is not supplied, and it may damage the tendon when trying to recover it, so the supply must be reliably prevented.

Further, as the anchor length becomes longer and the depth of drilling increases, tendon is greatly influenced by the buoyancy of the grout material before hardening in the drilling, so that the tendon easily rises.
It will also be a factor of supply.

The present invention has been made in view of the above background, and proposes a device for preventing the tendon of the ground anchor from being raised and a construction method using the device.

[0005]

According to the present invention, the tendon is prevented from being lifted up when the casing pipe is pulled out by connecting a device which abuts the hole wall and resists the pulling force to the tip of the fixing portion of the tendon.

The device for preventing the feeding is provided with a tubular portion connected to the tip of the fixing portion and a projecting member on the outer periphery of the tubular portion. It consists of a wing with a restoring force applied in that direction, and the wing expands from the inside diameter of the casing pipe by the restoring force and resists the pulling force to the anchor head side when it hits the hole wall of the drilled hole. By doing so, the fixing position at the tip of the fixing unit is held.

Construction of the ground anchor is carried out by inserting the casing pipe into the target ground and drilling, then injecting grout material into the casing pipe, and inserting the tendon connected to the feeding prevention device before hardening, It is done by pulling out the casing pipe and fixing the tip of the tendon fixing part in the grout material.When pulling out the casing pipe, after pulling the casing pipe a distance larger than the length of the blade of the anti-raising device, the tendon is pulled out. By pushing in and projecting the feed-up prevention device from the tip of the casing pipe, its blades abut against the hole wall, and the casing pipe is pulled out with the tip of the fixing part stabilized in the drilled hole. It is possible to perform the work while surely fixing the tip in the grout material.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is to insert a casing pipe 5 into a target ground and drill a hole, then inject a grout material 6 into the casing pipe 5 and, before hardening, tendon 2
Insert the casing pipe 5 and pull out the tendon 2
In the construction method of fixing the fixing part of the inside of the grout material 6, the apparatus is a device for preventing the tendon 2 from being raised when the casing pipe 5 is pulled out.

As the tensile material for the tendon 2, a structural steel rod made of aramid fiber reinforced plastic or a strand, a PC steel rod or a PC steel twisted wire is used.

As shown in FIG. 1, the feeding-up prevention device 1 is provided with a cylindrical portion 11 connected to the tip 3 of the fixing portion and a protrusion provided on the outer periphery thereof.
The blade 12 is gradually inclined from the tip end side of the tubular portion 11 to the anchor head 4 side in a direction away from the center of the fixing portion tip 3 and is provided with a restoring force in that direction. It expands from the inner diameter of the pipe 5 and resists the pulling force toward the anchor head 4 side in a state of hitting the hole wall of the drilled hole.

2 and 3 shows a case where the feeding prevention device 1 has radial blades 12 projecting from a cylindrical portion 11 circumscribing an outer cylinder 31 which constitutes the tip 3 of the fixing portion. It is manufactured by notching a part of the above in the axial direction and bending the remaining part toward the outer peripheral side.

Here, the bent portion becomes the wing 12, and the outer cylinder
It is fixed to 31 by a screw 13 penetrating the tubular portion 11.

In the feeding prevention device 1 shown in FIGS. 4 and 5, a screw is formed on the outer circumference of the tubular portion 11 inscribed in the outer barrel 31 of the tip 3 of the fixing portion, and this is a female screw cut on the inner periphery of the outer barrel 31. It is an example of manufacturing when fixing by screwing into. The wing 12 is the cylinder 11
Are rotatably supported by the leg portions 14 integrated with each other, and connected by springs 15 to each other so that the legs can be freely opened.

The blade 12 of the feeding prevention device 1 is opened by the restoring force by the tip 3 of the fixing portion projecting from the tip of the casing pipe 5 and strikes the hole wall, and the tendon 2 is pulled out together with the casing pipe 5. To prevent. The buildup prevention device 1 also resists the buoyancy acting on the tendon 2 before the grout material 6 is cured, and prevents the tendon 2 from rising.

According to a second aspect of the present invention, after the casing pipe 5 is inserted into the target ground to form a hole, the grout material 6 is injected into the casing pipe 5, and before the hardening, the fixing portion tip 3 is provided. In the construction method of inserting the tendon 2 to which the feeding prevention device 1 described in 1 is connected and pulling out the casing pipe 5 to fix the tendon 2 in the grout material 6, the feeding prevention device 1 prevents feeding of the tendon 2. However, this is a method of fixing this in the hole.

The present invention comprises steps from the insertion of the tendon 2 shown in FIG. 6 to the withdrawal of the casing pipe 5 shown in FIG.

FIG. 8 shows the hole bottom portion before the insertion of the tendon 2, but the casing pipe 5 before the tendon 2 is completely inserted to the hole bottom, as shown in FIG. Is raised by a distance greater than the length of. After that, as shown in FIGS. 10 and 11, the tendon 2 is pushed to the bottom of the hole to cause the upkeep device 1 to protrude from the tip of the casing pipe 5. At this time, the feeding prevention device 1 is
11 hits the hole wall and stabilizes the tip 3 of the fixing portion in the drilled hole. FIG. 12 and FIG. 13 show a state when the tendon 2 is pushed in when the feeding prevention device 1 shown in FIG. 4 is used.

[0018]

As described above, the present invention is as described above.
Since the described invention is a device that abuts against the hole wall and resists the pulling force, it is possible to reliably prevent the tendon of the ground anchor from being raised when the casing pipe is pulled out.

According to the second aspect of the present invention, a device which abuts against the hole wall and resists the pulling force is connected to the tip of the tendon, and the casing pipe is pulled out while the tip of the fixing part is stabilized in the drilled hole. Since the fixing position of the tip can be held, the tip of the fixing portion can be installed while being surely fixed in the grout material.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an installed state of a ground anchor.

FIG. 2 is a vertical cross-sectional view showing a supply prevention device.

FIG. 3 is an end view of FIG.

FIG. 4 is an elevational view showing another feeding prevention device.

FIG. 5 is an end view of FIG.

FIG. 6 is a cross-sectional view showing how the tendon is inserted into the grout material.

FIG. 7 is a cross-sectional view showing how the casing pipe is pulled out.

FIG. 8 is an enlarged view of a hole bottom portion of FIG.

FIG. 9 is an enlarged view of FIG. 6 showing a state where the casing pipe is slightly pulled up.

FIG. 10 is a cross-sectional view showing a state where the tendon is pushed in with the feeding prevention device of FIG. 2 connected.

FIG. 11 is a cross-sectional view showing a state when the insertion of the tendon is completed.

FIG. 12 is a cross-sectional view showing a state when the tendon is pushed in with the supply prevention device of FIG. 4 connected.

FIG. 13 is a cross-sectional view showing a state when the insertion of the tendon is completed.

[Explanation of symbols]

1 ... Supply prevention device, 11 ... Tube part, 12 ... Wing, 13 ...
… Screws, 14 …… Legs, 15 …… Springs, 2 …… Tendons, 3
...... Tip of fixing section, 31 …… Outer cylinder, 4 …… Anchor head,
5 ... Casing pipe, 6 ... Grout material.

Claims (2)

[Claims] 1. A casing pipe is inserted into a target ground to make a hole, a grout material is injected into the casing pipe, and a tendon of a ground anchor is inserted before hardening of the casing pipe. In the construction method for fixing the fixing part in the grout material, it is a device that prevents the tendon from being raised when the casing pipe is pulled out. From the tip side of the anchor head to the anchor head side, there is an inclination in a direction away from the center of the tip of the fixing part, and the blade is provided with a restoring force in that direction, and the blade expands from the inner diameter of the casing pipe by the restoring force, Service of tendon at ground anchor that resists pulling force to the anchor head side while hitting the hole wall of drilling hole Anti-slip device. 2. A casing pipe is inserted into a target ground to form a hole, a grout material is injected into the casing pipe, and the curing prevention device according to claim 1 is connected to the tip of the fixing portion before hardening. In the construction method of inserting the tendon of the ground anchor, pulling out the casing pipe and fixing the fixing part of the tendon in the grout material, pull up the casing pipe by a distance larger than the length of the wing prevention device and then push in the tendon. The construction method of the ground anchor that pulls out the casing pipe with the tendon prevention device protruding from the tip of the casing pipe, its blades abutting against the hole wall, and the tendon being stabilized in the drilled hole.