JP4577893B2 - Ground anchor head structure - Google Patents

Description

  The present invention relates to a ground anchor used to stabilize slopes and slopes, and more particularly to a head structure of a re-tensionable ground anchor that can be prestressed again according to secular changes such as natural ground. It is.

  Ground anchor introduces pre-stress to tensile steel materials such as PC steel wire, and presses concrete structure built on slopes and slopes firmly against the ground to increase slip resistance on sliding surfaces. It is intended to stabilize the whole natural ground against the sliding force caused by earth pressure, earthquake, rainfall, etc., but the pre-stress introduced in the initial stage is designed with the slack in the tensile steel due to the secular change of the natural ground. Since the load may not be maintained, a ground anchor having a head structure that can be re-tensioned is installed.

For example, a head structure as shown below is known as a conventional ground anchor that can be re-tensioned.
Japanese Utility Model Publication 7-25364 Japanese Patent Publication No. 4-26645 An anchor head structure described in Patent Document 1 is a disk-shaped penetrating through a PC steel material insertion hole having a tapered opening in which a male screw is formed on the outer periphery and a wedge can be inserted. It has a fixing body and a nut body that can be screwed to the fixing body and abuts against a pressure plate. The outer periphery of these PC steel fixing members is covered with an oil cap for anticorrosion, and filled with oil. It was. When re-tensioning the ground anchor, screw a tension jig into the male screw of the disk-shaped fixing body, pull it with a jack, and then lower the nut body separated from the bearing plate to bring it back to the bearing plate again. It was in contact.

  Patent Document 2 describes a nut body that is placed on an anchor plate that is a bearing plate, an anchor head that is screwed to the nut body, and a crimping grip that fixes a tensile steel material on the upper surface thereof. The head fixing member was also sealed with a cap filled with rust preventive oil. When re-tensioning this tensile steel material, remove the cap, screw the ram attachment of the re-tensioning jack to the male screw that protrudes above the top surface of the nut body, and pull it. The nut body was turned and brought into contact with the anchor plate.

  However, in the conventional anchor head structure, since the entire head including the nut body placed on the bearing plate is covered with a rust prevention cap, the head protruding to the natural ground surface becomes large, There was a problem that the amount of oil to be filled increased. In particular, when the outer shape of the nut body is a polygonal shape, the outer peripheral surface of the cap is located outside each apex, which causes a problem that the outer periphery of the cap becomes excessive.

  This invention is made in view of this point, and it aims at providing the head structure of the ground anchor which can reduce the quantity of the rust preventive oil with which a head shape is smaller than the conventional thing, and is filled. .

  In order to solve the above-described problems and achieve the object, the present invention is configured as follows.

The invention according to claim 1 is a bearing plate through which a tensile steel material is inserted, a fixing member that holds a head side end of the tensile steel material and a lower end abuts against the bearing plate, and at least outward of the bearing plate. In the head structure of the ground anchor provided with a lid body that encloses the tensile steel material and is filled with antirust oil inside,
The fixing member is
An annular body forming an internal thread on the inner surface;
A locking body for threading at least a lower part of a male screw formed on the outer surface through the tensile steel material and screwed into the female screw of the annular body;
The lid is
The engagement body is screwed into the upper part of the male screw , and the front end surface of the lid body is brought into contact with the end surface of the annular body.

  The annular body is a nut body that is placed on the bearing plate, and the engaging body that is screwed to the annular body may be a cylindrical body that accommodates a tensile steel material in the inner space as long as it forms a male screw on the outer surface. Further, it may be a rod-like body that accommodates the tensile steel material in a partially cutout portion of the outer surface or inserts the tensile steel material into the through hole. The tip of the tensile steel material may be fixed by a wedge method, a crimping grip, or a nut. The locking body may be one in which the annular body screwing portion and the tensile steel material fixing portion are separated, or may be an integration of these.

  Further, the locking body needs to have a length that can protrude at least as an upper surface of the annular body as a portion to be screwed to the lid body, and a jack is screwed to the male screw portion at the time of re-tensioning. In addition, the screwed length of the annular body and the locking body is such that the ring body can be in contact with each other in a state in which sufficient engagement is maintained even when the annular body is lowered with respect to the supporting plate separated at the time of re-tensioning. is necessary.

Annular body in the head structure of the ground anchor according to claim 2, the annular body has a water stopping structure at the surface in contact with the bearing capacity plate,
The lid is characterized in that it has a water-stop structure at the surface in contact with the annular body.
As the water-stopping structure, for example, an O-ring is embedded in the circumferential direction of the lower surface of each of the annular body and the lid, and this is brought into contact with the upper surface of the bearing plate or the annular body and tightened until the O-ring contracts to stop the water. The water stop structure may be a structure other than the O-ring as long as the water stop effect can be reliably obtained.

  With the above configuration, the present invention has the following effects.

In the invention of claim 1, since the front end face of the screwed lid lid filling the rust-preventive oil is the male threaded upper portion of the locking body are structures in contact with the end face of the annular body, annular body It is not necessary to confine the inside of the lid body, and even if the wall thickness of the annular body is increased or the outer surface shape is made polygonal, it does not affect the lid shape, so the head shape can be made smaller than the previous one and filled The amount of rust preventive oil can also be reduced.

  In the invention according to claim 2, since the water-stopping structure is provided on the lower surface of the annular body and the lid body, a reliable water-stopping effect can be obtained without sealing the entire head with the lid body that contains the antirust oil. .

  Hereinafter, although the embodiment of the head structure of the ground anchor of this invention is described, this invention is not limited to this embodiment. The embodiment of the present invention shows the most preferable mode of the present invention, and the terminology of the present invention is not limited to this.

  FIG. 1 is a sectional view showing a head structure of a ground anchor. A tensile steel material 1 is composed of a PC steel wire, and a sheath tube 2 is covered on the head side of the wire material. In this tensile steel material 1, the portion covered with the sheath tube 2 becomes an anchor free long portion with elongation, and the uncovered tip side becomes an anchor body portion fixed with a grout material (not shown).

  When installing the ground anchor, first, a concrete structure, for example, a lattice-shaped pressure receiving plate 4 is constructed on the ground 3 which becomes a slope or a slope, excluding the ground anchor insertion portion 4a. A drilling machine (not shown) is set on the structure, and a drilling rod is inserted into the ground anchor insertion part 4a of the pressure receiving plate 4 to drill the ground 3 to a predetermined depth. Thereafter, the grout material is injected, and the tip side of the tensile steel material 1 is inserted before the hardening.

  The head structure of the ground anchor that is set after the grouting material is hardened and held includes a supporting plate 5 that is inserted through the tensile steel material 1 and placed on the pressure receiving plate 4, and an end portion on the head side of the tensile steel material 1. An anchor head 6 to be engaged, a re-tensioning washer 7 for supporting the anchor head 6, a nut 8 whose lower end is in contact with the support plate 5, and a re-tensioning washer 7 to be screwed together, and the peripheral surface of the tip is a nut 8 The oil cap 9 is in contact with the upper surface of the oil. The oil cap 9 is filled with a rust preventive oil 10 for protecting the head of the tensile steel material 1, and a hexagon bolt 9 a is screwed into the tip of the cap 9.

  The anchor head 6 has a taper groove, and holds the tensile steel material 1 using a fixing wedge 6a. The anchor head 6 can be fixed by a nut depending on the type of the tensile steel material 1. After the bearing plate 5 is set on the tensile steel material 1 and the nut 8 and the re-tension washer 7 are attached, the water stop tube 11 is inserted from the head of the tensile steel material 1 and the water stop rubber 12 is loaded therein.

  A compression cylinder 13 is mounted above the water-stopping rubber 12, and when the tensile steel material is fixed, the compression cylinder 13 is moved to the water-stopping rubber 12 side and pressed and compressed, covering the portion of the tensile steel material 1 protruding from the sheath tube 2. Make sure to stop the water.

  The nut 8 has a female screw 8a formed on the inner surface, and an O-ring 8b is embedded in the contact surface with the bearing plate 5 to stop water. The nut 8 is subjected to a rust-proof surface treatment such as plating. The peripheral surface of the nut 8 may be polygonal or circular. In the case of a circular shape, a hole is formed in the peripheral surface for rotation, and a tool is engaged therewith and rotated.

  The re-tensioning washer 7 screwed into the nut 8 forms a male screw 7a on the outer surface. At least the lower part of the male screw 7a is screwed into the nut 8, and the oil cap 9 is screwed into the upper part of the male screw continuous therewith. At the time of re-tensioning, a jack is screwed to the male screw portion. The re-tension washer 7 is provided with a counterbore 7b for fixing a water-stopping pipe 11 with a hook for water-stopping the tensile steel material 1.

  An O-ring 9b is embedded in the peripheral surface of the tip of the oil cap 9, and this abuts against the nut 8 to stop water. When the hexagon bolt 9a is screwed to the re-tension washer 8, the hexagon bolt 9a is removed, and the rust preventive oil 10 is discharged to check the filling state.

At the time of re-tensioning, the oil cap 9 is removed, and a female screw of a jack (not shown) is screwed into the re-tensioning washer 7 and loaded to a predetermined tension. At this time, when the nut 8 connected to the washer 7 floats up from the pressure plate 5, the nut 8 is brought into contact with the pressure plate 5 while being loaded to a predetermined tension force and tightened until the O-ring 8 b is contracted. Then release the load and remove the jack. Thereafter, the rust preventive oil 10 is added to the oil cap 9 and screwed into the washer 7 in the same manner as the beginning.

  Thus, since the nut 8 does not need to be confined in the oil cap 9, the internal capacity of the oil cap 9 can be reduced. Further, just by fitting the oil cap 9 to the re-tension washer 7, the water stop of the ground anchor head is sufficient.

It is sectional drawing which shows the head structure of a ground anchor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tensile steel material 4 Pressure receiving plate 5 Supporting plate 6 Anchor head 7 Re-tension washer 8 Nut 9 Oil cap 10 Antirust oil

Claims (2)

A bearing plate for inserting the tensile steel material; a fixing member for holding the head side end of the tensile steel material and abutting the lower end against the bearing plate; and at least enclosing the tensile steel material outside the bearing plate. In the head structure of the ground anchor provided with a lid body filled with rust preventive oil inside,
The fixing member is
An annular body forming an internal thread on the inner surface;
A locking body for threading at least a lower part of a male screw formed on the outer surface through the tensile steel material and screwed into the female screw of the annular body;
The lid is
Head structure of the ground anchor, characterized in that screwed to the male threaded upper portion of the locking member abuts against the front end surface of the lid to the end face of the annular body. It said annular body has a water stopping structure at the surface in contact with the bearing capacity plate,
The lid has a head structure of the ground anchor according to claim 1, wherein a water stopping structure at the surface in contact with the annular body.