JPH0426645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention is useful for preventing high-rise buildings or tower-like buildings from falling during earthquakes or storms, or for buildings with deep underground areas where the groundwater level is relatively high. Permanent ground anchors are used to prevent groundwater from surfacing when a building is constructed, or to prevent uneven earth pressure or sliding in buildings erected on slopes, and more specifically, stability. An anchor head fixing structure that uses a highly reliable crimp grip.

Prior Art As illustrated in Fig. 6, a conventional general permanent ground anchor has a bearing plate 2 attached to the tip of a tensile steel member 1 through a crimp grip 4, and a tubular load-bearing plate attached to the pull-out side of the bearing plate 2. body 3 is installed, and this load-bearing body 3
The configuration is such that force is transmitted to the surrounding ground 5 through the ground. Each tensile steel member 1 is attached to the bearing pressure plate 2 via a grip 4 by passing it through a hole in the bearing pressure plate 2 in advance, and then inserted and installed into an anchor hole in the ground. To fix the anchor head, place the anchor head 7 on the anchor plate 6 on the ground,
The tensile steel member 1 is projected through a wedge hole in the head 7 and is fixed by driving a wedge 8 thereinto.

In addition, Utility Model Publication No. 12606/1982 and Japanese Patent Application Laid-open No. 1983-12606
Japanese Patent Publication No. 117940 discloses a wedge-type fixing structure for an anchor head in which an anchor head having a tensile steel member fixed thereto by a wedge is screwed to a head bearing pressure plate (ring nut) on the outer periphery of the anchor head.

Problems to be solved by the present invention () In the case of the conventional wedge-type fixing structure described above,
When tensioning the tensile steel material 1 to introduce prestress of a predetermined amount and fixing it, a slippage of about 3 to 6 mm will inevitably occur before the wedge is completely engaged, which will affect the magnitude of the prestress and, ultimately, the performance of the anchor. There is a problem in that it causes deviations.

() Also, with permanent anchors, it is necessary to leave the tensile steel member 1 in an unbonded state.
Since the wedge is subjected to repeated loads due to earthquakes, etc., it is necessary to provide extremely high reliability for the wedge anchorage, but there are some points that cannot be said to be fully satisfactory.

() In addition, in the case of the above-mentioned wedge-type anchoring structure, considering the case where the tensile steel material 1 is to be re-tensioned, a re-tensioning jack should be installed upward from the position of the wedge 8 to provide at least 1 m of extra length for re-tensioning. There is a problem in that the space for this extra length must be secured for many years.

The wedge-type anchoring structure described in the above-mentioned Japanese Utility Model Publication No. 50-12606 has a configuration in which pre-stress (pre-tension stress) is introduced into one tensile steel member for anchoring, and the upper end of the tensile steel member has a conical wedge. It is secured by driving it into the wedge hole of the anchor head. Since it is recognized that the head bearing plate (ring nut) is rotated and the tensile steel material is tensioned by screw movement, the tension force is applied to the tension steel material only within the effective length of the male thread of the anchor head. Can not. However, tensile steel materials for ground anchors (such as prestressed steel rods and prestressed steel stranded wires), which can be as short as several meters or as long as several tens of meters, cannot be prestressed to the extent that they perform their original anchor function. , for example, a large elongation of 30cm to 60cm occurs. Therefore, considering the large elongation of such tensile steel, the male thread of the anchor head must have an effective length of at least 1 m, resulting in a large and expensive anchoring structure. Moreover, since it is necessary to introduce a predetermined prestress into the tensile steel by endless screwdriving movements within the above-mentioned effective length range,
It has very poor workability and is extremely impractical. Of course, fixing tensile steel using wedges has the drawback that it can loosen due to repeated loads such as earthquakes.
Therefore, permanent ground anchors have the problem that they cannot be used with full confidence.

In the case of the wedge-type anchoring structure described in JP-A No. 62-117940, the upper part of the tensile steel member is fixed to the anchor head with a wedge, and the problem of loosening of the wedge cannot be eliminated, and permanent ground anchors cannot be used. difficult to apply. In addition, although the multiple tensile steel members have no choice but to pass through the fixing holes of the anchor head one by one and also through the conical wedge, the remaining length of the above-ground portion of the tensile steel members before prestressing is Since the process is long, the above operation is troublesome and time-consuming. Moreover, after the above-mentioned work has been completed, it is necessary to perform pre-tensioning work using jacks, so during that work it is necessary to support the anchor head etc. in a predetermined position by some means to prevent it from falling. No means in this regard are disclosed.

Means for Solving the Problems As a means for solving the problems of the prior art described above, a grip-type fixing structure for a permanent ground anchor head according to the present invention is suitable as shown in FIGS. 1 to 5 of the drawings. As shown in the embodiment, the bearing plate 2 is attached to the tip of the tensile steel material 1, the load bearing body 3 is installed on the pull-out side of the bearing pressure plate 2, and the load bearing body 3
In a permanent ground anchor configured to transmit force to the surrounding ground through
The crimp grip 11 is fixed at a portion that extends slightly above the anchor plate 13 on the ground at the stage where the prestress of a predetermined magnitude is introduced by being tensed at zero. and an anchor head having a male thread 12a formed on its outer circumferential surface, and provided with at least the same number of cut grooves 12b as the number of tensile steel members 1 in the longitudinal direction of the outer circumferential surface into which the plurality of tensile steel members 1 can be inserted from the lateral direction. 12 is each cut groove 12a
The tensile steel members 1 are inserted one by one into the crimping grips 11 and placed directly below the crimp grips 11. In addition, a female thread 14a is formed on the inner peripheral surface, and the head bearing pressure plate 1 is placed on the anchor plate 13.
The anchor head 12 is attached to the female thread 14a of No. 4.
Each is characterized in that a male screw 12a is screwed in and fixed.

The grip-type anchoring structure of the present invention also provides that the external thread 12a of the anchor head 12 has at least an effective length necessary for re-tensioning the tensile steel member 1, and has a head long enough to allow threaded connection of the ram attachment of the jack. The tension steel member 1 is fixed in a state protruding upward from the support pressure plate 14, and the portion of the tensile steel member 1 that protrudes above the crimp grip 11 is cut as short as possible, so that the tension steel member 1 is
1 and the anchor head 12 are installed in an oil-tight manner on the anchor plate 13, and the head cap 19 is filled with a rust preventive agent 20.

Function The crimping grip 11 is firmly fixed in a predetermined position on the tensile steel material 1 in a high quality manner, for example, by factory processing. The anchor plate 13 has its cut groove 12
Since the tensile steel material 1 can be inserted laterally into b, there is no problem in attaching the crimp grip 11 in advance.

At the stage where the tensile steel material 1 is tensioned with the jack 10 and a predetermined prestress is introduced, the head bearing plate 14 on the anchor plate 13 is screwed into the anchor head 12 which is in contact with the bottom of the crimp grip 11, and the head bearing plate 14 is loosened. After tightening it lightly so that it is not tight, release the tension of Jacket 10. In this way, the introduced prestress is applied to the anchor head 1.
2 and the head bearing pressure plate 14 on the anchor plate 13, the size is reliably held, and there is no room for construction errors.

Since the fixing structure is based on the pressure grip 11, the stability against repeated loads is high, resulting in a highly reliable fixing structure.

Furthermore, if necessary, re-tensioning can be performed by connecting the ram attachment of the re-tensioning jack to the external thread 12a protruding upward from the head bearing pressure plate 14 on the outer circumferential surface of the anchor head 12. The extra length of 11 is hardly needed.

The anchor head 12 installed at a predetermined position on the tensile steel material 1 is suspended below the crimping grip 11 with a fixing bolt 16, and is suitable for introducing prestress and screwing the anchor head 12 and the head bearing plate 14. held in position.

Example Next, the illustrated embodiment will be explained.

First of all, FIG. 1 shows a crimping grip 1 installed in advance as a factory processing at a predetermined position on the upper end of a tensile steel material 1.
1 and the anchor head 12 attached to the tensile steel member 1 at a position below the crimp grip 11. As illustrated in FIG. 6, the anchor head 12 has a bearing plate 2 attached to the tip of the tensile steel member 1, and a load-bearing body 3 on the pull-out side of the bearing plate 2.
It is attached to the tensile steel material 1 after it is installed and inserted into the ground anchor hole. This is because the anchor head 12 is connected to the tensile steel member 1 before the load-bearing member 3.
This is because, if the load-bearing body 3 is attached to the anchor, the inner diameter of the load-bearing body 3 must be larger than the outer diameter of the anchor head 12, which is uneconomical as it results in an unnecessarily large-diameter anchor frame.

Therefore, in order to make it possible to install the anchor head 12 in the order described above, the anchor head 1
2, as shown in Fig. 5A and B, is approximately U-shaped for installation by inserting from the side between four (but not limited to) tensile steel members 1... The cut grooves 12 are vertically provided at positions divided into four equal parts in the circumferential direction. One tensile steel member 1 is placed in each cut groove 12b, and the anchor head 12 is installed at the center of the four tensile steel members 1.

The outer peripheral surface of this anchor head 12 has a male thread 1.
2a is formed. Further, a through hole 12c is provided in the axial direction of the central portion of the anchor head 12. This through hole 12c is for temporarily fixing the anchor head 12 to the grip 11 for a period of time at the beginning of construction. That is, the presser plate 15 is placed on the crimp grip 11, and the anchor head 12
The fixing bolt 16 passed upward through the through hole 12c is screwed into the nut 17 on the holding plate 15, and the anchor head 12 is temporarily fixed under the crimp grip 11 (see FIG. 2).

Next, FIG. 2 shows that the tensile steel material 1 having the above-mentioned structure is inserted into the anchor hole in the ground,
This shows the stage when preparations for tension work are complete.

The anchor plate 13 is installed on the frame 18 on the ground, and the jack 10 is placed on the anchor plate 13.
A ramchea air 10a is installed.

On the same anchor plate 13 and inside the ram chair air 10a, there is a head bearing plate 1 having a nut structure.
4 is installed to surround the outer periphery of the tensile steel members 1. As shown in FIG.
It is formed into a nut shape with an internal thread 14a having the same specifications as that of 2a.

In the preparation stage shown in FIG. 2, the position of the fixing grip 11 of the tensile steel material 1 is approximately 30 cm to 60 cm below the position of the head bearing plate 14 on the frame 18, leading to the introduction of a predetermined amount of prestress. We plan to increase the growth of tensile steel 1 up to

Figure 3 shows that the prestress of a predetermined amount has been introduced and fixed by tensioning the tensile steel material 1, and the tension steel material 1 has been tensioned.
This shows the stage where 0 has been removed.

That is, from the stage shown in FIG. 2, tension is applied by the jack 10, and as the tensile steel material 1 stretches, the fixing grip 11 rises and reaches the position of the head bearing pressure plate 14.
The head bearing plate 14 is rotated in the normal rotation direction and screwed to the anchor head 12. Then, when the prestress of the planned size is introduced, the head bearing plate 1
4 is lightly tightened, the prestress is maintained due to the threaded connection with the anchor head 12.

FIG. 4 shows that the holding plate 15, fixing bolt 16 and nut 17 which temporarily fixed the anchor head 12 to the crimp grip 11 have been removed, and the tensile steel member 1 has been removed.
Cut the part above the fixing grip 11 as short as possible, attach the head cap 19,
This shows a stage in which rust-preventive grease 20 is filled through the injection pipe 21 and fixing is completed.

Note that if it becomes necessary to re-tension the tensile steel material 1 later, the head cap 19 is removed and the outer circumferential threaded portion 12a of the exposed anchor head 12 that protrudes upward from the upper surface of the head bearing plate 14 is removed. Screw the ram attachment of the re-tensioning jack onto the holder and perform re-tensioning. Therefore, no extra length of the tensile steel material 1 is required. On the other hand, the anchor head 12 is configured to protrude from the upper surface of the head bearing pressure plate 14 by a length that allows the ram attachment of the re-tensioning jack to be easily screwed onto the top surface of the head bearing pressure plate 14 at the time of initial fixation. Moreover, anchor head 12
The length is such that there is still enough room for the amount of screwing between the head support plate 14 and the head support plate 14.

Effects of the present invention As described above in detail in conjunction with the embodiments, the permanent ground anchor head grip-type fixing structure according to the present invention is the first ground anchor in which the head can be fixed in a grip-type manner. Unlike conventional wedge-type anchoring, there is no slippage during anchoring, resulting in highly accurate, stable, and reliable installation. In addition, installation of the anchor head 12 and temporary fixing of the anchor head 12 are easy, and construction can be carried out efficiently with a degree of freedom in terms of process.

Furthermore, a ground anchor with high stability against repeated loads can be obtained.

Furthermore, since there is no need for extra length in the tensile steel material 1 for re-tensioning, the structure can be made smaller accordingly, contributing to effective use of space.

[Brief explanation of drawings]

1 to 4 are cross-sectional views showing the important steps of constructing the grip-type anchoring structure for the anchor head according to the present invention, and FIGS. 5A and 5B are front views of the plan view of the anchor head. Figure c is a cross-sectional view of the head bearing plate.
FIG. 6 is a sectional view of a conventional anchor fixing structure.

Claims (1)

[Claims] 1. A bearing pressure plate 2 is attached to the tip of the tensile steel material 1, a load-bearing body is installed on the pulling side of the bearing pressure plate 2, and a load-bearing body 3 is installed on the pulling-out side of the bearing pressure plate 2.
In a permanent ground anchor configured to transmit force to the surrounding ground through multiple tensile steel members 1, it is
The crimp grip 11 is fixed to a part that protrudes slightly above the anchor plate 13 on the ground when the prestress of a predetermined magnitude is introduced. The tensile steel material 1 is inserted into each of the cut grooves 12a of the anchor head 12, which is provided with at least the same number of cut grooves 12b as the tensile steel materials 1 in the longitudinal direction and into which the plurality of tensile steel materials 1 can be inserted from the lateral direction. Insert the crimp grip 1 one by one.
1, and a female thread 14a is formed on the inner peripheral surface of the anchor plate 13.
The female screw 1 of the head bearing plate 14 placed on the
A grip-type fixing structure for a permanent ground anchor head, characterized in that a male thread 12a of the anchor head 12 is screwed into and fixed to the anchor head 4a. 2. The male thread 12a of the anchor head 12 described in claim 1 has at least the tensile steel material 1.
It has an effective length necessary for re-tensioning, and is fixed in such a state that it protrudes upward from the head bearing pressure plate 14 by a length that allows the ram attachment of the jack to be connected by screws. Grip-type anchoring structure for permanent ground anchor head. 3. The tensile steel material 1 described in claim 1 or 2 is cut as short as possible at the portion protruding above the crimp grip 11, and
1 and an anchor head 12a, the head cap 19 is oil-tightly installed on the anchor plate 13, and the head cap 19 is filled with a rust preventive agent 20. Grip type fixing structure.