JP3490145B2 - Center riser for ground anchor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground anchor center riser for aligning a tubular member having a corrugated cross section holding a plurality of anchor rods with the center of an excavation hole.

[0002]

2. Description of the Related Art For example, in order to stabilize the ground on a sloping ground and prevent slipping or overturning due to uneven earth pressure on a building built on a sloping ground, a ground anchor is placed at a predetermined angle on the ground on the sloping ground. Sometimes.

That is, while forming an inclined excavation hole in the ground, a plurality of anchor rods and grout injection pipes are held in a tubular member having a corrugated cross section which constitutes a fixing body inside the excavation hole, and the cylinder is formed. A center riser that aligns the member with the center of the drill hole is provided to form an anchor body,
After inserting this anchor body into the casing for excavation installed in the excavation hole and inserting into the excavation hole, grout is injected, and only the casing is pulled out from the excavation hole, and the anchor body is removed by the center riser described above. Align with the center of the inclined drill hole so that it floats,
The ground anchor is driven so that a tension force is applied to the anchor rod after the predetermined grout is hardened and the compressive force is transmitted to the sloping ground through the grout.

Here, it is considered that the tubular member has a corrugated cross-section so that the grout inside and outside the tubular member, which is cut off by the tubular member, can be integrated to increase the tension load of the ground anchor. As the tubular member, for example, a flexible pipe formed by spirally winding a stainless steel strip having a corrugation in the width direction and caulking the overlapping edges of the strip is used. .

On the other hand, the above-mentioned center riser raises the anchor body toward the center side of the inclined drilling hole to prevent the anchor body from being biased to the lower wall side of the tilted drilling hole by its own weight. When the body is biased to the wall surface of the drill hole, the grout covering the anchor body becomes thin and the tension load of the ground anchor decreases, and further,
When the grout is prone to cracks and the grout is extremely thin, the anchor rod is exposed and the function of rust prevention against groundwater deteriorates. It is aligned to ensure the grout's cover thickness.

[0006]

Various center risers for the center alignment have been proposed in the past. For example, the center riser is urged to expand the outer peripheral surface of the anchor body in the circumferential direction. A configuration in which a plurality of leaf springs are attached is proposed in Japanese Patent Laid-Open No. 4-189917, Japanese Patent Laid-Open No. 5-118035, and the like.

In the center riser having such a structure, each of the leaf springs is fixed at one end side, and the other end side of the free is urged and brought into contact with the wall surface of the excavation hole so that the anchor body is not Although it is lifted to the center side, the excavation hole is not necessarily a perfect circle, and boulders are peeled off from the wall surface when excavating the hole, so there are recesses in places on the wall surface of the excavation hole. However, if the other end of the leaf spring falls into this recess, the anchor body may be biased in that direction.

In addition to this, the hip breaking link is used as a spacer for center alignment, one end side of this hip breaking link is fixed, and the other end side is pulled to one end side by a wire, and the intermediate connecting portion of this hip breaking link is made into a drill hole. A center riser that is pressed against the wall surface (for example, Japanese Patent Laid-Open No. 3-24
No. 16) or a center riser in which both ends of the hip break link are brought closer to each other by springs to press the intermediate connecting portion of the hip break link against the wall surface of the drill hole (for example, Japanese Patent Laid-Open No. 5-202521). reference)
Are also proposed.

According to the center riser having such a configuration,
Since the both ends of the hip break link are fixedly held by the anchor body under the pressing of the wall surface of the drill hole by the intermediate connecting part of the hip break link, the position holding strength of the anchor body with respect to the drill hole is high. Although excellent, there was a problem in that the overall structure was very complicated and costly.

Further, when the intermediate connecting portion of the waist bending link falls into the recess of the wall surface of the hole, the anchor body is still biased in that direction, and further, in any of the above-mentioned configurations. However, there is a problem that it takes a lot of time and effort to attach the center riser to the anchor body.

The above-mentioned problems are remarkable when the ground anchor is to be driven in an inclined drilling hole, but the present invention is not limited to this, and the ground anchor is driven in a vertical drilling hole. Needless to say, it can be a problem.

It is an object of the present invention to provide a center riser capable of accurately aligning the anchor body without any of the above inconveniences.

[0013]

The technical means taken by the present invention to achieve the above object are as follows. That is, the center anchor center riser according to the present invention,
A ring that holds and holds a tubular member that holds a plurality of anchor rods from the side and a center position made of a leaf spring in which one end side in the longitudinal direction is fixed to the ring at a predetermined interval in the circumferential direction. And a flat portion extending over two or more corrugated portions of the tubular member is formed on the other end side of each spacer, and an elastic portion is provided between the flat portion of the spacer and the fixed portion to the ring. Forming a plurality of corrugated portions that are urged against the wall surface of the drill hole by a restoring force, and
It is characterized in that it is provided with spacer diameter reducing means for slidably abutting the flat portion against the corrugated portion of the tubular member. It is preferable to attach elastic rubber to the inner surface of the ring for the reason described later.

[0014]

According to the above construction, the center riser is attached to the tubular member by holding the ring from the side of the tubular member and fixing it, and the flat portion on the other end side of the spacer by the spacer diameter reducing means. It can be easily done by a simple operation of just reducing the diameter.

Further, a corrugated portion is formed in the longitudinal middle portion of the leaf spring spacer, and a flat portion having an appropriate width formed on the other end side of the spacer is slidable with respect to the corrugated portion of the tubular member. Therefore, it is possible to easily insert the anchor body into the casing installed in the excavation hole and pull out the casing.

That is, when the above-mentioned center riser is pushed into the casing, the spacer is mainly bent at the corrugated portion in accordance with the pushing, and the flat portion extending over the two corrugated portions of the tubular member does not fall between the corrugated portions. The spacer slides smoothly, and the diameter of the spacer is easily reduced. Moreover, since the leaf spring spacer comes into contact with the inner surface of the casing at the top of the corrugated portion, the contact area is small and the friction resistance is small. The insertion of the anchor body with the center riser can be easily achieved.

Even when only the casing is pulled out from the excavation hole after the anchor body is inserted, the contact area of the leaf spring spacer is small, so that the friction resistance is reduced and the casing can be easily pulled out.

When the casing is pulled out, the corrugated portion of the spacer is pressed against the wall surface of the excavation hole by the elastic restoring force of the spacer itself, thereby aligning the tubular member and thus the anchor body with the center of the excavation hole. However, according to the above configuration, since both end sides of the spacer are fixedly held by the tubular member, sufficient strength for holding the position is obtained, and there is a recess on the pressing wall surface of the excavation hole by the corrugated portion. Even if you do so, it is rare that all of the multiple corrugated parts fall into this recess, so the reliability of center positioning of the anchor body with respect to the excavation hole will be extremely high, and the grout cover thickness against the anchor body will be reliable. Will be secured.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a vertical cross section of a ground anchor placed at a predetermined angle on the ground of a sloping ground, and FIG. 2 shows a horizontal cross section of the ground anchor. An anchor body inserted into the hole 1, 3 is a grout injected into the excavation hole 1 so that the anchor body 2 is embedded, 4 is a foundation of an inclined wall surface, and 5 is a slide sheath with which an anchor rod 6 described later is inserted. A pressure bearing plate, 7 is an anchor head, 8 is a wedge that fixes the anchor rod 6 to the anchor head 7 after post tension is applied to the anchor rod 6, and 9 is an oil cap that forms a holding space for rust preventive oil.

The anchor body 2 is composed of a plurality of anchor rods 6 each having a PC steel strand 11 inserted through a sheath tube 10 extending over a range of a free length B, an inner and an outer grout injection tube 12, 13 and 13 are inserted into the tubular member 14 that constitutes the fixing body C in the excavation hole 1, these are fixedly attached to the tubular member 14 via the position holding spacers 15, and a predetermined amount is provided outside the tubular member 10. Two sets of center risers 16 and 16 are provided at intervals.

Incidentally, the sheath tube 10 of the anchor rod 6
Is for placing the PC steel strand 11 under the bond with respect to the grout 3 in the free length portion B between the vicinity of the head A of the ground anchor and the fixing body C.
The inside of the is filled with grease.

Further, as shown in FIG. 3, the tubular member 14 is formed by spirally winding a stainless steel strip 20 having a corrugated portion b formed in an intermediate portion in the width direction and overlapping each other. It has a corrugated cross-section with the edge portion being swaged c, and the tubular member 14 is designed to integrate the grout 3 inside and outside the tubular member that is in an edge-cutting state to increase the tension load of the ground anchor. Returning to FIG. 1, a distal end cap 17 having a discharge port a of the grout 3 and a stopper 19 for a water blocking material 18 are provided on the distal end side of the tubular member 14, and the anchor distal end portion is provided. D is configured.

Next, the specific structure of the center riser 16 will be described.
As shown in FIGS. 2 to 6, for connecting with a bolt d and a nut e to one end side of a semicircular ring member 21 having a width extending over at least two corrugated portions b of the tubular member 14, The flange f is formed, the pair of other ends of the ring member 21 are connected to each other by a hinge h, and
A ring 23 provided with an elastic rubber 22 on the inner surface of each ring member 21 to hold and hold the tubular member 14 from the side.
On the other hand, a spacer 24 for center positioning made of a leaf spring is provided on the outer surface of the ring 23 at a predetermined interval in the circumferential direction, for example, by welding.

On the other end side of each spacer 24, at least two (two or more) corrugated portions b of the tubular member 14 are formed, and a flat portion i extending over the corrugated portion b is formed. Between the flat portion i of the spacer 24 and the fixed portion j to the ring, due to the elastic restoring force, the drill hole 1
A plurality of corrugated portions m that are urged and abutted against the wall surface of the cylindrical member 14 and a spacer diameter reducing means 25 that slidably abuts the flat portion i with respect to the corrugated portion b of the tubular member 14 There is.

The spacer diameter reducing means 25 has, for example, a locking body 25a formed at one end of a narrow rubber belt, and an engaging hole 25 for locking and fixing the locking body 25a.
Although b is formed on the other end side of the rubber belt, the spacer diameter-reducing means 25 may be changed to, for example, a structure in which the ends of small-diameter coil springs are connected to each other. In any case, in order to prevent the spacer diameter reducing means 25 from coming off, it is desirable to bend and form a locking piece n at the end of the flat portion i of the spacer 24.

The center riser 16 having the above structure is attached to the tubular member 14, and the anchor body 2 with the center riser 16 is inserted into the excavation casing 26 installed in the excavation hole 1 as shown in FIG. After that, while the grout 3 is injected, only the casing 26 is pulled out, the anchor body 2 is aligned with the center of the excavation hole 1 by the center riser 16, and after the predetermined grout is hardened, the PC steel strand 11 of the anchor rod 6 is tensioned. By applying the force, the placement of the ground anchor for transmitting the compressive force to the sloping ground through the grout 3 is completed.

To mount the center riser 16 on the tubular member 14, as shown in FIGS. 5 and 6, the pair of ring members 21 and 21 are expanded and the flat portion i of the spacer 24 is fixed to the head of the anchor body 2. In the state of being directed to the portion side, it is held from a side at a predetermined position of the tubular member 14 and is fixed to the tubular member 14 by bolts d and nuts e, while the spacer diameter reducing means using, for example, a narrow rubber belt. 25,
The flat portions i of the plurality of spacers 24 are wound around, and the locking bodies 25a thereof are locked in the engagement holes 25b, and the flat portions i of the plurality of spacers 24 are corrugated in two or more corrugations of the tubular member 14. This is easily achieved by slidably contacting the portions b and b.

Since the elastic rubber 22 is provided on the inner surface side of the pair of ring members 21, it is hard to slip with respect to the tubular member 14, and a so-called electric current is generated between the different metals of the tubular member 14 and the ring 23. Corrosion is prevented, and it is also suitable in terms of durability.

When the anchor body 2 provided with the center riser 16 is pushed into the casing 26 from the tip side thereof, the spacer 24 is bent mainly at the corrugated portion m, while the flat portion i is corrugated portion of the tubular member 14. By sliding b and reducing the diameter of the spacer 24, the insertion of the anchor body 2 with the center riser 16 into the casing 26 is easily achieved.

On the other hand, after the anchor body 2 is inserted, only the casing 26 is pulled out in the excavation hole 1, and the spacer 24 is expanded as shown in FIGS. By urging the wall surface to urge the anchor body 2,
Is aligned with the center of the excavation hole 1. At this time, since both ends of the spacer 24 are fixedly held by the tubular member 14, it is preferable in terms of the strength of retaining the position of the anchor body 2 with respect to the excavation hole 1. Therefore, even if there is a recess r on the wall surface of the excavation hole 1 pressed by the corrugated portion m, all of the plurality of corrugated portions m should fall into the recess r. Is rare,
The reliability of center alignment of the anchor body 2 with respect to the drill hole 1 becomes extremely high, and the grout 3 with respect to the anchor body 2
The overburden thickness is surely secured.

In the embodiment, the spacer 24 has three
Although the number of corrugated portions m is formed, it is sufficient that the number of corrugated portions m is two or more, and the number of corrugated portions m does not need to be common to all the spacers 24, that is, the number of corrugated portions m is different. Various spacers 24 can be modified, for example, by providing every other spacer 24 in the circumferential direction of the ring 23,
Alternatively, even if the number is the same, the pitches and the formation positions of the corrugated portions m may be different from each other.

Further, although the spacer diameter reducing means 25 is constituted by a narrow rubber belt, it may be changed to a belt of a metal plate or a split ring structure such as the ring 23 described above. Needless to say,
The center riser 16 according to the present invention is not limited to use when the ground anchor is to be driven in an inclined drilling hole, and can be suitably implemented when driving the ground anchor into a vertical drilling hole. Needless to say.

[0033]

According to the first aspect of the present invention, not only the mounting of the center riser on the tubular member and thus the anchor body, but also the insertion of the anchor body to the casing and the pulling-out of the casing can be easily achieved, and both end sides of the spacer are tubular members. Since it is fixedly held, a state of suitable center alignment appears in terms of the strength of holding the position of the anchor body with respect to the drill hole.

In particular, since a plurality of corrugated portions are formed in the spacer for this center alignment, even if there is a recess on the wall surface of the drill hole, the center alignment of the anchor body with respect to the drill hole is performed. Is extremely high, and it is possible to accurately secure the covering thickness of the grout with respect to the anchor body.

According to the second aspect, in addition to the above effects, since the elastic rubber is attached to the inner surface side of the ring, it is difficult to slip with respect to the tubular member, and depending on the material, the tubular member and the ring may be combined. It is possible to prevent so-called electrolytic corrosion that may occur between different kinds of metals, and it is possible to obtain an effect that it is also suitable in terms of durability.

[Brief description of drawings]

FIG. 1 is a vertical cross section of a ground anchor placed on a sloping ground at a predetermined angle.

FIG. 2 is a cross section of a ground anchor.

FIG. 3 is an explanatory diagram showing a state of center alignment by a center riser.

FIG. 4 is a perspective view of a center riser.

FIG. 5 is a side view of a center riser in which a pair of ring members are expanded.

FIG. 6 is a front view of the center riser showing a state before the diameter reduction by the spacer diameter reduction means.

FIG. 7 is an explanatory view showing a state in which an anchor body with a center riser is installed in a casing and the casing is inserted into an excavation hole.

[Explanation of symbols]

1 ... Drilled hole, 6 ... Anchor rod, 14 ... Cylindrical member, 23
... ring, 24 ... spacer, 25 ... spacer diameter reducing means, b ... corrugated part, i ... flat part, j ... fixed part, m ... corrugated part.

Front Page Continuation (73) Patent Holder 000222668 Toyo Construction Co., Ltd. 4-1-1 Koraibashi, Chuo-ku, Osaka-shi, Osaka (73) Patent Holder 591079030 Nissan Construction Co., Ltd. 1-2-6 Minami-Aoyama, Minato-ku, Tokyo (73) Patent holder 390036504 Nittoku Construction Co., Ltd. 8-14-14 Ginza, Chuo-ku, Tokyo (73) Patent holder 000231198 Japan Land Development Co., Ltd. 4-9-9 Akasaka, Minato-ku, Tokyo (73) Patent Holder 000150615 Haseko Corporation, 32-32-1, Shiba, Minato-ku, Tokyo (73) Patent holder 000236610 Fudo Construction Co., Ltd. 4-2-1, Hiranocho, Chuo-ku, Osaka-shi, Osaka (73) Patent holder 591214804 Matsumura Gumi Co., Ltd. 1-10-20 Higashi-tenma, Kita-ku, Osaka-shi, Osaka (72) Inventor Makabe 2 32-32-1, Shiba 2-chome, Minato-ku, Tokyo (72) Ryoji Tahara, Inventor 2-8 Koraku, Bunkyo-ku, Tokyo Goyo Construction Co., Ltd. (72) Inventor Kazuhiko Okiyama Higashi 1-2-1 Taito, Taito-ku, Kyoto Fudo Construction Co., Ltd. (56) Reference JP-A-7-229143 (JP, A) JP-A-5-331850 (JP, A) Registered utility model 3003096 (JP, U) ) (58) Fields investigated (Int.Cl. ⁷ , DB name) E02D 5/80

Claims (2)

(57) [Claims] 1. A center anchor center riser for aligning a tubular member having a corrugated cross section, which holds a plurality of anchor rods, at the center of an excavation hole, and holding the tubular member from the side. It consists of a ring to be fixed and a centering spacer made of a leaf spring whose one end side in the longitudinal direction is fixed to the ring at a predetermined interval in the circumferential direction, and the other end side of each spacer has While forming a flat portion over two or more corrugated portions, between the flat portion of the spacer and the fixed portion to the ring, a plurality of corrugated portions that are urged and abutted against the wall surface of the drill hole by the elastic restoring force. And a spacer diameter reducing means for slidably contacting the flat portion with the corrugated portion of the tubular member. 2. The center riser for a ground anchor according to claim 1, wherein an elastic rubber is attached to the inner surface side of the ring.