JP6077706B1 - U-turn compound resistance mechanism type ground anchor - Google Patents
U-turn compound resistance mechanism type ground anchor Download PDFInfo
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- JP6077706B1 JP6077706B1 JP2016137623A JP2016137623A JP6077706B1 JP 6077706 B1 JP6077706 B1 JP 6077706B1 JP 2016137623 A JP2016137623 A JP 2016137623A JP 2016137623 A JP2016137623 A JP 2016137623A JP 6077706 B1 JP6077706 B1 JP 6077706B1
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- 230000008261 resistance mechanism Effects 0.000 title claims description 9
- 150000001875 compounds Chemical class 0.000 title claims 2
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 34
- 239000010959 steel Substances 0.000 claims abstract description 34
- 210000003205 muscle Anatomy 0.000 claims abstract description 16
- 238000005553 drilling Methods 0.000 claims abstract description 13
- 239000011440 grout Substances 0.000 claims description 19
- 210000002435 tendon Anatomy 0.000 claims description 14
- 239000002131 composite material Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 abstract description 11
- 239000011248 coating agent Substances 0.000 abstract description 10
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 abstract description 7
- 238000010276 construction Methods 0.000 abstract description 6
- 229920003002 synthetic resin Polymers 0.000 abstract description 2
- 239000000057 synthetic resin Substances 0.000 abstract description 2
- 238000005452 bending Methods 0.000 abstract 1
- 239000000463 material Substances 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 8
- 239000004698 Polyethylene Substances 0.000 description 7
- -1 polyethylene Polymers 0.000 description 7
- 229920000573 polyethylene Polymers 0.000 description 7
- 238000006073 displacement reaction Methods 0.000 description 6
- 230000006835 compression Effects 0.000 description 5
- 238000007906 compression Methods 0.000 description 5
- 238000003780 insertion Methods 0.000 description 3
- 230000037431 insertion Effects 0.000 description 3
- 238000007586 pull-out test Methods 0.000 description 3
- 125000006850 spacer group Chemical group 0.000 description 3
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 241000221535 Pucciniales Species 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000000452 restraining effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Piles And Underground Anchors (AREA)
Abstract
【課題】錆の発生を考慮する必要をなくし、かつ、施工性を高め、低コストで引き抜き耐力の大きなＵターン型グラウンドアンカーを構築する。【解決手段】ＰＣ鋼より線の芯線及び側線が合成樹脂塗膜で保護されたＰＣ鋼より線４０を折り曲げてＵターン状にした緊張材４のＵターン部５に支圧具を設けずに地盤内のアンカー体３１に直接埋設し、引張力がＵターン部５からアンカー体３１に直接伝達されるようにすると共にＵターン部５より先に延びる先端スパイラル７１を有するスパイラル筋７が緊張材４の定着長部３を包囲しており、また、スパイラル筋７の先端スパイラル７１のスパイラル径をＵターン部５のそれより小さなものとして削孔に挿入する際のガイドとし、グラウンドアンカーの設置を迅速に行なうことを可能にした。Ｕターン部５の支圧具を省略したので軽量化され、施工しやすく、低コストとなった。【選択図】図1A U-turn type ground anchor that eliminates the need to consider the occurrence of rust, improves workability, and is low in cost and has a high pulling strength. A PC steel wire whose core wire and side wires are protected by a synthetic resin coating film is bent without bending a PC wire into a U-turn shape, and a support member is not provided. The spiral muscle 7 is embedded in the anchor body 31 in the ground so that the tensile force can be directly transmitted from the U-turn portion 5 to the anchor body 31 and has a tip spiral 71 extending ahead of the U-turn portion 5. 4 is surrounded by the fixing length portion 3, and the spiral diameter of the tip spiral 71 of the spiral muscle 7 is smaller than that of the U-turn portion 5, and is used as a guide when inserting into the drilling hole. It was possible to do it quickly. Since the support pressure tool of the U-turn part 5 is omitted, the weight is reduced, the construction is easy, and the cost is low. [Selection] Figure 1
Description
本発明は、引張力を緊張材からアンカー体に伝達する耐荷体を省略したＵターン型グラウンドアンカーに関する。 The present invention relates to a U-turn type ground anchor that omits a load bearing body that transmits a tensile force from a tendon to an anchor body.
グラウンドアンカーがアンカー力を得る機構として圧縮型、引張型、支圧型があり、それぞれ長所と欠点を有している。また、引張型と圧縮型のアンカー体を多段とした分散型グラウンドアンカーも実用化されている。
圧縮型として特許文献１（特公平５−３０９３２号公報）に示されるように、緊張材を耐荷体に巻き掛けたＵターン型グラウンドアンカーは、緊張材に作用する引張力を耐荷体を介してアンカー体に伝達し、更に、アンカー体から周囲の地盤に伝えており、引張力はアンカー体に圧縮力として作用している。
耐荷体は、鋼製または鋳鉄製であり緊張材を掛け回す半円形の湾曲体が形成されている。
There are a compression type, a tension type and a bearing type as a mechanism by which the ground anchor obtains the anchor force, each having advantages and disadvantages. In addition, a distributed ground anchor having a multi-stage tension type and compression type anchor body has been put into practical use.
As shown in Patent Document 1 (Japanese Patent Publication No. 5-30932) as a compression type, a U-turn type ground anchor in which a tension material is wound around a load-bearing body has a tensile force acting on the tension material via the load-bearing body. It is transmitted to the anchor body, and further transmitted from the anchor body to the surrounding ground, and the tensile force acts as a compressive force on the anchor body.
The load-bearing body is made of steel or cast iron, and a semicircular curved body around which the tension material is hung is formed.
グラウンドアンカーを地中に設置する際には、鋳鉄製の耐荷体と緊張材を削孔中に挿入するものであり、比較的重量のあるアンカー体を地上で組み立てて挿入するので施工に時間を要し、また、耐荷体の部材を必要とするのでコストがかかっていた。 When installing a ground anchor in the ground, a cast iron load-bearing body and a tension material are inserted into the drilling hole, and a relatively heavy anchor body is assembled and inserted on the ground. In addition, since a load-bearing member is required, it is expensive.
従来のＵターン型グラウンドアンカーは、緊張材のＰＣ鋼より線が引張方向に対して断面が小さいので耐荷体を介さずに直接アンカー体に埋設すると応力がＵターン部に集中してアンカー体が破壊されと考えられており、引張力を分散してアンカー体に伝達するための耐荷体や支圧板などの支圧部材を用いて引張力をアンカー体に伝達していた。
アンカー体はセメントグラウト等を固化させた固化体であるため、錆の問題は生じないが、支圧部材及びＰＣ鋼より線は鋼鉄製のため、アンカー体に何らかの原因でひび割れが生じてアンカー体内に地中水が浸透すると錆が発生するという問題がある。錆が発生するとグラウンドアンカーの機能を低下させ、寿命を短くすることがある。
本発明は、Ｕターン型グラウンドアンカーの施工時の取り扱いを容易にし、部品点数を少なくすることによって低コストでグラウンドアンカーを構築できるようにすると共にアンカー体にひび割れが生じた場合であっても錆が発生しにくいものとするものである。
The conventional U-turn type ground anchor has a smaller cross section than the tension steel PC steel in the tensile direction, so if it is buried directly in the anchor body without a load-bearing body, the stress concentrates on the U-turn and the anchor body is It is considered to be destroyed, and the tensile force is transmitted to the anchor body using a load bearing member such as a load bearing body and a bearing plate for distributing the tensile force to the anchor body and transmitting it to the anchor body.
Since the anchor body is a solidified body made of cement grout, etc., there is no problem of rust, but the bearing member and the PC steel strand are made of steel. There is a problem that rust is generated when underground water penetrates the ground. When rust is generated, the function of the ground anchor is lowered and the life may be shortened.
The present invention facilitates handling at the time of construction of a U-turn type ground anchor, makes it possible to construct a ground anchor at a low cost by reducing the number of parts, and rusts even when the anchor body is cracked. It is assumed that is difficult to occur.
ＰＣ鋼より線をＵターンさせた緊張材のＵターン部に支圧具を設けずに定着長部とし、この定着長部にはＵターン部の先まで延びる先端スパイラルを有し、緊張材を包囲するスパイラル筋が設けてあって緊張材を拘束すると共にアンカー体のグラウトを補強しており、先端スパイラルのスパイラル径が、Ｕターン部のそれより小さくしてあるＵターン型グラウンドアンカーユニットであり、また、このＵターン型グラウンドアンカーユニットを削孔内に設置してＵターン部をアンカー体内に設置したＵターン複合抵抗機構型グラウンドアンカーである。 The U-turn part of the tendon made of U-turned PC steel wire is used as a fixing length without providing a support tool, and this fixing length has a tip spiral that extends to the tip of the U-turn. It is a U-turn type ground anchor unit that has an encircling spiral line to restrain the tension material and reinforce the grout of the anchor body, and the spiral diameter of the tip spiral is smaller than that of the U-turn part. In addition, this U-turn type ground anchor unit is a U-turn composite resistance mechanism type ground anchor in which the U-turn type ground anchor unit is installed in the drilling hole and the U-turn portion is installed in the anchor body.
本発明のＵターン型グラウンドアンカーユニットを用いたＵターン型グラウンドアンカーは、Ｕターン部の支圧具を省略したことにより支圧具の錆の問題が解消されており、かつ、Ｕターン部の緊張材を包囲するスパイラル筋が設けてあり、グラウトからなるアンカー体の割裂ひび割れの発生を防止することができるため、Ｕターン部の内側面が支圧板と同様に機能することからＵターン部は安定した支圧抵抗機構となって圧縮型アンカーとして機能し、それより上側の緊張材は、包囲されているスパイラル筋の拘束によってグラウトと緊張材との付着力が大幅にアップされて安定した摩擦抵抗機構が得られ、アンカー体は引張型となり、アンカー体全体としては、圧縮型と引張型が複合化されたアンカー体として引張力を有効に地盤に伝達することができることから、アンカー体を小型化でき、コストの低減及び工期の短縮を図ることができる。
更に、支圧具を省略したのでグラウンドアンカーユニットが軽量化されており、施工時の取り扱いが容易となり施工効率を高めることができ、工期の短縮およびコストの削減となる。
緊張材の外周にスパイラル筋が被せてあることによって引張力が回転方向の力に変換されるのでアンカー体との摩擦抵抗が増大することによって従来のＰＣ鋼より線の付着力を超える引き抜き力を得ることができるので、アンカー体の長さを短縮することが可能となり、コストを削減することができる。
また、定着長部に設けられたスパイラル筋がＵターン部の先まで延びる先端スパイラルを有すると共に、先端スパイラルのスパイラル径がＵターン部のそれより小さくしてあることによって、アンカーユニットを削孔に挿入するときのガイドとなって挿入作業を円滑に実施できると共に、先端スパイラルが削孔の底部に到達して停止すると、Ｕターン部は余長部の上部のスライムなどが無い位置に確実に停止させることが可能となる。
In the U-turn type ground anchor using the U-turn type ground anchor unit of the present invention, the problem of rust of the pressure bearing member is eliminated by omitting the pressure bearing member of the U-turn part, and Since the spiral muscle that surrounds the tendon material is provided and the occurrence of split cracks in the anchor body made of grout can be prevented, the inner surface of the U-turn part functions in the same manner as the bearing plate, so the U-turn part is It functions as a compression anchor with a stable bearing resistance mechanism, and the tension material on the upper side of the tension material is greatly improved in the adhesive force between the grout and the tension material due to the restraint of the surrounding spiral muscles, and stable friction. A resistance mechanism is obtained, the anchor body becomes a tension type, and the anchor body as a whole is an anchor body that combines the compression type and the tension type, and effectively transmits the tensile force to the ground. Because it can be Rukoto, the anchor body can be miniaturized, can be reduced and shortening of the construction period of the cost.
Furthermore, since the bearing support is omitted, the ground anchor unit is lightened, handling at the time of construction is facilitated, construction efficiency can be improved, construction period is shortened, and cost is reduced.
Since the tensile force is converted into a force in the direction of rotation by covering the outer periphery of the tendon material with the spiral muscle, the frictional resistance with the anchor body is increased, so that the pulling force exceeding the adhesion force of the wire than the conventional PC steel is achieved. Therefore, the length of the anchor body can be shortened, and the cost can be reduced.
In addition, the spiral muscle provided in the fixing length portion has a tip spiral that extends to the tip of the U-turn portion, and the spiral diameter of the tip spiral is smaller than that of the U-turn portion, so that the anchor unit can be drilled. As a guide for insertion, the insertion work can be carried out smoothly, and when the tip spiral reaches the bottom of the drilling hole and stops, the U-turn part reliably stops at the position where there is no slime etc. above the extra length part It becomes possible to make it.
本発明のＵターン型グラウンドアンカーの緊張材４は、ＰＣ鋼より線４０がポリエチレン製の被覆４２で被覆されたもの、所謂アンボンドＰＣ鋼より線を使用する。グラウンドアンカーの自由長部２（Ｌ１）においては、ポリエチレン被覆４２によってＰＣ鋼より線４０にグラウトは付着することがなく、自由に変形することができる。定着長部３（Ｌ２）においては、ポリエチレン被覆４２は除去されており、ＰＣ鋼より線４０にグラウトが付着して一体化されており、ＰＣ鋼より線４０に作用する引張力はグラウトを介して地盤に伝達されるようにしてある。本発明においては、このＰＣ鋼より線４０の芯線及び側線がそれぞれ全周に単独に合成樹脂塗膜が形成された防錆機能の高いものであって、地中水がＰＣ鋼より線４０の素線の間に浸入した場合であっても錆が生ずることがないものである。
このＰＣ鋼より線４０は、例えば、特公平７−１０３６４３号公報に示された素線を撚り合わせてブルーイングしたＰＣ鋼より線の撚りを部分的に一時的にほぐし、各素線にエポキシ樹脂静電粉体塗装法によってエポキシ樹脂塗膜を形成したものであり、本発明のＵターン型グラウンドアンカーの緊張材として好ましいものである。但し、これに限ることは無く、亜鉛メッキ防請処理したＰＣ鋼より線を使用することも可能であり、また、裸線に適切な防錆処理を施したものであればよい。
The tension material 4 of the U-turn type ground anchor of the present invention uses a so-called unbonded PC steel wire in which a PC steel wire 40 is covered with a polyethylene coating 42. In the free length portion 2 (L 1 ) of the ground anchor, the grout does not adhere to the PC steel strand 40 by the polyethylene coating 42 and can be freely deformed. In the fixing length portion 3 (L 2 ), the polyethylene coating 42 is removed, the grout is attached to and integrated with the wire 40 from the PC steel, and the tensile force acting on the wire 40 from the PC steel is the grout. To be transmitted to the ground. In the present invention, the core wire and the side wire of the PC steel wire 40 have a high rust prevention function in which a synthetic resin coating is independently formed on the entire circumference. Even when it enters between the strands, rust does not occur.
The PC steel strand 40 is, for example, partly temporarily loosened by twisting the strands of the PC steel twisted and bluened by twisting the strands disclosed in Japanese Patent Publication No. 7-103643. An epoxy resin coating film is formed by a resin electrostatic powder coating method, which is preferable as a tension material for the U-turn type ground anchor of the present invention. However, the present invention is not limited to this, and it is possible to use a stranded galvanized PC steel wire as long as the bare wire is appropriately rust-proofed.
図１は、本発明のグラウンドアンカーユニット１を地中に設置した状態の全体図であり、図２はグラウンドアンカーの先端部の定着長部の拡大図である。グラウンドアンカーは、アンカー頭部定着具１０、自由長部２（Ｌ１）定着長部３（Ｌ２）及び削孔余長部Ｌ３からなるものであり、アンカー長はＬ０である。
緊張材４は、自由長部Ｌ１においては、アンボンドＰＣ鋼より線のポリエチレン被覆４２を残したままとしてあり、定着長部Ｌ２においては、ポリエチレン被覆４２が除去されてＰＣ鋼より線４０が露出した状態としてある。
このポリエチレン被覆を除去したＰＣ鋼より線４０をベンダーで１８０度折り曲げてＵターン部５を形成し、ＰＣ鋼より線を所定の間隔で平行にし、ＰＣ鋼より線をガイドする溝６１が形成された円形のスペーサー６によって緊張材４の間隔を保持し、結束バンド６２で固定してその状態を維持するものとしてある。図に示した例は、Ｕターン部５を形成したＰＣ鋼より線２本を９０°ずらして配置したものを緊張材４としたものであるが、グラウンドアンカーに要求される引抜耐力に応じて所要のＰＣ鋼より線の直径及び本数を決定することができる。
FIG. 1 is an overall view of the ground anchor unit 1 according to the present invention installed in the ground, and FIG. 2 is an enlarged view of a fixing length portion at the tip of the ground anchor. The ground anchor includes an anchor head fixing tool 10, a free length portion 2 (L 1 ), a fixing length portion 3 (L 2 ), and a drilling surplus length portion L 3 , and the anchor length is L 0 .
Tendon 4 is in a free length portion L 1, there as leaving the polyethylene coating 42 of the wire from the unbonded PC steel, the fixing length unit L 2 is a line 40 from the PC steel polyethylene coated 42 is removed It is in an exposed state.
The PC steel wire 40 from which the polyethylene coating has been removed is bent 180 degrees with a bender to form a U-turn portion 5, and the PC steel wire is made parallel at a predetermined interval, and a groove 61 for guiding the PC steel wire is formed. The gap between the tendon members 4 is held by a circular spacer 6 and fixed with a binding band 62 to maintain the state. In the example shown in the figure, the tension material 4 is formed by shifting two strands of the PC steel forming the U-turn portion 5 by 90 °, but depending on the pulling strength required for the ground anchor. The diameter and number of wires can be determined from the required PC steel.
Ｕターン部５は耐荷体を設けずに定着長部３（Ｌ２）の先端に配置されており、このＵターン部５には所用の長さまでスパイラル筋７を被せてグラウトと一体化されてアンカー体３１が形成される。Ｕターン部５が支圧抵抗機構として引張力をアンカー体３１に伝達させるものである。平行に延びるＰＣ鋼より線４０の間隔が２０〜４０ｍｍと小さく、Ｕターン部５の曲率半径が２０〜３０ｍｍと小さいので素線の撚りが緩んで素線間に隙間が生じており、この隙間にグラウトが入り込みＰＣ鋼より線と一体化するので、引張方向に対するＵターン部５の断面が大きくなって引張力がアンカー体３１に効率よく伝達される。 The U-turn portion 5 is disposed at the tip of the fixing length portion 3 (L 2 ) without providing a load bearing body. The U-turn portion 5 is covered with a spiral muscle 7 to a desired length and integrated with the grout. Anchor body 31 is formed. The U-turn part 5 transmits a tensile force to the anchor body 31 as a bearing resistance mechanism. Since the distance between the wires 40 of the PC steel extending in parallel is as small as 20 to 40 mm and the radius of curvature of the U-turn part 5 is as small as 20 to 30 mm, the strands of the strands are loosened and gaps are formed between the strands. Since the grout enters and is integrated with the wire from the PC steel, the cross section of the U-turn part 5 with respect to the tensile direction becomes large and the tensile force is efficiently transmitted to the anchor body 31.
図２の定着長部３の拡大図に示すように、定着長部３（Ｌ２）はスパイラル筋７によって包囲されている。スパイラル筋７は、直径４〜８ｍｍの鉄筋をスパイラルに加工したものであり、スパイラル径はＵターンさせた緊張材４を包囲する大きさとしてある。 As shown in the enlarged view of the fixing length portion 3 in FIG. 2, the fixing length portion 3 (L 2 ) is surrounded by the spiral streaks 7. The spiral muscle 7 is obtained by processing a reinforcing bar having a diameter of 4 to 8 mm into a spiral, and the spiral diameter has a size surrounding the U-turned tension material 4.
削孔の先端部にはグラウトとＰＣ鋼より線の付着を阻害するスライムや泥土、ごみが残留しているため、グラウトの強度が十分でなく、ＰＣ鋼より線４０との十分な付着力が得られないので、従来の技術では余長部として緊張鋼材、耐荷体及び定着長部が余長部に位置しないようにグラウンドアンカーの先端にスペーサーとなるパイロットキャップを取付けてグラウンドアンカーの先端が削孔底から一定間隔離れるようにし、Ｕターン部がスライム等が存在している余長部Ｌ３に位置しないようにしている。そのため、本発明では、先端スパイラル７１の径はＵターン部５が通り抜け不可能な大きさとしてありＵターン部５が削孔底より所定の距離（Ｌ３）隔てた位置に設置される。 Since the slime, mud and dirt that hinder the adhesion of the wire from the grout and the PC steel remain at the tip of the drilling hole, the strength of the grout is not sufficient, and the adhesive strength to the wire 40 from the PC steel is sufficient. In the conventional technology, a pilot cap serving as a spacer is attached to the tip of the ground anchor so that the tension steel, load bearing member, and fixing length are not located in the extra length as the extra length. from the hole bottom away regular intervals, so that not located in the elongated portion L 3 of the U-turn portion is present is slime like. Therefore, in the present invention, the diameter of the tip spiral 71 is set such that the U-turn portion 5 cannot pass through, and the U-turn portion 5 is installed at a predetermined distance (L 3 ) from the drilling hole bottom.
図示はしていないが、スパイラル筋７は、緊張材４の削孔への挿入時に位置がずれたり脱落したりしないように結束バンドなどの適宜の固定手段によって緊張材４に固定してあり、グラウトの充填固化後はアンカー体３１と一体化されるものである。 Although not shown, the spiral muscle 7 is fixed to the tension member 4 by appropriate fixing means such as a binding band so that the position of the spiral muscle 7 is not shifted or dropped when the tension member 4 is inserted into the drilling hole. After filling and solidifying the grout, the anchor body 31 is integrated.
グラウンドアンカーの施工は、地盤にボーリング装置でアンカー長（Ｌ０）に余長部（Ｌ３）の長さを加えた深さの削孔を形成し、この削孔にアンカーユニット１を挿入する。スパイラル筋７の先端スパイラル７１の直径が小さなものとしてあるので、削孔に挿入するときのガイドとなって挿入作業を容易にすると共に、先端スパイラル７１が削孔の底部に到達して停止すると、Ｕターン部５は余長部（Ｌ３）より上のスライムなどが無い位置に確実に停止した状態にすることが可能となる。
グラウトを注入して削孔内にアンカー体３１を形成し、Ｕターン部５及びスパイラル筋７をアンカー体内に埋設する。グラウトが硬化し、Ｕターン部５がアンカー体３１に固定された後に緊張材４を緊張してアンカーヘッドなどの定着具１０に緊張定着する。
The ground anchor is constructed by forming a hole having a depth obtained by adding the length of the extra length (L 3 ) to the anchor length (L 0 ) on the ground with a boring device, and inserting the anchor unit 1 into this hole. . Since the diameter of the tip spiral 71 of the spiral muscle 7 is small, it serves as a guide when inserting into the drilling hole and facilitates the insertion work, and when the tip spiral 71 reaches the bottom of the drilling hole and stops, The U-turn portion 5 can be surely stopped at a position where there is no slime or the like above the extra length portion (L 3 ).
The grout is injected to form the anchor body 31 in the drilling hole, and the U-turn portion 5 and the spiral muscle 7 are embedded in the anchor body. After the grout is hardened and the U-turn portion 5 is fixed to the anchor body 31, the tension material 4 is tensioned and fixed to the fixing tool 10 such as an anchor head.
実験例及び比較例
本発明のアンカーの引張耐力を以下の条件で施工し、アンカー体による緊張材４の拘束力を測定して従来技術による比較例と比較した。
比較例及び実施例ともにφ１５．２ｍｍの素線の全周を塗膜で保護してあるＳＣストランド（商品名）を用い、φ９０ｍｍの削孔を鉛直に形成し、自由長部と定着長部の境界部にはチューブのゴム製のパッカーを装着して設置し、自由長部２（Ｌ２）にはグラウトが充填されないようにして摩擦抵抗が生じないようにした。
試験に用いたグラウンドアンカーの諸元を表１に示す。見掛けの周長とは、ＰＣ鋼より線の直径を１５．２ｍｍとし、２本のＰＣ鋼より線の周囲の長さである。
比較例は２本のＳＣストランドからなる引張型のグラウンドアンカーであり、実施例は１本のＳＣストランドをＵターンさせたものである。
Experimental Example and Comparative Example The anchor strength of the anchor of the present invention was applied under the following conditions, and the restraining force of the tension material 4 by the anchor body was measured and compared with the comparative example of the prior art.
In both the comparative example and the example, an SC strand (trade name) in which the entire circumference of a wire having a diameter of 15.2 mm is protected with a coating film, a hole having a diameter of 90 mm is formed vertically, and a free length portion and a fixing length portion are formed. A rubber rubber packer was attached to the boundary portion, and the free length portion 2 (L 2 ) was not filled with grout so as not to generate frictional resistance.
Table 1 shows the specifications of the ground anchor used in the test. The apparent perimeter is the length of the circumference of two PC steel wires with a diameter of 15.2 mm from the PC steel.
The comparative example is a tension type ground anchor composed of two SC strands, and the example is a U-turn of one SC strand.
グラウトを充填してグラウンドアンカーを設置した後、４週間後に実施例と比較例各々について引き抜き試験を実施したところ、以下の結果が得られた。
図５及び図６は比較例と実施例の引抜試験の荷重−変位量のグラフであり、▲は試験体のグラウンドアンカーの計測値を示し、●はアンカーヘッドの変位の開始時点から緊張材４に引張力が作用したものとして計算した値を示している。
After filling the grout and installing the ground anchor, a pull-out test was conducted for each of the Examples and Comparative Examples after 4 weeks, and the following results were obtained.
5 and 6 are graphs of the load-displacement amount of the pull-out test of the comparative example and the example, ▲ indicates the measured value of the ground anchor of the test body, and ● indicates the tension material 4 from the start of the displacement of the anchor head. Shows the value calculated as if the tensile force was applied.
図５に示す比較例の引抜試験の結果からは、引抜荷重２８０ｋＮまでは荷重とアンカーヘッドにおける緊張材の変位量は比例関係にあり直線的であるが、２８０ｋＮを超えたところでアンカー体による緊張材の拘束が失われており、緊張材がアンカー体から抜け始めたものと推定される。
一方、図６に示す本発明の実施例の試験結果では、緊張材４のＰＣ鋼より線の降伏引張荷重４４４ｋＮまで直線的な変位を示している。それ以上の引抜荷重は緊張材４が破断して計測機器を破損するおそれがあるので引抜試験を中止した。
以上の結果から、本発明のグラウンドアンカーは、表１に示すように、自由長、アンカー体長、及びアンカー体のグラウトモルタルの圧縮強度を同一条件とした従来の引張型アンカーの少なくとも１．５７倍の引張荷重に耐えることができたものといえる。
From the result of the pull-out test of the comparative example shown in FIG. 5, the load and the displacement amount of the tendon at the anchor head are proportional and linear until the pull-out load of 280 kN, but the tendon by the anchor body when it exceeds 280 kN. It is presumed that the restraint material has been lost, and the tendon has started to come off the anchor body.
On the other hand, the test result of the embodiment of the present invention shown in FIG. 6 shows a linear displacement up to the yield tensile load 444 kN of the wire from the PC steel of the tendon 4. The pulling test was stopped because there is a possibility that the tension material 4 breaks and the measuring instrument is damaged by a pulling load beyond that.
From the above results, as shown in Table 1, the ground anchor of the present invention is at least 1.57 times that of a conventional tensile anchor having the same length, anchor length, and compressive strength of the grout mortar of the anchor body. It can be said that it was able to withstand the tensile load of.
１ アンカーユニット
１０ 定着具
２ 自由長部
３ 定着長部
３１ アンカー体
４ 緊張材
４０ ＰＣ鋼より線
４２ ポリエチレン被覆
５ Ｕターン部
６ スペーサー
６１ 溝
６２ 結束バンド
７ スパイラル筋
７１ 先端スパイラル
DESCRIPTION OF SYMBOLS 1 Anchor unit 10 Fixing tool 2 Free length part 3 Fixation length part 31 Anchor body 4 Tension material 40 PC steel strand 42 Polyethylene coating 5 U-turn part 6 Spacer 61 Groove 62 Binding band 7 Spiral muscle 71 Tip spiral
Claims (3)
It is a tendon made of U-turned strands of PC steel, and it is used as a fixing length without providing a supporting tool in the U-turn part of this tendon. The spiral muscle surrounding the tendon is provided to restrain the tendon and to reinforce the grout of the anchor body, and the spiral diameter of the tip spiral is smaller than the spiral diameter of the U-turn part. U-turn composite resistance mechanism type ground anchor unit.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108104121A (en) * | 2018-01-11 | 2018-06-01 | 中冶集团武汉勘察研究院有限公司 | For improving the structure and method of pressure anchor wire cement grout body compression strength |
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|---|---|---|---|---|
| JPH0827788A (en) * | 1994-07-18 | 1996-01-30 | Toko Kensetsu Kk | Anchor fixing body, its manufacture and anchor assemblage |
| JPH09143991A (en) * | 1995-11-21 | 1997-06-03 | Kurosawa Kensetsu Kk | Ground anchor construction method |
| JP2000328568A (en) * | 1999-05-21 | 2000-11-28 | Kurosawa Construction Co Ltd | Ground anchor having arresting body |
| JP2002129555A (en) * | 2000-10-19 | 2002-05-09 | Geo Front:Kk | Anchor installation method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0827788A (en) * | 1994-07-18 | 1996-01-30 | Toko Kensetsu Kk | Anchor fixing body, its manufacture and anchor assemblage |
| JPH09143991A (en) * | 1995-11-21 | 1997-06-03 | Kurosawa Kensetsu Kk | Ground anchor construction method |
| JP2000328568A (en) * | 1999-05-21 | 2000-11-28 | Kurosawa Construction Co Ltd | Ground anchor having arresting body |
| JP2002129555A (en) * | 2000-10-19 | 2002-05-09 | Geo Front:Kk | Anchor installation method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108104121A (en) * | 2018-01-11 | 2018-06-01 | 中冶集团武汉勘察研究院有限公司 | For improving the structure and method of pressure anchor wire cement grout body compression strength |
| CN108104121B (en) * | 2018-01-11 | 2023-08-15 | 中冶集团武汉勘察研究院有限公司 | Structure and method for improving compressive strength of pressure type anchor cable cement grouting body |
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| JP2018009320A (en) | 2018-01-18 |
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