JP2004084407A

JP2004084407A - Installation method for rodlike support, and rodlike support

Info

Publication number: JP2004084407A
Application number: JP2002250173A
Authority: JP
Inventors: Makoto Nishio; 西尾　誠; Yoshijiro Furuya; 古屋　義二郎
Original assignee: DAIYONKI CHISHITU KENKYUSHO KK; GROUND ENGINEERING KK
Current assignee: DAIYONKI CHISHITU KENKYUSHO KK; GROUND ENGINEERING KK
Priority date: 2002-08-29
Filing date: 2002-08-29
Publication date: 2004-03-18

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a reduction in a protection function, a reduction in soundness of a rodlike support, and the like by a ground surface variation. <P>SOLUTION: A hollow lock bolt 16 is inserted in a support insertion hole 22 deep beyond a frost heaving region L3 of natural ground 12, and the hollow lock bolt is fixed with inner grout 20 and outer grout 30. An elastic tension member 18 of a raw material having tensile strength capable of enduring ground anchorage is inserted in a hollow portion 16a of the hollow steel rod 16, wherein the inner grout 20 integrates an anchorage length portion L1 with the hollow steel rod to form the rodlike support 10. The outer grout 30 fixedly integrates a fixation length portion L5 of the hollow steel rod with the natural ground 12. With the elastic tension member 18 tensed under a given tensile load, a head portion of the elastic tension member extended via a bearing plate 36 on a structure surface is engaged with and held on the bearing plate through threading of a nut 38 or the like to hold a structure 14 fixed on a ground surface 12a. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、棒状支持体を、地すべり対策工において地山に設置する施工方法であり、特に寒冷地等での施工に適した棒状支持体の施工方法、およびその棒状支持体に関する。
【０００２】
【従来の技術】
地表面に法枠等の構造物を構築し、地山に設置した、たとえばロックボルト等の棒状支持体によってこの構造物を固定的に保持する工法が、地山を保護、補強する、いわゆる地すべり対策工として知られている。
【０００３】
このような、ロックボルト（棒状支持体）を用いる地すべり対策工においては、通常、このロックボルトが、法枠の、たとえば十字状の交点毎等に、地山へのその全長付着のもとで設置、定着されている。
【０００４】
【発明が解決しようとする課題】
ところで、降雨や日照り等の自然現象を直接的に受ける地山の地表面は、これら自然現象による微小な動き、たとえば膨張、収縮等の地表面変動を絶えず繰り返している。そして、その自然現象の中でも地表面の動きが特に著しいのは、地山の凍結によりその地表面を隆起させる、いわゆる凍上であり、地山の凍上の生じやすい寒冷地等においては、この凍上が原因と見られるロックボルト、および構造物の浮き上がり、あるいはロックボルトの破断や構造物の損壊等が多く確認されている。
【０００５】
地山に対するロックボルトの固定強度が地山の凍上により生じる力、つまり凍上圧に満たなければ、前者のような、地山の凍上に伴ったロックボルト、および構造物の浮き上がりは生じる。そして、地山は、その凍上部分の融解により元の体積に戻るが、一旦浮き上がったロックボルトは地山の融解後も元の位置に戻ることなくその浮き上がった状態で残されるため、このロックボルトでの支持状態にある構造物にも、元の位置に戻る力は十分に得られない。
【０００６】
このようなロックボルトの浮き上がりに起因する地表面からの構造物の浮き上がりは、地表面と構造物との間に隙間を生じさせる原因となることから、それに伴った地表面に対する保護機能の低下、および構造物の破損、損壊や地表面の崩壊等を招く虞れが否定できない。
【０００７】
そして、ロックボルトは、この隙間での露出部分において錆びやすく、この錆に起因する腐食等がこのロックボルトに発生しやすいため、ロックボルトの健全度の低下も避けられない。
【０００８】
また、地山に対するロックボルトの固定強度が地山の凍上圧以上であれば、凍上に起因するロックボルトの浮き上がりは十分に防止できる。しかし、この場合の凍上圧は、他に吸収されることなくロックボルト、あるいは構造物に直接的に作用されるため、地山に対するロックボルトの固定強度を地山の凍上圧以上とした場合においては、ロックボルトの浮き上がりが防止できる反面、後者のような、ロックボルトの破断や構造物の損壊等が避けられなくなる。
【０００９】
つまり、いずれにしても、ロックボルトを棒状支持体として用いた公知の地すべり対策工においては、この凍上に対する対策が十分にはかられていないのが現状である。
【００１０】
ここで、このような凍上対策として、たとえば、ロックボルトに弾性部材（コイルスプリング等）を組み合わせ、この弾性部材の弾性変形によって地山の凍上分を吸収しようとする構成が、特開２０００−８７３５０号公報に開示されている。
【００１１】
確かに、この構成においては、構造物に所定範囲の移動ストロークが確保できるため、凍上に起因する増加荷重の吸収により、構造物、およびロックボルトへの過剰な引張荷重の付与、伝達は十分に防止可能となる。
【００１２】
ところで、地表面から浮き上がった構造物を元の位置に押し戻すためには、その自重や変形分等を考慮すると、およそ数トンの押し戻し力が必要と推定されている。しかし、コイルスプリングでの付勢力は一般に３００〜５００ｋｇ程度とされ、１ｔを越える付勢力をコイルスプリングによって得るには経済的、および構造的に困難であることから、このコイルスプリング等の弾性部材をロックボルトに組み合わせた公知の構成では、浮き上がった構造物の押し戻しは期待できない。
【００１３】
つまり、コイルスプリングの弾性変形のもとで引張荷重の増加分が吸収できたとしても、浮き上がり方向に移動した構造物に対する押し戻しが十分に得られないことから、この公知の構成においても、地山融解後の不十分な戻りに起因する保護機能の低下、およびロックボルトの健全度の低下等は避けられない。
【００１４】
この発明は、地表面変動による保護機能の低下、および棒状支持体の健全度の低下等を防止可能とする棒状支持体の施工方法、およびその棒状支持体の提供を目的としている。
【００１５】
【課題を解決するための手段】
この目的を達成するために、請求項１に係るこの発明の棒状支持体の施工方法によれば、地表面から所定深度までの範囲として、その地山における凍上領域を予め想定するとともに、この凍上領域を越える深度の支持体挿入孔を、地表面上の構造物から連続して形成する。そして、中空のパイプ状部材としてなる中空棒状鋼材を、構造物との非一体形態を維持しつつ支持体挿入孔のほぼ全長に亘って挿入配置して、この中空棒状鋼材の内外にグラウトを行う。
【００１６】
さらに、地山定着に耐え得る引張耐力を持った素材からなる弾性引張材を、この中空棒状鋼材の中空部に内挿し、その先端側に規定した弾性引張材の定着長部を、その内部グラウトによって中空棒状鋼材と一体化させることにより、少なくとも中空棒状鋼材に対する、その自由長部における弾性引張材の伸縮性の確保された棒状支持体を構成させるとともに、凍上領域との非整列部として中空棒状鋼材の先端側に規定された固定長部を、その外部グラウトによって地山に一体的に固定することにより、これを地山に対する棒状支持体の設置とする。そして、その後、弾性引張材を所定の引張荷重のもとで緊張し、構造物表面の支圧板を介して延出された弾性引張材の頭部を、定着具により支圧板に係合保持させることによって、構造物を地表面上に固定的に保持するものとしている。
【００１７】
また、この発明の請求項２においては、弾性引張材の自由長部に、グラウトの付着を抑止するアンボンド加工を施し、この弾性引張材の先端側に設けたその露出部分を、少なくとも中空棒状鋼材と一体化させる弾性引張材の定着長部として規定するものとしている。
【００１８】
さらに、この発明の請求項３においては、弾性引張材を、より線ワイヤを被覆チューブで部分的に被覆した部分アンボンドより線とし、この弾性引張材の先端側に設けた、この部分アンボンドより線のより線ワイヤ露出部を、少なくとも中空棒状鋼材と一体化させる弾性引張材の定着長部として規定するものとしている。
【００１９】
そして、この発明の請求項４においては、弾性引張材の素材を、異形棒鋼、ＰＣ鋼材、炭素繊維、およびアラミド繊維のいずれかとして具体化し、さらに、この発明の請求項５においては、地山の凍上により受ける構造物側の凍上受圧を、地表面に対する構造物の接地面積に基づいて算出するとともに、その地山の凍上量を予め実測、あるいは推定し、この凍上受圧と凍上量と、弾性引張材の断面積、およびその素材のヤング率とに基づいて、弾性引張材の自由長部の長さを算出するとともに、その地山において可能な支持体挿入孔の深度と要求される自由長部の長さとを考慮して、弾性引張材に要求される伸び量を確保可能な素材を選定し、これを中空棒状鋼材に組み合わせるものとしている。
【００２０】
また、この発明の請求項６では、自立する地層の地山においては、単管削孔のみにより支持体挿入孔を掘削形成し、その形成された支持体挿入孔に対し、中空棒状鋼材を挿入するものとし、自立しない地層の地山においては、１回目削孔として単管削孔による下孔形成を行い、その後、２回目削孔として中空棒状鋼材自体をドリルパイプとした削孔のもとで、その挿入を同時に行うものとしている。
【００２１】
そして、この発明の請求項７においては、中空棒状鋼材の全長のうち、少なくとも地山の凍上領域と構造物とに整列する部分の外周面を、その先端側の固定長部に対する非付着長部として規定し、この非付着長部に、周辺他部材の付着を抑止するアンボンド加工を予め施すものとしている。
【００２２】
さらに、請求項８に係るこの発明の棒状支持体によれば、中空棒状鋼材に、地山定着に耐え得る引張耐力を持った素材からなる弾性引張材を内挿し、この弾性引張材の先端側に規定された定着長部を、中空棒状鋼材の中空部に対する内部グラウトのもとで中空棒状鋼材に一体化することによりなる、弾性引張材の自由長部での伸縮性を確保した内外二重構造とされている。そして、地山に想定された凍上領域との非整列部としてこの中空棒状鋼材の先端側に規定された固定長部が、その外周部に対する外部グラウトによって地山に一体的に固定されるとともに、所定の引張荷重のもとで緊張された弾性引張材の頭部が、構造物表面の支圧板に、定着具によって係合保持されるものとして、この棒状支持体は構成されている。
【００２３】
また、この発明の請求項９においては、弾性引張材の自由長部に、グラウトの付着を抑止するアンボンド加工が施されるとともに、この弾性引張材の先端側に設けたその露出部分が、少なくとも中空棒状鋼材と一体化される弾性引張材の定着長部として規定されている。
【００２４】
さらに、この発明の請求項１０においては、弾性引張材が、より線ワイヤを被覆チューブで部分的に被覆した部分アンボンドより線としてなり、この弾性引張材の先端側に設けた、この部分アンボンドより線のより線ワイヤ露出部が、少なくとも中空棒状鋼材と一体化される弾性引張材の定着長部として規定されている。
【００２５】
そして、この発明の請求項１１においては、弾性引張材の素材が、異形棒鋼、ＰＣ鋼材、炭素繊維、およびアラミド繊維のいずれかとして具体化されている。
【００２６】
さらに、この発明の請求項１２においては、中空棒状鋼材の全長のうち、少なくとも地山の凍上領域と構造物とに整列する部分の外周面が、周辺他部材の付着を抑止するアンボンド加工により、その先端側の固定長部に対する非付着長部として規定されている。
【００２７】
【発明の実施の形態】
以下、図面を参照しながらこの発明の実施の形態について詳細に説明する。
【００２８】
図１に示すように、この発明に係る棒状支持体の施工方法において施工される棒状支持体１０は、おもに地山１２の保護、補強をはかる地山の地すべり対策工等において広く採用されるものであり、地山に対するその設置、定着のもとで、地山の地表面１２ａに沿って構築された所定の構造物１４を地表面上に固定的に保持しようとするものである。
【００２９】
なお、地山の地表面（法面とも称する）に法枠、あるいは擁壁等の構造物を構築し、それを地山に設置、定着させた、たとえばロックボルト等の棒状支持体によって固定的に保持すること自体は公知であり、また、地表面上に構築される法枠等の構造物の基本構造自体はこの発明の趣旨でないため、これらに対するここでの詳細な説明はいずれも省略するものとする。
【００３０】
図１を見るとわかるように、この発明における棒状支持体１０は、中空のパイプ状部材としてなる中空棒状鋼材、たとえば、その外周面にねじ部を持つ中空ロックボルト１６をその主体として使用するものであり、この中空ロックボルトの中空部１６ａに、地山定着に耐え得る引張耐力を持った素材からなる弾性引張材１８を副資材として内挿した、いわゆる内外二重構造として具体化されている。
【００３１】
この中空ロックボルト（中空棒状鋼材）１６に内挿される弾性引張材１８には、たとえば、後述する内部グラウト２０のもとで中空ロックボルトに一体化される定着長部Ｌ１と、この中空ロックボルトに対する伸縮性の確保される自由長部Ｌ２とが予め規定されている。つまり、中空ロックボルト１６に弾性引張材１８を内挿してなるこの内外二重構造の棒状支持体１０は、弾性引張材の先端側に位置するその定着長部Ｌ１を中空ロックボルトに部分的に一体化させた、いわゆる部分一体ものとして形成されている。
【００３２】
この弾性引張材１８としては、各種弾性素材からなるより線ワイヤ、あるいはロッド等が利用でき、この弾性引張材となり得る素材としては、異形棒鋼、ＰＣ鋼材、炭素繊維、およびアラミド繊維等が例示できる。
【００３３】
なお、ＰＣ鋼材、あるいは炭素繊維がその素材である場合においては、より線ワイヤ形態が一般的であり、また、異形棒鋼、およびアラミド繊維がその素材である場合においては、ロッド形態が一般的となっている。
【００３４】
この発明の実施の形態においては、ＰＣ鋼材からなるより線ワイヤ（ＰＣ鋼より線）１８ａを被覆チューブ（アンボンドチューブ）１８ｂで部分的に被覆し、かつこの被覆チューブ内にグリース等の潤滑材を充填することにより形成された、いわゆる部分アンボンドＰＣ鋼より線を、弾性引張材１８として具体的に示す。そして、このような部分アンボンドＰＣ鋼より線としてなる弾性引張材１８においては、その先端側に設けたより線ワイヤ１８ａの露出部が、中空ロックボルト１６と一体化される弾性引張材の定着長部Ｌ１として、また、被覆チューブ１８ｂによる被覆部分が、中空ロックボルトに対して伸縮される自由長部Ｌ２として、それぞれ規定されている。
【００３５】
このような棒状支持体１０は、構造物１４、および地山１２に連続して形成した所定深度の支持体挿入孔２２ヘの挿入配置を伴って、その地山に対して設置、定着される。
【００３６】
構造物１４、および地山１２に対する支持体挿入孔２２の掘削手法としては、削孔機、たとえばインバータチゼルによる単管削孔が例示できる。
【００３７】
たとえば、図２に示すように、先端にビット２４を有したロッド２６を削孔機（インバータチゼル）２８の駆動部３０にセットし、このロッドを介して、先端のビットに打撃力、および回転力を付与しながらこれを推進させることにより、対応径の支持体挿入孔２２が地山１２に形成される。
【００３８】
なお、このような支持体挿入孔の掘削工程は従来のアンカー工法等において行われているものと何等変わりなく、また、削孔機自体も従来のものが利用できるため、これらに対する、ここでの詳細な説明は省略する。
【００３９】
ここで、図１、および図２に示すように、この発明においては、まず、地山１２の凍結によって体積の膨張されるであろう領域、つまり凍上領域Ｌ３を、地表面１２ａから所定深度までの範囲として予め想定する。そして、図３に示すような、この地山１２の凍上領域Ｌ３を越える深度となる、全長Ｌ４の支持体挿入孔２２を、前出の削孔機２８による、たとえば単管削孔のもとで掘削する。
【００４０】
なお、凍上領域Ｌ３としては、通常、５０ｃｍ程度の深度の領域が想定される。
【００４１】
この支持体挿入孔２２の径は、単管削孔機のロッド先端に設けられたビット２４の有効外径によりほぼ決定されるが、一般的な有効外径である６５ｍｍのビットの使用により掘削された支持体挿入孔２２であれば、たとえば外径４２．７ｍｍ、あるいは外径４８．６ｍｍ程度の中空ロックボルト１６の挿入が可能となる。
【００４２】
図３に示すような、所定長（全長Ｌ４）の支持体挿入孔２２を掘削した後、ロッド２６はこの支持体挿入孔から引き抜かれ、図４に示すように、次に、支持体挿入孔の全長Ｌ４にほぼ相当する長さＬ４′の中空ロックボルト１６を、構造物１４との非一体形態を維持しつつ、この支持体挿入孔内に挿入配置する。
【００４３】
ここで、この中空ロックボルト１６においては、先端側の固定長部Ｌ５と後端側の非付着長部Ｌ６とが連続規定されている。図１を見るとわかるように、この中空ロックボルト１６の固定長部Ｌ５は、地山１２の凍上領域Ｌ３との非整列部として規定され、たとえば、他方の非付着長部Ｌ６に、周辺他部材の付着を抑止するアンボンド加工を施すことによって、これらは明確に区分されている（図４参照）。
【００４４】
図１、および図４を見るとわかるように、この、中空ロックボルト１６の非付着長部Ｌ６に対するアンボンド加工としては、被覆部材２８による非付着長部周りの被覆が具体化できる。そして、この被覆部材２８としては、薄肉管やフィルム状テープ等が例示でき、この被覆部材と中空ロックボルト１６の周面との間には、防錆材が塗布される。
【００４５】
図５に示すように、支持体挿入孔２２への中空ロックボルト１６の挿入配置後においては、たとえば、この中空ロックボルトの中空部１６ａを介して、中空ロックボルトに対する内部グラウト２０、および外部グラウト３０がそれぞれ施される（図１参照）。
【００４６】
この内部グラウト２０、および外部グラウト３０となるグラウト材は、中空ロックボルト１６の端末に連結された、グラウトポンプ（図示しない）からのグラウトホース３２を介して、中空ロックボルトの中空部１６ａ内に圧送、注入され、そのグラウト材を、中空ロックボルトの先端からその外部に流出させることによって、内部グラウト、および外部グラウトの連続注入がはかられる。
【００４７】
なお、内部グラウト２０、および外部グラウト３０のグラウト材としては、たとえばセメントミルク等が例示できる。
【００４８】
そして、図６に示すように、内部グラウト２０、および外部グラウト３０の終了後、詳細にいえば、グラウト材の注入後でこのグラウト材の固結前に、定着長部Ｌ１、および自由長部Ｌ２の規定された弾性引張材（部分アンボンドＰＣ鋼より線）１８を、中空ロックボルトの中空部１６ａに、少なくともその全長に亘って内挿して、その後、内部グラウト、および外部グラウトとしたグラウト材の固結を待つ。
【００４９】
内部グラウト２０が固結すると、弾性引張材１８の定着長部Ｌ１が中空ロックボルト１６に対して一体化され、また、外部グラウト３０が固結すると、中空ロックボルトの固定長部Ｌ５が地山１２に対して一体的に固定される。
【００５０】
なお、内部グラウト２０が弾性引張材１８の自由長部Ｌ２周りに達し、これが固結しても、この弾性引張材の自由長部Ｌ２は被覆チューブ１８ｂにより隔離されているため、その内部におけるより線ワイヤ１８ａの伸縮は円滑に確保される。また、同様に、外部グラウト３０が中空ロックボルト１６の非付着長部Ｌ６周りに達しても、この非付着長部Ｌ６には被覆部材２８でのアンボンド加工が施されているため、この非付着長部Ｌ６の中空ロックボルトに対する周辺他部材の付着、たとえば外部グラウト３０の付着は確実に防止可能となる。
【００５１】
ところで、図６に示すように、弾性引張材１８の端部には、たとえば、周面をねじ部としたグリップ３４が頭部定着体として一体的に固着されている。そして、図１に示すように、このグリップ３４を、構造物１４の表面に配した支圧板３６を介して支持体挿入孔２２の外部に延出、露出させ、このグリップに対する、保持具となるナット３８の螺着、およびその螺進によって、弾性引張材１８を所定の引張荷重のもとで緊張するとともに、このナットを支圧板に係合保持させることによって、棒状支持体１０が地山１２に対して施工され、この弾性引張材に付与された引張荷重のもとで、構造物が地表面１２ａ上に固定的に保持される。
【００５２】
このように施工された棒状支持体１０においては、中空ロックボルト１６の固定長部Ｌ５が外部グラウト３０により地山１２に一体的に固定されるとともに、弾性引張材１８の定着長部Ｌ１が内部グラウト２０により中空ロックボルトに対して一体化されるため、弾性引張材の定着長部Ｌ１は、地山に対しても一体的に固定されることになる。
【００５３】
つまり、図１に示す状態において、地山１２に凍上が生じると、その凍上圧は、地表面１２ａから構造物１４、受圧板３６、およびナット３８を経て弾性引張材１８に作用し、この弾性引張材においては、中空ロックボルト１６に対する伸縮性の確保されたその自由長部Ｌ２が、この凍上圧での地山の凍上に追従して伸長される。
【００５４】
なお、中空ロックボルト１６の固定長部Ｌ５は、凍上領域Ｌ３との非整列位置で地山１２に対して一体的に固定されているため、たとえ地山に凍上が生じても、その凍上の影響は受けず、その凍上に追従して浮き上がることなく元の位置に残される。そして、地山１２に固定されたこの中空ロックボルト１６は、地すべり抑止材としての機能を十分に持つ剛体であるため、棒状支持体１０としての機能を損なうことはない。
【００５５】
また、地山１２の凍上領域Ｌ３が融解し、地山の体積が元に戻れば、弾性引張材１８の自由長部Ｌ２に発生した復元力のもとで、構造物１４は地表面１２ａの復元に追従して元の位置に戻される。
【００５６】
この弾性引張材１８の自由長部Ｌ２に発生する復元力によれば、数トン以上の復元力、つまり構造物１４に対する押し戻し力は容易に確保できる。つまり、数トンとして推定される押し戻し力が、この弾性引張材１８によれば十分に確保できるものとなる。
【００５７】
上記のように、この発明の施工方法によりなる棒状支持体１０によれば、地山１２が凍上を生じた際、地表面１２ａの構造物１４が、弾性引張材１８の自由長部Ｌ２での伸長のもとで、中空ロックボルト１６を伴うことなく地表面の変動に追従して移動される。そして、地山１２の融解後、弾性引張材１８の自由長部Ｌ２に発生した押し戻し力のもとで、地表面上の構造物１４は地山の体積減少に追従して元の位置に押し戻されるため、この棒状支持体１０によれば、凍上時における、中空ロックボルト１６を伴うことのない構造物１４の移動、および融解時におけるその押し戻しの双方が円滑に確保可能となる。
【００５８】
このように、地山１２の凍上時に、中空ロックボルト１６の浮き上がりを伴うことなく構造物１４を凍上方向に移動させれば、この移動による荷重の吸収により、中空ロックボルトに対する過度の引張荷重の付与、伝達が確実に防止されるため、中空ロックボルトの浮き上がり、および中空ロックボルトの破断や構造物の損壊等が防止される。そして、地山１２の融解時、弾性引張材１８からの押し戻し力のもとで構造物１４を押し戻せば、地山の体積減少に追従した構造物の移動が容易に確保できるため、融解後における、地表面１２ａからの構造物の浮き上がり、つまり地表面、構造物間の隙間の形成が十分に防止されることから、錆の発生等に起因する棒状支持体１０の健全度の低下が、これによれば確実に防止可能となる。
【００５９】
従って、この発明によれば、凍上等の地表面変動による保護機能の低下、および棒状支持体１０の健全度の低下等が確実に防止される。
【００６０】
なお、この発明の実施の形態においては、いわゆる凍上を、地山１２における地表面変動として具体化しているが、降雨や日照り等による膨張、収縮等の微小な地表面変動に対しても、この発明が有効であることはいうまでもない。
【００６１】
ここで、この発明の実施の形態においては、弾性引張材１８の自由長部Ｌ２、および中空ロックボルト１６の非付着長部Ｌ６にアンボンド加工を施すことで、自由長部Ｌ２における弾性引張材の伸縮性、および非付着長部Ｌ６に対する周辺他部材の付着規制を行っているが、弾性引張材の自由長部Ｌ２が伸縮自在であり、また、中空ロックボルトが地山１２の凍上領域から確実に隔離されれば足りるため、たとえば、これらのアンボンド加工を特に施さず、この弾性引張材の定着長部Ｌ１、および中空ロックボルトの固定長部Ｌ５のみに内部グラウト２０、外部グラウト３０をそれぞれ施す構成としてもよい。
【００６２】
しかしながら、この実施の形態のように、弾性引張材１８の自由長部Ｌ２、および中空ロックボルト１６の非付着長部Ｌ６にそれぞれのアンボンド加工を施せば、各部の長さの明確化が容易に可能となり、その機能性が容易に確保できる。そして、内部グラウト２０、および外部グラウト３０の充填作業が簡単化でき、また、ほぼ全長に亘るグラウトのもとで弾性引張材１８、および中空ロックボルト１６の安定性が容易に確保できるため、その機能性の一層の向上も容易にはかられる。
【００６３】
また、この発明の実施の形態においては、中空ロックボルト１６を中空棒状鋼材として具体化しているが、その内部に弾性引張材１８の内挿可能な中空のパイプ状部材であれば足りるため、これに限定されず、たとえばガス管等の鋼管を、ここでいう中空棒状鋼材として利用してもよい。
【００６４】
しかしながら、外周面をねじ部とした中空ロックボルト１６を中空棒状鋼材として利用すれば、その外周面に対する、外部グラウト３０の付着力が確実に増強されるため、地山１２に対する中空棒状鋼材の固定の確実性が一層向上される。
【００６５】
なお、この実施の形態においては、繋ぎのない、いわゆる一本ものとして、中空ロックボルト１６を図示しているが、要求されるその全長、つまり支持体挿入孔２２の全長に応じて、中空ロックボルトを必要本数だけ繋ぎ合わせてもよい。
【００６６】
さらに、この実施の形態においては、周面をねじ部としたグリップ３４を、頭部定着体として弾性引張材１８の端部に設け、このグリップに対するナット３８の螺着のもとでその緊張、および保持をはかっているが、弾性引張材の頭部定着部の構造はこれに限定されず、たとえば、アンボンドＰＣ鋼より線等のより線ワイヤとしてなる弾性引張材であれば、くさび、およびアンカーヘッドの組み合わせ等を保持具として支圧板３６に保持、係合させる構造も採用できる。
【００６７】
しかしながら、この実施の形態のように、弾性引張材１８のグリップ３４にナット３８を螺着させる構成であれば、ナットの螺進によって弾性引張材の緊張も得られるため、弾性引張材の緊張、保持作業が確実に簡素化される。
【００６８】
ここで、この発明の実施の形態においては、ＰＣ鋼材を素材とした部分アンボンドＰＣ鋼より線を弾性引張材１８として具体化しているが、この弾性引張材は、地山定着に耐え得る引張耐力を持った素材からなるものであれば足りるため、これに限定されず、前述のような、異形棒鋼、炭素繊維、およびアラミド繊維等を素材としたより線ワイヤ、あるいはロッドを、この弾性引張材として利用してもよい。
【００６９】
ところで、弾性引張材１８の素材としてここで具体的にあげたうちの、たとえばＰＣ鋼材、炭素繊維、およびアラミド繊維は、それぞれ異なるヤング率等を持つ、性質の異なる素材であるため、棒状支持体１０として得られる特性も、組み合わせる素材によって大きく異なることになる。
【００７０】
たとえば、弾性引張材１８の自由長部Ｌ２の長さは、たとえば、構造物１４の接地面積や地山１２に発生する凍上圧等に基づいた算出結果により決定される。
【００７１】
たとえば、図７に示すような形状、大きさの法枠を、１体当たりの棒状支持体１０が受け持つ構造物１４と仮定した場合、地表面１２ａに対するこの構造物の接地面積は、たとえば、
４０×２００＋４０×８０×２＝８０００＋６４００＝１４，４００ｃｍ^２
として算出され、地山１２に生じる凍上圧を０．２ｋｇ／ｃｍ^２と仮定すれば、この構造物の受ける地表面からの凍上受圧は、
０．２×１４４００＝２，８８０ｋｇ
として算出される。
【００７２】
そして、地山１２の凍上領域Ｌ３における凍上量、つまりは凍上時における地表面１２ａの移動量を、たとえば３０ｍｍと仮定するとともに、融解後に構造物１４を戻す力を、凍上時における凍上受圧と同一と考えれば、２，８８０ｋｇの荷重が掛かったときに伸び量が３０ｍｍとなるような自由長部Ｌ２の長さを選定すればよいため、たとえば直径１２．７ｍｍ、および断面積９８．７１ｍｍ^２の部分アンボンドＰＣ鋼より線を弾性引張材１８として使用する場合においては、ＰＣ鋼材のヤング率が約２０，０００であるから、これらの数値を
（伸び量）＝｛（自由長部Ｌ２）×（荷重）｝／｛（断面積）×（ヤング率）｝
の数式に当てはめることで、
３０＝｛（自由長部Ｌ２）×２８８０｝／（９８．７１×２００００）
（自由長部Ｌ２）＝２０，５６４ｍｍ
が算出される。つまり、この種の部分アンボンドＰＣ鋼より線を弾性引張材１８として使用する場合においては、自由長部Ｌ２を約２０．５ｍとすることによって、３０ｍｍの凍上に追従したこの自由長部Ｌ２の伸長、および３０ｍｍの復元に追従した構造物１４の押し戻しを得ることが可能となる。
【００７３】
また、ヤング率が約１５，０００である炭素繊維を素材とした、直径１２．５ｍｍ、断面積７０　ｍｍ^２の部分アンボンドより線の場合においては、
３０＝｛（自由長部Ｌ２）×２８８０｝／（７０×１５０００）
（自由長部Ｌ２）＝１０，９３７ｍｍ
が算出される。つまり、この炭素繊維を素材とした部分アンボンドより線の場合においては、自由長部Ｌ２を約１０．９ｍとすることによって、３０ｍｍの凍上、および復元に追従した構造物１４の移動を得ることが可能となる。
【００７４】
さらに、ヤング率が約５，４００であるアラミド繊維を素材とした、直径７．４ｍｍ、断面積４２，４ｍｍ^２の部分アンボンドロッドの場合においては、
３０＝｛（自由長部Ｌ２）×２８８０｝／（４２．４×５４００）
（自由長部Ｌ２）＝２，３８５ｍｍ
が算出される。つまり、このアラミド繊維を素材とした部分アンボンドロッドの場合においては、自由長部Ｌ２を約２．４ｍとすることによって、３０ｍｍの凍上、および復元に追従した構造物１４の移動を得ることが可能となる。
【００７５】
このように、凍上受圧と凍上量と、弾性引張材１８の断面積、およびその素材のヤング率とに基づいて、弾性引張材の自由長部Ｌ２の長さを算出し、その地山１２において可能な支持体挿入孔２２の深度と要求される自由長部Ｌ２の長さとを考慮して、弾性引張材に要求される伸び量を確保可能な素材を選定すれば、同じ構造であっても種々の態様に適応可能な棒状支持体１０が提供できるため、棒状支持体としての汎用性が一層向上される。
【００７６】
なお、ここでは、現時点での主力素材であるＰＣ鋼材、炭素繊維、およびアラミド繊維を、弾性引張材１８の素材として具体的にあげてその算出例を示しているが、これに限定されず、これ以外の素材から弾性引張材を形成してもよいことはいうまでもない。
【００７７】
ところで、この発明の実施の形態においては、支持体挿入孔２２の掘削手法として、単管削孔を具体化している。しかし、この単管削孔は、自立する地層の地山１２において有効な手法であるため、自立しない地層の地山ヘの適用は多少の困難を伴うことが否定できない。
【００７８】
自立しない地層の地山に有効なものとして、たとえば、ロックボルトの先端にビットを固定することでこのロックボルト自体をドリルパイプとして兼用する、いわゆる自穿孔ロックボルトが例示できる。この自穿孔ロックボルトであれば、支持体挿入孔の掘削とロックボルトの挿入とが同時に行われるため、自立しない地層の地山であっても、その地山に対するロックボルト、つまりは中空棒状鋼材の挿入が容易に可能となる。
【００７９】
しかしながら、この種の自穿孔ロックボルトは、そのまま地山に残される、いわゆるロストビットを先端に有したものであり、また、ドリルパイプを兼ねるこのロックボルト自体に、削孔に耐え得るに十分な剛性が要求されるため、コスト面での有効性に劣ることも起り得る。
【００８０】
そこで、自立しない地層の地山に有効な他の手法として、たとえば、１回目削孔として単管削孔による下孔形成を行い、その後、２回目削孔として中空棒状鋼材１６自体をドリルパイプとした削孔、およびその挿入を同時に行う、いわゆる２段階削孔による手法が例示できる。
【００８１】
この２段階削孔においては、単管削孔による１回目削孔後、この単管削孔に使用したロッドを一旦抜くため、自立しない地層の地山では、掘削した孔周壁の崩れが多分に起り得る。しかし、この発明の実施の形態で示す２段階削孔においては、単管削孔により形成した下孔に沿って、中空棒状鋼材１６を打設し挿入すれば足りるため、ビット等を先端に設けることなく、またドリルパイプとしての剛性を有することなく、中空棒状鋼材を地山に対して打設、挿入することが可能となる。
【００８２】
つまり、このような２段階削孔によれば、自穿孔ロックボルトのような高価な部材、および手法を用いることなく、自立しない地層の地山１２に対する中空棒状鋼材１６の打設、挿入、つまりは棒状支持体１０の設置、施工が行えるため、自立しない地層の地山に対する施工であっても、その作業コストの上昇は十分に抑制できる。
【００８３】
そして、単管削孔によって形成された下孔に中空棒状鋼材１６を打設すれば足りるため、この中空棒状鋼材に対する剛性はさほど高く要求されない。従って、この点においても、作業コストの上昇が十分に抑制でき、また、中空棒状鋼材１６の打設も容易となることから、その作業性の向上も十分にはかられる。
【００８４】
なお、この実施の形態においては、棒状支持体１０を、ロックボルト等の従来の棒状鋼材に代わるものとして具体化している。しかし、弾性引張材１８を所定の引張荷重のもとで緊張し保持する点においては、ＰＣ鋼より線等を引張材とする従来の一般的なアンカーと共通することから、グラウンドアンカー等におけるアンカー体に代わるものとして、この発明の棒状支持体１０を用いてもよい。
【００８５】
上述した実施の形態は、この発明を説明するためのものであり、この発明を何等限定するものでなく、この発明の技術範囲内で変形、改造等の施されたものも全てこの発明に包含されることはいうまでもない。
【００８６】
【発明の効果】
上記のように、この発明によれば、地表面変動を生じた際、地表面上の構造物が、弾性引張材の自由長部での伸縮、およびその押し戻し力のもとで、中空棒状鋼材を伴うことなく地表面変動に追従して移動される。
【００８７】
特に、地山の凍上時に、中空棒状鋼材の浮き上がりを伴うことなく構造物を凍上方向に移動させれば、この移動による荷重の吸収により、中空棒状鋼材に対する過度の引張荷重の付与、伝達が確実に防止されるため、中空棒状鋼材の浮き上がり、および中空棒状鋼材の破断や構造物の損壊等が防止される。そして、地山の融解時、弾性引張材からの押し戻し力のもとで構造物を押し戻せば、地山の体積減少に追従した構造物の移動が容易に確保できるため、融解後における、地表面からの構造物の浮き上がりに起因する地表面、構造物間の隙間の形成が十分に防止されることから、錆の発生等に起因する棒状支持体の健全度の低下が、これによれば確実に防止可能となる。
【００８８】
従って、この発明によれば、地表面変動による保護機能の低下、および棒状支持体の健全度の低下等が確実に防止される。
【００８９】
そして、弾性引張材の自由長部、あるいは中空棒状鋼材の非付着長部にアンボンド加工を施せば、各部の長さの明確化が容易に可能となり、その機能性が容易に確保できる。さらに、内部グラウト、および外部グラウトの充填作業が簡単化でき、また、ほぼ全長に亘るグラウトのもとで弾性引張材、および中空棒状鋼材の安定性が容易に確保できるため、その機能性の一層の向上も容易にはかられる。
【００９０】
また、その地山において可能な支持体挿入孔の深度と要求される自由長部の長さとを考慮して、弾性引張材に要求される伸び量を確保可能な素材を選定すれば、同じ構造であっても種々の態様に適応可能な棒状支持体が提供できるため、棒状支持体としての汎用性が一層向上される。
【００９１】
さらに、自立する地層の地山においては、単管削孔のみにより支持体挿入孔を掘削形成し、また、自立しない地層の地山においては、単管削孔のもとでの下孔削孔、およびこの下孔に沿った中空棒状鋼材の打設による２段階削孔を行えば足りるため、いずれの地層の地山に対してもこの棒状支持体の施工が容易に可能となる。
【００９２】
そして、下孔を形成する２段階削孔であれば、自立しない地層の地山に対する支持体挿入孔の掘削が、自穿孔ロックボルトのような高価な部材を用いることなく行えるため、作業コストの上昇が十分に抑制できる。さらに、２回目削孔に用いる中空棒状鋼材にさほど高い剛性は要求されないため、この点においても、作業コストの上昇が十分に抑制でき、また、中空棒状鋼材の打設も容易となることから、その作業性の向上も十分にはかられる。
【図面の簡単な説明】
【図１】この発明に係る棒状支持体の概略縦断面図である。
【図２】この発明に係る棒状支持体の施工方法における、概略の工程図である。
【図３】この発明に係る棒状支持体の施工方法における、概略の工程図である。
【図４】この発明に係る棒状支持体の施工方法における、概略の工程図である。
【図５】この発明に係る棒状支持体の施工方法における、概略の工程図である。
【図６】この発明に係る棒状支持体の施工方法における、概略の工程図である。
【図７】構造物の一例を示す、その概略斜視図である。
【符号の説明】
１０　棒状支持体
１２　地山
１４　構造物
１６　中空棒状鋼材（中空ロックボルト）
１８　弾性引張材
２０　内部グラウト
２２　支持体挿入孔
２８　被覆部材
３０　外部グラウト[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a construction method for installing a bar-shaped support at the ground in a landslide countermeasure, and more particularly, to a construction method of a bar-shaped support suitable for construction in a cold region or the like, and to the rod-shaped support.
[0002]
[Prior art]
A method of constructing a structure such as a lawn on the ground surface and installing it on the ground, for example, a method of fixedly holding this structure with a rod-shaped support such as a lock bolt protects and reinforces the ground, a so-called landslide. Known as a countermeasure.
[0003]
In such a landslide countermeasure using a lock bolt (bar-shaped support), the lock bolt is usually attached to the ground at the intersection of a cross, for example, at the intersection of the full length and the like. Installed and established.
[0004]
[Problems to be solved by the invention]
By the way, the ground surface of the ground which directly receives natural phenomena such as rainfall and sunshine constantly repeats minute movements due to these natural phenomena, for example, ground surface fluctuations such as expansion and contraction. Among the natural phenomena, the movement of the ground surface is particularly remarkable.It is so-called frost heaving, which raises the ground surface by freezing the ground. It has been confirmed that rock bolts and structures which are considered to be the cause are lifted up, or the lock bolts are broken or the structures are damaged.
[0005]
If the fixing strength of the rock bolt to the ground does not satisfy the force generated by the frost heave of the ground, that is, the frost heave pressure, the rock bolt and the structure are lifted due to the frost heave of the ground as in the former. Then, the ground returns to its original volume due to the thawing of the frost heaving portion, but once the rock bolts have floated, they remain in the floating state without returning to their original positions even after the ground has been thawed. In the structure supported by the above, the force to return to the original position is not sufficiently obtained.
[0006]
Since the lifting of the structure from the ground surface due to the lifting of the lock bolts causes a gap between the ground surface and the structure, the protection function for the ground surface is reduced, In addition, there is a possibility that damage or damage to the structure or collapse of the ground surface may be caused.
[0007]
The lock bolt is easily rusted at the exposed portion in the gap, and corrosion or the like due to the rust easily occurs in the lock bolt. Therefore, a decrease in the soundness of the lock bolt is inevitable.
[0008]
In addition, if the fixing strength of the rock bolt to the ground is higher than the frost heave pressure of the ground, floating of the lock bolt due to frost heaving can be sufficiently prevented. However, since the frost heave pressure in this case is directly applied to the rock bolt or the structure without being absorbed by others, when the fixing strength of the rock bolt to the ground is set to be higher than the frost heave pressure of the ground, Although the lifting of the lock bolt can be prevented, the breakage of the lock bolt and the damage of the structure as in the latter cannot be avoided.
[0009]
In other words, in any case, in the known landslide countermeasures using the lock bolt as the rod-shaped support, at present, measures against this frost heave are not sufficiently taken.
[0010]
Here, as a countermeasure against such frost heave, for example, a configuration in which an elastic member (a coil spring or the like) is combined with a lock bolt to absorb the frost heave of the ground by elastic deformation of the elastic member is disclosed in JP-A-2000-87350. No. 5,009,045.
[0011]
Certainly, in this configuration, since a predetermined range of movement stroke can be secured in the structure, the application and transmission of an excessive tensile load to the structure and the lock bolt by absorbing the increased load due to frost heaving is sufficient. It can be prevented.
[0012]
By the way, it is estimated that a pushing back force of about several tons is required in order to push the structure raised from the ground surface back to the original position, in consideration of its own weight and deformation. However, the urging force of the coil spring is generally about 300 to 500 kg, and it is economically and structurally difficult to obtain the urging force exceeding 1 t by the coil spring. With the known configuration in combination with the lock bolt, it is not possible to expect the raised structure to be pushed back.
[0013]
In other words, even if the increase in the tensile load can be absorbed under the elastic deformation of the coil spring, the structure that has moved in the floating direction cannot be sufficiently pushed back. A decrease in the protection function due to insufficient return after melting and a decrease in the soundness of the lock bolt are inevitable.
[0014]
An object of the present invention is to provide a method of constructing a rod-shaped support capable of preventing a reduction in a protection function due to a change in ground surface and a decrease in soundness of the rod-shaped support, and to provide the rod-shaped support.
[0015]
[Means for Solving the Problems]
In order to achieve this object, according to the method for constructing a rod-shaped support of the present invention according to claim 1, a frost heave area in the ground is assumed in advance as a range from the ground surface to a predetermined depth. A support insertion hole at a depth exceeding the area is continuously formed from the structure on the ground surface. Then, the hollow rod-shaped steel material serving as the hollow pipe-shaped member is inserted and arranged over substantially the entire length of the support insertion hole while maintaining the non-integral form with the structure, and grouting is performed inside and outside the hollow rod-shaped steel material. .
[0016]
Furthermore, an elastic tensile member made of a material having a tensile strength capable of withstanding the ground fixing is inserted into the hollow portion of the hollow rod-shaped steel material, and the fixed length portion of the elastic tensile member defined at the distal end is inserted into the internal grout. By integrating with the hollow rod-shaped steel material by at least the hollow rod-shaped steel material, a rod-shaped support body having elasticity of the elastic tensile material at its free length is secured, and the hollow rod-shaped material is not aligned with the frost heave area. The fixed length portion defined on the front end side of the steel material is integrally fixed to the ground by its outer grout, and this is set as a rod-shaped support for the ground. Thereafter, the elastic tension member is tensioned under a predetermined tensile load, and the head of the elastic tension member extended through the pressure plate on the surface of the structure is engaged and held by the fixing device with the pressure plate. Thereby, the structure is fixedly held on the ground surface.
[0017]
According to a second aspect of the present invention, the free length portion of the elastic tensile member is subjected to an unbonding process for suppressing the adhesion of grout, and the exposed portion provided on the tip side of the elastic tensile member is at least a hollow rod-shaped steel material. It is defined as a fixing length part of an elastic tensile material to be integrated with the fixing member.
[0018]
Further, in the third aspect of the present invention, the elastic tensile member is a partially unbonded stranded wire in which a stranded wire is partially covered with a covering tube, and the partial unbonded stranded wire provided on the distal end side of the elastic tensile member. The exposed portion of the stranded wire is defined as a fixing length portion of an elastic tensile material to be integrated with at least the hollow rod-shaped steel material.
[0019]
According to a fourth aspect of the present invention, the material of the elastic tensile material is embodied as any of deformed steel bars, PC steel, carbon fiber and aramid fiber. The frost heave pressure on the structure side received by the frost heave is calculated based on the contact area of the structure with the ground surface, and the frost heave amount of the ground is measured or estimated in advance. Based on the cross-sectional area of the tensile member and the Young's modulus of the material, calculate the length of the free length portion of the elastic tensile member, and determine the depth of the support insertion hole possible in the ground and the required free length. In consideration of the length of the part, a material capable of securing the required amount of elongation of the elastic tensile material is selected, and this material is combined with the hollow bar-shaped steel material.
[0020]
According to a sixth aspect of the present invention, in the ground of the self-supporting stratum, a support insertion hole is excavated and formed only by a single pipe drilling, and a hollow rod-shaped steel material is inserted into the formed support insertion hole. In the case of a non-self-supporting stratum, a pilot hole is formed by single pipe drilling as the first drilling, and then the second drilling is performed using a hollow rod-shaped steel material itself as a drill pipe. Therefore, the insertion is performed at the same time.
[0021]
According to a seventh aspect of the present invention, at least the outer peripheral surface of a portion aligned with the frost heap region of the ground and the structure in the entire length of the hollow rod-shaped steel material is provided with a non-adhesion length portion with respect to a fixed length portion on the tip end side. The unbonded long portion is subjected to an unbonding process for suppressing the adhesion of other peripheral members in advance.
[0022]
Further, according to the rod-shaped support of the present invention according to claim 8, an elastic tensile member made of a material having a tensile strength capable of withstanding ground fixing is inserted into the hollow rod-shaped steel material, and a distal end side of the elastic tensile member is inserted. Inner / outer duplex that secures elasticity at the free length of the elastic tensile material by integrating the anchoring length specified in the above into the hollow steel bar under the internal grout for the hollow of the hollow steel bar It has a structure. And, as a non-aligned portion with the frost heaving area assumed in the ground, a fixed length portion defined on the tip side of this hollow rod-shaped steel material is integrally fixed to the ground by an external grout with respect to the outer periphery thereof, The rod-shaped support is configured such that the head of the elastic tensile member that is tensioned under a predetermined tensile load is engaged and held by a fixing device on a support plate on the surface of the structure.
[0023]
According to a ninth aspect of the present invention, the free length portion of the elastic tensile material is subjected to an unbonding process for suppressing the adhesion of grout, and the exposed portion provided on the tip side of the elastic tensile material has at least an exposed portion. It is defined as the anchoring length of the elastic tensile material integrated with the hollow bar-shaped steel material.
[0024]
Furthermore, in the tenth aspect of the present invention, the elastic tensile member is formed as a partially unbonded stranded wire in which the stranded wire is partially covered with the covering tube, and the elastic untensible member is provided on the distal end side of the elastic tensile member. The exposed portion of the stranded wire of the wire is defined as a fixing length portion of the elastic tensile material integrated with at least the hollow rod-shaped steel material.
[0025]
In the eleventh aspect of the present invention, the material of the elastic tensile material is embodied as any one of a deformed steel bar, a PC steel material, a carbon fiber, and an aramid fiber.
[0026]
Furthermore, in claim 12 of the present invention, at least the outer peripheral surface of a portion aligned with the frost heap region of the ground and the structure in the entire length of the hollow rod-shaped steel material is subjected to unbond processing for suppressing adhesion of other peripheral members, It is defined as a non-adhesion length portion with respect to the fixed length portion on the tip side.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0028]
As shown in FIG. 1, a rod-shaped support 10 constructed in the method for constructing a rod-shaped support according to the present invention is widely used mainly in a landslide countermeasure work of a ground to protect and reinforce the ground 12. Under the installation and fixation on the ground, a predetermined structure 14 constructed along the ground surface 12a of the ground is fixedly held on the ground surface.
[0029]
In addition, a structure such as a sill or a retaining wall is constructed on the ground surface (also referred to as a slope) of the ground, and the structure is installed and fixed on the ground, and is fixed by a rod-shaped support such as a rock bolt. Is not publicly known, and since the basic structure itself of a structure such as a legal frame constructed on the ground surface is not the purpose of the present invention, any detailed description thereof will be omitted here. Shall be.
[0030]
As can be seen from FIG. 1, a rod-shaped support 10 according to the present invention uses a hollow rod-shaped steel material as a hollow pipe-shaped member, for example, a hollow lock bolt 16 having a threaded portion on its outer peripheral surface as a main component. The hollow lock bolt is embodied as a so-called inner / outer double structure in which an elastic tensile member 18 made of a material having a tensile strength capable of withstanding the ground is inserted as a secondary material in the hollow portion 16a of the hollow lock bolt. .
[0031]
The elastic tension member 18 inserted into the hollow lock bolt (hollow rod-shaped steel material) 16 includes, for example, a fixing length portion L1 integrated with the hollow lock bolt under an internal grout 20 described later, And a free-length portion L2 for ensuring elasticity with respect to are defined in advance. That is, the rod-shaped support body 10 having the inner / outer double structure in which the elastic tension member 18 is inserted into the hollow lock bolt 16 partially fixes the fixing length L1 located at the tip end side of the elastic tension member to the hollow lock bolt. It is formed as a so-called partially integrated one.
[0032]
As the elastic tensile member 18, a stranded wire or a rod made of various elastic materials can be used. Examples of the material that can be the elastic tensile member include deformed steel bars, PC steel, carbon fiber, and aramid fiber. .
[0033]
In addition, when the PC steel material or the carbon fiber is the material, the stranded wire form is generally used, and when the deformed steel bar and the aramid fiber are the material, the rod form is generally used. Has become.
[0034]
In the embodiment of the present invention, a stranded wire (PC steel stranded wire) 18a made of PC steel is partially covered with a coating tube (unbonded tube) 18b, and a lubricating material such as grease is put in the coating tube. A so-called partially unbonded PC steel stranded wire formed by filling is specifically shown as the elastic tensile member 18. In the elastic tensile member 18 formed of a partially unbonded PC steel strand, the exposed portion of the stranded wire 18a provided on the distal end side is fixed to the fixed length portion of the elastic tensile member integrated with the hollow lock bolt 16. L1 and a portion covered by the coating tube 18b are defined as a free length portion L2 which expands and contracts with respect to the hollow lock bolt.
[0035]
Such a rod-shaped support 10 is installed and fixed to the ground with the insertion arrangement into the support insertion hole 22 having a predetermined depth formed continuously with the structure 14 and the ground 12. .
[0036]
As a method of excavating the support insertion hole 22 with respect to the structure 14 and the ground 12, a single pipe drilling using a drilling machine, for example, an inverter chisel can be exemplified.
[0037]
For example, as shown in FIG. 2, a rod 26 having a bit 24 at the tip is set on a driving unit 30 of a drilling machine (inverter chisel) 28, and a hitting force and a rotation are applied to the bit at the tip via this rod. By propelling this while applying force, a support insertion hole 22 having a corresponding diameter is formed in the ground 12.
[0038]
In addition, the excavation process of such a support insertion hole is no different from that performed in the conventional anchoring method and the like, and since the conventional drilling machine itself can be used, the Detailed description is omitted.
[0039]
Here, as shown in FIG. 1 and FIG. 2, in the present invention, first, an area that is likely to expand in volume due to freezing of the ground 12, that is, a frost heave area L <b> 3 is moved from the ground surface 12 a to a predetermined depth. Is assumed in advance. Then, as shown in FIG. 3, the support insertion hole 22 having a total length L4 having a depth exceeding the frost heave region L3 of the ground 12 is formed by a drilling machine 28 described above, for example, under a single pipe drilling. Excavate with
[0040]
In addition, as the frost heave area L3, an area having a depth of about 50 cm is generally assumed.
[0041]
The diameter of the support insertion hole 22 is substantially determined by the effective outer diameter of the bit 24 provided at the tip of the rod of the single pipe drilling machine. With the support insertion hole 22 thus formed, for example, the hollow lock bolt 16 having an outer diameter of about 42.7 mm or an outer diameter of about 48.6 mm can be inserted.
[0042]
After excavating the support insertion hole 22 having a predetermined length (total length L4) as shown in FIG. 3, the rod 26 is pulled out of the support insertion hole, and as shown in FIG. A hollow lock bolt 16 having a length L4 'substantially equivalent to the total length L4 of the above is inserted and arranged in the support insertion hole while maintaining a non-integral form with the structure 14.
[0043]
Here, in the hollow lock bolt 16, a fixed length portion L5 on the front end side and a non-adhered length portion L6 on the rear end side are continuously defined. As can be seen from FIG. 1, the fixed length portion L5 of the hollow lock bolt 16 is defined as a non-aligned portion with the frost heap region L3 of the ground 12, and, for example, the other non-adhered length portion L6 has These are clearly separated by performing an unbonding process for suppressing the attachment of the members (see FIG. 4).
[0044]
As can be seen from FIGS. 1 and 4, as the unbonding process for the non-adhered length L6 of the hollow lock bolt 16, coating around the non-adhered length with the coating member 28 can be embodied. The covering member 28 can be exemplified by a thin-walled tube, a film tape, or the like, and a rust preventive is applied between the covering member and the peripheral surface of the hollow lock bolt 16.
[0045]
As shown in FIG. 5, after the hollow lock bolt 16 is inserted and arranged in the support insertion hole 22, for example, the internal grout 20 and the external grout for the hollow lock bolt are inserted through the hollow portion 16a of the hollow lock bolt. 30 are applied respectively (see FIG. 1).
[0046]
The grout material which becomes the inner grout 20 and the outer grout 30 is inserted into the hollow portion 16a of the hollow lock bolt via a grout hose 32 from a grout pump (not shown) connected to the end of the hollow lock bolt 16. The inner grout and the outer grout are continuously injected by being pumped and poured, and the grout material flowing out from the tip of the hollow lock bolt to the outside.
[0047]
In addition, as a grout material of the internal grout 20 and the external grout 30, for example, cement milk or the like can be exemplified.
[0048]
As shown in FIG. 6, after the internal grout 20 and the external grout 30 are completed, specifically, after the grout material is injected and before the grout material is consolidated, the fixing length portion L1 and the free length portion are formed. An elastic tensile material (partially unbonded PC steel strand) 18 defined by L2 is inserted into the hollow portion 16a of the hollow lock bolt at least over the entire length thereof, and thereafter, a grout material is formed into an internal grout and an external grout. Wait for consolidation.
[0049]
When the internal grout 20 is consolidated, the fixing length portion L1 of the elastic tension member 18 is integrated with the hollow lock bolt 16, and when the external grout 30 is consolidated, the fixed length portion L5 of the hollow lock bolt is grounded. 12 are integrally fixed.
[0050]
Even if the internal grout 20 reaches around the free length portion L2 of the elastic tension member 18 and solidifies, the free length portion L2 of the elastic tension member is isolated by the covering tube 18b, so that the inner grout 20 is hardened. The expansion and contraction of the wire 18a is ensured smoothly. Similarly, even if the outer grout 30 reaches around the non-adhered length L6 of the hollow lock bolt 16, the non-adhered length L6 is unbonded by the covering member 28, so Attachment of other peripheral members to the hollow lock bolt of the long portion L6, for example, attachment of the external grout 30 can be reliably prevented.
[0051]
By the way, as shown in FIG. 6, a grip 34 having a threaded peripheral surface, for example, is integrally fixed to the end of the elastic tensile member 18 as a head fixing body. Then, as shown in FIG. 1, the grip 34 extends to the outside of the support insertion hole 22 through a support plate 36 disposed on the surface of the structure 14 and is exposed, and serves as a holder for the grip. The elastic tension member 18 is tensioned under a predetermined tensile load by the screwing of the nut 38 and the screwing thereof, and the rod-shaped support 10 is engaged with the supporting plate so that the rod-shaped support 10 The structure is fixedly held on the ground surface 12a under the tensile load applied to the elastic tensile member.
[0052]
In the rod-shaped support 10 thus constructed, the fixed length L5 of the hollow lock bolt 16 is integrally fixed to the ground 12 by the outer grout 30, and the fixed length L1 of the elastic tensile material 18 is fixed to the inside. Since it is integrated with the hollow lock bolt by the grout 20, the fixing length portion L1 of the elastic tensile material is integrally fixed to the ground.
[0053]
That is, in the state shown in FIG. 1, when frost heave occurs on the ground 12, the frost heave pressure acts on the elastic tensile member 18 from the ground surface 12a via the structure 14, the pressure receiving plate 36, and the nut 38, and In the tensile member, the free length portion L2 of the hollow lock bolt 16 which is secured in elasticity is extended following the frost heave of the ground due to the frost heave pressure.
[0054]
Since the fixed length portion L5 of the hollow lock bolt 16 is integrally fixed to the ground 12 at a position not aligned with the frost heaving region L3, even if frost heaving occurs in the ground, the frost heaving occurs. It is not affected and remains in its original position without floating following the frost heave. The hollow lock bolt 16 fixed to the ground 12 is a rigid body having a sufficient function as a landslide suppressing member, so that the function as the rod-shaped support 10 is not impaired.
[0055]
Further, if the frost heap area L3 of the ground 12 melts and the volume of the ground returns to its original state, the structure 14 is moved to the ground surface 12a under the restoring force generated in the free length L2 of the elastic tensile member 18. Following the restoration, it is returned to the original position.
[0056]
According to the restoring force generated in the free length portion L2 of the elastic tensile member 18, a restoring force of several tons or more, that is, a pushing back force against the structure 14 can be easily secured. That is, the push-back force estimated as several tons can be sufficiently ensured by the elastic tensile member 18.
[0057]
As described above, according to the rod-shaped support body 10 according to the construction method of the present invention, when the ground pile 12 freezes, the structure 14 on the ground surface 12a is moved by the free length L2 of the elastic tensile member 18. Under elongation, it is moved to follow the fluctuation of the ground surface without involving the hollow lock bolt 16. Then, after the ground 12 is melted, the structure 14 on the ground surface is pushed back to its original position following the volume reduction of the ground under the push-back force generated in the free length portion L2 of the elastic tensile member 18. Therefore, according to the rod-shaped support 10, both the movement of the structure 14 without the hollow lock bolt 16 during frost heaving and the pushback thereof during thawing can be smoothly ensured.
[0058]
As described above, when the structure 14 is moved in the frost heaving direction without the floating of the hollow lock bolts 16 during the frost heaving of the ground 12, the load due to this movement is absorbed, and an excessive tensile load is applied to the hollow lock bolts. Since the application and transmission are reliably prevented, the lifting of the hollow lock bolt, the breakage of the hollow lock bolt, the damage of the structure, and the like are prevented. Then, when the ground 12 is melted, if the structure 14 is pushed back under the push-back force from the elastic tensile member 18, the movement of the structure following the volume reduction of the ground can be easily secured. In the above, the lifting of the structure from the ground surface 12a, that is, the formation of a gap between the ground surface and the structure is sufficiently prevented, so that the deterioration of the soundness of the rod-shaped support body 10 due to the generation of rust, According to this, it is possible to reliably prevent this.
[0059]
Therefore, according to the present invention, a decrease in the protection function due to a change in the ground surface such as frost heave and a decrease in the soundness of the rod-shaped support 10 are reliably prevented.
[0060]
In the embodiment of the present invention, the so-called frost heave is embodied as the ground surface fluctuation in the ground 12. However, even the minute ground surface fluctuation such as expansion and contraction due to rainfall, sunshine, etc. It goes without saying that the invention is effective.
[0061]
Here, in the embodiment of the present invention, the free length portion L2 of the elastic tension member 18 and the non-adhesion length portion L6 of the hollow lock bolt 16 are subjected to unbonding processing, so that the elastic tension member in the free length portion L2 is formed. Although the elasticity and the attachment of other peripheral members to the non-adhesion length portion L6 are regulated, the free length portion L2 of the elastic tensile material is stretchable, and the hollow lock bolt is surely secured from the freezing area of the ground 12. For example, the inner grout 20 and the outer grout 30 are respectively applied only to the fixing length portion L1 of the elastic tensile material and the fixing length portion L5 of the hollow lock bolt without performing the unbonding process. It may be configured.
[0062]
However, if the free length L2 of the elastic tension member 18 and the non-adhesion length L6 of the hollow lock bolt 16 are unbonded as in this embodiment, the length of each portion can be easily clarified. And its functionality can be easily secured. Then, the filling work of the inner grout 20 and the outer grout 30 can be simplified, and the stability of the elastic tension member 18 and the hollow lock bolt 16 can be easily secured under the grout over almost the entire length. Further improvement in functionality can be easily achieved.
[0063]
Further, in the embodiment of the present invention, the hollow lock bolt 16 is embodied as a hollow rod-shaped steel material. However, a hollow pipe-shaped member in which the elastic tension member 18 can be inserted is sufficient. However, the present invention is not limited to this. For example, a steel pipe such as a gas pipe may be used as the hollow rod-shaped steel material here.
[0064]
However, if the hollow lock bolt 16 having the outer peripheral surface threaded portion is used as the hollow rod-shaped steel material, the adhesive force of the external grout 30 to the outer peripheral surface is surely strengthened, so that the hollow rod-shaped steel material is fixed to the ground 12. Is further improved.
[0065]
In this embodiment, the hollow lock bolt 16 is illustrated as a single piece without any connection, however, the hollow lock bolt 16 depends on the total length required, that is, the total length of the support insertion hole 22. The required number of bolts may be connected.
[0066]
Further, in this embodiment, a grip 34 having a threaded peripheral surface is provided at the end of the elastic tension member 18 as a head fixing body, and the tension is applied by screwing a nut 38 to the grip. Although the structure of the head fixing portion of the elastic tensile material is not limited to this, for example, if the elastic tensile material is a stranded wire such as an unbonded PC steel stranded wire, a wedge and an anchor A structure in which a combination of heads or the like is held and engaged with the support plate 36 as a holding tool can also be adopted.
[0067]
However, if the nut 38 is screwed onto the grip 34 of the elastic tension member 18 as in this embodiment, the tension of the elastic tension member can also be obtained by the screw advancement of the nut. The holding operation is reliably simplified.
[0068]
Here, in the embodiment of the present invention, a partially unbonded PC stranded wire made of PC steel is embodied as the elastic tensile member 18, but this elastic tensile member has a tensile strength capable of withstanding the ground fixing. The material is not limited to this as long as the wire is made of a material having deformed steel bars, carbon fibers, and aramid fibers. You may use as.
[0069]
By the way, among the materials specifically mentioned here as the material of the elastic tensile material 18, for example, PC steel, carbon fiber, and aramid fiber are materials having different Young's modulus and the like, and are different in properties. The characteristics obtained as 10 also differ greatly depending on the materials to be combined.
[0070]
For example, the length of the free length portion L2 of the elastic tensile member 18 is determined based on a calculation result based on, for example, the ground contact area of the structure 14, the frost heave pressure generated on the ground 12, and the like.
[0071]
For example, assuming that a normal frame having a shape and a size as shown in FIG. 7 is a structure 14 that is supported by one rod-shaped support body 10, the ground contact area of this structure with respect to the ground surface 12a is, for example,
40 × 200 + 40 × 80 × 2 = 8000 + 6400 = 14,400cm²
And the frost heave pressure generated at the ground 12 is 0.2 kg / cm.²Assuming that, the frost heave pressure received from the ground surface received by this structure is
0.2 x 14400 = 2,880 kg
Is calculated as
[0072]
The amount of frost heap in the frost heap region L3 of the ground 12, that is, the amount of movement of the ground surface 12 a during frost heave is assumed to be, for example, 30 mm, and the force for returning the structure 14 after thawing is the same as the pressure for frost heave during frost heave. In consideration of this, it is sufficient to select the length of the free length portion L2 such that the amount of elongation becomes 30 mm when a load of 2,880 kg is applied. For example, the diameter is 12.7 mm, and the cross-sectional area is 98.71 mm.²When a partially unbonded PC steel strand is used as the elastic tensile member 18, the Young's modulus of the PC steel is about 20,000.
(Elongation) = {(Free length L2) × (Load)} / {(Cross-sectional area) × (Young's modulus)}
By applying to the formula of
30 = {(free length L2) × 2880} / (98.71 × 20,000)
(Free length L2) = 20,564 mm
Is calculated. In other words, in the case of using this kind of partially unbonded PC steel strand as the elastic tensile member 18, by setting the free length L2 to about 20.5 m, the elongation of the free length L2 following the frost heave of 30 mm is achieved. , And a pushback of the structure 14 following the restoration of 30 mm.
[0073]
Further, a carbon fiber having a Young's modulus of about 15,000 was used as a material, and had a diameter of 12.5 mm and a cross-sectional area of 70 mm.²In the case of partial unbonded strand,
30 = {(free length L2) × 2880} / (70 × 15000)
(Free length L2) = 10,937 mm
Is calculated. In other words, in the case of a partially unbonded stranded wire made of carbon fiber, by setting the free length L2 to about 10.9 m, it is possible to obtain the frost heave of 30 mm and the movement of the structure 14 following the restoration. It becomes possible.
[0074]
Furthermore, aramid fiber having a Young's modulus of about 5,400 was used as the material, and had a diameter of 7.4 mm and a cross-sectional area of 42.4 mm.²In the case of the partial unbonded rod,
30 = {(free length L2) × 2880} / (42.4 × 5400)
(Free length L2) = 2,385 mm
Is calculated. In other words, in the case of a partially unbonded rod made of this aramid fiber, by setting the free length L2 to be about 2.4 m, it is possible to obtain a 30 mm frost heave and the movement of the structure 14 following the restoration. It becomes.
[0075]
As described above, the length of the free length portion L2 of the elastic tensile member is calculated based on the frost heave receiving pressure and the frost heave amount, the cross-sectional area of the elastic tensile member 18, and the Young's modulus of the material. Considering the possible depth of the support insertion hole 22 and the required length of the free length portion L2, if a material capable of securing the required amount of elongation of the elastic tensile member is selected, the same structure can be obtained. Since the rod-shaped support 10 adaptable to various aspects can be provided, the versatility as the rod-shaped support is further improved.
[0076]
In addition, here, PC steel, carbon fiber, and aramid fiber, which are the main materials at the present time, are specifically given as examples of the material of the elastic tensile material 18, and a calculation example thereof is shown, but the present invention is not limited to this. It goes without saying that the elastic tensile material may be formed from other materials.
[0077]
Incidentally, in the embodiment of the present invention, a single pipe drilling is embodied as a method of excavating the support insertion hole 22. However, since this single-pipe drilling is an effective technique in the ground 12 of a self-supporting stratum, it cannot be denied that the application to the ground of a non-self-supporting stratum involves some difficulty.
[0078]
A so-called self-drilling lock bolt, in which a bit is fixed to the tip of a lock bolt and the lock bolt itself is also used as a drill pipe, can be exemplified as an example that is effective for the ground of a non-self-supporting stratum. In the case of this self-drilling rock bolt, the excavation of the support insertion hole and the insertion of the lock bolt are performed at the same time. Therefore, even if the ground is not self-supporting, the rock bolt for the ground, that is, the hollow rod-shaped steel material Can be easily inserted.
[0079]
However, this type of self-drilling lock bolt has a so-called lost bit at its tip, which is left in the ground as it is, and the lock bolt itself, which also serves as a drill pipe, has sufficient strength to withstand drilling. Since rigidity is required, it may be inferior in cost effectiveness.
[0080]
Therefore, as another method effective for the formation of a non-self-supporting stratum, for example, a pilot hole is formed by single pipe drilling as the first drilling, and then the hollow rod-shaped steel material 16 itself is used as a drill pipe as the second drilling. A method using a so-called two-stage drilling in which a drilled hole and its insertion are simultaneously performed can be exemplified.
[0081]
In this two-stage drilling, after the first drilling by single pipe drilling, the rod used for this single pipe drilling is once pulled out. It can happen. However, in the two-stage drilling shown in the embodiment of the present invention, it is sufficient to drive and insert the hollow rod-shaped steel material 16 along the prepared hole formed by the single tube drilling, so that a bit or the like is provided at the tip. Without this, and without having the rigidity of a drill pipe, a hollow rod-shaped steel material can be driven and inserted into the ground.
[0082]
That is, according to such a two-stage drilling, the hollow bar-shaped steel material 16 is placed and inserted into the ground 12 of the non-self-supporting stratum without using an expensive member such as a self-drilling rock bolt and a method, that is, Since the rod-shaped support 10 can be installed and constructed, the rise of the operation cost can be sufficiently suppressed even when the construction is performed on the ground of a non-self-supporting stratum.
[0083]
Then, since it is sufficient to drive the hollow bar-shaped steel material 16 into the prepared hole formed by the single tube drilling, the rigidity of the hollow bar-shaped steel material is not required to be very high. Accordingly, also in this respect, an increase in working cost can be sufficiently suppressed, and the casting of the hollow bar-shaped steel material 16 becomes easy, so that the workability can be sufficiently improved.
[0084]
In this embodiment, the bar-shaped support 10 is embodied as a substitute for a conventional bar-shaped steel material such as a lock bolt. However, in that the elastic tensile member 18 is tensioned and held under a predetermined tensile load, it is common to a conventional general anchor using a PC steel stranded wire or the like as a tensile member. As an alternative to the body, the rod-shaped support 10 of the present invention may be used.
[0085]
The embodiments described above are for explaining the present invention, and do not limit the present invention in any way, and all modifications and alterations within the technical scope of the present invention are included in the present invention. Needless to say.
[0086]
【The invention's effect】
As described above, according to the present invention, when a ground surface change occurs, the structure on the ground surface is expanded and contracted at the free length portion of the elastic tensile material and the hollow rod-shaped steel material under the pushing back force. It is moved following the ground surface change without accompanying.
[0087]
In particular, if the structure is moved in the frost heaving direction without lifting the hollow rod-shaped steel material during the frost heaving of the ground, the transfer of the load due to this movement will ensure the application and transmission of the excessive tensile load to the hollow rod-shaped steel material. Therefore, floating of the hollow rod-shaped steel material, breakage of the hollow rod-shaped steel material, damage to the structure, and the like are prevented. Then, when the ground is melted, if the structure is pushed back under the push-back force from the elastic tensile material, the movement of the structure following the volume decrease of the ground can be easily secured. Since the formation of gaps between the ground surface and structures due to the lifting of the structures from the surface is sufficiently prevented, the reduction in the soundness of the rod-shaped support due to the occurrence of rust, etc. Prevention can be reliably achieved.
[0088]
Therefore, according to the present invention, a decrease in the protection function due to a change in the ground surface and a decrease in the soundness of the rod-shaped support are reliably prevented.
[0089]
If the unbonded portion is applied to the free length portion of the elastic tensile material or the non-adhered length portion of the hollow bar-shaped steel material, the length of each portion can be easily clarified, and its functionality can be easily secured. Furthermore, the filling operation of the inner grout and the outer grout can be simplified, and the stability of the elastic tensile material and the hollow bar-shaped steel material can be easily secured under the grout over almost the entire length, so that the functionality thereof can be further improved. Can be easily improved.
[0090]
In addition, if a material capable of securing the required amount of elongation of the elastic tensile material is selected in consideration of the depth of the support insertion hole that is possible in the ground and the required length of the free length portion, the same structure can be obtained. Even so, a rod-shaped support that can be applied to various aspects can be provided, so that the versatility as a rod-shaped support is further improved.
[0091]
In addition, the support insertion hole is excavated and formed only by a single pipe drilling in the ground of the self-supporting stratum, and the pilot hole is drilled by the single pipe drilling in the rock of the non-self-supporting stratum. In addition, since it is sufficient to perform two-stage drilling by driving a hollow rod-shaped steel material along the prepared hole, the rod-shaped support can be easily applied to the ground of any stratum.
[0092]
In the case of a two-stage drilling for forming a pilot hole, the excavation of the support insertion hole in the ground of a non-self-supporting stratum can be performed without using an expensive member such as a self-drilling lock bolt. The rise can be sufficiently suppressed. Further, since a high rigidity is not required for the hollow bar-shaped steel material used for the second drilling, also in this respect, an increase in working cost can be sufficiently suppressed, and the casting of the hollow bar-shaped steel material is also facilitated. The workability can be sufficiently improved.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view of a rod-shaped support according to the present invention.
FIG. 2 is a schematic process diagram in a method of constructing a rod-shaped support according to the present invention.
FIG. 3 is a schematic process drawing in a method of constructing a rod-shaped support according to the present invention.
FIG. 4 is a schematic process drawing in the method for constructing a rod-shaped support according to the present invention.
FIG. 5 is a schematic process drawing in the method for constructing a rod-shaped support according to the present invention.
FIG. 6 is a schematic process drawing in the method for constructing a rod-shaped support according to the present invention.
FIG. 7 is a schematic perspective view showing an example of a structure.
[Explanation of symbols]
10 mm rod-shaped support
12 Chiyama
14 structure
16mm hollow rod steel (hollow lock bolt)
18 elastic tensile material
20 internal grout
22 support insertion hole
28mm covering member
30 external grout

Claims

A structure constructed on the ground surface of the ground, the tension of the rod-shaped support installed on the ground, and a construction method of a rod-shaped support that is fixedly held on the ground surface by its fixation,
As a range from the ground surface to a predetermined depth, while presuming a frost heave region in the ground in advance, a support insertion hole at a depth exceeding this frost heave region is formed continuously from a structure on the ground surface,
A hollow rod-shaped steel material serving as a hollow pipe-shaped member is inserted and arranged over substantially the entire length of the support insertion hole while maintaining a non-integral form with the structure, and grouting is performed inside and outside the hollow rod-shaped steel material,
An elastic tensile member made of a material having a tensile strength that can withstand the ground fixing is inserted into the hollow portion of this hollow steel bar, and the fixed length portion of the elastic tensile member defined at the tip side is hollowed out by its internal grout. By integrating with the bar-shaped steel material, at least for the hollow bar-shaped steel material, to constitute a rod-shaped support body in which elasticity of the elastic tensile material is secured in the free length portion, and as a non-aligned portion with the frost heave region, By fixing the fixed length portion defined on the tip side integrally to the ground by its outer grout, this is set as a rod-shaped support for the ground,
Thereafter, the elastic tension member is tensioned under a predetermined tensile load, and the head of the elastic tension member extended through the pressure plate on the surface of the structure is engaged with the pressure plate by the fixing device and held. A method of constructing a rod-shaped support for holding a structure fixedly on the ground surface.

A free length portion of the elastic tensile material is subjected to an unbonding process for suppressing adhesion of grout, and an exposed portion provided on a tip side of the elastic tensile material is integrated with at least the hollow rod-shaped steel material. The method for constructing a rod-shaped support according to claim 1, defined as:

The elastic tensile material is a partially unbonded stranded wire in which the stranded wire is partially covered with the coating tube, and at least the hollow portion of the partially unbonded stranded wire exposed portion provided on the distal end side of the elastic tensile material is hollow. 2. The method according to claim 1, wherein the fixing length of the elastic tensile material integrated with the bar-shaped steel material is defined.

4. The method according to claim 1, wherein the material of the elastic tensile member is any one of deformed steel bars, PC steel materials, carbon fibers, and aramid fibers.

The frost heave pressure on the structure side received by the frost heave of the ground is calculated based on the contact area of the structure with the ground surface, and the frost heave amount of the ground is measured or estimated in advance,
The length of the free length portion of the elastic tensile member is calculated based on the frost heave receiving pressure and the frost heave amount, the cross-sectional area of the elastic tensile member, and the Young's modulus of the material. 5. The rod-shaped support according to claim 4, wherein a material capable of securing an amount of elongation required for the elastic tensile member is selected in consideration of a depth of the elastic member and a required length of the free length portion, and the material is combined with a hollow rod-shaped steel material. Construction method.

In the ground of the self-supporting stratum, a support insertion hole is excavated only by a single pipe drilling, and a hollow rod-shaped steel material is inserted into the formed support insertion hole,
In the formation of a non-self-supporting stratum, a pilot hole is formed by single pipe drilling as the first drilling, and then, as a second drilling, the hollow rod-shaped steel material itself is drilled under a drill pipe and inserted. 6. The method for constructing a rod-shaped support according to any one of claims 1 to 5, wherein the steps are performed simultaneously.

Of the entire length of the hollow rod-shaped steel material, at least the outer peripheral surface of a portion aligned with the frost heap region of the ground and the structure is defined as a non-adhesion length portion with respect to a fixed length portion on the tip side, and in this non-adhesion length portion, 7. The method for constructing a rod-shaped support according to claim 1, wherein an unbonding process for preventing adhesion of other peripheral members is performed in advance.

An elastic tension member made of a material having a tensile strength capable of withstanding the ground anchor is inserted into the hollow rod-shaped steel material, and the fixing long portion defined at the distal end side of the elastic tension material is inserted into the hollow rod-shaped steel material with respect to the hollow portion. By being integrated with the hollow rod-shaped steel material under the grout, it becomes an inner and outer dual structure that secures elasticity at the free length of the elastic tensile material,
A fixed length portion defined at the tip side of this hollow rod-shaped steel material as a non-aligned portion with the frost heave area assumed on the ground is integrally fixed to the ground by an external grout with respect to an outer peripheral portion thereof, and a predetermined length. A rod-shaped support in which a head of an elastic tensile material that is tensioned under a tensile load is engaged and held by a fixing device on a support plate on a surface of a structure.

The elastic tensile member is provided with an unbonding process for suppressing the adhesion of grout to a free length portion of the elastic tensile member, and an exposed portion provided at a tip side of the elastic tensile member is integrated with at least the hollow rod-shaped steel material. 9. The rod-shaped support according to claim 8, wherein the support is defined as a fixing length.

The elastic tensile member is a partially unbonded stranded wire in which the stranded wire is partially covered with the coating tube, and the exposed portion of the stranded wire of the partially unbonded stranded wire provided at the distal end side of the elastic tensile member is at least hollow. 9. The rod-shaped support according to claim 8, wherein the rod-shaped support is defined as a fixing length of an elastic tensile material integrated with the rod-shaped steel material.

The rod-shaped support according to any one of claims 8 to 10, wherein the material of the elastic tensile material is any one of deformed steel bars, PC steel, carbon fibers, and aramid fibers.

Of the entire length of the hollow rod-shaped steel material, at least the outer peripheral surface of a portion aligned with the frost heaving region of the ground and the structure has a non-adhesion length with respect to a fixed length portion on the distal end side thereof by unbonding processing for suppressing adhesion of other peripheral members. The rod-shaped support according to any one of claims 8 to 11, defined as a part.