JP3633326B2

JP3633326B2 - Ground reinforcement method

Info

Publication number: JP3633326B2
Application number: JP33461998A
Authority: JP
Inventors: 山本　　彰
Original assignee: Obayashi Corp
Current assignee: Obayashi Corp
Priority date: 1998-11-25
Filing date: 1998-11-25
Publication date: 2005-03-30
Anticipated expiration: 2018-11-25
Also published as: JP2000160572A

Description

【０００１】
【発明の属する技術分野】
本発明は、地山斜面の崩落防止工法に関する。
【０００２】
【従来の技術】
地滑り地山や、各種構造物の構築に伴う地下開削壁面等の斜面が、例えば急勾配で斜面各自特有の安定勾配以上の勾配を有する斜面である場合、そのままなんら補強措置を施さなければ、その急勾配斜面より地山の崩落が生じるおそれがあり、係る崩落の防止を図るため、従来、各種の補強工法が行われてきた。
【０００３】
従来の地山補強工法としては、地山斜面から鉄筋等を地山内に向け適宜間隔をおいて複数打設した後、打設孔にモルタルなどを流入させて地山に鉄筋を定着させ、係る鉄筋の引張り抵抗をもって斜面を一体に縫地するといった地山補強土工法があった。
【０００４】
また、グラウンドアンカー工法と呼ばれ、対象地山に掘削孔を形成し係る孔内にワイヤー等のアンカー材を挿入した後、孔内奥部のアンカー定着部をもって周辺地山と定着させ、定着後にアンカーに緊張力を与えて地山を締付け一体化し補強するといった工法もあった。
【０００５】
他に、地山ののり肩部分や、斜面中腹から略鉛直下方に向けて大口径の鋼管杭やコンクリート杭などを打設するといった杭工などもあった。
【０００６】
しかしながら、これら従来の補強工法には以下に述べるような課題があった。
【０００７】
【発明が解決しようとする課題】
すなわち、まず地山補強土工法において、対象地山斜面の地質状況等により崩落すべり面位置が比較的深いか、または、地山斜面ののり面高が高くそれだけ崩落すべり面の半径も大きいといった状況下では、鉄筋などの補強材が有する程度の長さでは補強材が崩落すべり面以深の地山に到達できなくなり、補強材の引張り抵抗が有効に機能せず斜面を一体に縫地するといったことは困難となる。
【０００８】
また、グラウンドアンカー工において、上記の如く崩落すべり面が地山内深くに位置していると、必要とするアンカー長もそれに応じただけ長大なものになり、それに伴い後背の施工区域が狭小である場合にはこの工法の適用自体を難しくし、アンカー材料費や周辺対策にとられる費用を要することとなり全体の施工コストを増大させることにつながる。
【０００９】
加えて、上記崩落すべり面の勾配が急であれば、地山の崩落を抑止する効果は、アンカーによる地山の締付け一体化の効果にほぼ限られてしまい、例えば地盤のクリープ現象が生じてアンカーの緊張力が低下するなどの事態が生起すれば、このグランドアンカー工法そのものの施工効果を失することになりかねない。
【００１０】
しかも、上記の地山補強土工法及びグラウンドアンカー工法のいずれについても、所定の補強効果を発揮するまでにある程度の養生時間を要するため、例えば掘削直後の斜面などに適用すると、施工によりかえって斜面の変状や崩壊を引き起こすおそれもある。
【００１１】
他方、杭工についても、通常の杭のごとく軸力が主な外力として作用する場合と違い、崩落防止のための抑止杭として、係る杭に作用する外力がすべり土砂に起因する主に曲げモーメントであることを考慮して設計するものであり、通常より比較的大きな杭径の杭を必要とする。
【００１２】
したがって、杭打設用の大型で重量の大きな重機類を斜面付近に配置して大型の杭を打設することとなって、施工コストと施工効率とに与える悪影響は大きい。
【００１３】
そこで、本発明は、このような従来の課題に着目してなされたもので、掘削直後の地山斜面の安定を図ることを可能にし、また、地山斜面の崩落すべり面が地山内深く位置している場合及び地山斜面ののり高が高い場合においても、簡便確実かつ低コストにて地山補強を施しうる地山補強工法を提供するものである。
【００１４】
【課題を解決するための手段】
この発明は、上記目的を達成するためになされたもので、地山斜面の崩落防止を図る補強工法であって、地山斜面ののり肩もしくは中腹から略鉛直下方の地山内に向けて杭を打設する地山補強杭工と、棒状の補強材を地山内に向け地山斜面から略鉛直に打設し、さらに地山と補強材とを定着させる地山補強土工と、補強対象となる地山斜面表面の一部もしくは全部を覆って地山斜面表面からの崩落防止を図るとともに、前記地山補強杭工において打設される杭と前記地山補強土工において打設される補強材とを地山斜面の表面上で連結する地山補強のり面工とからなることを特徴とする。
【００１５】
また、上記の地山補強杭工が地山補強土工に先行して行われると好適である。
【００１６】
【発明の実施の形態】
以下、本発明の好ましい実施の形態につき、添付図面を参照して詳細に説明する。
図１（ａ）は、本発明の地山補強杭工１０、地山補強土工２０及びのり面工３０を施工した斜面Ｓの断面図である。
例えば、山間部での道路建設や宅地造成などの土工事が実施される地山について、ある施工段階において図のような切土斜面Ｓが存在し、そののり面勾配が急であってなんら補強措置をとらねば斜面崩落のおそれがあるといった場合、本発明の地山補強工法を実施した例を示す。
【００１７】
その実施手順は、まず対象となる地山斜面Ｓの近傍に杭打設用機械を配置して、斜面のり肩部Ｋから地山内略鉛直下方に向けて、例えば径３００ｍｍ以下の小口径杭１１を打設する。係る杭１１の打設本数と杭長とは、地山の地質状況と必要とされる補強後地山強度、及び地山の崩落すべり面Ｍの位置とを考慮して設計されるものであり、打設に際しては図に示す如くのり肩部Ｋより下方の崩落すべり面Ｍ以深に向け打設を行って、地山のすべりに起因する曲げモーメントに対抗しうる支持力を杭１１が発現するよう勘案されるのである。
【００１８】
このように地山補強杭工１０が先行施工された地山斜面Ｓはそれだけでもある程度の補強効果が得られるため、それ以降に続いて行われるのり面掘削や地山補強土工２０及び地山補強のり面工３０の施工を実施しやすくし施工効率向上に資するという効果は大きい。
【００１９】
地山補強杭工１０の施工後は、例えば鉄筋などの補強材２１を地山内に向け地山斜面Ｓから略鉛直に打設し、さらに地山と補強材２１とを定着させ一体化させる地山補強土工２０を行う。前記補強材２１は、地山補強杭工１０における杭１１と同様に地山の地質状況と補強後の地山強度、及び地山の崩落すべり面Ｍの位置とを考慮して、打設本数と打設長とが設計される。
【００２０】
さらに、地山補強土工２０の施工後は地山補強のり面工３０が実施されることとなり、かかるのり面工３０は例えば吹付け枠工や現場打ちコンクリート枠工などを地山斜面Ｓののり面に施工し、のり面表面の一部もしくは全部を覆って、地山斜面Ｓ表面の剥落から始まる崩落防止を図るのである。
【００２１】
それとともに、先に地山補強杭工１０において打設された杭１１と地山補強土工２０において打設された補強材２１とを地山斜面の表面上で連結する役割も担って、地山補強杭工１０、地山補強土工２０、及び地山補強のり面工３０が施された地山斜面Ｓを、構造物の如く一体化することになる。
【００２２】
のり面高が高い場合、（ｂ）図のごとく上記補強材２１に長尺のものを使用すれば、より補強効果を高めることが出来る。
【００２３】
なお、施工手順としては本実施例のごとく、地山補強杭工、地山補強土工、そして地山補強のり面工の順とすると好ましいが、地質状況や各種施工条件などに応じて適宜変更してもよい。
【００２４】
【発明の効果】
以上詳細に説明したように、本発明の地山補強工法によれば、所定の補強効果を発揮するまでにある程度の養生時間を要する地山補強土工及び地山補強のり面工の施工に先立って地山補強杭工を実施することにより、ある程度の補強効果を対象斜面に施して、それ以降に行われる各種作業を簡便に行いやすくすることが可能となる。
【００２５】
しかも、上記地山補強杭工を地山補強土工と併せて行うことで、両者各々の施工に必要とされる杭や補強材等の部材数やサイズを抑制して施工コストを改善するとともに、施工機械の小型軽量化につながって施工効率向上の効果も著しいものとなる。
【００２６】
また、例えば、対象地山斜面の地質状況等により崩落すべり面位置が深いか、または、地山斜面ののり面が高く、それだけ崩落すべり面の半径も大きいといった状況下においても、地山補強杭工で用いられる杭がすべり面位置以深まで打設されるため、単独で地山補強土工を施工した場合と比較して大幅に補強材長を短縮することが可能となり、後背の施工区域が狭小で従来のグラウンドアンカー工法では施工が困難であるといった場合でも、地山補強工を実施可能とし、加えて施工コストの低減と施工効率の向上とを同時に図ることが可能である。
さらに、地山補強のり面工によって地山補強杭工において打設された杭と地山補強土工において打設された補強材とが地山斜面の表面上で連結されることになるので、地山斜面を構造物のように一体化することができ、地山斜面表面の剥落から始まる崩落を確実に防止することができる。
【図面の簡単な説明】
【図１】（ａ）は、本発明の地山補強杭工、地山補強土工及びのり面工を施工した斜面の断面図であり、（ｂ）は、地山補強土工に用いる補強材を長尺のものに変更して適用した斜面の断面図である。
【符号の説明】
Ｓ地山斜面
Ｋ地山のり肩
１０地山補強杭工
１１杭
２０地山補強土工
２１補強材
３０地山補強のり面工[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fall prevention method for natural slopes.
[0002]
[Prior art]
If slopes such as landslide mountains and underground excavation walls due to construction of various structures are, for example, steep slopes with slopes greater than their own stable slope, if no reinforcement measures are taken as they are, There is a possibility that a natural mountain collapses from a steep slope, and various reinforcing methods have been conventionally performed in order to prevent the collapse.
[0003]
As a conventional natural ground reinforcement method, after placing a plurality of reinforcing bars, etc. from the natural slope into the natural ground at appropriate intervals, mortar is poured into the placement hole to fix the reinforcing bars in the natural ground. There was a natural ground reinforced earth method in which the slopes were sewn together with the tensile resistance of the reinforcing bars.
[0004]
Also called the ground anchor method, after forming a drilling hole in the target ground and inserting an anchor material such as a wire into the hole, fix it to the surrounding ground with the anchor fixing part at the back of the hole, and after fixing There was also a method of applying tension to the anchors to tighten and integrate the natural ground.
[0005]
In addition, there were pile works such as placing a large-diameter steel pipe pile or concrete pile, etc. from the slope of the natural mountain or from the middle of the slope to the vertical direction.
[0006]
However, these conventional reinforcing methods have the following problems.
[0007]
[Problems to be solved by the invention]
In other words, in the natural ground reinforcement earth method, the slip surface position is relatively deep due to the geological conditions of the target natural slope, or the slope height of the natural slope is high and the radius of the slip surface is large accordingly. Below, the length of the reinforcing material such as a reinforcing bar will not reach the natural ground deeper than the sliding surface where the reinforcing material collapses, and the tensile resistance of the reinforcing material will not function effectively, and the slope will be sewn together. Will be difficult.
[0008]
Also, in the ground anchor work, if the slipping surface is located deep in the ground as described above, the required anchor length will be correspondingly long and the construction area on the back will be narrow accordingly. In some cases, application of this construction method itself becomes difficult, and costs for anchor materials and peripheral measures are required, leading to an increase in overall construction cost.
[0009]
In addition, if the slope of the landslide surface is steep, the effect of suppressing the collapse of the natural ground is almost limited to the effect of anchoring the natural ground by the anchor. For example, the ground creep phenomenon occurs. If a situation such as a decrease in the tension of the anchor occurs, the construction effect of this ground anchor method itself may be lost.
[0010]
In addition, both the above-mentioned ground-strand reinforced earth method and ground anchor method require a certain amount of curing time to exhibit the prescribed reinforcement effect.For example, when applied to a slope immediately after excavation, the slope of the slope is changed by construction. There is also a risk of causing deformation and collapse.
[0011]
On the other hand, unlike piles where the axial force acts as the main external force for piles, the external force acting on the pile as a deterrent pile for preventing collapse is mainly due to the bending moment caused by the sliding soil. Therefore, a pile having a relatively larger pile diameter than usual is required.
[0012]
Therefore, a large pile for driving piles is placed near the slope to place a large pile, which has a large adverse effect on construction cost and construction efficiency.
[0013]
Therefore, the present invention has been made paying attention to such conventional problems, and makes it possible to stabilize the natural slope immediately after excavation, and the slip surface of the natural slope is located deep in the natural ground. Therefore, the present invention provides a natural ground reinforcement construction method that can provide natural ground reinforcement easily and reliably at low cost even when the ground slope is high.
[0014]
[Means for Solving the Problems]
The present invention has been made to achieve the above object, and is a reinforcing method for preventing the collapse of a natural slope, in which a pile is placed from the shoulder or middle of the natural slope into the natural ground approximately vertically below. The ground pile reinforcement to be laid, the rod-shaped reinforcement material to be placed in the ground, almost vertically from the slope, and the ground and the reinforcement material are fixed, A pile that is placed in the natural ground reinforcement pile work and a reinforcing material that is placed in the natural ground reinforcement earth work while preventing a collapse from the natural slope surface by covering part or all of the natural slope surface It is characterized by comprising a natural ground reinforcement slope work that connects the ground on the natural slope surface .
[0015]
In addition, it is preferable that the natural ground reinforcing pile work is performed prior to the natural ground reinforcing earth work.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig.1 (a) is sectional drawing of the slope S which constructed the natural ground reinforcement pile construction 10, the natural ground reinforcement earthwork 20, and the slope surface construction 30 of this invention.
For example, there is a cut slope S as shown in the figure at a certain construction stage for earthwork where road construction and residential land development are implemented in mountainous areas, and the slope of the slope is steep and reinforcement If there is a risk of slope collapse if measures are not taken, an example in which the natural ground reinforcement method of the present invention is implemented will be shown.
[0017]
The implementation procedure is as follows. First, a pile driving machine is arranged in the vicinity of the target natural slope S, and the small-diameter pile 11 having a diameter of 300 mm or less, for example, from the slope shoulder K toward the vertical direction in the natural ground. To cast. The number of piles 11 and the pile length of the piles 11 are designed in consideration of the geological condition of the natural ground, the strength of the natural ground after reinforcement, and the position of the ground slide surface M. When placing, as shown in the figure, the pile 11 is placed deeper than the slipping surface M below the shoulder K, and the pile 11 develops a bearing force that can resist the bending moment caused by the slip of the natural ground. This is taken into consideration.
[0018]
Thus, since the natural slope S on which the natural ground reinforcing pile work 10 is preliminarily constructed can provide a certain degree of reinforcing effect, the slope excavation, the natural ground reinforcing earth work 20 and the natural ground reinforcement performed subsequently are performed. The effect of facilitating the construction of the slope work 30 and contributing to the improvement of construction efficiency is great.
[0019]
After the construction of the natural ground reinforcing pile 10, for example, a reinforcing material 21 such as a reinforcing bar is directed into the natural ground from the natural slope S, and the ground and the reinforcing material 21 are fixed and integrated. Mountain reinforcement earthwork 20 is performed. In the same manner as the pile 11 in the natural ground reinforcing pile construction 10, the reinforcing material 21 is placed in consideration of the geological condition of the natural ground, the strength of the natural ground after reinforcement, and the position of the slip surface M of the natural ground. And the placement length are designed.
[0020]
Furthermore, after the construction of the natural ground reinforcement earthwork 20, the natural ground reinforcement slope work 30 will be carried out. It is constructed on the surface, covering a part or all of the surface of the slope, and preventing the collapse starting from the peeling of the surface of the natural slope S.
[0021]
At the same time, it also plays a role of connecting the pile 11 previously placed in the natural ground reinforcement pile work 10 and the reinforcing material 21 placed in the natural ground reinforcement earth work 20 on the surface of the natural ground slope. The natural slope S to which the reinforcing pile work 10, the natural ground reinforcement earthwork 20, and the natural ground reinforcement slope work 30 are applied is integrated like a structure.
[0022]
When the slope height is high, the reinforcing effect can be further enhanced by using a long reinforcing material 21 as shown in FIG.
[0023]
As the construction procedure, as in this example, it is preferable to follow the order of natural ground reinforcement pile construction, natural ground reinforcement earthwork, and natural ground reinforcement slope surface construction, but it can be changed appropriately according to the geological conditions and various construction conditions. May be.
[0024]
【The invention's effect】
As explained in detail above, according to the natural ground reinforcement construction method of the present invention, prior to the construction of the natural ground reinforcement earthwork and the natural ground reinforcement slope work that requires a certain amount of curing time to exhibit a predetermined reinforcing effect. By implementing the natural ground reinforcement pile work, it is possible to apply a certain degree of reinforcement effect to the target slope and to easily perform various operations performed thereafter.
[0025]
Moreover, by performing the above natural ground reinforcement pile work together with the natural ground reinforcement earth work, while improving the construction cost by suppressing the number and size of the piles and reinforcing materials required for each construction, This leads to a reduction in the size and weight of the construction machine, and the effect of improving the construction efficiency becomes remarkable.
[0026]
In addition, for example, in the situation where the slip surface is deep due to the geological conditions of the target natural slope, or the slope of the natural slope is high and the radius of the slip surface is large, the natural ground reinforcement pile Since the piles used in the construction are driven deeper than the slip surface position, it is possible to significantly shorten the length of the reinforcing material compared to the case where the earth-reinforced concrete earth is constructed alone, and the construction area on the back is narrow. Even when it is difficult to construct with the conventional ground anchor method, it is possible to implement ground reinforcement, and at the same time, it is possible to simultaneously reduce the construction cost and improve the construction efficiency.
Furthermore, the piles laid in the natural ground reinforcement pile work and the reinforcements laid in the natural ground reinforcement earthwork by the natural ground reinforcement slope work are connected on the surface of the natural ground slope. The mountain slope can be integrated like a structure, and the collapse starting from the peeling of the ground slope surface can be reliably prevented.
[Brief description of the drawings]
FIG. 1 (a) is a cross-sectional view of a slope where a natural ground reinforcing pile work, a natural ground reinforcing earth work and a slope surface construction of the present invention are constructed, and (b) is a diagram showing a reinforcing material used for the natural ground reinforcing earth work. It is sectional drawing of the slope applied by changing into a long thing.
[Explanation of symbols]
S Natural ground slope K Natural ground shoulder 10 Natural ground reinforcement pile 11 Pile 20 Natural ground reinforcement 21 Reinforcement material 30 Natural ground reinforcement slope work

Claims

This is a reinforcement method to prevent the collapse of a natural slope, and a pile-shaped reinforcement pile work in which a pile is placed from the shoulder or middle of the natural slope to the ground in the vertical direction, and a rod-shaped reinforcement material A natural earth reinforcement earthwork that is placed almost vertically from the natural slope toward the mountain, and that fixes the natural ground and the reinforcing material, and a natural slope surface that covers part or all of the natural slope surface to be reinforced In addition to preventing the collapse of the ground, the ground pile reinforcement slope surface connecting the pile cast in the natural ground reinforcement pile work and the reinforcing material cast in the natural ground reinforcement earth work on the surface of the natural ground slope A natural ground reinforcement method characterized by comprising

2. The natural ground reinforcing method according to claim 1, wherein the natural ground reinforcing pile work is performed prior to the natural ground reinforcing earth work.