JP2001207437A - Reinforcing method for lower ground of existing structure - Google Patents
Reinforcing method for lower ground of existing structureInfo
- Publication number
- JP2001207437A JP2001207437A JP2000018302A JP2000018302A JP2001207437A JP 2001207437 A JP2001207437 A JP 2001207437A JP 2000018302 A JP2000018302 A JP 2000018302A JP 2000018302 A JP2000018302 A JP 2000018302A JP 2001207437 A JP2001207437 A JP 2001207437A
- Authority
- JP
- Japan
- Prior art keywords
- ground
- existing structure
- ground improvement
- boring
- reinforcing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本願発明は、地盤沈下や地震
時の液状化の恐れがある既設構造物下方地盤の地盤改良
による補強工法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reinforcing method for improving the ground below an existing structure, which is liable to liquefy during land subsidence or earthquake.
【０００２】[0002]
【従来の技術】軟弱地盤では、基礎に十分な支持力が得
られないことや地盤沈下の問題などから、構造物を構築
する場合に、セメント系固化材あるいは薬液の注入によ
る地盤改良あるいは排水ドレーンの設置など、何らかの
対策を施す必要がある。2. Description of the Related Art In the case of a soft ground, when a structure is constructed, a ground improvement by injecting a cement-based solidifying material or a chemical solution or drainage drainage is performed due to problems such as insufficient supporting capacity of a foundation and ground subsidence. It is necessary to take some measures such as installing
【０００３】また、地下水位が比較的高く飽和した緩い
砂地盤では液状化のおそれがあり、さらに、阪神淡路大
震災の例などから、大地震の際には、従来、液状化のお
それが少ないと考えられていた地盤でも液状化が生じる
ことが分かっており、その見直しが必要になっている。[0003] In addition, there is a risk of liquefaction in a loose sandy ground where the groundwater level is relatively high, and in the case of the Great Hanshin-Awaji Earthquake, if there is little danger of liquefaction conventionally, It is known that liquefaction will occur even on the ground that had been considered, and it is necessary to review it.
【０００４】例えば、図６に示すように、港湾における
既設構造物１としてのケーソン式岸壁（重力式構造物）
は、軟弱な海底地盤上に建設されている場合が多く、大
地震の際に、置換砂からなるケーソン直下の地盤３や背
面４の埋立土からなる地盤４が液状化し、せん断抵抗の
低下による甚大な被害を被るおそれがある。For example, as shown in FIG. 6, a caisson type quay (gravity type structure) as an existing structure 1 in a harbor
Is often constructed on soft submarine ground, and in the event of a large earthquake, the ground 3 immediately below the caisson made of displacement sand and the ground 4 made of landfill on the back 4 liquefy, resulting in a decrease in shear resistance. There is a risk of severe damage.
【０００５】この場合、特に被害を大きくしているのが
下方地盤３の液状化によるせん断抵抗の低下であり、そ
の復旧には多大な費用と時間を要することになる。背面
地盤４については、地盤改良を施したり、あるいは地震
時に地盤内の過剰間隙水圧を逸散させるための排水ドレ
ーンを設置するなど、従来、開発されている種々の地盤
沈下対策、液状化抑止対策の適用が考えられる。[0005] In this case, the damage is particularly large is the decrease in shear resistance due to liquefaction of the lower ground 3, and the restoration thereof requires a great deal of cost and time. For the back ground 4, various ground subsidence countermeasures and liquefaction control measures have been developed, such as improving the ground or installing drainage drains to dissipate excessive pore water pressure in the ground during an earthquake. Can be applied.
【０００６】これらは、通常、鉛直方向あるいは斜め方
向の施工によって行われるが、既設構造物１の下方地盤
３については、構造物１が存在することによって、従来
の対策工法をそのまま適用することが難しく、また構造
物１を貫通させて施工するには多大の費用を要すること
になる。[0006] These are usually carried out by vertical or diagonal construction. However, the existing ground structure 3 can be applied directly to the ground 3 below the existing structure 1 because the structure 1 exists. It is difficult and requires a lot of expense to penetrate the structure 1.
【０００７】これに対し、特開平９−１２０６６１号公
報や特開平１０−３１７８８３号公報には、構造物の外
側の地表面から曲線状のボーリングを行い、既設構造物
下を横断するボーリング孔を形成し、そのボーリング孔
を利用して地盤改良や液状化対策を施すことができる旨
が記載されている。On the other hand, Japanese Patent Application Laid-Open Nos. Hei 9-120661 and Hei 10-317883 disclose curving boring from the ground surface outside the structure, and form a boring hole that crosses below the existing structure. It is described that ground improvement and liquefaction countermeasures can be performed using the bored holes.
【０００８】[0008]
【発明が解決しようとする課題】上述した特開平９−１
２０６６１号公報や特開平１０−３１７８８３号公報に
記載されている施工方法によれば、従来の鉛直方向ある
いは斜め方向の施工に代わり、既設構造物下については
ほぼ水平方向の施工が行われるため、既設構造物を貫通
させることなく、構造物を迂回する形で地盤改良あるい
は排水設備の施工が可能である。SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Application Laid-Open No. 9-1 is disclosed.
According to the construction method described in 20661 gazette or JP-A-10-317883, instead of the conventional construction in the vertical direction or diagonal direction, the construction is performed in a substantially horizontal direction under the existing structure, Ground improvement or construction of drainage equipment is possible without bypassing the existing structure and bypassing the structure.
【０００９】また、鉛直あるいは斜め方向にボーリング
孔を設ける場合、ボーリング孔の削孔回数が多く、しか
も１回当りの延長距離が短くならざるを得ず、既設構造
物直下の地盤全体について、均一に地盤改良を施した
り、あるいは排水ドレーンなどを密に配置することは、
経済性の面でも難しい。In addition, when boring holes are provided in a vertical or oblique direction, the number of drilling holes is large, and the extension distance per one hole must be short, so that the entire ground immediately below the existing structure is uniform. Improving the ground or placing drainage drains densely
It is difficult in terms of economy.
【００１０】本願発明は、上述のような事情のもとに開
発されたものであり、既設構造物下方の地盤を、経済的
にかつ効率よく地盤改良し、地盤沈下や地震時における
該地盤の液状化を抑止することを目的としている。The present invention has been developed in view of the above-mentioned circumstances. The present invention improves the ground under an existing structure economically and efficiently, and improves the ground in the event of land subsidence or earthquake. It aims to prevent liquefaction.
【００１１】[0011]
【課題を解決するための手段】本願の請求項１に係る既
設構造物下方地盤の補強工法、既設構造物下方の地盤に
対し、該地盤内をほぼ水平にボーリングしながら、ボー
リング孔を利用してボーリング孔の周囲に地盤改良部分
を造成し、このようなボーリング孔の周囲に形成される
地盤改良部分を平面的に見て井桁状または格子状に設け
ることを特徴とする。According to a first aspect of the present invention, there is provided a method for reinforcing a ground below an existing structure, wherein a boring hole is used while boring substantially horizontally in the ground below the existing structure. A ground improvement portion is formed around the boring hole, and the ground improvement portion formed around the boring hole is provided in a grid or grid shape when viewed in plan.
【００１２】本発明では、ボーリング孔を利用したほぼ
水平方向に延びる地盤改良部分を井桁状または格子状に
設けるため、井桁または格子内部の地盤についても、強
度を確保した地盤改良部分で周囲から拘束することにな
り、少ないボーリング本数で経済的に、かつ効率よく既
設構造物下の地盤を補強することができ、またこの地盤
内における地震時の液状化を抑止することができる。In the present invention, since the ground improvement portion extending in the substantially horizontal direction using the boring hole is provided in a cross-girder or lattice shape, the ground inside the cross-girder or the lattice is also restrained from the periphery by the ground improvement portion ensuring the strength. Therefore, it is possible to economically and efficiently reinforce the ground under the existing structure with a small number of boring holes, and to suppress liquefaction in the ground during an earthquake.
【００１３】ボーリング孔の径としては、直径３００ｍ
ｍ程度以下が望ましく、より好ましくは直径１５０ｍｍ
以下とすることで、ボーリング施工におけるコストダウ
ンが図れる。ボーリング孔の周囲に形成される地盤改良
部分については、ボーリング孔からセメント系固化材あ
るいは薬液などを高圧で噴出させるなどして、直径１〜
１０ｍ程度の範囲で地盤改良部分を造成することを想定
している。The diameter of the boring hole is 300 m in diameter.
m or less, more preferably 150 mm in diameter.
By doing the following, the cost in boring can be reduced. For the ground improvement part formed around the boring hole, a cement-based solidifying material or a chemical solution is ejected from the boring hole at a high pressure, etc.
It is assumed that the ground improvement part will be created within a range of about 10 m.
【００１４】ボーリング孔を水平に設けるための手段と
しては、既設構造物の外側に立坑を構築し、立坑から水
平方向にボーリングを行うことが考えられるが、前述し
た特開平９−１２０６６１号公報や特開平１０−３１７
８８３号公報に記載されているような自在ボーリングを
地表から行えば、より経済的な施工が可能である。As a means for providing the boring holes horizontally, it is conceivable to construct a shaft outside the existing structure and perform boring in the horizontal direction from the shaft. JP-A-10-317
If free boring as described in Japanese Patent No. 883 is performed from the ground surface, more economical construction is possible.
【００１５】請求項２は、請求項１に係る既設構造物下
方地盤の補強工法において、ボーリング孔を利用して造
成した前記地盤改良部分を鉛直方向に複数段設けること
を特徴とする。地盤改良の対象となる地盤の層厚やボー
リング孔の周囲に造成される地盤改良部分の径によって
は、このような地盤改良部分を鉛直方向に複数段設ける
ことで、井桁あるいは格子内部の地盤を拘束しつつ、層
厚全体にわたってより確実な液状抑止効果を期待するこ
とができる。According to a second aspect of the present invention, in the method of reinforcing the ground below the existing structure according to the first aspect, the ground improvement portion formed by using a boring hole is provided in a plurality of steps in the vertical direction. Depending on the layer thickness of the ground to be improved and the diameter of the ground improvement part formed around the boring hole, such ground improvement parts may be provided in multiple stages in the vertical direction to reduce the ground inside the girder or lattice. While restrained, a more reliable liquid deterrent effect can be expected over the entire layer thickness.
【００１６】本願の請求項３に係る既設構造物下方地盤
の補強工法は、既設構造物下方の地盤に対し、該地盤内
をほぼ水平にボーリングしながら、ボーリング孔を利用
してボーリング孔の周囲に地盤改良部分を造成し、この
ようなボーリング孔の周囲に形成される地盤改良部分
を、鉛直断面で見て補強の対象となる地盤の周囲または
内部を取り囲むように設けることを特徴とする。According to a third aspect of the present invention, in the method of reinforcing the ground below an existing structure, the boring hole is formed by using the boring hole while boring the ground substantially horizontally with respect to the ground below the existing structure. And a ground improvement portion formed around such a boring hole is provided so as to surround the periphery or inside of the ground to be reinforced as viewed in a vertical cross section.
【００１７】請求項１に係る補強工法は、既設構造物が
面的に広がる場合、あるいは比較的小さい場合に適する
のに対し、例えばケーソン岸壁などの港湾構造物のよう
に１方向に連続する構造物の場合には、この請求項３の
ようにボーリング孔を利用した地盤改良部分を、補強の
対象となる地盤を鉛直断面で見てその周囲または内部を
取り囲むように設けることが考えられる。The reinforcing method according to the first aspect is suitable for a case where the existing structure is spread over a surface or is relatively small, whereas a structure which is continuous in one direction like a harbor structure such as a caisson quay. In the case of an object, it is conceivable to provide a ground improvement part using a borehole as in claim 3 so as to surround the periphery or the inside of the ground to be reinforced in a vertical cross section.
【００１８】対象地盤の層厚や範囲がそれ程大きくない
場合には、対象地盤全体を取り囲むような形も考えられ
るが、状況に応じてその一部を取り囲むような形や、そ
のような取り囲む部分を複数設けるといった場合が考え
られる。取り囲む形状は、最も一般的には方形である
が、円形や楕円形に取り囲むことも考えられ、その場合
には補強部分のアーチ効果も期待される。If the layer thickness and range of the target ground are not so large, a shape surrounding the entire target ground may be considered. However, depending on the situation, a shape surrounding a part of the target ground or a part surrounding the target ground may be considered. Is provided. The surrounding shape is most generally a square, but it is also conceivable that the surrounding shape is a circle or an ellipse. In this case, an arch effect of the reinforcing portion is expected.
【００１９】請求項４は、請求項３に係る既設構造物下
方地盤の補強工法において、対象となる地盤の周囲また
は内部を取り囲むように設けた前記地盤改良部分の内側
を仕切るように、さらに同様の地盤改良部分を版状に設
けることを特徴とする。層厚や幅が大きい場合には、そ
の内側を仕切るように地盤改良部分で補強することで未
改良部分を小分けに拘束し、全体としての補強効果を高
めることができる。According to a fourth aspect of the present invention, in the method for reinforcing the ground below the existing structure according to the third aspect, the inside of the ground improvement portion provided so as to surround the periphery or the inside of the target ground is further divided. Characterized in that the ground improvement portion is provided in the form of a plate. When the layer thickness or width is large, the unimproved portion is restrained in a small portion by reinforcing the ground with a ground improvement portion so as to partition the inside, and the reinforcing effect as a whole can be enhanced.
【００２０】請求項５は、請求項４において、内側を仕
切る前記地盤改良部分が斜壁であることを特徴とする。
例えば、鉛直断面で見て方形に取り囲んだ場合に、その
内側を地盤改良部分で構成される斜壁で補強することに
より、この斜壁部分がブレース的に機能し、地盤改良体
全体としての強度を高めることができる。A fifth aspect of the present invention is characterized in that, in the fourth aspect, the ground improvement portion that partitions the inside is a slope wall.
For example, when a rectangular cross section is seen in a vertical section, the inside is reinforced with a slope wall composed of a ground improvement part, so that the slope wall part functions like a brace, and the strength of the ground improvement body as a whole Can be increased.
【００２１】請求項６は、請求項３、４または５に係る
既設構造物下方地盤の補強工法において、対象となる地
盤の周囲または内部を取り囲むように設けた前記地盤改
良部分とほぼ直交する方向にも該地盤改良部分を長手方
向に仕切る形で、同様の地盤改良部分を鉛直壁状に設け
ることを特徴とする。According to a sixth aspect of the present invention, in the method for reinforcing the lower ground of an existing structure according to the third, fourth or fifth aspect, a direction substantially orthogonal to the ground improvement portion provided to surround or surround the target ground. Also, a similar ground improvement portion is provided in the shape of a vertical wall so as to partition the ground improvement portion in the longitudinal direction.
【００２２】長手方向に対し直交するような鉛直壁状の
地盤改良部分は、地震時の水平力に対して耐震壁的な働
きもする。なお、地盤沈下対策としては、請求項４、５
などとの組合せにより立体網目状に地盤改良部分を形成
することが効果的である。請求項７は、請求項１〜６に
係る既設構造物下方地盤の補強工法において、前記ボー
リング孔の施工を、先端部所定区間に複数のグラウト材
注入用のノズルを有し、前記複数のノズルを設けた区間
の後方に径方向に膨張可能なパッカーを有するボーリン
グ装置によって行い、前記パッカーを収縮させた状態で
所定区間掘進する工程と、その後、前記パッカーを膨張
させてボーリング孔の孔壁に密着させた状態で、前記ノ
ズルからグラウト材を高圧で噴出させてボーリング孔周
囲の地盤改良を行う工程とを所要回数繰り返すことで、
前記地盤改良部分を造成することを特徴とする。The ground improvement portion in the form of a vertical wall perpendicular to the longitudinal direction also functions as an earthquake-resistant wall against horizontal forces during an earthquake. In addition, as measures against land subsidence, claims 4 and 5
It is effective to form the ground improvement portion in a three-dimensional mesh shape by combining with the above. Claim 7 is the method of reinforcing the ground below the existing structure according to Claims 1 to 6, wherein the boring holes are formed by providing a plurality of grout material injection nozzles in a predetermined section at a tip end of the plurality of nozzles. By a boring device having a radially inflatable packer behind the section provided with, a step of digging a predetermined section in a state in which the packer is contracted, and thereafter, expanding the packer to a hole wall of a boring hole. In a state where the nozzles are in close contact with each other, a process of performing ground improvement around the boring hole by ejecting grout material from the nozzle at a high pressure by repeating the required number of times,
It is characterized in that the ground improvement part is formed.
【００２３】この請求項７は、パッカーの膨張、収縮
と、ノズルからのセメントミルク等のグラウト材の噴出
を連動させ、ボーリングとグラウト工程を一元化し、限
定した位置に十分なグラウト浸透注入を行うことを可能
とするものであり、さらに経済性、施工性の向上が期待
できる。According to the present invention, the expansion and contraction of the packer and the ejection of the grout material such as cement milk from the nozzle are linked, so that the boring and grout processes are unified, and sufficient grout infiltration and injection are performed at a limited position. It is possible to further improve economy and workability.
【００２４】[0024]
【発明の実施の形態】図１は、本願の請求項１、２に係
る発明を既設構造物１としてのケーソン岸壁の下方地盤
３に適用した場合の一実施形態を示したものである。背
面地盤４については、従来の深礎工法などを応用してボ
ーリング孔６’からセメントミルクなどの固化材をノズ
ルから水平方向に高圧で噴出させ、直径数ｍ程度の地盤
改良部分７’を適切な間隔で造成して行くことにより、
この部分の地盤沈下や液状化を抑止することができる。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment in which the invention according to claims 1 and 2 of the present application is applied to the ground 3 below a caisson quay as an existing structure 1. FIG. For the back ground 4, a solidified material such as cement milk is ejected from a borehole 6 'at a high pressure in a horizontal direction from a nozzle by applying a conventional deep foundation method or the like, and a ground improvement portion 7' having a diameter of about several meters is appropriately formed. By building at regular intervals,
Subsidence and liquefaction of this part can be suppressed.
【００２５】一方、液状化が生じた場合に、より既設構
造物１の移動、変形に影響を与える下方地盤３につい
て、本実施形態では地表から構造物１の下方を横断する
形で自在ボーリングを行い、下方地盤３部分で水平方向
の地盤改良部分７を造成する。地盤改良部分７の造成
は、背面地盤４と同様、セメントミルクなどの固化材を
ノズルから水平方向に高圧で噴出させて行うことができ
る。On the other hand, in the case of the lower ground 3 which affects the movement and deformation of the existing structure 1 when liquefaction occurs, in the present embodiment, free boring is performed so as to cross from the ground surface to below the structure 1. Then, a horizontal ground improvement portion 7 is formed in the lower ground 3 portion. The formation of the ground improvement portion 7 can be performed by ejecting a solidified material such as cement milk from a nozzle at a high pressure in the horizontal direction, similarly to the back ground 4.
【００２６】ただし、背面地盤４と下方地盤３とで必ず
しも同様の地盤改良を行う必要はなく、また背面地盤４
について、排水パイプなどを利用した対策を施すことも
考えられる。図２は、請求項１、２に係る発明における
既設構造物１とその下方地盤３に造成される地盤改良部
分７との関係を概念的に示したもので、地盤改良部分７
を２方向から井桁状に造成し、これを対象地盤の層厚に
応じて複数段（図では３段）設けている。However, it is not always necessary to perform the same ground improvement on the back ground 4 and the lower ground 3.
It is also conceivable to take countermeasures using drainage pipes. FIG. 2 conceptually shows the relationship between the existing structure 1 and the ground improvement portion 7 formed below the ground 3 according to the first and second aspects of the present invention.
Are formed in a double-girder shape from two directions, and a plurality of (three in the figure) are provided according to the layer thickness of the target ground.
【００２７】このような構成とすることで、直接的には
地盤改良がなされていない井桁内部についても地盤改良
部分７で周囲から拘束されることで、せん断抵抗力の低
下が抑制され、例えば仮にこの部分について部分的な液
状化が生じても井桁部分で地盤としての耐力を維持する
ことができる。With such a configuration, the inside of the girder, which has not been directly improved in ground, is also restrained from the surroundings by the ground improvement portion 7, so that the reduction in shear resistance is suppressed. Even if partial liquefaction occurs in this part, the strength as the ground can be maintained at the well girder part.
【００２８】図２は構造物１を立方体に簡略化して示し
ているが、図１のケーソン岸壁のように一方向に連続す
る構造物であれば地盤改良部分７により井桁をその方向
に多数連続させ、また平面的な広がりが大きい構造物で
あれば、地盤改良部分７を格子状に配置することもでき
る。FIG. 2 schematically shows the structure 1 as a cube, but if the structure is continuous in one direction, such as the caisson quay in FIG. If the structure has a large planar spread, the ground improvement portions 7 can be arranged in a lattice.
【００２９】図３は、本願の請求項３〜５に係る発明の
一実施形態を概略的に示したもので、既設構造物１下方
の軟弱な地盤３に対し、離れた位置の地表からボーリン
グによるボーリング孔６を穿孔し、このボーリング孔６
を利用して、その周囲に地盤改良部分７を造成する。FIG. 3 schematically shows one embodiment of the invention according to claims 3 to 5 of the present application. The soft ground 3 below the existing structure 1 is drilled from a ground surface at a remote position. The boring hole 6 is drilled, and the boring hole 6
The ground improvement part 7 is formed around it by utilizing.
【００３０】このような地盤改良部分７を対象地盤を取
り囲むように方形に設け（図中、７Ａが方形部分）、さ
らのその内側に地盤改良部分７を版状に斜めに設けるこ
とで、斜壁部分７Ｂを形成している。方形部分７Ａは、
ケーソン岸壁などの構造物１の長手方向に延びる形で、
構造物１下方の地盤を補強し、さらにその内側に、斜壁
部分７Ｂを設けることで、特に地震時の水平力に対し
て、この部分をトラス構造的に機能させることができ
る。Such a ground improvement portion 7 is provided in a square shape so as to surround the target ground (in the figure, 7A is a square portion), and the ground improvement portion 7 is further provided diagonally in the form of a plate, thereby forming a slope. A wall portion 7B is formed. The square part 7A is
In a form extending in the longitudinal direction of the structure 1 such as a caisson quay,
By reinforcing the ground below the structure 1 and further providing the slope wall portion 7B inside the ground, this portion can function as a truss structure particularly against horizontal force during an earthquake.
【００３１】図４は、本願の請求項６に係る発明におけ
る地盤改良部分の形態を概念的に示したもので、地盤改
良部分７を対象地盤を取り囲むように設けた方形部分７
Ａに対し、これと直交する方向からボーリング孔を利用
した地盤改良部分を鉛直壁状に設け、この鉛直壁状部分
７Ｃにより方形部分７Ａを長手方向に仕切っている。FIG. 4 conceptually shows the form of the ground improvement portion in the invention according to claim 6 of the present application. The ground improvement portion 7 is provided with a rectangular portion 7 provided so as to surround the target ground.
In contrast to A, a ground improvement portion using a boring hole is provided in a vertical wall shape from a direction orthogonal to this, and a rectangular portion 7A is partitioned in the longitudinal direction by the vertical wall portion 7C.
【００３２】この鉛直壁状部分７Ｃは、地盤沈下対策と
しての機能に加え、地震時の水平力に対し、耐震壁的に
機能させることができる。図５は、ボーリングとグラウ
ト工程を一元化した本願の請求項７に係る発明における
ボーリングおよびボーリング孔６からのグラウトによる
地盤改良の施工手順の一例を示したもので、以下のよう
な手順で作業を行うことができる。The vertical wall portion 7C can function not only as a countermeasure against ground subsidence but also as a seismic wall against horizontal force during an earthquake. FIG. 5 shows an example of a procedure for soil improvement by boring and grouting from the boring hole 6 in the invention according to claim 7 in which the boring and grouting processes are unified. It can be carried out.
【００３３】図１に示すような自在ボーリングによ
り、液状化対策の対象となる下方地盤まで削孔する（図
５(a) 参照）。 ボーリング装置のロッド１１の先端部ノズルの後方に
設けたゴム製の袋体などからなるパッカー１２を膨張さ
せ、先端部のノズルから径方向にグラウト（セメントミ
ルクなど）を高圧で噴射し、地盤改良を行う（図５(b)
参照）。A free boring as shown in FIG. 1 is used to drill a hole to the lower ground to be subjected to liquefaction countermeasures (see FIG. 5 (a)). The packer 12 made of a rubber bag or the like provided behind the tip nozzle of the rod 11 of the boring device is inflated, and grout (cement milk or the like) is jetted from the tip nozzle at a high pressure in the radial direction to improve the ground. (Fig. 5 (b)
reference).
【００３４】パッカー１２を収縮させ、次の区間を削
孔する（図５(c) 参照）。 パッカー１２を膨張させ、と同様、ノズルからグラ
ウトを高圧で噴射し、この区間の地盤改良を行う（図５
(d) 参照）。 以下、削孔、グラウトを繰り返し、所定の区間につい
て地盤改良体を造成した後、ロッド１１を引き抜きなが
ら、穴埋めする（図５(e) 参照）。The packer 12 is contracted, and the next section is drilled (see FIG. 5C). As in the case of expanding the packer 12, grout is injected from the nozzle at a high pressure to improve the ground in this section (FIG. 5).
(d)). Thereafter, drilling and grouting are repeated to form a ground improvement body for a predetermined section, and then the hole is filled while the rod 11 is pulled out (see FIG. 5 (e)).
【００３５】以上により、１つの地盤改良部分７が造成
されることになる。As described above, one ground improvement portion 7 is formed.
【００３６】[0036]
【発明の効果】本願の請求項１、２に係る発明では、
ボーリング孔を利用したほぼ水平方向に延びる地盤改良
部分を井桁状または格子状に設けるため、井桁または格
子内部の地盤についても、強度を確保した地盤改良部分
で周囲から拘束することになり、少ないボーリング本数
で経済的に、かつ効率よく既設構造物下を地盤改良し、
地盤沈下や地盤の液状化を抑止することができる。According to the first and second aspects of the present invention,
Since the ground improvement part that extends in the substantially horizontal direction using the boring holes is provided in the shape of a girder or lattice, the ground inside the girder or lattice is also constrained from the surroundings by the ground improvement part that has ensured strength, and less boring Economically and efficiently improve the ground under the existing structure with the number of
Land subsidence and ground liquefaction can be suppressed.
【００３７】本願の請求項３〜５に係る発明では、ボ
ーリング孔を利用した地盤改良部分を鉛直断面において
対象地盤を取り囲むように設けることで、その内側の未
改良部分の拘束効果も含めて、対象地盤を補強し、さら
に必要に応じその内側を仕切る版状あるいは斜壁状の地
盤改良体を形成することで、地盤の補強効果を高めるこ
とができる。In the invention according to claims 3 to 5 of the present application, by providing the ground improvement portion using the boring hole so as to surround the target ground in the vertical cross section, it includes the effect of restraining the unimproved portion inside the ground. The reinforcing effect of the ground can be enhanced by reinforcing the target ground and, if necessary, forming a plate-shaped or inclined wall-shaped ground improvement body that partitions the inside thereof.
【００３８】本願の請求項６に係る発明では、請求項
３〜５に係る発明に対し、さらにその内側を長手方向と
ほぼ直角な鉛直壁状部分で仕切ることで、補強効果をさ
らに高めることができる。 また、請求項７に係る発明では、パッカーの膨張、収
縮と、ノズルからのセメントミルク等のグラウト材の噴
出を連動させ、ボーリングとグラウト工程を一元化し、
さらに経済性、施工性の向上を図ることができる。In the invention according to claim 6 of the present application, the reinforcing effect can be further enhanced by further dividing the inner side by a vertical wall portion substantially perpendicular to the longitudinal direction, as compared with the invention according to claims 3 to 5. it can. Further, in the invention according to claim 7, the expansion and contraction of the packer and the ejection of grout material such as cement milk from the nozzle are linked, and the boring and grout processes are unified,
Further, the economy and workability can be improved.
【図１】 本願の請求項１、２に係る発明を既設構造物
としてのケーソン岸壁下の地盤に適用した場合の一実施
形態を示す鉛直断面図である。FIG. 1 is a vertical sectional view showing an embodiment in which the invention according to claims 1 and 2 of the present application is applied to the ground under a caisson quay as an existing structure.
【図２】 本願の請求項１、２に係る発明における構造
物と構造物下の地盤に造成される地盤改良部分との関係
を概念的に示した図である。FIG. 2 is a diagram conceptually showing a relationship between a structure and a ground improvement portion formed on the ground under the structure in the invention according to claims 1 and 2 of the present application.
【図３】 本願の請求項３〜５に係る発明を既設構造物
としてのケーソン岸壁下の地盤に適用した場合の一実施
形態を示す鉛直斜視図である。FIG. 3 is a vertical perspective view showing one embodiment in which the invention according to claims 3 to 5 of the present application is applied to the ground under a caisson quay as an existing structure.
【図４】 本願の請求項６に係る発明における地盤改良
部分の形態を概念的に示したもので、(a) は断面斜視
図、(b) は平面図である。FIGS. 4A and 4B conceptually show a form of a ground improvement portion in the invention according to claim 6 of the present application, wherein FIG. 4A is a perspective sectional view and FIG. 4B is a plan view.
【図５】 本願の請求項７に係る発明におけるボーリン
グおよびボーリング孔からのグラウトによる地盤改良の
施工手順を示す断面図である。FIG. 5 is a cross-sectional view showing a construction procedure of soil improvement by boring and grout from a boring hole in the invention according to claim 7 of the present application.
【図６】 液状化対策が施されなかった場合の既設構造
物としてのケーソン岸壁の被災状況を概念的に示した鉛
直断面図である。FIG. 6 is a vertical sectional view conceptually showing a damage situation of a caisson quay as an existing structure when no liquefaction countermeasures are taken.
１…既設構造物、２…基礎捨石、３…下方地盤（置換
砂）、４…背面地盤（埋立土）、５…粘土層、６…ボー
リング孔、７…地盤改良部分、７Ａ…方形部分、７Ｂ…
斜壁部分、７Ｃ…鉛直壁状部分、１１…ロッド、１２…
パッカーDESCRIPTION OF SYMBOLS 1 ... Existing structure, 2 ... Foundation rubble, 3 ... Lower ground (replacement sand), 4 ... Back ground (reclaimed soil), 5 ... Clay layer, 6 ... Boring hole, 7 ... Ground improvement part, 7A ... Square part, 7B ...
Sloping wall part, 7C ... vertical wall-like part, 11 ... rod, 12 ...
Packer
───────────────────────────────────────────────────── フロントページの続き (72)発明者 相河 清実 東京都港区元赤坂１丁目２番７号 鹿島建 設株式会社内 Ｆターム(参考） 2D040 AA01 AB01 BB01 BD02 BD03 BD05 CA01 CB03 DC02 2D043 CA01 EA01 EA06 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kiyomi Aikawa 2-7 Motomoto Akasaka, Minato-ku, Tokyo Kashima Construction Co., Ltd. F-term (reference) 2D040 AA01 AB01 BB01 BD02 BD03 BD05 CA01 CB03 DC02 2D043 CA01 EA01 EA06
Claims (7)
をほぼ水平にボーリングしながら、ボーリング孔を利用
してボーリング孔の周囲に地盤改良部分を造成し、この
ようなボーリング孔の周囲に形成される地盤改良部分を
平面的に見て井桁状または格子状に設けることを特徴と
する既設構造物下方地盤の補強工法。1. A boring hole is used to form a ground improvement portion around a boring hole while boring the ground under the existing structure substantially horizontally in the ground. A method for reinforcing the ground below an existing structure, wherein the ground improvement portion formed on the ground is provided in a cross-girder or lattice shape when viewed in plan.
盤改良部分を鉛直方向に複数段設けることを特徴とする
請求項１記載の既設構造物下方地盤の補強工法。2. The method for reinforcing ground below an existing structure according to claim 1, wherein the ground improvement portion formed by using a boring hole is provided in a plurality of stages in a vertical direction.
をほぼ水平にボーリングしながら、ボーリング孔を利用
してボーリング孔の周囲に地盤改良部分を造成し、この
ようなボーリング孔の周囲に形成される地盤改良部分
を、鉛直断面で見て補強の対象となる地盤の周囲または
内部を取り囲むように設けることを特徴とする既設構造
物下方地盤の補強工法。3. A boring hole is used to form a ground improvement portion around a boring hole while boring the ground under the existing structure substantially horizontally in the ground. A method for reinforcing the ground below an existing structure, wherein the ground improvement portion formed on the ground is provided so as to surround the periphery or the inside of the ground to be reinforced when viewed in a vertical cross section.
囲むように設けた前記地盤改良部分の内側を仕切るよう
に、さらに同様の地盤改良部分を版状に設けることを特
徴とする請求項３記載の既設構造物下方地盤の補強工
法。4. A similar ground improvement part is provided in the form of a plate so as to partition the inside of the ground improvement part provided so as to surround or surround the target ground. Reinforcement method for the ground below the existing structure.
あることを特徴とする請求項４記載の既設構造物下方地
盤の補強工法。5. The method of reinforcing the ground below an existing structure according to claim 4, wherein the ground improvement portion partitioning the inside is a slope wall.
囲むように設けた前記地盤改良部分とほぼ直交する方向
にも該地盤改良部分を長手方向に仕切る形で、同様の地
盤改良部分を鉛直壁状に設けることを特徴とする請求項
３、４または５記載の既設構造物下方地盤の補強工法。6. A similar ground improvement part is formed by partitioning the ground improvement part in a longitudinal direction also in a direction substantially orthogonal to the ground improvement part provided to surround or surround the target ground. The method for reinforcing the ground below an existing structure according to claim 3, wherein the reinforcement is provided in a shape like a circle.
区間に複数のグラウト材注入用のノズルを有し、前記複
数のノズルを設けた区間の後方に径方向に膨張可能なパ
ッカーを有するボーリング装置によって行い、前記パッ
カーを収縮させた状態で所定区間掘進する工程と、その
後、前記パッカーを膨張させてボーリング孔の孔壁に密
着させた状態で、前記ノズルからグラウト材を高圧で噴
出させてボーリング孔周囲の地盤改良を行う工程とを所
要回数繰り返すことで、前記地盤改良部分を造成するこ
とを特徴とする請求項１〜６の何れか１項に記載の既設
構造物下方地盤の補強工法。7. The boring hole is formed by boring having a plurality of grout material injection nozzles in a predetermined section at a tip end and a radially expandable packer behind a section provided with the plurality of nozzles. Performed by a device, a step of digging a predetermined section in a state where the packer is contracted, and then, in a state where the packer is expanded and in close contact with the hole wall of the boring hole, a grout material is ejected from the nozzle at a high pressure. The method of reinforcing the ground below the existing structure according to any one of claims 1 to 6, wherein the ground improvement portion is formed by repeating the step of performing the ground improvement around the boring hole a required number of times. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000018302A JP3714395B2 (en) | 2000-01-27 | 2000-01-27 | Reinforcement method for the ground below existing structures |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000018302A JP3714395B2 (en) | 2000-01-27 | 2000-01-27 | Reinforcement method for the ground below existing structures |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001207437A true JP2001207437A (en) | 2001-08-03 |
| JP3714395B2 JP3714395B2 (en) | 2005-11-09 |
Family
ID=18545166
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2000018302A Expired - Fee Related JP3714395B2 (en) | 2000-01-27 | 2000-01-27 | Reinforcement method for the ground below existing structures |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3714395B2 (en) |
Cited By (9)
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|---|---|---|---|---|
| JP2001355229A (en) * | 2000-06-13 | 2001-12-26 | Takenaka Komuten Co Ltd | Grid interval simplified calculating method for liquefaction prevention on grid-like improved ground by deep layer mixing process method |
| JP2005248632A (en) * | 2004-03-05 | 2005-09-15 | Kanpai Co Ltd | Liquid injection method, recharge method and chemical grouting method |
| JP2007046343A (en) * | 2005-08-10 | 2007-02-22 | Takenaka Komuten Co Ltd | Liquefaction preventive construction method of ground just under existing building |
| JP2007284875A (en) * | 2006-04-12 | 2007-11-01 | Tekken Constr Co Ltd | Soil improvement construction method by high-pressure injection stirring |
| JP2008267008A (en) * | 2007-04-20 | 2008-11-06 | Ohbayashi Corp | Ground reinforcement structure, construction method for the ground reinforcement structure and ground reinforcing member |
| CN101900533A (en) * | 2010-07-23 | 2010-12-01 | 水利部交通运输部国家能源局南京水利科学研究院 | Optical fiber grating measurement method for monitoring embankment section settlement |
| JP2011184915A (en) * | 2010-03-08 | 2011-09-22 | Chemical Grouting Co Ltd | Aseismatic reinforcing method for existing revetment |
| JP2019112836A (en) * | 2017-12-25 | 2019-07-11 | 鹿島建設株式会社 | Liquefaction countermeasure method |
| JP2020002539A (en) * | 2018-06-25 | 2020-01-09 | 株式会社フジタ | Soil improvement body and foundation structure of building |
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| JPH11217837A (en) * | 1998-01-30 | 1999-08-10 | Shimizu Corp | Soil improvement method |
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| JPH05311638A (en) * | 1992-05-08 | 1993-11-22 | Kajima Corp | Liquefaction-suppressed ground |
| JPH07317052A (en) * | 1994-05-30 | 1995-12-05 | Nittoc Constr Co Ltd | Method of dynamic injection construction for foundation improvement |
| JPH08120661A (en) * | 1994-10-19 | 1996-05-14 | Nippon Steel Corp | Device for ground under existing structure for preventing liquefaction of ground |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001355229A (en) * | 2000-06-13 | 2001-12-26 | Takenaka Komuten Co Ltd | Grid interval simplified calculating method for liquefaction prevention on grid-like improved ground by deep layer mixing process method |
| JP2005248632A (en) * | 2004-03-05 | 2005-09-15 | Kanpai Co Ltd | Liquid injection method, recharge method and chemical grouting method |
| JP2007046343A (en) * | 2005-08-10 | 2007-02-22 | Takenaka Komuten Co Ltd | Liquefaction preventive construction method of ground just under existing building |
| JP2007284875A (en) * | 2006-04-12 | 2007-11-01 | Tekken Constr Co Ltd | Soil improvement construction method by high-pressure injection stirring |
| JP2008267008A (en) * | 2007-04-20 | 2008-11-06 | Ohbayashi Corp | Ground reinforcement structure, construction method for the ground reinforcement structure and ground reinforcing member |
| JP2011184915A (en) * | 2010-03-08 | 2011-09-22 | Chemical Grouting Co Ltd | Aseismatic reinforcing method for existing revetment |
| CN101900533A (en) * | 2010-07-23 | 2010-12-01 | 水利部交通运输部国家能源局南京水利科学研究院 | Optical fiber grating measurement method for monitoring embankment section settlement |
| JP2019112836A (en) * | 2017-12-25 | 2019-07-11 | 鹿島建設株式会社 | Liquefaction countermeasure method |
| JP2020002539A (en) * | 2018-06-25 | 2020-01-09 | 株式会社フジタ | Soil improvement body and foundation structure of building |
| JP7098436B2 (en) | 2018-06-25 | 2022-07-11 | 株式会社フジタ | Foundation structure of the building |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3714395B2 (en) | 2005-11-09 |
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