JP3750065B1 - Ground improvement method - Google Patents

Ground improvement method Download PDF

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JP3750065B1
JP3750065B1 JP2005159316A JP2005159316A JP3750065B1 JP 3750065 B1 JP3750065 B1 JP 3750065B1 JP 2005159316 A JP2005159316 A JP 2005159316A JP 2005159316 A JP2005159316 A JP 2005159316A JP 3750065 B1 JP3750065 B1 JP 3750065B1
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injection
injection hole
reaction material
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ground improvement
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JP2006336219A (en
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廣貴 川崎
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Shimizu Corp
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Abstract

【課題】 硬化材と反応材を均一に混合して、排泥中に硬化材が混入しないようにするとともに、大径の地盤改良体を経済的かつ合理的に造成することができる地盤改良工法を提供する。
【解決手段】 注入ロッド1の先端部は、切削水および圧縮空気を噴射する上段部2と、硬化材および反応材を噴射する下段部3とを備えている。上段部2の側面には、切削水を噴射する第一噴射孔12aと、第一噴射孔12aの外周部に設けられ、圧縮空気を噴射する第二噴射孔12bとからなる上段噴射孔12が設けられており、圧縮空気に包囲された切削水が上段噴射孔12から噴射される。一方、下段部3の側面には、注入ロッド1の回転方向Rに対して、反応材噴射孔14が硬化材噴射孔13の下流側となるように、ほぼ同じ高さに硬化材噴射孔13と反応材噴射孔14が近接配置されており、硬化材と反応材は、それぞれ硬化材噴射孔13、反応材噴射孔14から同時に噴射される。
【選択図】 図1
PROBLEM TO BE SOLVED: To improve a ground improvement method capable of economically and rationally creating a large-diameter ground improvement body while uniformly mixing a hardening material and a reaction material so that the hardening material is not mixed in the waste mud. I will provide a.
The tip of an injection rod 1 includes an upper stage 2 for injecting cutting water and compressed air, and a lower stage 3 for injecting a hardener and a reactive material. On the side surface of the upper stage portion 2, there is an upper stage injection hole 12 comprising a first injection hole 12 a for injecting cutting water and a second injection hole 12 b provided on the outer periphery of the first injection hole 12 a for injecting compressed air. The cutting water that is provided and surrounded by the compressed air is injected from the upper injection hole 12. On the other hand, on the side surface of the lower stage portion 3, the hardener injection hole 13 is substantially level with the reaction material injection hole 14 on the downstream side of the hardener injection hole 13 with respect to the rotation direction R of the injection rod 1. And the reaction material injection hole 14 are disposed close to each other, and the curing material and the reaction material are simultaneously injected from the curing material injection hole 13 and the reaction material injection hole 14, respectively.
[Selection] Figure 1

Description

本発明は、地盤改良工法に関し、特に、地盤中に硬化材を噴射して攪拌混合することにより当該地盤中に地盤改良体を造成する高圧噴射攪拌工法に関する。   The present invention relates to a ground improvement method, and more particularly, to a high-pressure jet stirring method for creating a ground improvement body in the ground by spraying a hardener into the ground and mixing with stirring.

従来より、柱状の地盤改良体を地盤中に形成する地盤改良工法の一つとして高圧噴射攪拌工法が実施されている。しかし、硬化材の高圧噴射に伴って排出される泥土中に硬化材が混入するため、その処理に多大な費用が掛かるという問題があった。
そこで、特許文献1では、注入ロッドを引き上げつつ、圧縮空気で包囲した水を上部側の噴射ノズルから噴射するとともに、下部側の噴射ノズルからセメントミルク等の硬化材を噴射しつつ、水ガラス等の反応材を別の噴射ノズルから噴射して、硬化材を早期に硬化させる技術が開示されている。具体的には、先ず圧縮空気を伴った水を高圧で噴射することによって地盤を切削する。水だけを噴射するため、基本的に排泥中に硬化材は混入しないのであるが、下部側の噴射ノズルから噴射した硬化材が硬化していなければ、上部側での混気ジェット現象により、硬化材が吸い上げられて排泥中に混入するおそれがある。そのため、硬化材とともに反応材を噴射して硬化材を早期に硬化させ、排泥中に硬化材が混入しないようにしている。
他方、硬化材と反応材の噴射に関する先行技術文献としては、特許文献2や特許文献3がある。
特許第3626972号公報 (第4−5頁、第1−7図) 特開2000−199222号公報 (第3−6頁、第1−9図) 特開2000−290991号公報 (第3−6頁、第1−7図)
Conventionally, a high-pressure jet stirring method has been implemented as one of the ground improvement methods for forming a columnar ground improvement body in the ground. However, since the hardener is mixed in the mud discharged with the high-pressure injection of the hardener, there is a problem in that the processing is very expensive.
Therefore, in Patent Document 1, while pulling up the injection rod, water surrounded by compressed air is injected from the upper injection nozzle, and a hardening material such as cement milk is injected from the lower injection nozzle, water glass, etc. A technique is disclosed in which the reaction material is sprayed from another spray nozzle to harden the curing material at an early stage. Specifically, the ground is first cut by jetting water with compressed air at a high pressure. Since only water is injected, the hardener is basically not mixed in the sludge, but if the hardener injected from the lower injection nozzle is not hardened, due to the mixed jet phenomenon on the upper side, Hardened material may be sucked up and mixed in the waste mud. Therefore, the reaction material is injected together with the curing material to cure the curing material at an early stage so that the curing material is not mixed in the waste mud.
On the other hand, there are Patent Document 2 and Patent Document 3 as prior art documents relating to the injection of the curing material and the reaction material.
Japanese Patent No. 3626972 (page 4-5, FIG. 1-7) JP 2000-199222 A (page 3-6, FIG. 1-9) JP 2000-290991 A (page 3-6, FIG. 1-7)

しかしながら、特許文献1に記載された技術を実施した場合、硬化材と反応材の混合が不均一となるため、硬化材の強度発現が不充分となり、排泥中に硬化材が混入するのを充分に防止できないという問題があった。
この原因としては以下のようなことが考えられる。
a.反応材噴射ノズルが硬化材噴射ノズルの下方に位置している(特許文献1の図7参照)。
引き上げ時における注入なので、噴射された硬化材に後から反応材を噴射することになるが、一般に反応材のほうが硬化材よりも量が少ないため、多量の硬化材中に少量の反応材を噴射しても混合が不均一となる。
b.硬化材噴射ノズルと反応材噴射ノズルが同じ高さでかつ注入ロッドの正反対の位置に設けられている(特許文献1の図2参照)。
注入ロッドの引き上げは、一般に1回転ごとのピッチ上昇(通常2.5cm)なので、1ピッチにおいて、硬化材噴射ノズルが反応材噴射ノズルよりも回転方向の下流側にあって、硬化材の噴射後に反応材を噴射するような場合には、前記と同様に、硬化材と反応材の混合が不均一となる。
However, when the technique described in Patent Document 1 is implemented, since the mixing of the curing material and the reaction material becomes uneven, the strength expression of the curing material becomes insufficient, and the curing material is mixed into the waste mud. There was a problem that it could not be prevented sufficiently.
The following can be considered as the cause.
a. The reaction material injection nozzle is located below the curing material injection nozzle (see FIG. 7 of Patent Document 1).
Since the injection is performed at the time of pulling up, the reactive material is injected later onto the injected hardened material, but generally the amount of the reactive material is smaller than the hardened material, so a small amount of the reactive material is injected into a large amount of hardened material. Even so, the mixing becomes uneven.
b. The curing material injection nozzle and the reaction material injection nozzle are provided at the same height and at positions opposite to the injection rod (see FIG. 2 of Patent Document 1).
The injection rod is generally lifted at a pitch increase of one rotation (usually 2.5 cm), so that at one pitch, the curing material injection nozzle is located downstream of the reaction material injection nozzle in the rotation direction, and after the injection of the curing material. In the case of injecting the reaction material, the mixture of the curing material and the reaction material becomes non-uniform as described above.

他方、特許文献2では、反応材の噴射孔を硬化材の噴射孔の上方に設けている。しかし、噴射孔間の離間距離は明記されておらず、一般に行われている注入ロッドのピッチ引き上げによる場合、この離間距離が引上げピッチの整数倍になっていなければ、硬化材の噴射位置が反応材の噴射位置と合致せず、硬化材と反応材の混合が不均一となるおそれがある。
また、特許文献3では、硬化材(反応材)を噴射する内部ノズルと、当該内部ノズルを同芯(偏芯していてもよい)状に包囲し、反応材(硬化材)を噴射する外周ノズルから、それぞれ硬化材と反応材を同時に噴射するようにしている。しかし、例えば、外周ノズルから反応材を噴射する場合、引き上げ噴射では、外周ノズルの下側部分から噴射される反応材が硬化材と混合しないおそれがある。また、内部ノズルよりも外周ノズルから噴射したほうが噴射抵抗が大きいので、同じ圧力で噴射した場合、内部ノズルから噴射したほうが遠くまでとぶことになる。そのため、外周ノズルから反応材を噴射した場合、前記と同様に、硬化材と反応材の混合が不均一となる。
On the other hand, in patent document 2, the injection hole of the reaction material is provided above the injection hole of the hardening | curing material. However, the separation distance between the injection holes is not specified, and in the case of generally increasing the pitch of the injection rod, if the separation distance is not an integral multiple of the pulling pitch, the injection position of the curing material will react. There is a possibility that the mixing position of the curing material and the reaction material becomes non-uniform because it does not match the injection position of the material.
Moreover, in patent document 3, the outer nozzle which surrounds the internal nozzle which injects a hardening material (reaction material), and the said internal nozzle in the shape of concentricity (it may be eccentric), and injects a reaction material (hardening material). The curing material and the reactive material are simultaneously ejected from the nozzles. However, for example, when the reaction material is injected from the outer peripheral nozzle, the reaction material injected from the lower portion of the outer peripheral nozzle may not be mixed with the curing material in the pull-up injection. Moreover, since the injection resistance is larger when sprayed from the outer peripheral nozzle than the internal nozzle, when sprayed at the same pressure, the spray from the internal nozzle will be farther away. Therefore, when the reaction material is ejected from the outer peripheral nozzle, the mixture of the curing material and the reaction material becomes non-uniform as described above.

本発明は、上述する問題点に鑑みてなされたもので、硬化材と反応材を均一に混合して、排泥中に硬化材が混入しないようにするとともに、大径の地盤改良体を経済的かつ合理的に造成することができる地盤改良工法を提供することを目的とする。   The present invention has been made in view of the above-described problems. The hardened material and the reaction material are uniformly mixed so that the hardened material is not mixed in the waste mud, and a large-diameter ground improvement body is economically used. The purpose is to provide a ground improvement method that can be constructed reasonably and rationally.

上記目的を達成するため、本発明は、先端部に上下二段の噴射孔を備えた注入ロッドを地盤に挿入し、当該注入ロッドを回転させながら引き上げる際に、上段側の噴射孔から圧縮空気とともに切削水を噴射して地盤を切削しつつ、下段側の一方の噴射孔から硬化材を噴射するとともに、下段側の他方の噴射孔から反応材を噴射して、地盤中に柱状の地盤改良体を造成する地盤改良工法において、前記注入ロッドの回転時に、前記反応材を噴射する噴射孔(以下、反応材噴射孔と称す)が前記硬化材を噴射する噴射孔(以下、硬化材噴射孔と称す)の下流側となるように、ほぼ同じ高さに硬化材噴射孔と反応材噴射孔を近接配置し、前記硬化材と前記反応材を同時に噴射することを特徴とする。
本発明では、反応材噴射孔を硬化材噴射孔の下流側として、ほぼ同じ高さに近接配置するので、反応材の噴射後、ほぼ同じ位置で直ちに硬化材が噴射される。その結果、反応材を巻き込んだ硬化材が噴射されるようになり、硬化材と反応材が均一に混合される。
In order to achieve the above-mentioned object, the present invention inserts an injection rod having two upper and lower injection holes at the tip into the ground and pulls the compressed air from the upper injection hole when the injection rod is pulled up while rotating. In addition, while cutting the ground by cutting the cutting water, the hardened material is sprayed from one of the lower injection holes and the reactive material is injected from the lower injection hole to improve the columnar ground in the ground. In the ground improvement method for creating a body, an injection hole (hereinafter referred to as a reaction material injection hole) for injecting the reaction material when the injection rod rotates (hereinafter referred to as a reaction material injection hole) The curing material injection hole and the reaction material injection hole are arranged close to each other at substantially the same height so as to be on the downstream side, and the curing material and the reaction material are simultaneously injected.
In the present invention, since the reaction material injection hole is disposed on the downstream side of the curing material injection hole and close to substantially the same height, the curing material is injected immediately at substantially the same position after the reaction material is injected. As a result, the curing material including the reaction material is injected, and the curing material and the reaction material are uniformly mixed.

また、本発明は、先端部に上下二段の噴射孔を備えた注入ロッドを地盤に挿入し、当該注入ロッドを回転させながら引き上げる際に、上段側の噴射孔から圧縮空気とともに切削水を噴射して地盤を切削し、下段側の一方の噴射孔から硬化材を噴射しつつ、下段側の他方の噴射孔から反応材を噴射して、地盤中に柱状の地盤改良体を造成する地盤改良工法において、硬化材噴射孔と反応材噴射孔の位置を平断面視でほぼ同じ位置とし、前記硬化材噴射孔の上方に、前記注入ロッドの引上げピッチの整数倍の距離をおいて前記反応材噴射孔を配し、前記硬化材と前記反応材を同時に噴射することを特徴とする。
本発明では、硬化材噴射孔と反応材噴射孔の離間距離を注入ロッドの引上げピッチの整数倍としているので、反応材の噴出位置と硬化材の噴出位置が同一となり、硬化材と反応材の均一混合が可能となる。
The present invention also injects cutting water together with compressed air from an upper injection hole when an injection rod having two upper and lower injection holes at the tip is inserted into the ground and pulled up while rotating the injection rod. The ground is improved by cutting the ground and spraying the reaction material from the other injection hole on the lower side while injecting the hardened material from one injection hole on the lower side to create a columnar ground improvement body in the ground. In the construction method, the positions of the curing material injection hole and the reaction material injection hole are substantially the same in a plan view, and the reaction material is spaced above the curing material injection hole by an integral multiple of the pulling pitch of the injection rod. An injection hole is provided, and the curing material and the reaction material are simultaneously injected.
In the present invention, since the distance between the curing material injection hole and the reaction material injection hole is an integral multiple of the pulling pitch of the injection rod, the ejection position of the reaction material and the ejection position of the curing material are the same, and the curing material and the reaction material Uniform mixing is possible.

また、本発明では、前記反応材の噴射圧力は、前記硬化材の噴射圧力より小さいことを好適とする。
反応材の噴射圧力を硬化材の噴射圧力より大きくすると、反応材を硬化材よりも遠くにとばすことになり、遠くにとんだ反応材を無駄にすることになる。そこで、本発明では、反応材の噴射圧力を硬化材の噴射圧力より小さくし、経済的かつ合理的に地盤改良体を造成するものである。
Moreover, in this invention, it is suitable that the injection pressure of the said reaction material is smaller than the injection pressure of the said hardening material.
If the injection pressure of the reaction material is made larger than the injection pressure of the curing material, the reaction material is skipped farther than the curing material, and the reaction material that has come to a distance is wasted. Therefore, in the present invention, the ground material is formed economically and rationally by reducing the injection pressure of the reaction material to be lower than the injection pressure of the curing material.

本発明に係る地盤改良工法では、反応材噴射孔を硬化材噴射孔の下流側として、ほぼ同じ高さに近接配置するので、反応材の噴射後、ほぼ同じ位置で直ちに硬化材が噴射される。その結果、反応材を巻き込んだ硬化材が噴射されるようになり、硬化材と反応材が均一に混合される。
また、本発明に係る地盤改良工法では、硬化材噴射孔と反応材噴射孔の離間距離を注入ロッドの引上げピッチの整数倍としているので、反応材の噴射位置と硬化材の噴射位置が同一となり、硬化材と反応材の均一混合が可能となる。
さらに、本発明に係る地盤改良工法では、反応材の噴射圧力を硬化材の噴射圧力より小さくすることにより、経済的かつ合理的に地盤改良体を造成することができる。
In the ground improvement method according to the present invention, since the reaction material injection hole is arranged on the downstream side of the hardening material injection hole and close to substantially the same height, the hardening material is immediately injected at substantially the same position after the injection of the reaction material. . As a result, the curing material including the reaction material is injected, and the curing material and the reaction material are uniformly mixed.
Further, in the ground improvement method according to the present invention, the separation distance between the curing material injection hole and the reaction material injection hole is an integral multiple of the pulling pitch of the injection rod, so the injection position of the reaction material and the injection position of the hardening material are the same. The uniform mixing of the curing material and the reaction material becomes possible.
Further, in the ground improvement method according to the present invention, the ground improvement body can be economically and rationally created by making the injection pressure of the reaction material smaller than the injection pressure of the hardened material.

以下、本発明に係る地盤改良工法の実施形態について図面に基づいて説明する。
図1は、本発明に係る地盤改良工法において使用する注入ロッド先端部の一例を示したものである。
注入ロッド1は4本の筒体4、5、6、7から構成される四重管ロッドであり、その先端部は、切削水および圧縮空気を噴射する上段部2と、硬化材および反応材を噴射する下段部3とを備えている。
Hereinafter, embodiments of the ground improvement method according to the present invention will be described with reference to the drawings.
FIG. 1 shows an example of the tip of an injection rod used in the ground improvement method according to the present invention.
The injection rod 1 is a quadruple tube rod composed of four cylinders 4, 5, 6, and 7. The tip portion of the injection rod 1 is an upper stage 2 for injecting cutting water and compressed air, and a hardening material and a reaction material. The lower stage part 3 which injects this.

上段部2の側面には、第一噴射孔12aと、第一噴射孔12aの外周部に設けられた第二噴射孔12bとからなる上段噴射孔12が設けられており、第一噴射孔12a、第二噴射孔12bは、それぞれ第三の流路10、第四の流路11と連通している。第三の流路10、第四の流路11は、それぞれ超高圧の切削水、圧縮空気の流路とされており、上段噴射孔12からは圧縮空気に包囲された超高圧の切削水が噴射される。   An upper stage injection hole 12 including a first injection hole 12a and a second injection hole 12b provided on the outer periphery of the first injection hole 12a is provided on a side surface of the upper stage part 2, and the first injection hole 12a. The second injection holes 12b communicate with the third flow path 10 and the fourth flow path 11, respectively. The third flow path 10 and the fourth flow path 11 are respectively a flow path for ultra-high pressure cutting water and compressed air, and the ultra-high pressure cutting water surrounded by the compressed air is supplied from the upper injection holes 12. Be injected.

一方、下段部3の側面には、注入ロッド1の回転方向Rに対して、反応材噴射孔14が硬化材噴射孔13の下流側となるように、ほぼ同じ高さに硬化材噴射孔13と反応材噴射孔14が近接して配置されている(図1(c)参照)。硬化材噴射孔13、反応材噴射孔14は、それぞれ第一の流路8、第二の流路9と連通しており、硬化材と反応材は、それぞれ第一の流路8、第二の流路9を経由して、硬化材噴射孔13、反応材噴射孔14から同時に噴射される。この際、反応材の噴射圧力は、硬化材の噴射圧力よりも小さいほうがよい。本実施形態では、硬化材の噴射圧力50〜60MPaに対して、反応材の噴射圧力を10MPa程度としている。
また、噴射時のバランスをとるため、硬化材噴射孔13および反応材噴射孔14は、上段噴射孔12に対して、平断面視で注入ロッド1の反対側に設けられている。
On the other hand, on the side surface of the lower stage portion 3, the hardener injection hole 13 is substantially level with the reaction material injection hole 14 on the downstream side of the hardener injection hole 13 with respect to the rotation direction R of the injection rod 1. And the reaction material injection hole 14 are arranged close to each other (see FIG. 1C). The curing material injection hole 13 and the reaction material injection hole 14 communicate with the first flow path 8 and the second flow path 9, respectively. The curing material and the reaction material are respectively connected to the first flow path 8 and the second flow path 9. Are simultaneously injected from the curing material injection hole 13 and the reaction material injection hole 14. At this time, the injection pressure of the reaction material should be smaller than the injection pressure of the curing material. In the present embodiment, the injection pressure of the reaction material is about 10 MPa with respect to the injection pressure of the curing material of 50 to 60 MPa.
Moreover, in order to balance at the time of injection, the curing material injection hole 13 and the reaction material injection hole 14 are provided on the opposite side of the injection rod 1 in a plan view with respect to the upper injection hole 12.

なお、上段部2および下段部3の下端面には、それぞれ削孔ビット2a、3aが取り付けられており、注入ロッド1単体で地盤を削孔することができるようになっている。   Drilling bits 2a and 3a are respectively attached to the lower end surfaces of the upper stage 2 and the lower stage 3 so that the ground can be drilled with the injection rod 1 alone.

次に、本発明に係る地盤改良工法の施工手順について図2に基づいて説明する。
先ず、ボーリングマシン16を用いて注入ロッド1を回転させながら地盤内に挿入し、注入ロッド1の先端部に取り付けられた削孔ビット2a、3aで地盤を削孔することにより、所定深度までガイドホールを形成する(図2(a)参照)。
その後、切削水の噴射圧力を50〜60MPa、圧縮空気の噴射圧力を1MPa程度として、圧縮空気に包囲された切削水を上段噴射孔12から噴射しつつ、引上げ時間10〜15分/m、回転速度2.7〜4回転/分(2.5cmの引上げピッチで1回転する回転速度)として、注入ロッド1を引き上げながら地盤を切削する(図2(b)参照)。この時に、エアリフト効果で、切削水がガイドホールを通って地上に排出される。
圧縮空気に包囲された切削水を上段噴射孔12から噴射しつつ注入ロッド1を引き上げながら、下段部3の硬化材噴射孔13と反応材噴射孔14が切削地盤の下端部に達したら、硬化材の噴射圧力を50〜60MPa、反応材の噴射圧力を10MPa程度として切削地盤中に噴射する(図2(c)参照)。この時、反応材噴射孔14が硬化材噴射孔13よりも注入ロッド1の回転方向の下流側に近接配置されているので、反応材が硬化材と確実かつ速やかに混合され、硬化材は早期に硬化する。なお、ここでは、硬化材としてセメント系固化材スラリー、反応材として水ガラス系の珪酸ソーダなどを用いる。
以後、注入ロッド1を引き上げながら、圧縮空気に包囲された切削水を上段噴射孔12から噴射しつつ、下段部3の硬化材噴射孔13と反応材噴射孔14から硬化材と反応材をそれぞれ噴射して円柱状の地盤改良体15を造成していく(図2(d)参照)。
上段噴射孔12が地盤改良体15の上端部に達すると、切削水と圧縮空気の噴射を停止する。そして、硬化材噴射孔13と反応材噴射孔14が地盤改良体15の上端部に達するまで硬化材と反応材を噴射して地盤改良体15の造成を行う(図2(e)参照)。
Next, the construction procedure of the ground improvement method according to the present invention will be described with reference to FIG.
First, the injection rod 1 is rotated and inserted into the ground using a boring machine 16, and the ground is drilled with the drill bits 2a and 3a attached to the tip of the injection rod 1, thereby guiding to a predetermined depth. A hole is formed (see FIG. 2A).
Thereafter, the cutting water injection pressure is set to 50 to 60 MPa, the injection pressure of compressed air is set to about 1 MPa, the cutting water surrounded by the compressed air is injected from the upper injection holes 12, and the pulling time is 10 to 15 minutes / m, rotation. The ground is cut while pulling up the injection rod 1 at a speed of 2.7 to 4 rotations / minute (rotational speed of one rotation at a pulling pitch of 2.5 cm) (see FIG. 2B). At this time, the cutting water is discharged to the ground through the guide hole by the air lift effect.
While the cutting water surrounded by the compressed air is sprayed from the upper spray hole 12 and the injection rod 1 is pulled up, the curing material spray hole 13 and the reaction material spray hole 14 of the lower step part 3 reach the lower end of the cutting ground and harden. The material is injected into the cutting ground with an injection pressure of 50 to 60 MPa and an injection pressure of the reaction material of about 10 MPa (see FIG. 2C). At this time, since the reaction material injection hole 14 is disposed closer to the downstream side in the rotation direction of the injection rod 1 than the hardening material injection hole 13, the reaction material is reliably and quickly mixed with the hardening material, and the hardening material is in an early stage. To harden. Here, a cement-based solidifying material slurry is used as the curing material, and a water glass-based sodium silicate is used as the reaction material.
Thereafter, while pulling up the injection rod 1 and cutting water surrounded by compressed air from the upper injection hole 12, the hardening material and the reaction material are respectively supplied from the hardening material injection hole 13 and the reaction material injection hole 14 of the lower part 3. The cylindrical ground improvement body 15 is created by spraying (see FIG. 2D).
When the upper injection hole 12 reaches the upper end of the ground improvement body 15, the injection of cutting water and compressed air is stopped. Then, the ground improvement body 15 is created by injecting the curing material and the reaction material until the hardening material injection hole 13 and the reaction material injection hole 14 reach the upper end of the ground improvement body 15 (see FIG. 2E).

上記の説明において、切削水の噴射圧力および硬化材の噴射圧力を50〜60MPaとしているのは、主に大径の地盤改良体15を造成するうえで経済的な方法となるためであり、これは、本発明者が実施した実験結果に基づく以下の知見による。なお、この実験では、反応材を用いていないが、反応材の量は少ないため、反応材がある場合でも、反応材の吐出量や噴射圧力を考慮することなく、この実験結果からの知見が適用できる。   In the above description, the reason why the spraying pressure of the cutting water and the spraying pressure of the hardened material is set to 50 to 60 MPa is mainly because it is an economical method for creating the large-diameter ground improvement body 15. Is based on the following findings based on the results of experiments conducted by the present inventors. In this experiment, the reaction material is not used, but since the amount of the reaction material is small, even if there is a reaction material, the knowledge from this experiment result can be obtained without considering the discharge amount of the reaction material and the injection pressure. Applicable.

図3は、切削水の噴射圧力pwと切削水の単位時間当たりの吐出量qwとの積で表わされる切削能力pw×qwと地盤の切削径(直径)φcとの相関関係を示したものである。なお、この時の実験条件としては、注入ロッド1の引上げ時間を10分/mと15分/mとし、注入ロッド1の回転速度は上昇ピッチ2.5cmで1回転するようにしている。従って、引上げ時間10分/mの場合は4回転/分、引上げ時間15分/mの場合は2.7回転/分となる。また、圧縮空気の圧力は1MPaとした。
図4は、硬化材の噴射圧力psと硬化材の単位深さ当たりの注入量Qsとの積で表わされる改良体造成能力ps×Qsと地盤改良体の径(直径)φとの相関関係を示したものである。なお、この時の実験条件としては、前記切削水の時と同様に、注入ロッド1の引上げ時間を10分/mと15分/mとし、注入ロッド1の回転速度は上昇ピッチ2.5cmで1回転するようにした。
図中の曲線(1)および(2)は、実験値をもとに回帰分析により求めた相関関係式であり、次式で示されるものである。
φc=1.973・ln(pw×qw)+13.6 (1)
φ =1.985・ln(ps×Qs)+4.24 (2)
但し、各パラメータの単位は以下の通りである。
pw,ps:MPa、qw:リットル/分、Qs:m/m、φc,φ:m
FIG. 3 shows the correlation between the cutting ability pw × qw represented by the product of the cutting water injection pressure pw and the discharge amount qw per unit time of the cutting water and the ground cutting diameter (diameter) φc. is there. As experimental conditions at this time, the pulling time of the injection rod 1 is set to 10 minutes / m and 15 minutes / m, and the rotation speed of the injection rod 1 is set to rotate once at a rising pitch of 2.5 cm. Therefore, when the pulling time is 10 minutes / m, the rotation speed is 4 rotations / minute, and when the pulling time is 15 minutes / m, the rotation speed is 2.7 rotations / minute. The pressure of the compressed air was 1 MPa.
FIG. 4 shows the correlation between the improvement body formation capacity ps × Qs expressed by the product of the injection pressure ps of the hardener and the injection amount Qs per unit depth of the hardener and the diameter (diameter) φ of the ground improvement body. It is shown. As experimental conditions at this time, as in the case of the cutting water, the pulling time of the injection rod 1 was 10 minutes / m and 15 minutes / m, and the rotation speed of the injection rod 1 was 2.5 cm ascending pitch. It was made to rotate once.
Curves (1) and (2) in the figure are correlation equations obtained by regression analysis based on experimental values, and are represented by the following equations.
φc = 1.973 · ln (pw × qw) +13.6 (1)
φ = 1.985 · ln (ps × Qs) +4.24 (2)
However, the unit of each parameter is as follows.
pw, ps: MPa, qw: liter / min, Qs: m 3 / m, φc, φ: m

ここで、(1)式と(2)式をそれぞれ(3)式と(4)式のように変換する。
pw×qw=exp((φc+13.6)/1.973) (3)
ps×Qs=exp((φ +4.24)/1.985) (4)
また、硬化材の単位時間当たりの吐出量qsは(5)式によって与えられる。
qs=1000・Qs/t (5)
ここで、tは注入ロッドの単位長さ当たりの引上げ時間(分/m)であり、(5)式の係数1000は、qsの単位がリットル/分、Qsの単位がm/mであることによる。
Here, the equations (1) and (2) are converted into equations (3) and (4), respectively.
pw × qw = exp ((φc + 13.6) /1.973) (3)
ps × Qs = exp ((φ + 4.24) /1.985) (4)
Further, the discharge amount qs per unit time of the cured material is given by the equation (5).
qs = 1000 · Qs / t (5)
Here, t is the pulling-up time per unit length of the injection rod (min / m), and the coefficient 1000 in the equation (5) is that the unit of qs is liter / min and the unit of Qs is m 3 / m. It depends.

(3)式を用いて、地盤の切削径φcを3.0〜5.0mの範囲で変化させた際の切削水の噴射圧力pw(図では、切削水圧力と記す。)と切削水の単位時間当たりの吐出量qwとの相関関係を図5に示す。同図より、同一切削径φcを得るためには、切削水の噴射圧力pwが大きいほど、切削水の単位時間当たりの吐出量qwが少なくてよいことがわかる。また、切削径φcを大きくするためには、切削水の噴射圧力pwや切削水の単位時間当たりの吐出量qwを大きくしなければならないことがわかる。
同様に、(4)および(5)式を用いて、地盤改良体の径φを3.0〜5.0mの範囲で変化させた際の硬化材の噴射圧力ps(図では、硬化材圧力と記す。)と硬化材の単位時間当たりの吐出量qsとの相関関係を図6に示す。ここで、図6(a)は注入ロッド1の引上げ速度が10分/mの場合、図6(b)は15分/mの場合である。図5と同様に、地盤改良体の径φを大きくするためには、硬化材の噴射圧力psや硬化材の単位深さ当たりの吐出量qsを大きくする必要があることがわかる。
Using the equation (3), the cutting water injection pressure pw (referred to as cutting water pressure in the figure) and the cutting water when the ground cutting diameter φc is changed in the range of 3.0 to 5.0 m. FIG. 5 shows the correlation with the discharge amount qw per unit time. It can be seen from the figure that in order to obtain the same cutting diameter φc, the discharge amount qw per unit time of the cutting water may be smaller as the cutting water injection pressure pw is larger. It can also be seen that in order to increase the cutting diameter φc, the cutting water injection pressure pw and the cutting water discharge amount qw per unit time must be increased.
Similarly, by using the equations (4) and (5), the injection pressure ps of the cured material when the diameter φ of the ground improvement body is changed in the range of 3.0 to 5.0 m (in the figure, the cured material pressure). 6) and the discharge amount qs per unit time of the cured material are shown in FIG. Here, FIG. 6A shows the case where the pulling speed of the injection rod 1 is 10 minutes / m, and FIG. 6B shows the case where it is 15 minutes / m. Similarly to FIG. 5, it can be seen that in order to increase the diameter φ of the ground improvement body, it is necessary to increase the injection pressure ps of the hardener and the discharge amount qs per unit depth of the hardener.

図7は、切削水の噴射圧力pwと硬化材の噴射圧力psについて適宜の値を設定し、その値を図3および図4(関係式(1)、(2)を図化したもの)に当てはめて各注入率を算出し、注入ロッド1の引上げ時間10分/mおよび15分/mにおける切削水の噴射圧力pwと切削水注入率αwとの相関関係および硬化材の噴射圧力psと硬化材注入率αsとの相関関係を示したものである。ここで、切削水注入率αwは、地盤の切削径φcによる単位深さ当たりの切削体積Vcに対する切削水の単位深さ当たりの注入量Qw(qw×t)であり、硬化材注入率αsは、地盤改良体の径φによる単位深さ当たりの改良体積Vに対する硬化材の単位深さ当たりの注入量Qsである。
同図より、硬化材注入率αsを30%に設定する場合には、硬化材の噴射圧力psが約20MPaでよいことがわかる。切削水についても同様に仕様を設定することができる。
FIG. 7 sets appropriate values for the cutting water injection pressure pw and the hardening material injection pressure ps, and the values are shown in FIGS. 3 and 4 (representations of relational expressions (1) and (2)). Each injection rate is calculated by fitting, and the correlation between the cutting water injection pressure pw and the cutting water injection rate αw at the lifting time of 10 minutes / m and 15 minutes / m of the injection rod 1 and the injection pressure ps and hardening of the hardened material. The correlation with the material injection rate αs is shown. Here, the cutting water injection rate αw is the injection amount Qw (qw × t) per unit depth of the cutting water with respect to the cutting volume Vc per unit depth by the ground cutting diameter φc, and the hardener injection rate αs is The injection amount Qs per unit depth of the hardened material with respect to the improved volume V per unit depth according to the diameter φ of the ground improvement body.
From the figure, it can be seen that when the hardening material injection rate αs is set to 30%, the injection pressure ps of the hardening material may be about 20 MPa. The specifications can be set similarly for the cutting water.

大径の地盤改良体15を合理的に造成するには、硬化材注入率αsおよび総注入率α(切削水と硬化材の注入率の合計)が関係する。結論から言えば、硬化材注入率αsは、改良体強度の適切な大きさとバラツキを考慮し、出来るだけ少なくする中で10〜30%とし、切削水と硬化材とをあわせた総注入率αについては20〜50%とするのがよい。この範囲であれば、従来工法と比較してコスト的に優位となる。   In order to rationally create the large-diameter ground improvement body 15, the hardening material injection rate αs and the total injection rate α (the sum of the cutting water and the hardening material injection rate) are related. Speaking from the conclusion, the hardening material injection rate αs is set to 10 to 30% while considering the appropriate size and variation of the strength of the improved body, and the total injection rate α of cutting water and hardening material combined. About 20 to 50% is good about. If it is this range, it will become cost-dominant compared with the conventional construction method.

以下、具体的な適用例で説明する。
図7より、切削水および硬化材の噴射圧力pw、psを上げれば、切削水および硬化材の注入率αw、αsが減少する、つまりコスト的に安価になる傾向が示されている。一方、60MPa以上の噴射圧力pw、psになると、注入率αw、αsの低下がさほど見られなくなる傾向にある。そのため、実用的で効果的な切削水および硬化材の噴射圧力pw、psは50〜60MPaと設定できる。ここでは、切削水の噴射圧力pwを60MPa、硬化材の噴射圧力psを50MPaとする。このときの切削水および硬化材の注入率αw、αsは、注入ロッド1の引上げ時間を10分/mとすると10%である。この設定値を図5および図6(a)に当てはめると、各改良径ごとの施工仕様は表1のようになる。
Hereinafter, a specific application example will be described.
FIG. 7 shows that if the injection pressures pw and ps of the cutting water and the hardened material are increased, the injection rates αw and αs of the cutting water and the hardened material decrease, that is, the cost tends to be low. On the other hand, when the injection pressures pw and ps are 60 MPa or more, the injection rates αw and αs tend not to decrease much. Therefore, the practical and effective cutting water and the injection pressures pw and ps of the hardened material can be set to 50 to 60 MPa. Here, the cutting water spray pressure pw is set to 60 MPa, and the curing material spray pressure ps is set to 50 MPa. The injection rates αw and αs of the cutting water and the hardened material at this time are 10% when the lifting time of the injection rod 1 is 10 minutes / m. When this set value is applied to FIGS. 5 and 6A, the construction specifications for each improved diameter are as shown in Table 1.

Figure 0003750065
Figure 0003750065

なお、圧縮空気の噴射圧力は1MPa程度、反応材の噴射圧力は10MPa程度とし、反応材の吐出量は、硬化材の吐出量と所望のゲルタイムに応じて算出される量とする。   In addition, the injection pressure of compressed air is about 1 MPa, the injection pressure of the reaction material is about 10 MPa, and the discharge amount of the reaction material is an amount calculated according to the discharge amount of the curing material and the desired gel time.

本実施形態による地盤改良工法では、反応材噴射孔14を硬化材噴射孔13の下流側として、ほぼ同じ高さに近接配置するので、反応材の噴射後、ほぼ同じ位置で直ちに硬化材が噴射される。その結果、反応材を巻き込んだ硬化材が噴射されるようになり、硬化材と反応材が均一に混合される。
また、本実施形態による地盤改良工法では、切削水の噴射圧力および硬化材の噴射圧力を50〜60MPaとすることにより、大径の地盤改良体15を経済的かつ合理的に造成することができる。
In the ground improvement method according to the present embodiment, since the reaction material injection hole 14 is arranged close to the same height as the downstream side of the hardening material injection hole 13, the hardening material is injected immediately at substantially the same position after the reaction material is injected. Is done. As a result, the curing material including the reaction material is injected, and the curing material and the reaction material are uniformly mixed.
In the ground improvement method according to the present embodiment, the ground improvement body 15 having a large diameter can be economically and rationally created by setting the spraying pressure of the cutting water and the spraying pressure of the hardened material to 50 to 60 MPa. .

図8は、本発明に係る地盤改良工法において使用する注入ロッド先端部(下段側吐出口部分)の他の例を示したものである。
本実施形態では、硬化材噴射孔23と反応材噴射孔24の位置を平断面視でほぼ同じ位置とし、硬化材噴射孔23の上方に、注入ロッド1の引上げピッチの整数倍の距離をおいて反応材噴射孔24を設けている。即ち、硬化材噴射孔23と反応材噴射孔24の離間距離を、注入ロッド1の引上げピッチの整数倍の距離としている。硬化材噴射孔23、反応材噴射孔24は、先の実施形態と同様に、それぞれ第一の流路8、第二の流路9と連通しており、硬化材と反応材は、それぞれ第一の流路8、第二の流路9を経由して、硬化材噴射孔23、反応材噴射孔24から同時に噴射される。
FIG. 8 shows another example of the tip of the injection rod (lower discharge port portion) used in the ground improvement method according to the present invention.
In this embodiment, the positions of the curing material injection holes 23 and the reaction material injection holes 24 are substantially the same in a plan view, and a distance that is an integral multiple of the pulling pitch of the injection rod 1 is set above the curing material injection holes 23. The reaction material injection hole 24 is provided. That is, the distance between the curing material injection hole 23 and the reaction material injection hole 24 is set to an integral multiple of the pulling pitch of the injection rod 1. Similarly to the previous embodiment, the curing material injection hole 23 and the reaction material injection hole 24 communicate with the first flow path 8 and the second flow path 9, respectively. It is simultaneously injected from the curing material injection hole 23 and the reaction material injection hole 24 via the one flow path 8 and the second flow path 9.

本実施形態によれば、反応材の噴射位置と硬化材の噴射位置が同一となり、硬化材と反応材の均一混合が可能となる。なお、一般的な段階的ピッチ引き上げ方法を採用する場合(通常は、2.5cmピッチ)、硬化材噴射孔23と反応材噴射孔24の離間距離は1ピッチ分の距離であり、螺旋状に引き上げる場合でも、その螺旋形状の1ピッチ分の距離である。   According to this embodiment, the injection position of the reaction material and the injection position of the curing material are the same, and the curing material and the reaction material can be mixed uniformly. When a general stepwise pitch raising method is employed (usually 2.5 cm pitch), the separation distance between the curing material injection holes 23 and the reaction material injection holes 24 is a distance corresponding to one pitch, and is spiral. Even when it is pulled up, the distance is one pitch of the spiral shape.

以上、本発明に係る地盤改良工法の実施形態について説明したが、本発明は上記の実施形態に限定されるものではなく、その趣旨を逸脱しない範囲で適宜変更可能である。例えば、上記の実施形態では、硬化材の噴射圧力50〜60MPaに対して、反応材の噴射圧力を10MPa程度としているが、反応材の噴射圧力はこれに限定されるわけではなく、要は、硬化材の噴射圧力よりも小さい範囲で、所要のゲルタイムに応じて硬化材の早期硬化に必要な量の反応材を噴射できればよい。   As mentioned above, although embodiment of the ground improvement construction method concerning this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in the above embodiment, the injection pressure of the reaction material is about 10 MPa with respect to the injection pressure of the curing material of 50 to 60 MPa. However, the injection pressure of the reaction material is not limited to this, What is necessary is just to be able to inject an amount of the reaction material necessary for the early curing of the curing material in accordance with the required gel time within a range smaller than the injection pressure of the curing material.

また、本発明は、注入ロッドを回転させて円柱状の地盤改良体を造成するばかりでなく、例えば扇形柱状の地盤改良体を造成する場合も含むものである。この場合、注入ロッドを所定範囲の角度で正逆回転させて扇形の地盤改良体を造成する方法、注入ロッドを一方向に回転させる中で所定範囲の角度だけ硬化材を噴射して扇形の地盤改良体を造成する方法が考えられる。注入ロッドを正逆回転させる方法では、反射材噴射孔と硬化材噴射孔を上下に配置する本発明の他の実施形態がそのまま適用できるが、反射材噴射孔と硬化材噴射孔を同じ高さに配置する実施形態の場合、反射材噴射孔を挟んで硬化材噴射孔を2箇所設けるか、あるいは硬化材噴射孔を挟んで反射材噴射孔を2箇所設けるかして、反応材あるいは硬化材のいずれかの噴射を、この2箇所の噴射孔間で切り替え操作する必要がある。一方、注入ロッドを一方向に回転させる中で扇形の地盤改良体を造成する方法では、本発明の実施形態、本発明の他の実施形態ともに、所定角度の範囲だけ硬化材や反応材を噴射するような操作をする必要がある。   In addition, the present invention includes not only the creation of a columnar ground improvement body by rotating the injection rod, but also the case of creating a sectoral pillar-like ground improvement body, for example. In this case, a method of creating a fan-shaped ground improvement body by rotating the injection rod forward and backward at an angle within a predetermined range, while the injection rod is rotated in one direction, a curing material is sprayed at an angle within a predetermined range to form a fan-shaped ground. A method of creating an improved body is conceivable. In the method of rotating the injection rod forward and backward, other embodiments of the present invention in which the reflecting material injection holes and the curing material injection holes are arranged vertically can be applied as they are, but the reflecting material injection holes and the curing material injection holes are at the same height. In the case of the embodiment, the reaction material or the curing material is provided by providing two curing material injection holes with the reflection material injection hole interposed therebetween or by providing two reflection material injection holes with the curing material injection hole interposed therebetween. It is necessary to switch any one of these injections between the two injection holes. On the other hand, in the method of constructing a fan-shaped ground improvement body while rotating the injection rod in one direction, both the embodiment of the present invention and the other embodiments of the present invention inject a curing material and a reaction material within a predetermined angle range. It is necessary to do the operation to do.

本発明に係る地盤改良工法において使用する注入ロッド先端部の一例を示し、(a)はその縦断面図、(b)は上段部の平断面図、(c)は下段部の平断面図である。An example of the injection | pouring rod front-end | tip part used in the ground improvement construction method which concerns on this invention is shown, (a) is the longitudinal cross-sectional view, (b) is the top cross-sectional view of an upper stage part, (c) is the cross-sectional view of a lower step part. is there. 本発明に係る地盤改良工法の施工手順を示す概略図である。It is the schematic which shows the construction procedure of the ground improvement construction method which concerns on this invention. 切削能力pw×qwと地盤の切削径φcとの相関関係を示す図である。It is a figure which shows the correlation with cutting ability pwxqw and the cutting diameter (phi) c of a ground. 改良体造成能力ps×Qsと地盤改良体の径φとの相関関係を示す図である。It is a figure which shows the correlation with the improvement body creation capability psxQs and the diameter (phi) of a ground improvement body. 切削水の噴射圧力pwと切削水の単位時間当たりの吐出量qwとの相関関係を示す図である。It is a figure which shows the correlation with the injection pressure pw of cutting water, and the discharge amount qw per unit time of cutting water. 硬化材の噴射圧力psと硬化材の単位時間当たりの吐出量qsとの相関関係を示す図であり、(a)は注入ロッドの引上げ速度が10分/mの場合、(b)は注入ロッドの引上げ速度が15分/mの場合である。It is a figure which shows the correlation with the injection pressure ps of a hardening material, and the discharge amount qs per unit time of a hardening material, (a) is the case where the pulling-up speed of an injection rod is 10 minutes / m, (b) is an injection rod. This is the case where the pulling speed of 15 minutes / m. 切削水の噴射圧力pwと切削水注入率αwとの相関関係および硬化材の噴射圧力psと硬化材注入率αsとの相関関係を示す図である。It is a figure which shows the correlation of the injection pressure pw of cutting water, and the cutting water injection | pouring rate (alpha) w, and the correlation of the injection pressure ps of hardening material, and hardening | curing material injection | pouring rate (alpha) s. 本発明に係る地盤改良工法において使用する注入ロッド先端部(下段部)の他の例を示す縦断面図である。It is a longitudinal cross-sectional view which shows the other example of the injection rod front-end | tip part (lower stage part) used in the ground improvement construction method which concerns on this invention.

符号の説明Explanation of symbols

1 注入ロッド
2 上段部
3 下段部
4、5、6、7 筒体
8、9、10、11 流路
12 上段噴射孔
12a 第一噴射孔
12b 第二噴射孔
13、23 硬化材噴射孔
14、24 反応材噴射孔
15 地盤改良体
16 ボーリングマシン
R 回転方向
DESCRIPTION OF SYMBOLS 1 Injection rod 2 Upper stage part 3 Lower stage part 4, 5, 6, 7 Cylindrical body 8, 9, 10, 11 Channel 12 Upper stage injection hole 12a First injection hole 12b Second injection hole 13, 23 Hardening material injection hole 14, 24 Reaction material injection hole 15 Ground improvement body 16 Boring machine R Rotation direction

Claims (3)

先端部に上下二段の噴射孔を備えた注入ロッドを地盤に挿入し、当該注入ロッドを回転させながら引き上げる際に、上段側の噴射孔から圧縮空気とともに切削水を噴射して地盤を切削しつつ、下段側の一方の噴射孔から硬化材を噴射するとともに、下段側の他方の噴射孔から反応材を噴射して、地盤中に柱状の地盤改良体を造成する地盤改良工法において、
前記注入ロッドの回転時に、前記反応材を噴射する噴射孔(以下、反応材噴射孔と称す)が前記硬化材を噴射する噴射孔(以下、硬化材噴射孔と称す)の下流側となるように、ほぼ同じ高さに硬化材噴射孔と反応材噴射孔を近接配置し、前記硬化材と前記反応材を同時に噴射することを特徴とする地盤改良工法。
Insert an injection rod with two upper and lower injection holes at the tip into the ground, and when pulling up while rotating the injection rod, cut the ground by injecting cutting water together with compressed air from the upper injection hole. While injecting the hardener from one injection hole on the lower stage side, and injecting the reaction material from the other injection hole on the lower stage side, in the ground improvement construction method to create a columnar ground improvement body in the ground,
When the injection rod rotates, an injection hole for injecting the reaction material (hereinafter referred to as a reaction material injection hole) is located downstream of an injection hole for injecting the hardening material (hereinafter referred to as a hardening material injection hole). The ground improvement method is characterized in that the curing material injection hole and the reaction material injection hole are arranged close to each other at substantially the same height, and the curing material and the reaction material are simultaneously injected.
先端部に上下二段の噴射孔を備えた注入ロッドを地盤に挿入し、当該注入ロッドを回転させながら引き上げる際に、上段側の噴射孔から圧縮空気とともに切削水を噴射して地盤を切削し、下段側の一方の噴射孔から硬化材を噴射しつつ、下段側の他方の噴射孔から反応材を噴射して、地盤中に柱状の地盤改良体を造成する地盤改良工法において、
硬化材噴射孔と反応材噴射孔の位置を平断面視でほぼ同じ位置とし、前記硬化材噴射孔の上方に、前記注入ロッドの引上げピッチの整数倍の距離をおいて前記反応材噴射孔を配し、前記硬化材と前記反応材を同時に噴射することを特徴とする地盤改良工法。
Insert an injection rod with two upper and lower injection holes at the tip into the ground, and when pulling up while rotating the injection rod, cut the ground by injecting cutting water together with compressed air from the upper injection hole. In the ground improvement method of injecting the reaction material from the other injection hole on the lower stage side while injecting the curing material from one injection hole on the lower stage side, and creating a columnar ground improvement body in the ground,
The positions of the curing material injection hole and the reaction material injection hole are substantially the same in a plan view, and the reaction material injection hole is disposed above the curing material injection hole with an integer multiple of the pulling pitch of the injection rod. The ground improvement method is characterized in that the hardened material and the reaction material are injected simultaneously.
前記反応材の噴射圧力は、前記硬化材の噴射圧力より小さいことを特徴とする請求項1または2に記載の地盤改良工法。   The ground improvement method according to claim 1 or 2, wherein an injection pressure of the reaction material is smaller than an injection pressure of the curing material.
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