JP2024079320A - Ground improvement body construction device by intermediate pressure injection agitation, and ground improvement method by intermediate pressure injection agitation - Google Patents
Ground improvement body construction device by intermediate pressure injection agitation, and ground improvement method by intermediate pressure injection agitation Download PDFInfo
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- 230000006872 improvement Effects 0.000 title claims abstract description 221
- 238000002347 injection Methods 0.000 title claims abstract description 145
- 239000007924 injection Substances 0.000 title claims abstract description 145
- 238000010276 construction Methods 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims description 37
- 238000013019 agitation Methods 0.000 title abstract 6
- 239000000463 material Substances 0.000 claims abstract description 111
- 239000004927 clay Substances 0.000 claims abstract description 30
- 238000009412 basement excavation Methods 0.000 claims abstract description 16
- 238000003756 stirring Methods 0.000 claims description 39
- 230000007704 transition Effects 0.000 claims description 13
- 230000035515 penetration Effects 0.000 claims description 9
- 230000000149 penetrating effect Effects 0.000 claims description 8
- 239000002689 soil Substances 0.000 claims description 6
- 239000000853 adhesive Substances 0.000 abstract description 3
- 230000001070 adhesive effect Effects 0.000 abstract description 3
- 239000000243 solution Substances 0.000 abstract 1
- 230000002265 prevention Effects 0.000 description 15
- 230000008569 process Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
- 238000005553 drilling Methods 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 5
- 239000007921 spray Substances 0.000 description 5
- 239000004568 cement Substances 0.000 description 3
- 238000004401 flow injection analysis Methods 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 238000012669 compression test Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000013598 vector Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、攪拌翼や噴射ノズルを具備する注入ロッドを地盤内で前進（貫入）または後退（引上）させつつ回転させるとともに、地盤改良材を中圧（およそ５ＭＰａ～２０ＭＰａ未満の圧力）で地盤内に注入することによって柱状の地盤改良体を造成する地盤改良体造成装置および地盤改良工法に関するものである。 The present invention relates to a ground improvement body construction device and a ground improvement method that creates a columnar ground improvement body by rotating an injection rod equipped with an agitating blade and an injection nozzle while advancing (penetrating) or retreating (pulling up) the ground, and injecting ground improvement material into the ground at medium pressure (a pressure of approximately 5 MPa to less than 20 MPa).
地盤改良工法の一種として、中圧噴射機械攪拌工法が知られている。中圧噴射機械攪拌工法で用いる従来の地盤改良体造成装置を図１１に示す。従来の地盤改良体造成装置は、高圧流体である改良材（スラリー状のセメント系固化材）の流路を具備するロッド９１と、大流量の改良材を中圧噴射する噴射ノズル９３と、地盤と改良材を攪拌混合する攪拌翼９５を備えている。 The medium pressure jet mechanical mixing method is known as one type of ground improvement method. Figure 11 shows a conventional ground improvement body construction device used in the medium pressure jet mechanical mixing method. The conventional ground improvement body construction device is equipped with a rod 91 with a flow path for the improvement material (slurry-like cement-based solidification material), which is a high-pressure fluid, an injection nozzle 93 that injects a large flow rate of the improvement material at medium pressure, and an agitator 95 that mixes the ground and the improvement material.
中圧噴射機械攪拌工法では、改良材を原位置に添加する際、攪拌翼と改良材中圧噴射を併用し、強制的に地盤を改良し柱状の地盤改良体を造成する。そして、従来の地盤改良体造成装置を用いた中圧噴射機械攪拌工法では、攪拌翼９５の下に位置する噴射ノズル９３から大流量の改良材を噴射することで、地盤改良体造成装置を地中に貫入する時の攪拌翼掘削を補助している。 In the medium pressure jet mechanical mixing method, when the improvement material is added to the original location, the mixing blade and medium pressure injection of the improvement material are used in combination to forcibly improve the ground and create a columnar ground improvement body. In the medium pressure jet mechanical mixing method using a conventional ground improvement body creation device, a large flow rate of improvement material is injected from the injection nozzle 93 located below the mixing blade 95, which assists the mixing blade excavation when the ground improvement body creation device is inserted into the ground.
しかしながら、粘着性の高い粘土塊が対象地盤の地中に存在する場合、大流量の改良材を噴射するノズルでは、噴射した改良材の噴流径が大きく乱流構造のため、大流量噴射による粘土塊の細かい粉砕が困難であった。 However, when highly sticky clay lumps are present in the ground, it is difficult to finely crush the clay lumps using a nozzle that sprays a large amount of improvement material because the jet diameter of the improvement material is large and the jet structure is turbulent.
上述した従来技術の問題点に鑑み、本発明の目的は、粘着性の高い粘土塊が地中に存在する場合でも、粘土塊を細かく粉砕することが可能であって、高品質の地盤改良体を造成可能な、中圧噴射攪拌による地盤改良体造成装置および地盤改良工法を提供することにある。 In view of the problems with the conventional technology described above, the object of the present invention is to provide a ground improvement body construction device and a ground improvement method using medium pressure jet mixing that can finely crush clay lumps even when highly sticky clay lumps are present in the ground, and can create a high-quality ground improvement body.
上記目的は、攪拌翼を具備するロッドを地盤内で前進または後退させつつ回転させるとともに、地盤改良材を地盤内に注入することによって柱状の地盤改良体を造成する地盤改良体造成装置であって、
地盤内で噴射するスラリー状の地盤改良材の流路が形成されたロッドと、
前記ロッドに設けられ、地中の粘土塊を粉砕する噴流をなすように前記地盤改良材を中圧で噴射する第１の噴射ノズルと、
前記ロッドに設けられ、前記第１の噴射ノズルよりも大きいノズル径を有し、前記攪拌翼による地盤掘削の負担を軽減する噴流をなすように前記地盤改良材を中圧で噴射する第２の噴射ノズルと、
前記ロッドに設けられ、地中に噴射された前記地盤改良材と地盤を攪拌混合するための攪拌翼と、
を有する中圧噴射攪拌による地盤改良体造成装置によって達成される。
The above object is to provide a ground improvement body construction device that rotates a rod equipped with an agitating blade while moving it forward or backward in the ground and injects a ground improvement material into the ground to create a columnar ground improvement body,
A rod having a flow path for a slurry-like ground improvement material to be injected into the ground;
A first injection nozzle provided on the rod for injecting the ground improvement material at medium pressure to form a jet that crushes clay lumps in the ground;
A second injection nozzle is provided on the rod, has a nozzle diameter larger than that of the first injection nozzle, and injects the ground improvement material at medium pressure to form a jet that reduces the burden of ground excavation by the mixing blade;
A stirring blade provided on the rod for stirring and mixing the soil improvement material and the ground injected into the ground;
This is achieved by a ground improvement body construction device using medium pressure jet mixing.
上記地盤改良体造成装置において、第１の噴射ノズルは、ほぼ層流又はほぼ遷移領域の噴流をなすように前記地盤改良材を中圧で噴射する。また、第２の噴射ノズルは、ほぼ乱流の噴流をなすように前記地盤改良材を中圧で噴射する。 In the above-mentioned ground improvement body construction device, the first injection nozzle injects the ground improvement material at medium pressure so as to form a jet of approximately laminar flow or approximately transition region flow. The second injection nozzle injects the ground improvement material at medium pressure so as to form a jet of approximately turbulent flow.
また、上記地盤改良体造成装置において、第１の噴射ノズルと第２の噴射ノズルは、それぞれ、各噴射ノズルからの噴流が前記攪拌翼の端部に向かうように設けられている。 In addition, in the above-mentioned ground improvement body construction device, the first injection nozzle and the second injection nozzle are each arranged so that the jet from each injection nozzle is directed toward the end of the mixing blade.
また、前述した目的は、上記特徴の地盤改良体造成装置を用いた中圧噴射攪拌による地盤改良工法であって、
ロッドを回転させつつ地盤改良体造成装置を対象地盤に貫入する工程と、
ロッドを回転させつつ地盤改良体造成装置を対象地盤から引き上げる工程と、
を含んでおり、
前記貫入工程及び／又は前記引上工程において、地中の粘土塊を粉砕する噴流をなすように、第１の噴射ノズルからスラリー状の地盤改良材を中圧で噴射する、ことによって達成される。
The above-mentioned object is to provide a ground improvement method by medium pressure injection mixing using the ground improvement body construction device having the above-mentioned characteristics,
A step of penetrating the ground improvement body construction device into the target ground while rotating the rod;
A step of lifting the ground improvement body construction device from the target ground while rotating the rod;
Contains
This is achieved by injecting a slurry-like ground improvement material at medium pressure from a first injection nozzle in the penetration step and/or the pulling up step so as to form a jet that crushes the clay lumps in the ground.
また、前述した目的は、上記特徴の地盤改良体造成装置を用いた中圧噴射攪拌による地盤改良工法であって、
ロッドを回転させつつ地盤改良体造成装置を対象地盤に貫入する工程と、
ロッドを回転させつつ地盤改良体造成装置を対象地盤から引き上げる工程と、
を含んでおり、
前記貫入工程及び／又は前記引上工程において、
地中の粘土塊を粉砕する噴流をなすように、第１の噴射ノズルからスラリー状の地盤改良材を中圧で噴射するとともに、
攪拌翼による地盤掘削の負担を軽減する噴流をなすように、第２の噴射ノズルからスラリー状の地盤改良材を中圧で噴射する、ことによって達成される。
The above-mentioned object is to provide a ground improvement method by medium pressure injection mixing using the ground improvement body construction device having the above-mentioned characteristics,
A step of penetrating the ground improvement body construction device into the target ground while rotating the rod;
A step of lifting the ground improvement body construction device from the target ground while rotating the rod;
Contains
In the penetration step and/or the pulling step,
A slurry-like ground improvement material is injected from a first injection nozzle at medium pressure to form a jet that crushes clay lumps in the ground,
This is achieved by injecting the slurry-like ground improvement material from the second injection nozzle at medium pressure so as to produce a jet that reduces the burden of excavating the ground by the agitating blades.
上記地盤改良工法では、第１の噴射ノズルと第２の噴射ノズルから、ほぼ同じ圧力で地盤改良材を噴射する。 In the above ground improvement method, the ground improvement material is sprayed from the first and second spray nozzles at approximately the same pressure.
また、上記地盤改良工法では、第１の噴射ノズルからスラリー状の地盤改良材を中圧で噴射する際に、第１の噴射ノズルからの噴流のレイノルズ数Ｒｅが、ほぼ２３００又はこれより小さくなるように、あるいは、ほぼ２３００～ほぼ４０００の範囲に収まるように、地盤改良材を噴射する。 In addition, in the above-mentioned ground improvement method, when the slurry ground improvement material is injected from the first injection nozzle at medium pressure, the ground improvement material is injected so that the Reynolds number Re of the jet from the first injection nozzle is approximately 2300 or less, or falls within the range of approximately 2300 to approximately 4000.
本発明によれば、中圧噴射攪拌による地盤改良において、粘着性の高い粘土塊の細かい粉砕が可能になるため、粘着性の高い粘土塊が在る地盤において高品質の地盤改良体を造成することができる。 According to the present invention, in ground improvement using medium pressure injection mixing, it is possible to finely crush highly adhesive clay lumps, so that a high-quality ground improvement body can be created in ground containing highly adhesive clay lumps.
また、細切削噴射を担う小径噴射ノズルと大流量噴射を担う大径噴射ノズルを組み合わせた、複合中圧噴射攪拌により、掘削能力の向上と粘土塊粉砕による地盤改良体の高品質化が実現される。 In addition, by combining a small-diameter jet nozzle for fine cutting jets and a large-diameter jet nozzle for high-flow jets, combined medium-pressure jet mixing improves excavation capacity and the quality of ground improvement bodies by crushing clay lumps.
また、攪拌翼による地盤掘削の負担軽減を担う大径噴射ノズルとは別に、地中の粘土塊の粉砕を担う小径噴射ノズルを設けているので、地盤掘削の機能を損なうことなく粘土塊を粉砕することが可能となる。 In addition to the large-diameter jet nozzle, which reduces the burden of excavating the ground using the mixing blades, a small-diameter jet nozzle is provided to crush the clay lumps underground, making it possible to crush the clay lumps without impairing the function of excavating the ground.
本実施形態の地盤改良体造成装置は、中圧噴射機械攪拌工法で用いる装置であって、攪拌翼を具備するロッドを地盤内で前進（貫入）または後退（引上）させつつ回転させるとともに、地盤改良材を中圧で地盤内に注入することによって柱状の地盤改良体を造成する装置である。以下、地盤改良材を単に「改良材」という。 The ground improvement body construction device of this embodiment is a device used in the medium pressure jet mechanical mixing method, and is a device that creates a columnar ground improvement body by rotating a rod equipped with mixing blades while moving it forward (penetrating) or backward (pulling up) in the ground, and injecting the ground improvement material into the ground at medium pressure. Hereinafter, the ground improvement material will be simply referred to as "improvement material."
この出願における「中圧噴射」とは、およそ５ＭＰａ～２０ＭＰａ未満の圧力での改良材の噴射である。なお、２０ＭＰａ以上の高圧噴射領域では改良材噴流が乱流となるため、本発明は２０ＭＰａ未満の中圧噴射領域に適している。 In this application, "medium pressure injection" refers to injection of the improving agent at a pressure of approximately 5 MPa to less than 20 MPa. Note that in the high pressure injection range of 20 MPa or more, the improving agent jet becomes turbulent, so the present invention is suitable for the medium pressure injection range of less than 20 MPa.
（地盤改良体造成装置）
はじめに、図１に基づいて、中圧噴射攪拌による地盤改良体造成装置の構成について説明する。
(Ground improvement body construction device)
First, the configuration of the ground improvement body construction device using medium pressure jet mixing will be described with reference to FIG.
図１に示すように、本実施形態の地盤改良体造成装置１は、
・改良材の流路が内部に形成された単管のロッド１１（注入ロッド）と、
・ロッド１１の先端に設けられた削孔用の掘削ビット１３と、
・地中に噴射された改良材と地盤を攪拌混合する上下二段の攪拌翼２１，３１と、
・粘土塊を細かく粉砕可能な層流による細切削噴射を担う小径噴射ノズル４１と、
・攪拌翼２１による地盤掘削の負担を軽減させる大流量噴射を担う大径噴射ノズル５１と、を有している。
As shown in FIG. 1, the ground improvement body construction device 1 of this embodiment is,
A single-tube rod 11 (injection rod) having a flow path for the improvement material formed therein;
A drilling bit 13 for drilling holes provided at the tip of the rod 11;
- Upper and lower two-stage mixing blades 21, 31 for mixing and mixing the improvement material injected into the ground with the ground;
- A small diameter injection nozzle 41 that performs fine cutting injection by laminar flow that can finely crush clay lumps;
- It has a large diameter injection nozzle 51 that is responsible for injecting a large flow rate, which reduces the burden of ground excavation by the mixing blades 21.
ロッド１１には、地盤内で噴射する改良材（例えばスラリー状のセメント系等の固化材）あるいは水の流路が形成されている。ロッド内部の流路は、噴射ノズル４１，５１に通じている。ロッド１１の先端には、削孔用の掘削ビット１３が設けられている。所定圧力（５ＭＰａ～２０ＭＰａ未満の中圧で）改良材がロッド１１内の流路を介して圧送されて、噴射ノズル４１，５１からほぼ同圧で噴射される。 The rod 11 has a flow path for water or improvement material (e.g., a slurry-like cement-based solidification material) to be injected into the ground. The flow path inside the rod leads to the injection nozzles 41, 51. A drilling bit 13 for drilling holes is attached to the tip of the rod 11. The improvement material is pumped through the flow path inside the rod 11 at a predetermined pressure (medium pressure of 5 MPa to less than 20 MPa) and is injected from the injection nozzles 41, 51 at approximately the same pressure.
一対の攪拌翼２１（下段攪拌翼）は、ロッド１１の外周面から周囲に突き出るようにロッド中心軸に対して垂直に設けられている。また、一対の攪拌翼２１は互いに反対方向へ延びている。ロッド１１と一体回転する攪拌翼２１は、地中に噴射された改良材と地盤を攪拌混合する役割を担うほか、改良対象地盤を掘削する役割を担う。 A pair of stirring blades 21 (lower stirring blades) are provided perpendicular to the central axis of the rod 11 so as to protrude from the outer circumferential surface of the rod 11. The pair of stirring blades 21 also extend in opposite directions. The stirring blades 21 rotate together with the rod 11, and play a role in stirring and mixing the improvement material injected into the ground with the ground, as well as excavating the ground to be improved.
攪拌翼２１には、複数の掘削ビット２３が設けられている。また、攪拌翼２１の先端には、地盤内で噴射した改良材が逸走するのを防止する逸走防止板２５，２６が設けられている。 The agitator blade 21 is provided with multiple drilling bits 23. In addition, the tip of the agitator blade 21 is provided with escape prevention plates 25, 26 that prevent the improvement material injected into the ground from escaping.
一対の攪拌翼３１（上段攪拌翼）は、ロッド１１の外周面から突き出るようにロッド中心軸に対して垂直に設けられている。また、一対の攪拌翼３１は互いに反対方向へ延びている。ロッド１１と一体回転する攪拌翼３１は、地中に噴射された改良材と地盤を攪拌混合する役割を担う。なお、上段の攪拌翼３１は必須の構成要素ではなく、これを省いてもよい。また、一対の攪拌翼は必ずしも二段に限定されるものではなく、三段以上設けてもよい。 A pair of stirring blades 31 (upper stage stirring blades) are provided perpendicular to the central axis of the rod 11 so as to protrude from the outer circumferential surface of the rod. The pair of stirring blades 31 also extend in opposite directions. The stirring blades 31 rotate integrally with the rod 11 and play a role in stirring and mixing the improvement material injected into the ground with the ground. Note that the upper stage stirring blades 31 are not essential components and may be omitted. Also, the pair of stirring blades is not necessarily limited to two stages, and three or more stages may be provided.
第１の噴射ノズルである小径噴射ノズル４１はロッド１１の外周に設けられており、攪拌翼２１の上に位置し、大径噴射ノズル５１よりも小さいノズル径を有する。小径噴射ノズル４１は、その噴流が攪拌翼２１の端部に設けた逸走防止板２５に向かうように設けられている。小径噴射ノズル４１から中圧噴射された改良材噴流は、その先に立ちはだかる逸走防止板２５によって進路が遮断されるので、改良材が当該逸走防止板２５を超えて周囲に逸走することがない。すなわち、小径噴射ノズル４１から噴射された改良材は、逸走防止板２５による遮断作用によって、攪拌翼端部の回転軌跡の内側領域（すなわち攪拌翼２１による攪拌混合の領域内）に留まることになる。なお、逸走防止板の代わりに噴射ノズルを攪拌翼先端部に向かう角度とし、改良材噴流を攪拌翼先端に衝突させることで進路を遮断することも可能である。 The small-diameter injection nozzle 41, which is the first injection nozzle, is provided on the outer periphery of the rod 11, is located above the stirring blade 21, and has a nozzle diameter smaller than that of the large-diameter injection nozzle 51. The small-diameter injection nozzle 41 is provided so that its jet is directed toward the runaway prevention plate 25 provided at the end of the stirring blade 21. The improvement material jet injected at medium pressure from the small-diameter injection nozzle 41 is blocked by the runaway prevention plate 25 that stands in front of it, so the improvement material does not run away beyond the runaway prevention plate 25 and run away to the surroundings. In other words, the improvement material injected from the small-diameter injection nozzle 41 remains in the inner area of the rotation trajectory of the stirring blade end (i.e., within the area of stirring and mixing by the stirring blade 21) due to the blocking action of the runaway prevention plate 25. It is also possible to block the path by angling the injection nozzle toward the tip of the stirring blade instead of the runaway prevention plate and causing the improvement material jet to collide with the tip of the stirring blade.
この小径噴射ノズル４１は、地中の粘土塊を粉砕する噴流が形成されるように改良材を中圧で噴射する。ここでいう「地中の粘土塊を粉砕する噴流」は、ほぼ層流又はほぼ遷移領域の噴流によって達成される。すなわち、小径噴射ノズル４１は、ほぼ層流又はほぼ遷移領域の噴流をなすように改良材を中圧で噴射する。 The small diameter injection nozzle 41 injects the improvement material at medium pressure so as to form a jet that crushes the clay lumps in the ground. The "jet that crushes the clay lumps in the ground" referred to here is achieved by a jet that is almost laminar or almost in the transition region. In other words, the small diameter injection nozzle 41 injects the improvement material at medium pressure so as to form a jet that is almost laminar or almost in the transition region.
小径噴射ノズル４１からのほぼ層流又はほぼ遷移領域の噴流は、（大径噴射ノズル５１からの噴流径と比較して）噴流径を小さく設定してあるので、（大径噴射ノズル５１からの噴流と異なり）乱流とはならず、その結果、地中における粘土塊の細かい粉砕が可能である。したがって、小径噴射ノズル４１からの改良材噴流は、粘土塊を細かく粉砕する細切削噴流として機能し、地盤内における流動性と攪拌混合度を向上させる。 The jet of nearly laminar or nearly transitional flow from the small-diameter jet nozzle 41 has a small jet diameter (compared to the jet diameter from the large-diameter jet nozzle 51), so it does not become turbulent (unlike the jet from the large-diameter jet nozzle 51), and as a result, it is possible to finely crush clay lumps underground. Therefore, the improvement material jet from the small-diameter jet nozzle 41 functions as a fine cutting jet that finely crushes clay lumps, improving the fluidity and degree of mixing in the ground.
このように小径噴射ノズル４１は、主として粘土塊を細かく粉砕することを狙った細切削噴流を噴射する役割を担うことから、「細切削噴射ノズル」と言い換えることができる。 In this way, the small diameter injection nozzle 41 can be referred to as a "fine cutting injection nozzle" since its main role is to inject a fine cutting jet aimed at finely crushing clay lumps.
第２の噴射ノズルである大径噴射ノズル５１はロッド１１の外周に設けられており、攪拌翼２１の下に位置し、小径噴射ノズル４１よりも大きいノズル径を有する。すなわち、大径噴射ノズル５１の径をＤ、小径噴射ノズル４１の径をｄとした場合、Ｄ＞ｄである。大径噴射ノズル５１は、その噴流が攪拌翼２６の端部に設けた逸走防止板２６に向かうように設けられている。大径噴射ノズル５１から中圧噴射された改良材噴流は、逸走防止板２６によって進路が遮断されるので、当該逸走防止板２６を超えて改良材が逸走することがない。すなわち、大径噴射ノズル５１から噴射された改良材は、逸走防止板２６による遮断作用によって、攪拌翼先端の回転軌跡の内側領域（すなわち攪拌翼２１による攪拌混合の領域内）に留まることになる。 The second injection nozzle, the large-diameter injection nozzle 51, is provided on the outer periphery of the rod 11, is located below the stirring blade 21, and has a nozzle diameter larger than that of the small-diameter injection nozzle 41. In other words, if the diameter of the large-diameter injection nozzle 51 is D and the diameter of the small-diameter injection nozzle 41 is d, then D>d. The large-diameter injection nozzle 51 is provided so that its jet is directed toward the runaway prevention plate 26 provided at the end of the stirring blade 26. The improvement material jet injected at medium pressure from the large-diameter injection nozzle 51 is blocked by the runaway prevention plate 26, so the improvement material does not run away beyond the runaway prevention plate 26. In other words, the improvement material injected from the large-diameter injection nozzle 51 remains in the inner area of the rotation trajectory of the stirring blade tip (i.e., within the area of stirring and mixing by the stirring blade 21) due to the blocking action of the runaway prevention plate 26.
この大径噴射ノズル５１は、攪拌翼２１による地盤掘削の負担を軽減する噴流が形成されるように改良材を中圧で噴射する。ここでいう「攪拌翼による地盤掘削の負担を軽減する噴流」は、小径噴射ノズル４１よりも大流量であって、例えばほぼ乱流の噴流によって達成される。すなわち、大径噴射ノズル５１は、ほぼ乱流の噴流が形成されるように改良材を中圧で噴射する。本実施形態では、この大径噴射ノズル５１を攪拌翼２１の下方に設けることで、攪拌翼２１による地盤掘削に先行して、大径噴射によりある程度切削されるので、攪拌翼２１による地盤掘削の負担が軽減される。 This large-diameter injection nozzle 51 injects the improvement material at medium pressure so as to form a jet that reduces the burden of ground excavation by the agitator 21. The "jet that reduces the burden of ground excavation by the agitator" referred to here is achieved by a larger flow rate than the small-diameter injection nozzle 41, for example, a jet that is almost turbulent. In other words, the large-diameter injection nozzle 51 injects the improvement material at medium pressure so as to form a jet that is almost turbulent. In this embodiment, by providing this large-diameter injection nozzle 51 below the agitator 21, some cutting is performed by the large-diameter injection prior to the ground excavation by the agitator 21, and the burden of ground excavation by the agitator 21 is reduced.
このように大径噴射ノズル５１は、（前述した小径噴射ノズル４１とは異なり、地中の粘土塊を細かく粉砕することを狙ったものではなく）小径噴射ノズル４１よりも大流量の改良材を噴射する役割を担うことから、「大流量噴射ノズル」と言い換えることができる。 In this way, the large diameter injection nozzle 51 can be called a "large flow injection nozzle" because it has the role of injecting a larger flow rate of improvement material than the small diameter injection nozzle 41 (unlike the small diameter injection nozzle 41 described above, which is not intended to finely crush clay lumps underground).
なお、本実施形態では、小径噴射ノズルと大径噴射ノズルを併設する地盤改良体造成装置を例示したが、本発明の地盤改良体造成装置はこれに限定されるものではない。 In this embodiment, a ground improvement body construction device equipped with both a small diameter injection nozzle and a large diameter injection nozzle is exemplified, but the ground improvement body construction device of the present invention is not limited to this.
例えば、各噴射ノズルの数は特に限定されるものではなく、地盤改良体造成装置は、大径噴射ノズルを１つ又は複数具備するとともに、小径噴射ノズルを１つ又は複数具備するものとして構成してもよい。
例えば図２に示す地盤改良体造成装置の変形例は、小径噴射ノズル４１を１つ、大径噴射ノズル５１を２つ具備しており、本発明の実施形態としてこのような構成を採用することも可能である。
また、大径噴射ノズルを具備せず、小径噴射ノズルを１つ又は複数具備する地盤改良体造成装置を採用することも可能である。
さらに、大径噴射ノズル・小径噴射ノズルのいずれか一方を１つ具備し、他方を複数具備する地盤改良体造成装置を採用することも可能である。
For example, the number of each injection nozzle is not particularly limited, and the ground improvement body construction device may be configured to have one or more large diameter injection nozzles and one or more small diameter injection nozzles.
For example, a modified example of the ground improvement body construction device shown in FIG. 2 is equipped with one small diameter jet nozzle 41 and two large diameter jet nozzles 51, and such a configuration can also be adopted as an embodiment of the present invention.
It is also possible to adopt a ground improvement body construction device that does not have a large diameter injection nozzle, but has one or more small diameter injection nozzles.
Furthermore, it is also possible to adopt a ground improvement body construction device having one large diameter jet nozzle or one small diameter jet nozzle, and a plurality of the other.
また、本実施形態では、小径噴射ノズル４１を攪拌翼２１の上に設け、大径噴射ノズル５１を攪拌翼２１の下に設けているが、本発明において各噴射ノズルの設置位置はこれに限定されるものではない。
例えば、小径噴射ノズル４１を攪拌翼２１の下に設け、大径噴射ノズル５１を攪拌翼２１の上に設けてもよい。また、攪拌翼２１の上または下において、小径噴射ノズル４１と大径噴射ノズル５１を上下または左右に並べて設けてもよい。
In addition, in this embodiment, the small diameter injection nozzle 41 is provided above the stirring blade 21 and the large diameter injection nozzle 51 is provided below the stirring blade 21, but the installation positions of each injection nozzle are not limited to this in the present invention.
For example, the small diameter jet nozzle 41 may be provided below the stirring blade 21, and the large diameter jet nozzle 51 may be provided above the stirring blade 21. Also, the small diameter jet nozzle 41 and the large diameter jet nozzle 51 may be provided above or below the stirring blade 21, arranged vertically or horizontally.
（レイノルズ数に基づく改良材噴流の制御）
次に、図１、図３、図４に基づいて、レイノルズ数に基づく改良材噴流の制御について説明する。
(Control of the improvement jet based on the Reynolds number)
Next, the control of the improver jet flow based on the Reynolds number will be described with reference to Figs. 1, 3 and 4.
小径噴射ノズル４１は、噴流径（噴射ノズルからの噴流の径）が小さくなるように設計されており、ほぼ層流または層流に近いほぼ遷移領域の噴流を形成する。なお、小径噴射ノズル４１からの噴流径は、小径噴射ノズル４１の径によって定まるものである。
層流をなす改良材噴流のイメージを図３（ａ）に示す。同図に示すとおり、層流をなす改良材噴流は、流れの進行方向においてほとんど乱れが無く、規則正しい流れである。
The small-diameter jet nozzle 41 is designed to have a small jet diameter (diameter of the jet from the jet nozzle) and forms a jet that is almost laminar or almost in the transition region close to laminar flow. The jet diameter from the small-diameter jet nozzle 41 is determined by the diameter of the small-diameter jet nozzle 41.
An image of a laminar improver jet is shown in Figure 3(a). As shown in the figure, the laminar improver jet is a regular flow with almost no turbulence in the flow direction.
大径噴射ノズル５１は、小径噴射ノズル４１よりも噴流径が大きくなるように設計されており、小径噴射ノズル４１よりも大流量でほぼ乱流の噴流を形成する。なお、大径噴射ノズル５１からの噴流径は、大径噴射ノズル５１の径によって定まるものである。
乱流をなす改良材噴流のイメージを図３（ｂ）に示す。同図に示すとおり、乱流をなす改良材噴流は、噴射ノズルから遠ざかるにつれて流れに乱れが生じ、不規則な流れである。
The large-diameter jet nozzle 51 is designed to have a larger jet diameter than the small-diameter jet nozzle 41, and forms a substantially turbulent jet with a larger flow rate than the small-diameter jet nozzle 41. The jet diameter from the large-diameter jet nozzle 51 is determined by the diameter of the large-diameter jet nozzle 51.
An image of a turbulent improver jet is shown in Figure 3(b). As shown in the figure, the turbulent improver jet is an irregular flow in which turbulence occurs as the improver jet moves away from the injection nozzle.
図３（ａ）（ｂ）から分かるように、層流とは、乱流のような不規則な流速ベクトルを持たない、一様流を形成する流れである。 As can be seen from Figures 3(a) and (b), laminar flow is a uniform flow that does not have irregular flow velocity vectors like turbulent flow.
噴射ノズルからの噴流が層流になるか、乱流になるかは、レイノルズ数という無次元数によって整理することができる。レイノルズ数Ｒｅは次式によって定義される。 Whether the jet from the injection nozzle becomes laminar or turbulent can be determined by a dimensionless number called the Reynolds number. The Reynolds number Re is defined by the following equation:
Ｒｅ＝ＶＤ／ν Re = VD/ν
上記式において、
Ｖ：改良材噴流の流速（改良材の吐出後の速度）
Ｄ：改良材の噴流径（噴射ノズルのノズル径）
ν：改良材の粘性（動粘性係数）
である。
In the above formula,
V: Flow velocity of the improvement material jet (velocity after the improvement material is discharged)
D: Jet diameter of improvement material (nozzle diameter of injection nozzle)
ν: Viscosity of the improvement material (dynamic viscosity coefficient)
It is.
「層流」の改良材噴流は、レイノルズ数Ｒｅが約２３００より小さくなるように、Ｖ（改良材の流速）、Ｄ（改良材の噴流径）、ν（改良材の粘性）をそれぞれ設定することで実現できる。 A "laminar" improvement material jet can be achieved by setting V (flow velocity of the improvement material), D (jet diameter of the improvement material), and ν (viscosity of the improvement material) so that the Reynolds number Re is less than approximately 2300.
「乱流」の改良材噴流は、レイノルズ数Ｒｅが約４０００より大きくなるように、Ｖ（改良材の流速）、Ｄ（噴射ノズルのノズル径）、ν（改良材の粘性）をそれぞれ設定することで実現できる。 A "turbulent" improvement material jet can be achieved by setting V (flow velocity of the improvement material), D (nozzle diameter of the injection nozzle), and ν (viscosity of the improvement material) so that the Reynolds number Re is greater than approximately 4000.
「遷移領域」の改良材噴流は、レイノルズ数Ｒｅが約２３００～約４０００の範囲に収まるように、Ｖ（改良材の流速）、Ｄ（噴射ノズルのノズル径）、ν（改良材の粘性）をそれぞれ設定することで実現できる。「遷移領域」とは、層流から乱流に変化する領域（層流と乱流が混在した領域）の流れの状態である。 The improvement agent jet in the "transition region" can be achieved by setting V (flow velocity of the improvement agent), D (diameter of the injection nozzle), and ν (viscosity of the improvement agent) so that the Reynolds number Re falls within the range of approximately 2300 to approximately 4000. The "transition region" is the flow state in the region where laminar flow changes to turbulent flow (a region where laminar flow and turbulent flow are mixed).
なお、「Ｒｅ＝ＶＤ／ν」の式から分かるとおり、Ｖ（改良材の流速）が同じでも、ν（改良材の粘性）やＤ（改良材の噴流径／噴射ノズルのノズル径）により、改良材噴流の状態は層流または乱流、あるいは遷移領域の状態となる。 As can be seen from the formula "Re = VD/ν", even if V (flow velocity of the improvement material) is the same, the improvement material jet state will be laminar or turbulent, or in a transition region state, depending on ν (viscosity of the improvement material) and D (jet diameter of the improvement material/nozzle diameter of the injection nozzle).
例えば施工において、Ｖ（改良材の流速）が所定の値に定まっている場合には、例えば改良材のＷ／Ｃ（水セメント比）を１００％以下とするなどしてν（改良材の粘性）を高く設定するとともに、Ｄ（噴射ノズルのノズル径）を小さくすることで、レイノルズ数Ｒｅが低下し、ほぼ層流または層流に近いほぼ遷移領域の噴流を実現することができる。 For example, in construction, if V (flow velocity of the improvement material) is set to a predetermined value, then by setting ν (viscosity of the improvement material) high, for example by making the W/C (water-cement ratio) of the improvement material 100% or less, and by reducing D (nozzle diameter of the injection nozzle), the Reynolds number Re decreases, and a jet that is almost laminar or close to laminar flow and is almost in the transition region can be achieved.
また、例えば施工において、Ｖ（改良材の流速）、ν（改良材の粘性）が、所定の値に定まっている場合には、Ｄ（噴射ノズルのノズル径）を小さくすることで、レイノルズ数Ｒｅが低下し、ほぼ層流または層流に近いほぼ遷移領域の噴流を実現することができる。 For example, in construction, if V (flow velocity of the improvement material) and ν (viscosity of the improvement material) are set to predetermined values, the Reynolds number Re can be reduced by reducing D (nozzle diameter of the injection nozzle), and a jet flow that is almost laminar or close to laminar flow and is almost in the transition region can be achieved.
レイノルズ数に基づく改良材噴流の制御に関するシミュレーションの結果を図４に示す。なお、図４において、「大流量噴射」は、大径噴射ノズルによる噴射を示している。「細切削噴射」は、小径噴射ノズルによる噴射を示している。 The results of a simulation on the control of the improvement jet flow based on the Reynolds number are shown in Figure 4. In Figure 4, "large flow injection" indicates injection from a large diameter injection nozzle. "Fine cutting injection" indicates injection from a small diameter injection nozzle.
図４から分かるように、Ｖ（改良材の流速）、Ｄ（噴射ノズルのノズル径）、ν（改良材の粘性）を変化させることで、それに応じてレイノルズ数Ｒｅが変化していることが分かる。すなわち、Ｖ（改良材の流速）、Ｄ（噴射ノズルのノズル径）、ν（改良材の粘性）のいずれか１または２以上を所望の値に設定することで、改良材噴流のレイノルズ数Ｒｅを制御できることが分かる。そして、改良材噴流のレイノルズ数Ｒｅを制御できれば、改良材噴流の流れの状態を、層流・遷移領域・乱流のいずれかに設定することが可能になる。 As can be seen from Figure 4, the Reynolds number Re changes accordingly by changing V (flow velocity of the improvement material), D (nozzle diameter of the injection nozzle), and ν (viscosity of the improvement material). In other words, it can be seen that the Reynolds number Re of the improvement material jet can be controlled by setting one or more of V (flow velocity of the improvement material), D (nozzle diameter of the injection nozzle), and ν (viscosity of the improvement material) to desired values. Furthermore, if the Reynolds number Re of the improvement material jet can be controlled, it becomes possible to set the flow state of the improvement material jet to either laminar flow, transition region, or turbulent flow.
なお、２０ＭＰａ以上の高圧噴射領域では改良材噴流が乱流となるため、地盤改良体造成装置を用いた地盤改良工法は、２０ＭＰａ未満の中圧噴射領域に適している。 In addition, since the improvement material jet becomes turbulent in the high-pressure injection range of 20 MPa or more, the ground improvement method using the ground improvement body construction device is suitable for the medium-pressure injection range of less than 20 MPa.
（地盤改良体造成装置を用いた地盤改良工法）
次に、図１、図５に基づいて、前述した地盤改良体造成装置を用いた中圧噴射攪拌による地盤改良工法について説明する。
(Soil improvement method using a soil improvement body construction device)
Next, a ground improvement method by medium pressure jet mixing using the above-mentioned ground improvement body construction device will be described with reference to Figs.
図５に示すように、地盤改良工法の実施にあたっては、主として、前述した地盤改良体造成装置１と、その駆動制御機構を具備する地盤改良機２を用いる。地盤改良機としては、例えば図５に例示するバックホウタイプのベースマシンのほか、各種の地盤改良専用機を用いることができる。 As shown in Figure 5, the ground improvement method is carried out mainly using the above-mentioned ground improvement body construction device 1 and a ground improvement machine 2 equipped with its drive control mechanism. As the ground improvement machine, for example, a backhoe-type base machine as shown in Figure 5, or various dedicated ground improvement machines can be used.
これらの機材を用いた地盤改良工法では、攪拌翼２１，３１や噴射ノズル４１，５１を具備するロッド１１を地盤内で前進（貫入）または後退（引上）させつつ回転させるとともに、改良材を中圧で地盤内に注入することによって柱状の地盤改良体を造成する。 In the ground improvement method using these machines, a rod 11 equipped with stirring blades 21, 31 and injection nozzles 41, 51 is rotated while moving forward (penetrating) or backward (pulling up) in the ground, and improvement material is injected into the ground at medium pressure to create a columnar ground improvement body.
本実施形態の地盤改良工法は、主として、「貫入工程」と「引上工程」の二工程を含んでいる。 The ground improvement method of this embodiment mainly includes two processes: the "penetration process" and the "pulling up process."
貫入工程では、ロッド１１を正方向に回転させて、攪拌翼２１により地盤を掘削しつつ、地盤改良体造成装置１を対象地盤に貫入する。
引上工程では、ロッド１１を逆方向に回転させつつ、地盤改良体造成装置１を対象地盤から引き上げる。
In the penetration process, the rod 11 is rotated in the forward direction, and the ground improvement body creating device 1 is penetrated into the target ground while the stirring blade 21 excavates the ground.
In the pulling-up process, the rod 11 is rotated in the reverse direction while the ground improvement body construction device 1 is pulled up from the target ground.
また、貫入工程においてロッド１１を貫入する過程では、攪拌翼２１による地盤掘削の負担を軽減する噴流（例えば乱流）を形成するように、大径噴射ノズル５１からスラリー状の改良材を中圧で噴射する。同時に、地中の粘土塊を粉砕する噴流（ほぼ層流またはほぼ遷移領域の流れ）を形成するように、小径噴射ノズル４１からスラリー状の改良材を中圧で噴射する。 In addition, during the penetration process, when the rod 11 is being penetrated, the slurry-like improvement material is injected from the large-diameter injection nozzle 51 at medium pressure to form a jet (e.g., turbulent flow) that reduces the burden of ground excavation by the agitator 21. At the same time, the slurry-like improvement material is injected from the small-diameter injection nozzle 41 at medium pressure to form a jet (almost laminar flow or almost transition region flow) that breaks up the clay lumps in the ground.
具体的には、大径噴射ノズル５１からは、小径噴射ノズル４１とほぼ同じ圧力で、スラリー状の改良材を中圧で噴射する。大径噴射ノズル５１からの改良材噴流は、小径噴射ノズル４１からの噴流径よりも大径の大流量噴流となって、攪拌翼２１による地盤掘削の負担を軽減させる。大径噴射ノズル５１からの噴流のレイノルズ数Ｒｅは、例えば約４０００より大きくなるように設定される。 Specifically, the large diameter injection nozzle 51 injects a slurry-like improvement material at medium pressure, approximately the same pressure as the small diameter injection nozzle 41. The improvement material jet from the large diameter injection nozzle 51 is a large-diameter, high-flow jet larger than the jet diameter from the small diameter injection nozzle 41, reducing the burden of ground excavation by the agitator 21. The Reynolds number Re of the jet from the large diameter injection nozzle 51 is set to be greater than, for example, approximately 4000.
大径噴射ノズル５１による大流量の改良材噴流が、攪拌翼２１の回転動作に先行するため、攪拌翼２１による地盤掘削の負担が軽減される。すなわち、大径噴射ノズル５１による大流量噴流が攪拌翼２１による地盤掘削を支援し、その結果、ロッド１１の回転トルクを低減することができる。 The large-diameter jet nozzle 51 jets a high-flow rate of improvement material prior to the rotation of the agitator 21, reducing the burden of excavating the ground by the agitator 21. In other words, the large-flow rate jet from the large-diameter jet nozzle 51 assists the agitator 21 in excavating the ground, and as a result, the rotational torque of the rod 11 can be reduced.
また、小径噴射ノズル４１からは、大径噴射ノズル５１とほぼ同じ圧力で、スラリー状の改良材を中圧で噴射する。このとき、小径噴射ノズル４１からの噴流のレイノルズ数Ｒｅが、ほぼ２３００になるように又はこれより小さくなるように改良材を噴射する。あるいは、小径噴射ノズル４１からの噴流のレイノルズ数Ｒｅが、ほぼ２３００～ほぼ４０００の範囲に収まるように改良材を噴射する。 The small diameter injection nozzle 41 injects the slurry-like improvement material at medium pressure, approximately the same as the large diameter injection nozzle 51. At this time, the improvement material is injected so that the Reynolds number Re of the jet from the small diameter injection nozzle 41 is approximately 2300 or less. Alternatively, the improvement material is injected so that the Reynolds number Re of the jet from the small diameter injection nozzle 41 falls within the range of approximately 2300 to approximately 4000.
小径噴射ノズル４１からの改良材噴流は、大径噴射ノズル５１による噴流径によりも小径であり、ほぼ層流またはほぼ遷移領域の流れを形成するので、大径噴射ノズル５１による大流量噴流で粉砕できなかった地中の粘土塊を粉砕することが可能である。 The improvement material jet from the small diameter jet nozzle 41 has a smaller diameter than the jet diameter from the large diameter jet nozzle 51 and forms a nearly laminar flow or a flow in the transition region, making it possible to crush clay lumps underground that could not be crushed by the high flow rate jet from the large diameter jet nozzle 51.
そして、噴射ノズル４１，５１から噴射された改良材噴流は、その先に立ちはだかる逸走防止板２５，２６によって進路が遮断されるので、改良材が当該逸走防止板２５，２６を超えて周囲に逸走することがなく、攪拌翼先端の回転軌跡の内側空間（すなわち円柱状空間）の範囲内に留まることになる。なお、逸走防止板の代わりに噴射ノズルを攪拌翼先端部に向かう角度とし、改良材噴流を攪拌翼先端に衝突させることで進路を遮断することも可能である。そして、噴射ノズル４１，５１から噴射された当該改良材は、攪拌翼２１，３１によって地盤と攪拌混合される。 The improvement material jet sprayed from the spray nozzles 41, 51 has its path blocked by the escape prevention plates 25, 26 that stand in its way, so the improvement material does not escape beyond the escape prevention plates 25, 26 and remains within the inner space of the rotation trajectory of the agitator tip (i.e., the cylindrical space). It is also possible to block the path by angling the spray nozzle toward the agitator tip instead of the escape prevention plates and causing the improvement material jet to collide with the agitator tip. The improvement material sprayed from the spray nozzles 41, 51 is mixed and stirred with the ground by the agitator blades 21, 31.
なお、本実施形態では、地盤改良体造成装置１を貫入する過程で噴射ノズル４１，５１から改良材を中圧噴射しているが、貫入と引上の両過程において、噴射ノズル４１，５１から改良材を中圧噴射してもよい。あるいは、貫入する過程では改良材を噴射することなく、引上の過程において、噴射ノズル４１，５１から改良材を中圧噴射してもよい。 In this embodiment, the improvement material is injected at medium pressure from the injection nozzles 41, 51 during the process of penetrating the ground improvement body construction device 1, but the improvement material may be injected at medium pressure from the injection nozzles 41, 51 during both the penetration and lifting processes. Alternatively, the improvement material may not be injected during the penetration process, but may be injected at medium pressure from the injection nozzles 41, 51 during the lifting process.
上述した地盤改良体造成装置を用いた中圧噴射攪拌による地盤改良工法によれば、各噴射ノズルで流量は異なるものの、同じ圧力で大流量噴射と細切削噴射を組み合わせた、複合中圧噴射攪拌により、掘削能力の向上と粘土塊粉砕による地盤改良体の高品質化が実現される。 According to the ground improvement method using medium-pressure jet mixing with the above-mentioned ground improvement body construction device, although the flow rate differs for each jet nozzle, the combined medium-pressure jet mixing combines high-flow jetting and fine cutting jetting at the same pressure, improving excavation capacity and improving the quality of the ground improvement body by crushing clay lumps.
次に、本発明の具体的実施例について説明する。 Next, we will explain a specific example of the present invention.
地盤改良体造成装置として、図６（ａ）（ｂ）に示す二種の地盤改良体造成装置を用意し、試験施工を実施した。
図６（ａ）に示す比較例の地盤改良体造成装置は、上下二段の攪拌翼と上下二つの大径噴射ノズルを具備していた。
図６（ｂ）に示す実施例の地盤改良体造成装置は、本発明の具体的実施例であって、上下二段の攪拌翼と、細切削噴射を担う上下二つの小径噴射ノズルと、大流量噴射を担う一つの大径噴射ノズルを具備していた。
なお、比較例と実施例の地盤改良体造成装置は、小径噴射ノズルに係る部分を除いて同様に構成されていた。
As the ground improvement body construction device, two types of ground improvement body construction devices shown in Figures 6(a) and (b) were prepared and test construction was carried out.
The ground improvement body construction device of the comparative example shown in FIG. 6(a) was equipped with upper and lower two-stage stirring blades and two large-diameter injection nozzles, one above the other.
The soil improvement body construction device of the embodiment shown in Figure 6 (b) is a specific embodiment of the present invention, and is equipped with two upper and lower stirring blades, two upper and lower small diameter injection nozzles for fine cutting injection, and one large diameter injection nozzle for high flow rate injection.
The ground improvement body construction devices of the comparative example and the embodiment were configured similarly except for the parts relating to the small diameter jet nozzle.
実施例と比較例の地盤改良体造成装置を用いた試験施工の仕様は、図７に示すとおりであった。 The specifications for the test construction using the ground improvement body construction devices of the embodiment and the comparative example were as shown in Figure 7.
実施例と比較例の地盤改良体造成装置を用いて造成した地盤改良体は、図８、図９に示すとおりであった。
造成した各地盤改良体について一軸圧縮試験を実施したところ、その試験結果は図１０に示すとおりであった。
すなわち、本発明の実施例の装置で造成したと地盤改良体は、比較例の装置で造成したと地盤改良体よりも高い一軸圧縮強さを示し、高い品質を確保できることを確認した。
したがって、細切削噴射を担う小径噴射ノズルと大流量噴射を担う大径噴射ノズルを組み合わせた、複合中圧噴射攪拌により、掘削能力の向上と粘土塊粉砕による地盤改良体の高品質化が実現されることが試験施工において確認できた。
The ground improvement bodies constructed using the ground improvement body construction devices of the Example and Comparative Example were as shown in Figures 8 and 9.
A uniaxial compression test was carried out on each of the constructed ground improvement bodies, and the test results are shown in Figure 10.
In other words, it was confirmed that the ground improvement body prepared using the device of the embodiment of the present invention exhibited higher uniaxial compressive strength than the ground improvement body prepared using the device of the comparative example, ensuring high quality.
Therefore, it was confirmed in the test construction that the combined medium-pressure injection mixing, which combines a small-diameter injection nozzle for fine cutting injection and a large-diameter injection nozzle for high-flow injection, can improve excavation capacity and improve the quality of the ground improvement body by crushing clay lumps.
１ 地盤改良体造成装置
２ 地盤改良機
１１ ロッド（注入ロッド）
１３ 掘削ビット
２１ 攪拌翼
２３ 掘削ビット
２５ 逸走防止板
２６ 逸走防止板
３１ 攪拌翼
４１ 小径噴射ノズル（第１の噴射ノズル／細切削噴射ノズル）
５１ 大径噴射ノズル（第２の噴射ノズル／大流量噴射ノズル）
９１ ロッド
９３ 噴射ノズル
９５ 攪拌翼
1 Ground improvement body construction device 2 Ground improvement machine 11 Rod (injection rod)
13 Drilling bit 21 Agitating blade 23 Drilling bit 25 Runaway prevention plate 26 Runaway prevention plate 31 Agitating blade 41 Small diameter injection nozzle (first injection nozzle/fine cutting injection nozzle)
51 Large diameter injection nozzle (second injection nozzle/large flow rate injection nozzle)
91 Rod 93 Injection nozzle 95 Stirring blade
Claims (7)
地盤内で噴射するスラリー状の地盤改良材の流路が形成されたロッドと、
前記ロッドに設けられ、地中の粘土塊を粉砕する噴流をなすように前記地盤改良材を中圧で噴射する第１の噴射ノズルと、
前記ロッドに設けられ、前記第１の噴射ノズルよりも大きいノズル径を有し、前記攪拌翼による地盤掘削の負担を軽減する噴流をなすように前記地盤改良材を中圧で噴射する第２の噴射ノズルと、
前記ロッドに設けられ、地中に噴射された前記地盤改良材と地盤を攪拌混合するための攪拌翼と、
を有することを特徴とする中圧噴射攪拌による地盤改良体造成装置。 A ground improvement body construction device that rotates a rod equipped with an agitating blade while moving it forward or backward in the ground and injects a ground improvement material into the ground to create a columnar ground improvement body,
A rod having a flow path for a slurry-like ground improvement material to be injected into the ground;
A first injection nozzle provided on the rod for injecting the ground improvement material at medium pressure to form a jet that crushes clay lumps in the ground;
A second injection nozzle is provided on the rod, has a nozzle diameter larger than that of the first injection nozzle, and injects the ground improvement material at medium pressure to form a jet that reduces the burden of ground excavation by the mixing blade;
A stirring blade provided on the rod for stirring and mixing the soil improvement material and the ground injected into the ground;
A ground improvement body construction device using medium pressure jet mixing, characterized by having:
前記第２の噴射ノズルは、ほぼ乱流の噴流をなすように前記地盤改良材を中圧で噴射する、
ことを特徴とする請求項１に記載の中圧噴射攪拌による地盤改良体造成装置。 The first injection nozzle injects the ground improvement material at a medium pressure so as to form a jet of approximately laminar flow or approximately transition region;
The second injection nozzle injects the ground improvement material at medium pressure so as to form a substantially turbulent jet.
2. A ground improvement body construction device using medium pressure jet mixing as claimed in claim 1.
各噴射ノズルからの噴流が前記攪拌翼の端部に向かうように設けられている、
ことを特徴とする請求項１又は２に記載の中圧噴射攪拌による地盤改良体造成装置。 The first injection nozzle and the second injection nozzle each include
The jet from each jet nozzle is provided so as to be directed toward the end of the stirring blade.
3. A ground improvement body construction device using medium pressure jet mixing as claimed in claim 1 or 2.
ロッドを回転させつつ地盤改良体造成装置を対象地盤に貫入する工程と、
ロッドを回転させつつ地盤改良体造成装置を対象地盤から引き上げる工程と、
を含んでおり、
前記貫入工程及び／又は前記引上工程において、地中の粘土塊を粉砕する噴流をなすように、第１の噴射ノズルからスラリー状の地盤改良材を中圧で噴射する、
ことを特徴とする中圧噴射攪拌による地盤改良工法。 A ground improvement method by medium pressure injection mixing using the ground improvement body construction device according to claim 1,
A step of penetrating the ground improvement body construction device into the target ground while rotating the rod;
A step of lifting the ground improvement body construction device from the target ground while rotating the rod;
Contains
In the penetration step and/or the lifting step, a slurry-like ground improvement material is injected from a first injection nozzle at medium pressure to form a jet that crushes clay lumps in the ground.
A ground improvement method using medium pressure jet mixing.
ロッドを回転させつつ地盤改良体造成装置を対象地盤に貫入する工程と、
ロッドを回転させつつ地盤改良体造成装置を対象地盤から引き上げる工程と、
を含んでおり、
前記貫入工程及び／又は前記引上工程において、
地中の粘土塊を粉砕する噴流をなすように、第１の噴射ノズルからスラリー状の地盤改良材を中圧で噴射するとともに、
攪拌翼による地盤掘削の負担を軽減する噴流をなすように、第２の噴射ノズルからスラリー状の地盤改良材を中圧で噴射する、
ことを特徴とする中圧噴射攪拌による地盤改良工法。 A ground improvement method by medium pressure injection mixing using the ground improvement body construction device according to claim 1,
A step of penetrating the ground improvement body construction device into the target ground while rotating the rod;
A step of lifting the ground improvement body construction device from the target ground while rotating the rod;
Contains
In the penetration step and/or the pulling step,
A slurry-like ground improvement material is injected from a first injection nozzle at medium pressure to form a jet that crushes clay lumps in the ground,
The slurry-like ground improvement material is injected from the second injection nozzle at medium pressure so as to form a jet that reduces the burden of ground excavation by the mixing blades.
A ground improvement method using medium pressure jet mixing.
前記第１の噴射ノズルからの噴流のレイノルズ数Ｒｅが、ほぼ２３００又はこれより小さくなるように、あるいは、ほぼ２３００～ほぼ４０００の範囲に収まるように、前記地盤改良材を噴射する、
ことを特徴とする請求項４又は５に記載の中圧噴射攪拌による地盤改良工法。 When the slurry-like ground improvement material is injected from the first injection nozzle at medium pressure,
The ground improvement material is injected so that the Reynolds number Re of the jet from the first injection nozzle is approximately 2300 or less, or is within the range of approximately 2300 to approximately 4000.
6. The method for ground improvement using medium pressure jet mixing according to claim 4 or 5.
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