JP4370204B2 - Triaxial deep mixing method - Google Patents

Triaxial deep mixing method Download PDF

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JP4370204B2
JP4370204B2 JP2004169777A JP2004169777A JP4370204B2 JP 4370204 B2 JP4370204 B2 JP 4370204B2 JP 2004169777 A JP2004169777 A JP 2004169777A JP 2004169777 A JP2004169777 A JP 2004169777A JP 4370204 B2 JP4370204 B2 JP 4370204B2
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stirring
rotational speed
shaft
ground
rotating
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JP2005350870A (en
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卓弥 守安
廣貴 川崎
勝彦 横山
一義 上村
実 栗原
公之 本田
哲郎 小寺
俊郎 原
弘次 上原
健二 原田
修二 磯谷
辰夫 高橋
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Shimizu Corp
Fudo Tetra Corp
Aomi Construction Co Ltd
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Shimizu Corp
Fudo Tetra Corp
Aomi Construction Co Ltd
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Description

本発明は、３軸の回転軸を備えた３軸深層混合処理装置による地盤改良工法である３軸深層混合処理工法に関する。   The present invention relates to a three-axis deep mixing treatment method that is a ground improvement method using a three-axis deep mixing treatment apparatus having a three-axis rotation shaft.

この種の３軸深層混合処理工法としてはたとえば特許文献１に示されるものがあるが、これは図４に示すように３軸の回転軸１のうち両側の２軸の回転軸１ａをそれぞれ独立の駆動源２により逆方向に回転させ、中央の回転軸１ｂは動力伝達装置３を介して両側の回転軸１ａのいずれか一方と同方向（したがって他方とは逆方向）に回転させるというものである。   As this type of three-axis deep mixing method, for example, there is one disclosed in Patent Document 1, but as shown in FIG. 4, the two rotary shafts 1a on both sides of the three rotary shafts 1 are independent of each other. The central rotating shaft 1b is rotated in the same direction as one of the rotating shafts 1a on both sides via the power transmission device 3 (and thus in the opposite direction). is there.

そして従来の３軸深層混合処理工法では、各回転軸１をそれぞれ正回転させて各攪拌翼４により地盤を攪拌しながらその全体を地盤中に所定深度まで貫入した後、各回転軸１をそれぞれ逆回転させて引き抜くのであるが、そのような貫入工程や引き抜き工程の途中で各回転軸１の先端部からセメントスラリーやセメント粉体等の固化材を地盤中に供給して原地盤の土と攪拌混合することにより改良土とし、それを硬化させることで地盤改良を行うものである。
特許第３１５６０４３号公報 In the conventional three-axis deep mixing processing method, each rotary shaft 1 is rotated forward and the ground is stirred by each stirring blade 4 so that the whole is penetrated into the ground to a predetermined depth. It is pulled out by rotating in reverse, but solid materials such as cement slurry and cement powder are supplied into the ground from the tip of each rotating shaft 1 in the middle of such penetration process and drawing process. The soil is improved by stirring and mixing, and the ground is improved by curing it.
Japanese Patent No. 3156043

ところで、上記従来の３軸深層混合処理工法では、３軸の回転軸１の各攪拌翼４により図５に示されるような３連の攪拌領域５が形成されてそこで固化材と原地盤の土とが攪拌混合されることになるのであるが、そのような攪拌領域５における攪拌混合が必ずしも充分に行われずに所期の改良効果が得られない場合も想定される。特に、従来においては、中央の攪拌翼４の回転方向は両側の攪拌翼４のいずれかとは常に同方向に回転することから、図５（ａ），（ｂ）に示すように逆方向に回転するものどうしの間ではそれなりの攪拌効果も期待できるが、同方向に回転するものどうしの間では改良土の流れが分断されてしまってそこでは改良土が停滞してしまい、それにより攪拌領域５内において固化材と土との攪拌混合状態に偏りが生じる場合があることが指摘されている。   By the way, in the conventional three-axis deep mixing method, the three stirring regions 5 as shown in FIG. 5 are formed by the respective stirring blades 4 of the three-axis rotating shaft 1, and the solidified material and the soil of the original ground there. However, there may be a case where the stirring and mixing in the stirring region 5 is not always sufficiently performed and the desired improvement effect cannot be obtained. In particular, in the prior art, the rotation direction of the central stirring blade 4 always rotates in the same direction as one of the stirring blades 4 on both sides, so that it rotates in the opposite direction as shown in FIGS. 5 (a) and 5 (b). A moderate agitation effect can be expected between the two to be operated, but the flow of the improved soil is interrupted between the two rotating in the same direction, so that the improved soil stagnates and thereby the stirring region 5 It has been pointed out that bias may occur in the stirring and mixing state of the solidified material and the soil.

上記事情に鑑み、本発明は、３軸の回転軸により形成される３連の攪拌領域において土と固化材とをより確実かつ効率的に攪拌混合することを可能とする３軸深層混合処理工法を提供することを目的とする。   In view of the above circumstances, the present invention is a three-axis deep mixing method that enables more reliable and efficient stirring and mixing of soil and solidified material in a triple stirring region formed by three rotating shafts. The purpose is to provide.

請求項１の発明は、先端部に攪拌翼を備えた３軸の回転軸を並設し、それら回転軸を正回転させて地盤に貫入するとともに逆回転させて地盤から引き抜く間に、回転軸の先端部から固化材を地盤中に供給して各攪拌翼により形成される３連の攪拌領域において攪拌混合することにより地盤改良を行う３軸深層混合処理工法であって、３軸の回転軸のうち両側の回転軸を同一方向に回転させるとともに中央の回転軸を両側の回転軸とは逆方向に回転させることにより、前記攪拌領域全体にわたって改良土が連続して流れる一連の攪拌流を形成し、かつ、両側の回転軸の回転数と中央の回転軸の回転数に差をもたせることにより、前記攪拌領域の両側部と中心部とで改良土圧に差を生じさせてそれらの間における改良土の流れを促進せしめるようにしたものである。   According to the first aspect of the present invention, there are provided three rotating shafts each having a stirring blade at the tip, and the rotating shafts are rotated forwardly to penetrate into the ground and reversely rotated and pulled out from the ground. A three-axis deep mixing method for improving the ground by supplying solidified material from the tip of the ground into the ground and stirring and mixing in a triple stirring region formed by each stirring blade. The rotating shafts on both sides are rotated in the same direction, and the central rotating shaft is rotated in the opposite direction to the rotating shafts on both sides, thereby forming a series of stirring flow in which the improved soil continuously flows over the entire stirring region. In addition, by making a difference between the rotational speeds of the rotary shafts on both sides and the rotational speed of the central rotary shaft, a difference is caused in the improved earth pressure between the both sides and the center of the stirring region. To promote the flow of improved soil One in which the.

請求項２の発明は、請求項１の発明の３軸深層混合処理工法において、回転軸からの固化材の供給量を回転数に応じて設定し、回転数の大きい回転軸からの供給量を、回転数が小さい回転軸からの供給量よりも大きく設定するものである。   According to a second aspect of the present invention, in the triaxial deep mixing method according to the first aspect of the invention, the supply amount of the solidified material from the rotation shaft is set according to the rotation speed, and the supply amount from the rotation shaft having a higher rotation speed is set. The rotation amount is set larger than the supply amount from the rotation shaft.

請求項３の発明は、請求項１の発明の３軸深層混合処理工法において、回転軸の回転数を負荷に応じて設定し、高負荷の回転軸の回転数を低負荷の回転軸の回転数よりも小さく設定するものである。   According to a third aspect of the present invention, in the three-axis deep mixing method according to the first aspect of the invention, the rotational speed of the rotary shaft is set in accordance with the load, and the rotational speed of the high-load rotary shaft is set to rotate the low-load rotary shaft. It is set smaller than the number.

請求項１の発明によれば、基本的に各回転軸の回転方向を上記のように設定することにより、各攪拌翼による３連の攪拌領域全体にわたって改良土が連続して流れるような一連の攪拌流が自ずと形成され、それにより従来のように攪拌領域の一部において攪拌流が分断されて改良土がそこに停滞してしまうようなことがなく、より確実かつ効率的な攪拌混合効果が得られ、優れた地盤改良効果が得られる。しかも、両側の回転軸の回転数と中央の回転軸の回転数に差をもたせることにより、攪拌領域の両側部と中心部とで改良土圧に自ずと差が生じ、その結果、攪拌領域内において改良土が水平方向に移動するような改良土の流れが自ずと促進され、攪拌混合効果をより一層高めることができる。   According to the first aspect of the present invention, basically, by setting the rotation direction of each rotating shaft as described above, a series of such that the improved soil continuously flows over the entire triple stirring region by each stirring blade. A stir flow is naturally formed, and thus the stir flow is not divided in a part of the stir zone as in the prior art, and the improved soil does not stagnate there, and a more reliable and efficient stir and mix effect is obtained. Obtained, and an excellent ground improvement effect is obtained. Moreover, by making a difference between the rotational speeds of the rotating shafts on both sides and the rotational speed of the central rotating shaft, a natural difference is caused in the improved earth pressure between the both side portions and the central portion of the stirring region. The flow of the improved soil such that the improved soil moves in the horizontal direction is naturally promoted, and the stirring and mixing effect can be further enhanced.

また、請求項２の発明によれば、回転軸からの固化材の供給量を回転数に対応させて設定し、回転数の大きい回転軸からの供給量をより大きくすることにより、供給した固化材を上記のように水平方向に移動するような改良土の流れに乗せて攪拌領域全体にわたって効率的に行き渡らせることができ、優れた攪拌混合効率が得られる。   According to the second aspect of the present invention, the amount of solidification material supplied from the rotating shaft is set corresponding to the rotational speed, and the amount supplied from the rotating shaft having a large rotational speed is increased to increase the supplied solidification. As described above, the material can be efficiently spread over the entire stirring region by being put on the flow of the improved soil that moves in the horizontal direction, and excellent stirring and mixing efficiency can be obtained.

さらに、請求項３の発明によれば、地盤状況等によって両側の回転軸と中央の回転軸にかかる負荷に差が生じる場合、高負荷がかかる回転軸の回転数を低負荷の回転軸の回転数よりも小さくすることにより、それぞれのトルクを負荷に応じて調節することができ、それにより地盤状況に応じた最適な運転が可能となり、併せて、回転数に差をもたせることによる上記のような優れた攪拌混合効率を同時に得ることができる。   Further, according to the third aspect of the present invention, when there is a difference in the load applied to the rotary shafts on both sides and the central rotary shaft due to the ground condition or the like, the rotational speed of the rotary shaft to which a high load is applied is reduced. By making it smaller than the number, each torque can be adjusted according to the load, which makes it possible to optimally operate according to the ground condition, and at the same time, by making a difference in the rotation speed as described above Excellent stirring and mixing efficiency can be obtained at the same time.

本発明の一実施形態を図１〜図３に示す。図１に示すように本実施形態の３軸深層混合処理工法では、従来と同様に並設した３軸の回転軸１の先端部にそれぞれ複数段（図示例では４段）の攪拌翼４を備えた構成の３軸深層混合処理装置を用いて、それらの攪拌翼４により図２に示すような３連の攪拌領域５を形成してそこで原地盤の土と固化材とを攪拌混合して改良土とするのであるが、本実施形態の３軸深層混合処理工法では、各回転軸１をそれぞれ専用の駆動源２により独立に駆動するものとしておいて、それらの回転方向を、貫入時の正回転時および引き抜き時の逆回転時のいずれにおいても、図示しているように両側の回転軸１ａが同一方向に回転するとともに中央の回転軸１ｂがそれらとは逆方向に回転する（つまり、３軸の回転軸１ａ，１ｂ、１ａが交互に逆方向に回転する）ものとしている。   One embodiment of the present invention is shown in FIGS. As shown in FIG. 1, in the three-axis deep mixing processing method of this embodiment, a plurality of stages (four stages in the illustrated example) of stirring blades 4 are respectively provided at the tip of the three-axis rotating shaft 1 arranged in parallel as in the prior art. Using the three-axis deep mixing processing apparatus having the structure provided, the stirring blades 4 form the three stirring regions 5 as shown in FIG. 2, and the soil and solidified material of the original ground are stirred and mixed there. In the three-axis deep mixing method according to the present embodiment, each rotary shaft 1 is driven independently by a dedicated drive source 2 and the rotation direction thereof is determined at the time of penetration. In both the forward rotation and the reverse rotation at the time of extraction, as shown in the drawing, the rotary shafts 1a on both sides rotate in the same direction and the central rotary shaft 1b rotates in the opposite direction (that is, The three rotating shafts 1a, 1b, 1a rotate alternately in the opposite direction. To) it is assumed.

各回転軸１の回転方向をそのように設定したことにより、図２（ａ），（ｂ）に示すように貫入時および引抜き時のいずれにおいても３連の攪拌領域５全体にわたって改良土が連続して流れるような一連の攪拌流が形成され、したがって図６に示した従来の場合のように攪拌領域５の一部において改良土の流れが分断されてそこに停滞してしまうようなことがなく、それにより攪拌領域５全体にわたって固化材と土とを偏りなく確実かつ効率的に攪拌し混合できるものとなっている。なお、各回転軸１の先端部には、最下段の攪拌翼４付近と最上段の攪拌翼４付近に、それぞれ固化材の吐出口９，１０が設けられていて、貫入時には固化材を下段側の吐出口９から吐出し、引き抜き時には固化材を上段側の吐出口１０から吐出することが基本となっている。   By setting the rotation direction of each rotary shaft 1 in such a manner, the improved soil is continuously spread over the entire three stirring regions 5 at the time of penetration and at the time of withdrawal as shown in FIGS. 2 (a) and 2 (b). As a result, a flow of agitated flow is formed, so that the flow of the improved soil is divided and stagnated in a part of the agitated region 5 as in the conventional case shown in FIG. Accordingly, the solidified material and the soil can be reliably and efficiently stirred and mixed over the entire stirring region 5 without deviation. The tip of each rotating shaft 1 is provided with solidifying material discharge ports 9 and 10 in the vicinity of the lowermost stirring blade 4 and the uppermost stirring blade 4, respectively. The discharge is basically performed from the discharge port 9 on the side, and the solidified material is discharged from the discharge port 10 on the upper stage side at the time of drawing.

以上に加え、本実施形態の３軸深層混合処理工法では、両側の回転軸１ａの回転数と中央の回転軸１ｂの回転数に差をもたせることにより、上記の攪拌領域５の両側部と中心部とで改良土圧に差が生じるようにしており、それにより攪拌領域５において改良土が水平方向に移動するような流れを促進せしめるようにしている。   In addition to the above, in the three-axis deep mixing processing method of the present embodiment, the difference between the rotational speed of the rotary shaft 1a on both sides and the rotational speed of the central rotary shaft 1b is set, so A difference in the improved earth pressure is generated between the two parts, thereby promoting a flow in which the improved earth moves in the horizontal direction in the stirring region 5.

すなわち、たとえば図３（ａ）に示すように、中央の回転軸１ｂの回転数を両側の回転軸１ａの回転数よりも大きく設定することにより、攪拌領域５の中央部における改良土圧が両側よりも相対的に自ずと上昇し、それにより改良土が中央部から両側に向かって流れるような改良土の流れが促進されることになる。逆に、図３（ｂ）に示すように、両側の回転軸１ａの回転数を中央の回転軸１ｂの回転数よりも大きく設定することにより、攪拌領域５の両側における改良土圧が中央部よりも相対的に自ずと上昇し、それにより改良土が両側から中央部に向かって流れるような改良土の流れが促進されることになる。なお、回転軸１の回転数を大きくすれば自ずとトルクは低下し、回転数を小さくすれば自ずとトルクは増大することになる。   That is, for example, as shown in FIG. 3 (a), by setting the rotational speed of the central rotating shaft 1b to be larger than the rotational speeds of the rotating shafts 1a on both sides, the improved earth pressure at the central portion of the stirring region 5 is increased on both sides. Rather, the flow of the improved soil is promoted such that the improved soil flows from the central portion toward both sides. On the contrary, as shown in FIG. 3B, the improved earth pressure on both sides of the stirring region 5 is set at the central portion by setting the rotational speed of the rotary shaft 1a on both sides to be larger than the rotational speed of the central rotary shaft 1b. Rather, the flow of the improved soil is promoted so that the improved soil flows from both sides toward the center. Note that if the rotational speed of the rotary shaft 1 is increased, the torque will naturally decrease, and if the rotational speed is decreased, the torque will naturally increase.

本実施形態によれば、各攪拌翼４により形成される３連の攪拌領域５において基本的に図２に示したような一連の攪拌流が安定に生じていることに加え、回転軸１の回転数の制御により攪拌領域５内の改良土圧に積極的に差を生じさせることによって上記のような水平方向の流れも促進することができ、それにより優れた攪拌混合効果が得られ、優れた地盤改良効果が得られる。しかも、そのような改良土圧の差を回転軸１の回転数を増減することのみで行い得るから、そのために何等面倒な操作や複雑な機構を必要とせずコスト増の要因は殆どないし、攪拌混合効率の向上により固化材の総供給量を削減することも可能である。   According to the present embodiment, in addition to the fact that a series of stirring flows as shown in FIG. 2 is basically stably generated in the triple stirring region 5 formed by the respective stirring blades 4, By making a positive difference in the improved earth pressure in the stirring region 5 by controlling the rotational speed, it is possible to promote the horizontal flow as described above, thereby obtaining an excellent stirring and mixing effect. A ground improvement effect can be obtained. Moreover, since such a difference in improved earth pressure can be performed only by increasing or decreasing the rotational speed of the rotary shaft 1, there is almost no cause for cost increase without requiring any troublesome operations or complicated mechanisms. It is also possible to reduce the total supply of solidification material by improving the mixing efficiency.

なお、本実施形態の具体的な工程としては、図３の（ａ）の状態あるいは（ｂ）の状態のいずれかを選択してその状態のままで貫入工程と引き抜き工程を行うことでも良いが、たとえば貫入時には（ａ）の状態として引き抜き時には（ｂ）の状態（あるいはその逆）としたり、貫入工程と引き抜き工程の途中で（ａ）の状態と（ｂ）の状態を一定時間間隔で交互に繰り返すことでも良く、そのようにすれば攪拌領域５全体における攪拌混合状態をより均質化することができる。   In addition, as a specific process of the present embodiment, either the state of FIG. 3A or the state of FIG. 3B may be selected and the penetration process and the drawing process may be performed in that state. For example, the state of (a) at the time of penetration and the state of (b) at the time of withdrawal (or vice versa), or the state of (a) and the state of (b) are alternated at regular intervals during the penetration process and the withdrawal process. It is also possible to repeat the above, and by doing so, the stirring and mixing state in the entire stirring region 5 can be made more uniform.

また、（ａ）の状態あるいは（ｂ）の状態をそのまま一定時間継続した場合、地質や固化材の供給量その他の状況によっては、中央部あるいは両側部での改良土圧が次第に上昇していってある時点で上昇限界に達して急速に周囲に流れ出して土圧が安定するという現象が生じる場合があり、その場合は攪拌領域５内において改良土の脈動が自ずと生じることになり、そのような脈動によっても結果的に充分な攪拌混合効果が得られる。   In addition, when the state of (a) or (b) is continued for a certain period of time, the improved earth pressure at the center or both sides gradually increases depending on the geology, the supply amount of the solidified material, and other conditions. At some point in time, the rise limit may be reached and the earth pressure will flow out rapidly and the earth pressure will stabilize. In such a case, the pulsation of the improved soil will naturally occur in the stirring region 5, As a result, a sufficient stirring and mixing effect can be obtained even by pulsation.

ところで、回転軸１からの固化材（セメントスラリーやセメント粉体等）の供給は各回転軸１から均等に行うことでも良く、その吐出時期についても貫入時のみ、引き抜き時のみ、あるいは貫入時と引き抜き時の双方、のいずれとすることでも良いが、いずれにしても上記のような回転軸１の回転数の設定に併せて回転軸１からの固化材の供給量の調節を行うことも考えられる。すなわち、同じく図３（ａ）に示しているように、回転数を大きくした中央の回転軸１ｂからの固化材の供給量を相対的に大きくするとともに、回転数を小さくした両側の回転軸１ａからの供給量を相対的に小さく（あるいは供給停止）し、逆に（ｂ）に示しているように、回転数を大きくした両側の回転軸１ａからの固化材の供給量を相対的に大きくするとともに、回転数を小さくした中央の回転軸１ｂからの供給量を相対的に小さく（あるいは供給停止）すれば、固化材の供給量の差によっても改良土圧の差が生じて上記のような改良土の流れがより促進されるし、供給した固化材を上記のような改良土の流れにそのまま乗せて自ずと攪拌領域全体にスムーズに行き渡らせることができる。   By the way, the solidifying material (cement slurry, cement powder, etc.) from the rotating shaft 1 may be supplied from each rotating shaft 1 evenly, and the discharge timing thereof is only at the time of penetration, only at the time of withdrawal, or at the time of penetration. Either may be used at the time of drawing, but in any case, it is also possible to adjust the supply amount of the solidifying material from the rotating shaft 1 in accordance with the setting of the rotational speed of the rotating shaft 1 as described above. Be That is, as shown in FIG. 3 (a), the supply amount of the solidified material from the central rotating shaft 1b with the increased rotational speed is relatively increased, and the rotating shafts 1a on both sides with the decreased rotational speed are also provided. As shown in (b), the supply amount of the solidified material from the rotating shafts 1a on both sides whose rotation speed is increased is relatively increased. At the same time, if the supply amount from the central rotary shaft 1b having a reduced rotation speed is relatively small (or supply is stopped), the difference in the improved earth pressure is caused by the difference in the supply amount of the solidified material as described above. Thus, the flow of the improved soil can be further promoted, and the supplied solidified material can be put on the flow of the improved soil as it is and can be smoothly distributed over the entire stirring area.

さらに、本実施形態のような３軸深層混合処理工法では、地盤状況によっては両側の回転軸１ａと中央の回転軸１ｂにかかる負荷に差が生じる場合も想定される。たとえば原地盤が粘性土の場合には、両側の回転軸１ａに対する回転抵抗が中央の回転軸１ｂに対する回転抵抗よりも大きくなって両側の回転軸１ａに中央の回転軸１ｂよりも大きな負荷がかかる場合があり、逆に原地盤が砂質土の場合には両側の回転軸１ａよりも中央の回転軸１ｂにより大きな負荷がかかる場合がある。そこで、上記のような回転数の調節を回転軸１にかかる負荷の状況に応じて行うことも考えられる。   Further, in the three-axis deep mixing processing method as in the present embodiment, there may be a case where a difference occurs in the load applied to the rotary shaft 1a on both sides and the central rotary shaft 1b depending on the ground conditions. For example, when the original ground is cohesive soil, the rotational resistance with respect to the rotating shaft 1a on both sides is larger than the rotating resistance with respect to the rotating shaft 1b on the both sides, and a larger load is applied to the rotating shaft 1a on both sides than the central rotating shaft 1b. On the contrary, when the original ground is sandy soil, a larger load may be applied to the central rotating shaft 1b than to the rotating shaft 1a on both sides. Therefore, it is conceivable to adjust the rotational speed as described above in accordance with the load applied to the rotary shaft 1.

そのような負荷のアンバランスが生じた場合、同じく図３（ａ），（ｂ）に示しているように、高負荷がかかる回転軸１の回転数を相対的に小さくしてそのトルクを増大させるとともに、低負荷の回転軸１の回転数を相対的に大きくしてそのトルクを低下させることにより、それぞれの回転軸１のトルクを負荷に応じて適正に調整することができて地盤状況に応じた最適な運転が可能となる。しかも、それと同時に、回転数に差をもたせることによって上記のような改良土圧の差とそれによる改良土の流れが自ずと生じるので、併せて優れた攪拌混合効率を得ることができる。   When such a load imbalance occurs, as shown in FIGS. 3A and 3B, the rotational speed of the rotary shaft 1 to which a high load is applied is relatively reduced to increase its torque. In addition, by relatively increasing the number of rotations of the low-load rotary shaft 1 and reducing its torque, the torque of each rotary shaft 1 can be appropriately adjusted according to the load, and the ground condition can be obtained. The optimum operation according to the operation becomes possible. In addition, at the same time, by providing a difference in the rotational speed, the above-described difference in the improved earth pressure and the flow of the improved earth due to the difference naturally occur, so that it is possible to obtain an excellent stirring and mixing efficiency.

なお、そのような負荷の調整を目的として回転数の調節を行う場合において、それに併せて上述したような固化材の供給量の増減（回転数を大きくした回転軸からの供給量を大きくし、回転数を小さくした回転軸からの供給量を小さくする）を行うことは好ましくない場合がある。つまり、固化材の供給量を大きくすることは回転抵抗が軽減されて負荷を低減する効果を期待できるのであるが、供給量を小さくすることは回転抵抗が増大して負荷が増大してしまう場合があるので、高負荷の回転軸の負荷軽減を目的としてその回転数を小さくする（トルクを増大させる）にも拘わらずそこでの固化材の供給量を小さくすることは逆効果になる場合があり、むしろ供給量を大きくすることが好ましい場合もある。したがって、回転数の調節と供給量の調節は、地盤状況その他の諸条件を充分に考慮して、攪拌領域全体で好ましい攪拌混合状態が得られるように設定すべきである。   In the case of adjusting the rotational speed for the purpose of adjusting such a load, the increase / decrease in the supply amount of the solidified material as described above (increasing the supply amount from the rotating shaft with the increased rotational speed, It may not be preferable to reduce the amount of supply from the rotating shaft with a reduced rotational speed. In other words, increasing the supply amount of the solidified material can reduce the rotation resistance and expect the effect of reducing the load, but reducing the supply amount increases the rotation resistance and increases the load. Therefore, in order to reduce the load on a high-load rotating shaft, reducing the number of rotations (increasing torque), but reducing the amount of solidified material there may be counterproductive. Rather, it may be preferable to increase the supply amount. Therefore, the adjustment of the rotational speed and the adjustment of the supply amount should be set so that a preferable stirring and mixing state can be obtained in the entire stirring region in consideration of the ground conditions and other various conditions.

以上で本発明の一実施形態を説明したが、本発明は上記実施形態に限定されるものでは勿論なく、地盤の状況その他の諸条件を考慮して具体的な工程や装置の各部の構成については、本発明の要旨を逸脱しない範囲で様々な変更や応用が可能であることはいうまでもない。たとえば、上記実施形態では３軸の回転軸１をそれぞれの駆動源２により独立に駆動するものとしたが、両側の回転軸１ａと中央の回転軸１ｂの回転方向を逆にし、かつそれらの回転数を制御可能に構成する限りにおいて、従来のように２台の駆動源２により適宜の動力伝達機構３を介して駆動するようにしても良い。   Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and specific steps and configurations of each part of the apparatus are considered in consideration of ground conditions and other conditions. Needless to say, various modifications and applications are possible without departing from the scope of the present invention. For example, in the above embodiment, the three rotation shafts 1 are driven independently by the respective drive sources 2, but the rotation directions of the rotation shaft 1a on both sides and the central rotation shaft 1b are reversed and their rotations are reversed. As long as the number can be controlled, it may be driven by the two drive sources 2 via an appropriate power transmission mechanism 3 as in the prior art.

本発明の実施形態である３軸深層混合処理工法の基本工程を示す図である。It is a figure which shows the basic process of the triaxial deep-layer mixing processing method which is embodiment of this invention. 同、攪拌領域における攪拌状態を示す図である。It is a figure which shows the stirring state in a stirring area | region similarly. 同、具体的な工程を示す図である。It is a figure which shows a specific process same as the above. 従来の３軸深層混合処理工法を示す図である。It is a figure which shows the conventional triaxial deep-layer mixing processing method. 同、攪拌領域における攪拌状態を示す図である。It is a figure which shows the stirring state in a stirring area | region similarly.

符号の説明Explanation of symbols

１（１ａ、１ｂ） 回転軸
２ 駆動源
４ 攪拌翼
５ 攪拌領域
９，１０ 吐出口 1 (1a, 1b) Rotating shaft 2 Drive source 4 Stirring blade 5 Stirring area 9,10 Discharge port

Claims (3)

先端部に攪拌翼を備えた３軸の回転軸を並設し、それら回転軸を正回転させて地盤に貫入するとともに逆回転させて地盤から引き抜く間に、回転軸の先端部から固化材を地盤中に供給して各攪拌翼により形成される３連の攪拌領域において攪拌混合することにより地盤改良を行う３軸深層混合処理工法であって、
３軸の回転軸のうち両側の回転軸を同一方向に回転させるとともに中央の回転軸を両側の回転軸とは逆方向に回転させることにより、前記攪拌領域全体にわたって改良土が連続して流れる一連の攪拌流を形成し、
かつ、両側の回転軸の回転数と中央の回転軸の回転数に差をもたせることにより、前記攪拌領域の両側部と中心部とで改良土圧に差を生じさせてそれらの間における改良土の流れを促進せしめることを特徴とする３軸深層混合処理工法。 Three rotating shafts equipped with stirring blades at the tip are arranged side by side, and while rotating these rotating shafts into the ground and reversely rotating and withdrawing from the ground, the solidified material is removed from the tip of the rotating shaft. A triaxial deep-mixing method for improving the ground by stirring and mixing in a triple stirring region formed by the stirring blades supplied to the ground,
A series of three types of rotating shafts, the rotating shafts on both sides are rotated in the same direction and the central rotating shaft is rotated in the opposite direction to the rotating shafts on both sides, whereby the improved soil continuously flows over the entire stirring region. A stirring flow of
In addition, by making a difference between the rotational speed of the rotary shafts on both sides and the rotational speed of the central rotary shaft, a difference is caused in the improved earth pressure between the both side portions and the central portion of the stirring region, thereby improving the soil between them. A triaxial deep mixing treatment method characterized by promoting the flow of water. 請求項１記載の３軸深層混合処理工法であって、回転軸からの固化材の供給量を回転数に応じて設定し、回転数の大きい回転軸からの供給量を、回転数が小さい回転軸からの供給量よりも大きく設定することを特徴とする３軸深層混合処理工法。   The triaxial deep mixing method according to claim 1, wherein the supply amount of the solidified material from the rotation shaft is set according to the rotation speed, and the supply amount from the rotation shaft having the higher rotation speed is set to the rotation with the lower rotation speed. A triaxial deep-mixing processing method characterized in that it is set to be larger than the supply amount from the shaft. 請求項１記載の３軸深層混合処理工法であって、回転軸の回転数を負荷に応じて設定し、高負荷の回転軸の回転数を低負荷の回転軸の回転数よりも小さく設定することを特徴とする３軸深層混合処理工法。   The three-axis deep mixing method according to claim 1, wherein the rotational speed of the rotary shaft is set according to the load, and the rotational speed of the high-load rotary shaft is set smaller than the rotational speed of the low-load rotary shaft. A triaxial deep layer mixing method characterized by that.
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