JP2010163843A - Soil improving method - Google Patents

Soil improving method Download PDF

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JP2010163843A
JP2010163843A JP2009009047A JP2009009047A JP2010163843A JP 2010163843 A JP2010163843 A JP 2010163843A JP 2009009047 A JP2009009047 A JP 2009009047A JP 2009009047 A JP2009009047 A JP 2009009047A JP 2010163843 A JP2010163843 A JP 2010163843A
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tube
columnar
ground
reinforcing bar
casing tube
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Zendo Yoshida
善憧 吉田
Masahiko Yamada
昌彦 山田
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JUTAKU JIBAN KK
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JUTAKU JIBAN KK
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  • Piles And Underground Anchors (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil improving method increasing the shearing stress and allowable vertical bearing power of a columnar improving body and maintaining the diameter of the columnar improving body small to reduce a burying cost and construction surplus soil. <P>SOLUTION: The soil improving method for improving the soft ground includes steps for: pressing, into the soft ground 1, a casing tube 10 with a lower cover 30 detachably provided at a tip opening 21 on the press-in side of a tube body 20; erecting a reinforced structure 40 into the casing tube 10; filling mixed powder 51 containing a solidifying material, into the casing tube 10 with the reinforced structure 40 erected; and pulling out the tube body 20 leaving the lower cover 30 together with the columnar improving body 50 in the ground. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、建物の基礎部の軟弱地盤に縦孔を形成し、セメント系固化材を含む混合粉体を充填して地層中に柱状の改良体を造成する柱状地盤改良工法のうち、乾式柱状地盤改良工法に関する。   The present invention is a dry columnar shape among the columnar ground improvement methods in which vertical holes are formed in the soft ground at the foundation of a building and filled with a mixed powder containing a cement-based solidifying material to create a columnar improved body in the formation. It relates to ground improvement method.

鋼管杭工法よりも安価な地盤改良工法として柱状地盤改良工法が知られており、湿式柱状地盤改良工法と乾式柱状地盤改良工法とに大別される。   A columnar ground improvement method is known as a ground improvement method that is cheaper than a steel pipe pile method, and is roughly classified into a wet columnar ground improvement method and a dry columnar ground improvement method.

湿式柱状地盤改良工法は、セメントプラントでセメント系固化材と水を攪拌混合してセメントミルクを製造し、掘削地層中でセメントミルクを土とスラリー状になるまで攪拌混合させて柱状改良体（ソイルセメント柱）を造成する工法である。   In the wet columnar soil improvement method, cement-based solidification material and water are stirred and mixed in a cement plant to produce cement milk, and in the excavation formation, the cement milk is stirred and mixed until it becomes a slurry with soil. This is a method of building cement pillars.

一方、乾式柱状地盤改良工法は、掘削オーガなどで掘削した中空円柱状の縦孔内に、掘削土砂とセメント系固化材とを混合した土を埋戻し、掘削オーガで攪拌や締固めを行って柱状の改良体を形成する工法である。乾式柱状地盤改良工法は、湿式柱状地盤改良工法に比して、養生期間が不要で硬化に伴う体積収縮がなく、軟弱地盤の改良には好ましい工法である。   On the other hand, in the dry columnar ground improvement method, soil mixed with excavated earth and cement-based solidification material is backfilled in a hollow cylindrical vertical hole excavated with a drilling auger, etc., and stirred and compacted with a drilling auger. This is a method of forming a columnar improved body. Compared with the wet columnar ground improvement method, the dry columnar ground improvement method does not require a curing period and has no volume shrinkage due to hardening, and is a preferable method for improving soft ground.

乾式柱状地盤改良工法に関連する技術として、起立させた杭打装置等のリーダに設ける圧入機にセットされたケーシングチューブを土中に圧入させた後、改良添加材が投入された土中部分に、ケーシングチューブと並設してリーダに備えた撹拌ロッドを捻じ込み正逆回転させる乾式地盤改良工法が提案されている（下記特許文献１参照）。   As a technology related to the dry columnar ground improvement method, after the casing tube set in the press-fitting machine provided in the leader such as a pile driving device that has been erected is pressed into the soil, it is applied to the portion of the soil into which the improved additive is introduced. A dry ground improvement method has been proposed in which a stirring rod provided in a leader is screwed in parallel with a casing tube and rotated forward and reverse (see Patent Document 1 below).

特開平９−１２５３６７号公報JP-A-9-125367

特許文献１に開示された地盤改良工法は、ケーシングチューブを利用し、これと並設して撹拌ロッドを捻じ込んでおり、改良添加材を均等に攪拌して地盤の安定強化を図り、構造物の不同沈下を抑制することができる。   The ground improvement method disclosed in Patent Document 1 uses a casing tube, and a stirring rod is screwed in parallel with the casing tube. The improvement additive is stirred evenly to improve the stability of the ground. Can be suppressed.

しかし、近年、柱状改良体の剪断応力及び許容鉛直支持力を増すために柱状改良体の外径を大きくする傾向にあり、結果として埋設コスト及び建設残土が増大するという問題がある。   However, in recent years, there is a tendency to increase the outer diameter of the columnar improvement body in order to increase the shear stress and the allowable vertical support force of the columnar improvement body, resulting in an increase in burial cost and construction residual soil.

本発明は、上述した実情に鑑みてなされたものであり、柱状改良体の剪断応力及び許容鉛直支持力を増大させ、柱状改良体の外径を小さく維持して埋設コスト及び建設残土を低減することを目的とする。   The present invention has been made in view of the above-described circumstances, and increases the shear stress and the allowable vertical supporting force of the columnar improvement body, and maintains the outer diameter of the columnar improvement body to reduce the burial cost and construction residual soil. For the purpose.

前記目的を達成する本発明に係る地盤改良工法は、チューブ本体の圧入側の先端開口部に着脱可能に下蓋を備えたケーシングチューブを軟弱地盤に圧入する工程と、前記ケーシングチューブ内に鉄筋構造体を立て込む工程と、前記鉄筋構造体を立て込んだ前記ケーシングチューブ内に、固化材を含む混合粉体を充填する工程と、地中に前記柱状改良体と共に前記下蓋を留置して、前記チューブ本体を引き抜く工程と、を有することを特徴とする。   The ground improvement method according to the present invention for achieving the above object includes a step of press-fitting a casing tube having a lower lid detachably attached to a distal end opening on a press-fitting side of a tube body, and a reinforcing bar structure in the casing tube. A step of standing a body, a step of filling a mixed powder containing a solidified material in the casing tube in which the reinforcing bar structure is raised, and placing the lower lid together with the columnar improvement body in the ground, And a step of pulling out the tube main body.

本発明に係る地盤改良工法によれば、軟弱地盤に圧入したケーシングチューブ内に鉄筋構造体が立て込まれた状態で、固化材を含む混合粉体を充填した後、チューブ本体を引き抜くので、柱状改良体を鉄筋構造体により補強することができ、柱状改良体の剪断応力を増大させることができる。   According to the ground improvement method according to the present invention, after filling the mixed powder containing the solidifying material in a state where the reinforcing bar structure is stood in the casing tube press-fitted into the soft ground, the tube body is pulled out, so that the columnar shape The improved body can be reinforced by the reinforcing bar structure, and the shear stress of the columnar improved body can be increased.

また、チューブ本体の引き抜き時に転圧を掛けるようにすれば、柱状改良体の周面摩擦力を増大させ、許容鉛直支持力を増大させることができる。したがって、柱状改良体の外径を小さく維持することができ、埋設コスト及び建設残土を低減することができる。   If rolling pressure is applied when the tube body is pulled out, the peripheral frictional force of the columnar improvement body can be increased and the allowable vertical support force can be increased. Therefore, the outer diameter of the columnar improvement body can be kept small, and the burying cost and construction residual soil can be reduced.

さらに、下面に掘削刃が突設されている下蓋を使用すれば、掘削が容易になり、掘削作業を迅速に行うことができる。   Furthermore, if a lower lid having a drilling blade projecting on the lower surface is used, excavation becomes easy and excavation work can be performed quickly.

（Ａ）〜（Ｃ）は本発明に係る地盤改良工法の一実施形態を工程順に示す概略断面図である。(A)-(C) are schematic sectional drawing which shows one Embodiment of the ground improvement construction method which concerns on this invention to process order. 本実施形態におけるケーシングチューブの構造を示し、（Ａ）は正面断面図、（Ｂ）は側面断面図、（Ｃ）は下蓋の未装着状態の上面図、（Ｄ）は下蓋の装着状態の上面図である。The structure of the casing tube in this embodiment is shown, (A) is front sectional drawing, (B) is side sectional drawing, (C) is a top view of the unattached state of a lower lid, (D) is the attachment state of a lower lid FIG. 本実施形態における下蓋を示し、（Ａ）は上面図、（Ｂ）は下面図、（Ｃ）は正面図である。The lower lid in this embodiment is shown, (A) is a top view, (B) is a bottom view, and (C) is a front view. ケーシングチューブ内への鉄筋構造体の立て込み状態を模式的に示し、（Ａ）は概略側面図、（Ｂ）は鉄筋構造体の天端部に設ける上蓋の上面図、及び（Ｃ）は上蓋の下面図である。The standing state of the reinforcing bar structure in the casing tube is schematically shown, (A) is a schematic side view, (B) is a top view of the upper lid provided at the top end of the reinforcing bar structure, and (C) is the upper lid. FIG.

以下、本発明の実施の形態を添付図面に基づいて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

本実施形態の地盤改良工法は、いわゆる乾式の地盤改良工法であり、主として、ケーシングチューブ１０の圧入工程（図１Ａ）と、鉄筋構造体４０の立て込み工程（図１Ａ）と、柱状地盤改良体５０となる混合粉体５１の充填工程（図１Ｂ）と、チューブ本体２０の引き抜き工程（図１Ｃ）と、を有している。   The ground improvement method of the present embodiment is a so-called dry-type ground improvement method, and mainly includes a press-fitting process of the casing tube 10 (FIG. 1A), a step-up process of the reinforcing bar structure 40 (FIG. 1A), and a columnar ground improvement body. 50, a filling step 51 (FIG. 1B) of the mixed powder 51 to be 50, and a drawing step (FIG. 1C) of the tube body 20.

まず、図１（Ａ）に示すように、ケーシングチューブ１０の圧入工程を行う。ケーシングチューブ１０の圧入は、建物の基礎部となる軟弱な地盤１に、杭打ち機（不図示）等を用いて、有底筒体状のケーシングチューブ１０を所定の深度まで圧入する。   First, as shown in FIG. 1A, a press-fitting process of the casing tube 10 is performed. The press fitting of the casing tube 10 is performed by press-fitting the bottomed cylindrical casing tube 10 to a predetermined depth using a pile driving machine (not shown) or the like in the soft ground 1 which is the foundation of the building.

ここで、図２及び図３を参照して、本実施形態の地盤改良工法に用いるケーシングチューブ１０の構造について説明する。   Here, with reference to FIG.2 and FIG.3, the structure of the casing tube 10 used for the ground improvement construction method of this embodiment is demonstrated.

図２に示すように、ケーシングチューブ１０は、円筒体状のチューブ本体２０と、チューブ本体２０の圧入側の先端開口部２１に着脱可能に備えられた下蓋３０と、から構成される。   As shown in FIG. 2, the casing tube 10 includes a cylindrical tube main body 20 and a lower lid 30 that is detachably attached to a distal end opening 21 on the press-fitting side of the tube main body 20.

チューブ本体２０は、強度及び経済性を考慮して、例えば、直径Ｒがφ１６５．２ｍｍの炭素鋼管等の金属管体にて形成される。チューブ本体２０の先端開口部２１内には、下蓋３０を嵌入支持するための保持手段２２が配設されている。保持手段２２は、先端開口部２１内の径方向に対向配置されると共に、所定の間隔Ｄを隔てて対称配置された一対の挟持片２３，２４から形成されている。挟持片２３，２４は、正面視及び側面視が略直角三角形状を呈する楔状の部材であり、これら挟持片２３，２４の間には直状の受け溝２５が形成されている。   The tube main body 20 is formed of a metal tube body such as a carbon steel tube having a diameter R of φ165.2 mm in consideration of strength and economy. A holding means 22 for fitting and supporting the lower lid 30 is disposed in the distal end opening 21 of the tube main body 20. The holding means 22 is formed of a pair of sandwiching pieces 23 and 24 that are arranged to face each other in the radial direction in the distal end opening 21 and are symmetrically arranged with a predetermined distance D therebetween. The sandwiching pieces 23 and 24 are wedge-shaped members having a substantially right triangle shape in front view and side view, and a straight receiving groove 25 is formed between the sandwiching pieces 23 and 24.

図３に示すように、下蓋３０は、例えば、円形の炭素鋼板（鉄板）によって形成され、その上面には短片の帯材からなる直状の装着突起３１が突設されている。装着突起３１は、チューブ本体２０の保持手段２２の受け溝２５内へ嵌入配置され、挟持片２３，２４によって挟持される。すなわち、装着突起３１の厚みＴは、受け溝２５の間隔Ｄよりも若干小さく設定されている。   As shown in FIG. 3, the lower lid 30 is formed of, for example, a circular carbon steel plate (iron plate), and a straight mounting projection 31 made of a short strip is projected on the upper surface thereof. The mounting protrusion 31 is inserted into the receiving groove 25 of the holding means 22 of the tube body 20 and is sandwiched between the sandwiching pieces 23 and 24. That is, the thickness T of the mounting protrusion 31 is set slightly smaller than the interval D between the receiving grooves 25.

また、下蓋３０の下面には、短片の帯材からなる直状の掘削刃（掘削翼）３２が突設されている。本実施形態では、掘削刃３２は、装着突起３１と直交する方向に沿って配設されているが、これに限定されるものではなく、装着突起３１と同一方向等に配設してもよい。   Further, a straight excavation blade (excavation blade) 32 made of a short strip is projected on the lower surface of the lower lid 30. In the present embodiment, the excavating blade 32 is disposed along a direction orthogonal to the mounting protrusion 31, but is not limited thereto, and may be disposed in the same direction as the mounting protrusion 31. .

このようにチューブ本体２０の圧入側の先端開口部２１は、下蓋３０によって閉塞されており、杭打ち機のリーダ等によってケーシングチューブ１０を圧入する際に、軟弱地盤１を押し退けて地中に縦孔２を区画形成する。下蓋３０は、ケーシングチューブ１０を圧入する際に地盤１に押さえ付けられるので、チューブ本体２０から離脱することはない。   As described above, the distal end opening 21 on the press-fitting side of the tube main body 20 is closed by the lower lid 30, and when the casing tube 10 is press-fitted by a leader of a pile driving machine or the like, the soft ground 1 is pushed away into the ground. The vertical hole 2 is partitioned. Since the lower lid 30 is pressed against the ground 1 when the casing tube 10 is press-fitted, it does not leave the tube body 20.

また、下蓋３０の下面には掘削刃３２が突設されているので、ケーシングチューブ１０を回転させることにより、掘削刃３２で地盤１を掘削ながら掘進させて圧入することができる。その際、装着突起３１は、保持手段２２の挟持片２３，２４によって挟持されているので、下蓋３０の回り止め部材としても機能する。   In addition, since the excavating blade 32 protrudes from the lower surface of the lower lid 30, the ground tube 1 can be excavated while being excavated by the excavating blade 32 and can be press-fitted by rotating the casing tube 10. At that time, the mounting protrusion 31 is held by the holding pieces 23 and 24 of the holding means 22, and thus functions as a rotation preventing member for the lower lid 30.

次に、図１（Ａ）に示すように、鉄筋構造体４０を立て込む工程を行う。この鉄筋構造体４０を立て込む工程は、地中に圧入されたケーシングチューブ１０内に、予め組み立てた鉄筋構造体４０の立て込みを行う。   Next, as shown in FIG. 1 (A), a step of standing the reinforcing bar structure 40 is performed. In the step of setting up the reinforcing bar structure 40, the reinforcing bar structure 40 assembled in advance is put into the casing tube 10 press-fitted into the ground.

ここで、図４を参照して、ケーシングチューブ１０内に立て込む鉄筋構造体４０の構造について説明する。図４（Ａ）に示すように、鉄筋構造体４０は、複数本の鉄筋４１を環状の鉄筋囲４２で結束した構造体である。本実施形態では、例えば、円柱体の周面の長手方向に沿うように、４本の鉄筋４１を長手方向に沿って略平行に周方向に等間隔で配置して組み合せ、これら鉄筋４１を円環状の鉄筋囲４２で結束して構造体を形成している。なお、鉄筋４１は、例えば、外径Ｓが１３ｍｍである。   Here, with reference to FIG. 4, the structure of the reinforcing bar structure 40 stood in the casing tube 10 is demonstrated. As shown in FIG. 4A, the reinforcing bar structure 40 is a structure in which a plurality of reinforcing bars 41 are bound by an annular reinforcing bar enclosure 42. In the present embodiment, for example, four reinforcing bars 41 are arranged in parallel at equal intervals in the circumferential direction along the longitudinal direction so as to be along the longitudinal direction of the circumferential surface of the cylindrical body. The structure is formed by bundling at an annular reinforcing bar enclosure 42. Note that the reinforcing bar 41 has an outer diameter S of 13 mm, for example.

鉄筋囲４２は、直状鉄筋を円環状に成形し、両端部を突き合わせ溶接したものである。鉄筋囲４２は、４本の鉄筋４１の長手方向に略等間隔で配置され、各鉄筋４１にスポット溶接などにより取り付けられる。番線により強固に結束してもよい。なお、鉄筋囲４２は、例えば、内径Ｗがφ８０ｍｍであり、前記と同様に外径がφ１３ｍｍの鉄筋を成形する。   The rebar surrounding 42 is formed by forming a straight rebar into an annular shape and butt-welding both ends. The reinforcing bar surrounds 42 are arranged at substantially equal intervals in the longitudinal direction of the four reinforcing bars 41 and are attached to the reinforcing bars 41 by spot welding or the like. It may be firmly bound by a wire. The reinforcing bar enclosure 42 is formed of, for example, a reinforcing bar having an inner diameter W of φ80 mm and an outer diameter of φ13 mm as described above.

なお、鉄筋構造体４０の鉄筋４１の本数は、４本に限定されるものではない。鉄筋構造体４０の鉄筋４１の本数を増大すれば、それだけ鉄筋構造体自体が強固になり、後述する柱状改良体５０内に配設したときの剪断応力及び許容鉛直支持力を増大させることができる。   Note that the number of the reinforcing bars 41 of the reinforcing bar structure 40 is not limited to four. If the number of the reinforcing bars 41 of the reinforcing bar structure 40 is increased, the reinforcing bar structure itself becomes stronger, and the shear stress and the allowable vertical supporting force when disposed in the columnar improvement body 50 described later can be increased. .

鉄筋構造体４０の横断面形状は、円環状に限定されるものではなく、例えば、鉄筋囲４２の形状を三角形状、四角形状、多角形状及び井桁状等となるように形成してもよい。また、鉄筋囲４を設ける間隔を狭めて、鉄筋囲４の設置数を増加させ、鉄筋構造体４０の剛性を高めてもよい。   The cross-sectional shape of the reinforcing bar structure 40 is not limited to an annular shape, and for example, the reinforcing bar surrounding 42 may be formed in a triangular shape, a quadrangular shape, a polygonal shape, a cross-girder shape, or the like. Moreover, the space | interval which provides the reinforcing bar enclosure 4 may be narrowed, the installation number of the reinforcing bar enclosure 4 may be increased, and the rigidity of the reinforcing bar structure 40 may be improved.

次に、図１（Ｂ）に示すように、柱状改良体５０となる混合粉体５１の充填工程を行う。本実施形態の混合粉体５１は、砂と固化材とを所望の混合比で攪拌混合したものであり、鉄筋構造体４０が立て込まれたケーシングチューブ１０内に充填される。従来の乾式柱状地盤改良工法では、掘削土と固化材とを混合して縦孔内に埋め戻すが、本実施形態の地盤改良工法では、軟弱地盤１にケーシングチューブ１０を圧入して縦孔２を形成するので、掘削土が殆ど出ない。   Next, as shown in FIG. 1 (B), a filling process of the mixed powder 51 to be the columnar improvement body 50 is performed. The mixed powder 51 of this embodiment is obtained by stirring and mixing sand and a solidified material at a desired mixing ratio, and is filled in the casing tube 10 in which the reinforcing bar structure 40 is stood. In the conventional dry columnar ground improvement method, excavated soil and solidified material are mixed and backfilled in the vertical hole, but in the ground improvement method of this embodiment, the casing tube 10 is press-fitted into the soft ground 1 and the vertical hole 2 is filled. As a result, there is almost no excavated soil.

固化材には、周知のセメント系の粉体固化材を使用する。セメント系の固化材は、例えば、粘土質やシルト質、砂質などの軟弱土を水和反応で化学的に固化させるものである。これらセメント系の粉体固化材と砂とを柱状改良体５０が所望の強度となる混合比で攪拌混合し、この混合粉体５１をケーシングチューブ１０内へ投入充填する。   As the solidifying material, a well-known cement-based powder solidifying material is used. The cement-based solidifying material is, for example, a material that softens soft soil such as clay, silt and sand by chemical hydration. The cement-based powder solidified material and sand are mixed by stirring at a mixing ratio at which the columnar improvement body 50 has a desired strength, and the mixed powder 51 is charged into the casing tube 10 and charged.

次に、図１（Ｂ）（Ｃ）に示すように、チューブ本体２０の引き抜き工程を行う。チューブ本体２０の引き抜き工程は、杭打ち機等のリーダを上昇させてチューブ本体２０の引き抜く作業であるが、この場合、地中に形成される柱状改良体５０と共に下蓋３０を地中に留置する。下蓋３０を地中に留置すれば、軟弱地盤の強化になる。   Next, as shown in FIGS. 1B and 1C, the tube body 20 is pulled out. The tube body 20 is pulled out by lifting a leader such as a pile driving machine and pulling out the tube body 20. In this case, the lower lid 30 is placed in the ground together with the columnar improvement body 50 formed in the ground. To do. If the lower lid 30 is placed in the ground, the soft ground is strengthened.

チューブ本体２０を引き抜く際は、柱状改良体５０の天端部に転圧を掛けながら、チューブ本体２０の引き抜き作業を行う。チューブ本体２０の引き抜き時に柱状改良体５０に転圧を掛けると、柱状改良体５０の周面摩擦力を増大させることができる。   When pulling out the tube body 20, the tube body 20 is pulled out while rolling the top end of the columnar improvement body 50. When a rolling pressure is applied to the columnar improvement body 50 when the tube body 20 is pulled out, the peripheral frictional force of the columnar improvement body 50 can be increased.

チューブ本体２０の引き抜きにより、地中にはチューブ本体２０の外径Ｒよりも若干大きな外径の柱状改良体５０が造成され、柱状改良体５０は、固化材の水和反応によって固化することになる。なお、柱状改良体５０の外径は、例えば、２００〜２５０ｍｍ程度に形成される。   By pulling out the tube main body 20, a columnar improvement body 50 having an outer diameter slightly larger than the outer diameter R of the tube main body 20 is formed in the ground, and the columnar improvement body 50 is solidified by a hydration reaction of the solidifying material. Become. In addition, the outer diameter of the columnar improvement body 50 is formed in about 200-250 mm, for example.

チューブ本体２０の引き抜き工程後、図４（Ｂ）に示すように、所定の高さに調整した鉄筋構造体４０の天端部に上蓋６０を取り付ける工程を行ってもよい。   After the tube body 20 is pulled out, as shown in FIG. 4B, a step of attaching the upper lid 60 to the top end portion of the reinforcing bar structure 40 adjusted to a predetermined height may be performed.

上蓋６０は、図４（Ｂ）（Ｃ）に示すように、柱状改良体５０とほぼ同径の外径Ｍを有する外短管６１と、鉄筋構造体４０の天端部の鉄筋４１を内接する内径Ｗを有する内短管６３と、短管６１，６３の上部開口部を閉塞するように溶接した円形の鉄板６２と、から構成されている。すなわち、上蓋６０は、圧入された鉄筋構造体４０の天端部の鉄筋４１を内接させて嵌入できる構造となっている。図１では鉄筋構造体４０の天端部が地盤１と面一となるように示しているが、この上に建物の基礎を造成するので、地盤１よりも上方へ突き出させて配設してもよい。   As shown in FIGS. 4B and 4C, the upper lid 60 includes an outer short pipe 61 having an outer diameter M substantially the same as that of the columnar improvement body 50 and a reinforcing bar 41 at the top end of the reinforcing bar structure 40. An inner short pipe 63 having an inner diameter W in contact therewith and a circular iron plate 62 welded so as to close the upper openings of the short pipes 61 and 63 are constituted. That is, the upper lid 60 has a structure in which the reinforcing bar 41 at the top end of the press-fitted reinforcing bar structure 40 can be inscribed and fitted. In FIG. 1, the top end portion of the reinforcing bar structure 40 is shown to be flush with the ground 1. Also good.

以上説明したように、本実施形態の地盤改良工法によれば、軟弱地盤１に有底筒体状のケーシングチューブ１０を圧入し、軟弱地盤１に縦孔２を区画形成するので、従来の乾式の柱状地盤改良工法に比して建設残土が殆ど生じない。   As described above, according to the ground improvement method of the present embodiment, the bottomed cylindrical casing tube 10 is press-fitted into the soft ground 1 and the vertical holes 2 are defined in the soft ground 1, so that the conventional dry type Compared with the columnar ground improvement method, there is almost no construction residue.

また、簡易な工法で柱状改良体５０内に鉄筋構造体４０を埋設して、柱状改良体５０を補強することができ、地中に形成された柱状改良体５０の剪断応力を増大させることができる。   Moreover, the reinforcing structure 40 can be embed | buried in the columnar improvement body 50 with a simple construction method, the columnar improvement body 50 can be reinforced, and the shear stress of the columnar improvement body 50 formed in the ground can be increased. it can.

さらに、チューブ本体２０の引き抜き時に、柱状改良体５０の天端部に転圧を掛けることにより、柱状改良体５０の周面摩擦力を増大させて、許容鉛直支持力を増大させることができることになる。この結果、剪断応力及び許容鉛直支持力を増大させながら柱状改良体５０の外径を２００〜２５０ｍｍ程度に小さく維持することができ、埋設コスト及び建設残土を低減することができる。   Further, when the tube main body 20 is pulled out, the peripheral frictional force of the columnar improvement body 50 can be increased by rolling the top end portion of the columnar improvement body 50 to increase the allowable vertical support force. Become. As a result, the outer diameter of the columnar improvement body 50 can be kept as small as about 200 to 250 mm while increasing the shear stress and the allowable vertical supporting force, and the burying cost and the construction residual soil can be reduced.

本発明は、上述した実施形態のみに限定されるものではなく、本発明の技術的思想内において当業者により種々変更が可能である。例えば、上述の実施形態では、ケーシングチューブ１０の圧入工程を行った後に鉄筋構造体４０の立て込み工程を行っているが、これに限定されるものではなく、ケーシングチューブ１０内に予め鉄筋構造体４０を立て込んだ後にケーシングチューブを軟弱地盤１に圧入する工程を行ってもよい。ただし、下蓋３０はチューブ本体２０の先端開口部２１に着脱可能に装着されるので、鉄筋構造体４０の重量によって下蓋３０が脱離するのを防止する観点から、本実施形態の工程順に行うことが好ましい。   The present invention is not limited to the above-described embodiments, and various modifications can be made by those skilled in the art within the technical idea of the present invention. For example, in the above-described embodiment, the reinforcing step of the reinforcing bar structure 40 is performed after performing the press-fitting process of the casing tube 10, but the present invention is not limited to this, and the reinforcing bar structure is previously placed in the casing tube 10. You may perform the process of press-fitting a casing tube in the soft ground 1 after standing up 40. FIG. However, since the lower lid 30 is detachably attached to the distal end opening 21 of the tube main body 20, from the viewpoint of preventing the lower lid 30 from being detached due to the weight of the reinforcing bar structure 40, the process is performed in the order of the steps of this embodiment. Preferably it is done.

本発明は、建物の基礎部の軟弱地盤を改良する工法として利用できる。   INDUSTRIAL APPLICATION This invention can be utilized as a construction method which improves the soft ground of the foundation part of a building.

１…軟弱地盤、
２…縦孔、
１０…ケーシングチューブ、
２０…チューブ本体、
２１…先端開口部、
２２…保持手段、
３０…下蓋、
３１…装着突起、
３２ 掘削刃、
４０…鉄筋構造体、
５０…柱状改良体。 1 ... soft ground,
2 ... Vertical hole,
10 ... casing tube,
20 ... Tube body,
21 ... opening of the tip,
22 ... holding means,
30 ... lower lid,
31 ... Mounting protrusion,
32 drilling blades,
40 ... rebar structure,
50 ... Columnar improvement body.

Claims (4)

チューブ本体の圧入側の先端開口部に着脱可能に下蓋を備えたケーシングチューブを軟弱地盤に圧入する工程と、
前記ケーシングチューブ内に鉄筋構造体を立て込む工程と、
前記鉄筋構造体を立て込んだ前記ケーシングチューブ内に、固化材を含む混合粉体を充填する工程と、
地中に前記柱状改良体と共に前記下蓋を留置して、前記チューブ本体を引き抜く工程と、
を有する地盤改良工法。 A step of press-fitting a casing tube having a lower lid detachably attached to a distal end opening on the press-fitting side of the tube main body into a soft ground;
Stowing a reinforcing bar structure in the casing tube;
Filling the casing tube with the reinforcing bar structure embedded therein with a mixed powder containing a solidifying material;
Placing the lower lid together with the columnar improvement body in the ground, and pulling out the tube body;
A ground improvement method with 前記チューブ本体を引き抜く工程において、前記柱状改良体の天端部に転圧を掛けることを特徴とする請求項１に記載の地盤改良工法。   2. The ground improvement method according to claim 1, wherein in the step of pulling out the tube main body, rolling pressure is applied to the top end portion of the columnar improvement body. 前記チューブ本体を引き抜く工程の後、前記鉄筋構造体の天端部に上蓋を配設する工程を有する請求項１又は２に記載の地盤改良工法。   The ground improvement construction method according to claim 1 or 2, further comprising a step of disposing an upper lid at a top end portion of the reinforcing bar structure after the step of pulling out the tube main body. 前記下蓋は、下面に突設された掘削刃を有することを特徴とする請求項１〜３のいずれかに記載の地盤改良工法。   The ground improvement method according to any one of claims 1 to 3, wherein the lower lid has a digging blade protruding from a lower surface.
JP2009009047A 2009-01-19 2009-01-19 Soil improving method Pending JP2010163843A (en)

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Publication number Priority date Publication date Assignee Title
JP2013231282A (en) * 2012-04-27 2013-11-14 Travers Corp Construction method for tapered pile and casing for tapered pile construction
JP2015067950A (en) * 2013-09-26 2015-04-13 大和ハウス工業株式会社 Drilling blade mounting steel pipe for constructing cast-in-place concrete pile and construction method of cast-in-place concrete pile
JP2018044433A (en) * 2017-11-16 2018-03-22 大和ハウス工業株式会社 Excavation blade fitting steel pipe and method for constructing cast-in-place concrete-based pile
CN108425355A (en) * 2018-04-19 2018-08-21 中国建筑第八工程局有限公司 Earth pressure gauge embedding device and method for embedding

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JP2002105946A (en) * 2000-09-28 2002-04-10 Sekisui House Ltd Soil improving method
JP2003055965A (en) * 2001-08-10 2003-02-26 Tenox Corp Soil cement columnar body with thin steel pipe present as core material and its construction method

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JPS5186213A (en) * 1975-01-27 1976-07-28 Kyokado Eng Co Nanjakujibanno kyokahoho
JPH07331651A (en) * 1994-06-14 1995-12-19 Daido Concrete Kogyo Kk Construction of foundation column and its equipment
JP2002105946A (en) * 2000-09-28 2002-04-10 Sekisui House Ltd Soil improving method
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2013231282A (en) * 2012-04-27 2013-11-14 Travers Corp Construction method for tapered pile and casing for tapered pile construction
JP2015067950A (en) * 2013-09-26 2015-04-13 大和ハウス工業株式会社 Drilling blade mounting steel pipe for constructing cast-in-place concrete pile and construction method of cast-in-place concrete pile
JP2018044433A (en) * 2017-11-16 2018-03-22 大和ハウス工業株式会社 Excavation blade fitting steel pipe and method for constructing cast-in-place concrete-based pile
CN108425355A (en) * 2018-04-19 2018-08-21 中国建筑第八工程局有限公司 Earth pressure gauge embedding device and method for embedding
CN108425355B (en) * 2018-04-19 2024-01-23 中国建筑第八工程局有限公司 Soil pressure gauge embedding device and method

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