JP7510328B2

JP7510328B2 - Construction Method

Info

Publication number: JP7510328B2
Application number: JP2020175196A
Authority: JP
Inventors: 慎治廣澤; 章西村; 一斗 ▲高▼山; 貴穂河野; 康平大石
Original assignee: Takenaka Corp
Current assignee: Takenaka Corp
Priority date: 2020-10-19
Filing date: 2020-10-19
Publication date: 2024-07-03
Anticipated expiration: 2040-10-19
Also published as: JP2022066705A

Description

本発明は、基礎が直接基礎構造である直接基礎建物部を逆打ち工法を用いて構築する建築方法に関する。 The present invention relates to a construction method for constructing a building with a foundation structure using the inverted construction method.

逆打ち工法は、基礎の構築前の先行工程において、建物の地下躯体における本設の地下柱を建て込み、その建て込んだ地下柱に支持させる状態で地表面近くの床梁等の床構造部を支持させる。そして、その後の後行工程において、地表面近くの床構造部を作業床や山留め支保工として利用し、既に先行工程で建て込んだ地下柱を除く残りの地下躯体の構築と地上躯体の構築を並行実施することで、大幅な工期短縮を図る工法（例えば、特許文献１参照）である。 In the inverted construction method, in a preceding process before the foundation is constructed, permanent underground columns are erected in the underground structure of the building, and the floor structure parts such as floor beams near the ground surface are supported by the erected underground columns. Then, in a subsequent process, the floor structure parts near the ground surface are used as a work floor or earth retaining support, and the construction of the remaining underground structure excluding the underground columns already erected in the preceding process and the construction of the aboveground structure are carried out in parallel, which is a construction method that aims to significantly shorten the construction period (for example, see Patent Document 1).

このような逆打ち工法を用いて上述した直接基礎建物部を構築する場合、先行工程において、基礎の代わりに地下柱を仮支持するための仮設の杭である鉄筋コンクリート造の構真台柱を地中に構築し、この構真台柱に仮支持させる状態で地下柱を建て込むことが行われている。しかしながら、鉄筋コンクリート造の構真台柱の構築にはそれなりの工期とコストが必要となる。そのため、構真台柱の構築を省いて工期の短縮とコストの削減を図ることが望まれる。 When constructing the above-mentioned spread foundation building section using this type of inverted construction method, in the preceding process, reinforced concrete structural pillars, which are temporary piles to temporarily support the underground columns in place of the foundation, are constructed in the ground, and the underground columns are erected while being temporarily supported by these structural pillars. However, constructing reinforced concrete structural pillars requires a certain amount of construction time and cost. For this reason, it is desirable to shorten the construction time and reduce costs by eliminating the need to construct the structural pillars.

ちなみに、特許文献２には、直接基礎建物部を構築する場合の先行工程において、地下柱を建て込むことなく、山留め壁の上端に床構造部を架設して当該床構造部を山留め壁に支持させる特殊な建築方法が提案されているが、山留め壁のみで支持できる荷重は大きさ及び範囲が限られるため、中小規模の建物を構築する場合にしか採用できない。
また、一般的な工法として、直接基礎建物部において先行する階の床構造部を支持させる場合、下部をセメントミルクで固める仮設の構台杭を施工することもあるが、１本あたりで支持できる軸力に限度があるため、地上躯体を大きく先行させることができない。仮設の構台杭の本数を増やすこともできるが、工期やコストが大きく膨らむ他、地下躯体の施工時に細かい間隔で設置された構台杭により、重機が動きにくくなり、更に地下柱が後施工部分となって地下躯体の後施行部分が多くなることで、施工効率が大きく落ちる。 Incidentally, Patent Document 2 proposes a special construction method in which, in a preceding step of directly constructing the foundation building portion, a floor structure portion is erected on the upper end of the earth retaining wall and the floor structure portion is supported by the earth retaining wall, without erecting underground columns. However, since the size and range of the load that can be supported by the earth retaining wall alone is limited, this method can only be adopted when constructing small to medium-sized buildings.
In addition, as a general construction method, when supporting the floor structure of the preceding floor in the direct foundation building section, temporary gantry piles with cement milk at the bottom are sometimes installed, but since there is a limit to the axial force that each pile can support, the above-ground structure cannot be advanced significantly. The number of temporary gantry piles can be increased, but this significantly increases the construction period and costs, and the gantry piles installed at close intervals during the construction of the underground structure make it difficult for heavy machinery to move, and furthermore, the underground columns become later construction parts, and the number of later construction parts of the underground structure increases, which significantly reduces construction efficiency.

特開２０１９－０１９５０３号公報JP 2019-019503 A 特開平７－１５０５８０号公報Japanese Patent Application Laid-Open No. 7-150580

本発明は、上述の課題に鑑みてなされたものであって、その主たる課題は、直接基礎建物部を逆打ち工法を用いて構築するにあたり、先行工程において地表面近くの床構造部を支持する地下柱を構真台柱を用いずに適切に仮支持することができ、構真台柱を構築しない分の工期短縮とコスト削減を図ることできる建築方法を提供する点にある。 The present invention was made in consideration of the above-mentioned problems, and its main objective is to provide a construction method that, when constructing a direct foundation building section using the inverted construction method, can properly temporarily support the underground columns that support the floor structure section near the ground surface in the preceding process without using structural support columns, thereby shortening the construction period and reducing costs by the amount that would be required by not constructing structural support columns.

本発明の第１特徴構成は、基礎が直接基礎構造である直接基礎建物部を逆打ち工法を用いて構築する建築方法であって、
地盤を前記基礎の下の床付け面まで掘削し、当該床付け面との間に建方用支柱を介在させる状態で前記直接基礎建物部の地下躯体における地下柱を建て込む地下柱の建方を行い、その建て込んだ地下柱に荷重を支持させる状態で前記直接基礎建物部の地表面近くの階の床構造部を構築する先行工程と、
前記先行工程の実行後、前記基礎を含む前記地下躯体の構築と前記直接基礎建物部の地上躯体の構築を並行実施する後行工程と、を備え、
前記基礎は、前記後行工程において、当該基礎に前記建方用支柱が埋め込まれる状態で構築されて、その構築後に前記地下柱の下端を上面で支持するものであり、
前記建方用支柱が、前記地下柱よりも軸耐力の小さなもので、水平方向の一方向のみに延びる幅広のベース部と、当該ベース部の幅方向の中間部位から前記地下柱の柱幅よりも小さな支柱幅で鉛直方向に延びる支柱部とから構成され、
前記先行工程において、前記床付け面以深の地盤中に地盤改良を施して平面視で格子状の地盤改良体を構成し、前記ベース部が、その水平方向の一方向のみに延びる幅方向が前記地盤改良体の延在方向に沿って延びる姿勢で前記地盤改良体の上に設置され、かつ、前記支柱部が前記地下柱と上下に一直線状で直列に並ぶ配置で前記地下柱を仮支持する状態で、前記建方用支柱が前記地下柱の建方に使用される点にある。 The first characteristic configuration of the present invention is a construction method for constructing a building part having a foundation structure using a top-down construction method,
a preceding process of excavating the ground to a flooring surface below the foundation, erecting underground columns in the underground framework of the spread-foundation building section with construction supports interposed between the ground and the flooring surface, and constructing a floor structure section of the spread-foundation building section for a floor near the ground surface while the erected underground columns support the load;
A subsequent process of constructing the underground structure including the foundation and the above-ground structure of the spread foundation building part in parallel after the preceding process is performed ,
The foundation is constructed in the subsequent process with the construction support pillar embedded in the foundation, and after the construction, the lower end of the underground pillar is supported on the upper surface,
The erection support pillar has a smaller axial strength than the underground pillar and is composed of a wide base portion extending in only one horizontal direction and a support portion extending vertically from a middle portion of the base portion in the width direction with a support width smaller than the column width of the underground pillar;
In the preceding process, ground improvement is performed in the ground deeper than the bedding surface to form a lattice-shaped ground improvement body in a planar view, the base portion is installed on the ground improvement body in an orientation in which its width direction, which extends in only one horizontal direction, extends along the extension direction of the ground improvement body, and the construction support pillars are used to erect the underground pillars in a state in which the support pillar portions temporarily support the underground pillars in an arrangement in which they are lined up in series in a straight line above and below the underground pillars .

本構成によれば、上述の先行工程と後行工程を実行することで、逆打ち工法による工期短縮を図りながら直接基礎建物部を構築することができる。そして、先行工程において、直接基礎建物部の地下柱を建て込み、その地下柱に荷重を支持させる状態で地表面近くの階の床構造部を構築するので、構真台柱を用いず、建方用支柱を介して床付け面にて地下柱を適切に仮支持することができ、構真台柱を構築しない分の工期短縮とコスト削減を図ることできる。
又、本構成によれば、建方用支柱の下端に設けられる幅広のベース部によって、建方用支柱から荷重が伝達される床付け面の面積を広くして荷重を分散させることができ、地盤強度が低い場合でも、建方用支柱を介して床付け面にて地下柱を適切に仮支持することができる。
更に、本構成によれば、床付け面における地盤改良を施して地盤強度を高めた部分に建方用支柱を設置するので、もともとの地盤強度が低い場合でも、建方用支柱を介して床付け面にて地下柱を適切に仮支持することができる。 According to this configuration, by executing the above-mentioned preceding and following steps, it is possible to construct the direct foundation building section while shortening the construction period by the inverted construction method. In the preceding step, the underground columns of the direct foundation building section are erected, and the floor structure section of the floor near the ground surface is constructed with the underground columns supporting the load, so that the underground columns can be properly temporarily supported at the floor attachment surface via the construction supports without using the structural support columns, and the construction period can be shortened and costs can be reduced by the amount of the structural support columns not being constructed.
In addition, according to this configuration, the wide base portion provided at the lower end of the construction support increases the area of the flooring surface to which the load is transmitted from the construction support, thereby distributing the load, and even if the ground strength is low, the underground column can be properly temporarily supported on the flooring surface via the construction support.
Furthermore, according to this configuration, the construction supports are installed in the part of the flooring surface where ground strength has been increased by carrying out ground improvement work, so that even if the original ground strength is low, the underground columns can be properly temporarily supported at the flooring surface via the construction supports.

本発明の第２特徴構成は、前記先行工程を実施するにあたり、前記地盤改良体のうち、建設地の周囲の地盤中に構築される山留め壁の近傍に位置する地盤改良体を、前記床付け面よりも上方に余盛して延伸させて、前記山留め壁を支える掘削法面を略鉛直に自立させる点にある。 The second characteristic configuration of the present invention is that, when carrying out the preceding step, the ground improvement body located near the retaining wall constructed in the ground surrounding the construction site is extended with an excess above the flooring surface, so that the excavation slope supporting the retaining wall is made to stand approximately vertically .

本発明の第３特徴構成は、前記先行工程を平面視で複数の工区に分けてタイミングをずらして実施するにあたり、前記地盤改良体のうち、後で工事する後工区の地山部分の周囲に位置する地盤改良体を、前記床付け面よりも上方に余盛して延伸させて、前記後工区の地山部分の周囲の掘削法面を略鉛直に自立させておき、先に工事する先工区にて先行工程を実行する際、前記後工区の地山部分の上面を地山構台として利用して資材の搬出入を行う点にある。 The third characteristic configuration of the present invention is that when the preceding process is divided into multiple work sections in a plan view and carried out at staggered timing, the ground improvement bodies located around the ground portion of the subsequent work section to be constructed later are extended with an excess above the bedding surface, so that the excavation slope around the ground portion of the subsequent work section is made to stand independently approximately vertically, and when the preceding process is carried out in the prior work section to be constructed first, the upper surface of the ground portion of the subsequent work section is used as a ground platform for transporting materials in and out .

本建築方法の先行工程を模式的に示す図A schematic diagram showing the preceding steps of the construction method. 本建築方法の後行工程を模式的に示す図A schematic diagram showing the subsequent steps of this construction method. 先行工程の別実施形態を模式的に示す図FIG. 1 is a schematic diagram showing another embodiment of the preceding process;

本発明に係る建築方法の実施形態を図面に基づいて説明する。
本建築方法にて構築される建物は、図２に示すように、地下に位置する地下躯体２と、地上に位置する地上躯体３とを有する建物として構成される。地下躯体２は、鉄筋コンクリート造の基礎２１、基礎２１に支持される鋼管製又は鉄骨製の地下柱２２、鉄骨製の梁や鉄筋コンクリート製のスラブ等からなる床構造部２３等から構成される。地上躯体３は、鋼管製又は鉄骨製の地上柱３２、鉄骨製の梁や鉄筋コンクリート製のスラブ等からなる床構造部３３等から構成される。なお、地下躯体２や地上躯体３の具体的構成は各種の変更が可能である。 An embodiment of a construction method according to the present invention will be described with reference to the drawings.
As shown in Fig. 2, a building constructed by this construction method is configured as a building having an underground structure 2 located underground and an aboveground structure 3 located above ground. The underground structure 2 is configured from a reinforced concrete foundation 21, underground columns 22 made of steel pipes or steel frames supported by the foundation 21, and a floor structure 23 made of steel beams, reinforced concrete slabs, etc. The aboveground structure 3 is configured from aboveground columns 32 made of steel pipes or steel frames, and a floor structure 33 made of steel beams, reinforced concrete slabs, etc. Note that the specific configurations of the underground structure 2 and the aboveground structure 3 can be changed in various ways.

この建物は、基礎２１が直接基礎構造である低層（図中左側）の直接基礎建物部ｂ１と、基礎２１の下に杭２１Ａを有する杭基礎構造である図中右側の高層の杭基礎建物部ｂ２とを有している。
直接基礎構造は、基礎２１が設置される床付け面ｇ１にて建物の荷重を直接的に支持する基礎構造であり、杭基礎構造は、基礎２１が設置される床付け面ｇ１に建て込まれた杭２１Ａを介して床付け面ｇ１よりも深い位置にある支持地盤等で建物の荷重を支持する基礎構造である。 This building has a low-rise (left side of the figure) direct-foundation building section b1, whose foundation 21 is a direct-foundation structure, and a high-rise pile-foundation building section b2 on the right side of the figure, which is a pile-foundation structure with piles 21A below the foundation 21.
The direct foundation structure is a foundation structure that directly supports the load of the building on the flooring surface g1 on which the foundation 21 is installed, while the pile foundation structure is a foundation structure that supports the load of the building on a supporting ground or the like that is located deeper than the flooring surface g1 via piles 21A erected on the flooring surface g1 on which the foundation 21 is installed.

そして、本建築方法では、地表面近くの階（図示例では１階）の床構造部３３を先行構築する先行工程と、当該先行工程の実行後に基礎２１を含む地下躯体２の構築と地上躯体３の構築を並行実施する後行工程とを順番に実施することで、逆打ち工法による工期短縮を図りながら直接基礎建物部ｂ１及び杭基礎建物部ｂ２を構築することができる。以下、本建築方法の各工程について順番に説明する。 In this construction method, the preceding process of constructing the floor structure 33 of the floor near the ground surface (the first floor in the illustrated example) and the following process of constructing the underground structure 2 including the foundation 21 and the aboveground structure 3 in parallel after the preceding process are carried out in sequence, making it possible to directly construct the foundation building section b1 and the pile foundation building section b2 while shortening the construction period using the inverted construction method. Each process of this construction method will be explained in order below.

（先行工程）
図１に示すように、この先行工程では、建設地の周囲の地盤Ｇ中に山留め壁４を構築するとともに、直接基礎建物部ｂ１が構築される直接基礎エリアにおいて、直接基礎建物部ｂ１の基礎２１が設置される床付け面ｇ１以深の地盤Ｇ中に地盤改良を施す。地盤改良は、例えば、現位置土と固化材を機械撹拌して構成される柱状改良体５を平面視で格子状に配置して構成される。 (Preceding process)
As shown in Figure 1, in this preceding step, a retaining wall 4 is constructed in the ground G surrounding the construction site, and ground improvement is carried out in the ground G deeper than the flooring surface g1 on which the foundation 21 of the direct foundation building section b1 is to be installed in the direct foundation area where the direct foundation building section b1 is to be constructed. The ground improvement is carried out, for example, by arranging columnar improvement bodies 5, which are made by mechanically mixing the current location soil and solidification material, in a lattice pattern in a plan view.

また、杭基礎建物部ｂ２が建築される杭基礎エリアにおいて、杭基礎建物部ｂ２の基礎２１が設置される床付け面ｇ１以深の地盤Ｇ中に場所打ちコンクリート杭等からなる本設の杭２１Ａを構築し、当該杭２１Ａに下端を貫入して杭２１Ａに支持させる状態で鉄骨製等の構真柱７を建て込む。構真柱７は、本設の地下柱２２よりも小さな柱幅に構成される。また、構真柱７の上端の高さ位置は、後行工程にて構築される基礎２１の上面の高さ位置に設定される。
そして、直接基礎エリア及び杭基礎エリアにおいて、山留め壁４の近傍に当該山留め壁４を内側から支えるための掘削法面（押さえ斜面）８Ａを残す状態で、床付け面ｇ１まで地盤Ｇを掘削する。 In addition, in the pile foundation area where the pile foundation building part b2 is constructed, permanent piles 21A made of cast-in-place concrete piles or the like are constructed in the ground G deeper than the flooring surface g1 on which the foundation 21 of the pile foundation building part b2 is installed, and a structural column 7 made of steel or the like is erected in a state in which the lower end penetrates the pile 21A and is supported by the pile 21A. The structural column 7 is configured to have a smaller column width than the permanent underground column 22. In addition, the height position of the upper end of the structural column 7 is set to the height position of the upper surface of the foundation 21 constructed in the subsequent process.
Then, in the direct foundation area and pile foundation area, the ground G is excavated up to the flooring surface g1, while leaving an excavation slope (support slope) 8A near the retaining wall 4 to support the retaining wall 4 from the inside.

本実施形態では、地盤改良が施される直接基礎エリアにおいて、山留め壁４の近傍の柱状改良体５を床付け面ｇ１よりも上方に余盛して延伸させ、掘削法面８Ａ（押さえ斜面）を略鉛直に自立させることで、直接基礎エリアの掘削法面８Ａの存在範囲を小さくしている。なお、杭基礎エリアにおいても、山留め壁４の近傍に同様の柱状改良体５を設けて掘削法面８Ａ（押さえ斜面）を略鉛直に自立させるようにしてもよい。 In this embodiment, in the direct foundation area where ground improvement is performed, the columnar improvement body 5 near the retaining wall 4 is extended upward from the flooring surface g1 with an excess pile, and the excavation slope 8A (retaining slope) is made to stand approximately vertically, thereby reducing the range of the excavation slope 8A in the direct foundation area. Note that in the pile foundation area, a similar columnar improvement body 5 may be provided near the retaining wall 4 to make the excavation slope 8A (retaining slope) stand approximately vertically.

そして、杭基礎エリアにおいて杭基礎建物部ｂ２の地下柱２２を構真柱７の上端に接続する状態で建て込むとともに、直接基礎エリアにおいて直接基礎建物部ｂ１の地下柱２２を床付け面ｇ１との間に当該地下柱２２よりも軸耐力の小さな仮設の建方用支柱６を介在させる状態で建て込む。 Then, in the pile foundation area, the underground column 22 of the pile foundation building section b2 is erected while being connected to the upper end of the structural column 7, and in the direct foundation area, the underground column 22 of the direct foundation building section b1 is erected with a temporary construction support 6 having a smaller axial strength than the underground column 22 interposed between the underground column 22 and the floor attachment surface g1.

直接基礎エリアにおいて、構真台柱を用いずに床付け面ｇ１にて地下柱２２を適切に仮支持することができ、構真台柱を構築しない分の工期短縮とコスト削減を図ることできる。また、上述の如く、直接基礎エリアにおいて、掘削法面８Ａの存在範囲を小さくしているので、山留め壁４の近傍の地下柱２２についても建方用支柱６を介して床付け面ｇ１に設置することができる。 In the direct foundation area, the underground columns 22 can be properly temporarily supported on the flooring surface g1 without using structural support columns, and the construction period and costs can be shortened by not constructing the structural support columns. Also, as described above, the range of the excavation slope 8A is reduced in the direct foundation area, so that the underground columns 22 near the retaining wall 4 can also be installed on the flooring surface g1 via the construction support columns 6.

建方用支柱６の支柱部６Ａの幅（支柱幅）は、本設の地下柱２２の柱幅よりも小さく構成される。また、建方用支柱６の高さ寸法は、床付け面ｇ１から後行工程で構築される基礎２１の上面までの高さ寸法に設定され、建方用支柱６の上端の高さ位置は、基礎２１の上面の高さ位置に設定される。 The width (pillar width) of the pillar portion 6A of the construction pillar 6 is configured to be smaller than the pillar width of the permanent underground pillar 22. In addition, the height dimension of the construction pillar 6 is set to the height dimension from the floor attachment surface g1 to the upper surface of the foundation 21 that will be constructed in the subsequent process, and the height position of the upper end of the construction pillar 6 is set to the height position of the upper surface of the foundation 21.

更に、建方用支柱６の下端には、その支柱部６Ａの幅よりも幅広のベース部６Ｂが備えられる。例えば、支柱部６Ａは鉛直方向に延びるＨ形鋼等から構成され、ベース部６Ｂは水平方向の一方向に延びるＨ形鋼等から構成される。そのため、幅広のベース部６Ｂによって、建方用支柱６から荷重が伝達される床付け面ｇ１の面積を広くして荷重を分散させることができる。 Furthermore, the lower end of the construction support 6 is provided with a base portion 6B that is wider than the width of the support portion 6A. For example, the support portion 6A is made of an H-shaped steel or the like extending vertically, and the base portion 6B is made of an H-shaped steel or the like extending horizontally in one direction. Therefore, the wide base portion 6B increases the area of the floor attachment surface g1 to which the load is transmitted from the construction support 6, thereby distributing the load.

また、この建方用支柱６は、床付け面ｇ１において地盤改良を施した部分の上に設置される。具体的には、建方用支柱６は、ベース部６Ｂが柱状改良体５の連接方向に沿って延びる姿勢とされ、ベース部６Ｂの底面の全域が複数本（図示例では３本）の柱状改良体５の上に設置される。このようにすることで、建方用支柱６を介して床付け面ｇ１にて地下柱２２を適切に仮支持することができる。 The construction support 6 is also installed on the portion of the flooring surface g1 where ground improvement has been performed. Specifically, the construction support 6 is oriented so that the base portion 6B extends along the connection direction of the columnar improvement bodies 5, and the entire bottom surface of the base portion 6B is installed on multiple (three in the illustrated example) columnar improvement bodies 5. In this way, the underground column 22 can be appropriately temporarily supported on the flooring surface g1 via the construction support 6.

そして、直接基礎エリア及び杭基礎エリアにおいて、建て込んだ直接基礎建物部ｂ１の地下柱２２及び杭基礎建物部ｂ２の地下柱２２に荷重を支持させる状態で、直接基礎建物部ｂ１及び杭基礎建物部ｂ２における地表面近くの階の床構造部３３を構築し、当該床構造部３３の外周部を山留め壁４に連設して山留め支保工として機能させる。 Then, in the direct foundation area and pile foundation area, the floor structure section 33 of the floor near the ground surface of the direct foundation building section b1 and the pile foundation building section b2 is constructed in a state in which the load is supported by the underground columns 22 of the erected direct foundation building section b1 and the underground columns 22 of the pile foundation building section b2, and the outer periphery of the floor structure section 33 is connected to the retaining wall 4 to function as a retaining shoring.

（後行工程）
この先行工程に続いて実行される後行工程では、図２に示すように、直接基礎エリア及び杭基礎エリアにおいて、掘削法面８Ａを撤去し、直接基礎建物部ｂ１及び杭基礎建物部ｂ２の基礎２１を含む地下躯体２の構築と地上躯体３の構築を並行実施する。
具体的には、先行工程にて構築した地表面近くの階の床構造部３３を作業床として利用して床構造部３３の上方にて地上躯体３を構築しながら、その床構造部３３を山留め支保工に利用して床構造部３３の下方にて基礎２１を含む地下躯体２を構築する。 (Subsequent process)
In the subsequent process which follows this preceding process, as shown in Figure 2, the excavation slope 8A is removed in the direct foundation area and pile foundation area, and the construction of the underground structure 2 including the foundations 21 of the direct foundation building section b1 and the pile foundation building section b2 and the construction of the above-ground structure 3 are carried out in parallel.
Specifically, the floor structure 33 of the floor near the ground surface constructed in the preceding process is used as a work floor to construct the above-ground structure 3 above the floor structure 33, while the underground structure 2 including the foundation 21 is constructed below the floor structure 33 using the floor structure 33 as a retaining support.

このように、後行工程にて、既に先行工程で構築した地下柱２２を除く、残りの地下躯体２の構築と地上躯体３の構築とを並行実施することで、大幅な工期の短縮を図ることができる。
しかも、地下柱２２の柱幅よりも支柱幅の小さい建方用支柱６の上端の高さ位置、及び、地下柱２２の柱幅よりも柱幅の小さい構真柱７の上端の高さ位置が、基礎２１の上面の高さ位置に設定されているので、後行工程にて構真柱７及び建方用支柱６を埋め込む状態で基礎２１を構築することで、基礎２１の上面にて地下柱２２の下端を適切に支持することができる。 In this way, by carrying out the construction of the remaining underground structure 2, excluding the underground columns 22 that have already been constructed in the preceding process, and the construction of the above-ground structure 3 in parallel in the subsequent process, it is possible to significantly shorten the construction period.
Furthermore, the height position of the upper end of the construction support 6, which has a width narrower than the column width of the underground column 22, and the height position of the upper end of the structural column 7, which has a width narrower than the column width of the underground column 22, are set to the height position of the upper surface of the foundation 21. Therefore, by constructing the foundation 21 in a state in which the structural column 7 and the construction support 6 are embedded in a subsequent process, the lower end of the underground column 22 can be properly supported on the upper surface of the foundation 21.

〔別実施形態〕
本発明の他の実施形態について説明する。
なお、以下に説明する各実施形態の構成は、夫々単独で適用することに限らず、他の実施形態の構成と組み合わせて適用することも可能である。 [Another embodiment]
Another embodiment of the present invention will now be described.
The configurations of the embodiments described below are not limited to being applied alone, but may also be applied in combination with the configurations of other embodiments.

（１）上記実施形態の改良として、先行工程を複数の工区に分けてタイミングをずらして実施してもよい。例えば、図３に示すように、平面視の一部のエリア（図中の左右両端のエリア）を先に工事を行う第１工区とし、平面視の別のエリア（図中の左右中央のエリア）を第１工区の後に工事を行う第２工区とする。 (1) As an improvement to the above embodiment, the preceding process may be divided into multiple work sections and the timing may be staggered to carry out the work. For example, as shown in FIG. 3, a part of the area in plan view (the areas at both the left and right ends of the figure) is designated as the first work section where work is carried out first, and another area in plan view (the areas in the center of the left and right sides of the figure) is designated as the second work section where work is carried out after the first work section.

このようにすれば、第１工区にて先行工程を実行する際、第２工区の地山部分の上面を地山構台として利用して資材の搬出入等を行うことができ、第１工区にて先行工程を効率良く実施することができる。このときも、第２工区の近傍の一部の柱状改良体５を床付け面ｇ１よりも上方に余盛して延伸しておけば、地山部分の周囲の掘削法面８Ｂを略鉛直に自立させることができ、掘削法面８Ｂの存在範囲を小さくして第１工区にて一層効率良く作業を行うことができる。 In this way, when the preceding process is carried out in the first section, the top surface of the natural ground in the second section can be used as a natural ground platform to load and unload materials, and the preceding process can be carried out efficiently in the first section. In this case, too, if some of the columnar improvement bodies 5 near the second section are extended above the bedding surface g1, the excavation slope 8B around the natural ground can be made to stand upright approximately vertically, and the range of the excavation slope 8B can be reduced, allowing work to be carried out more efficiently in the first section.

また、第２工区にて先行工程を実行する際には、第１工区にて建築した地表面近くの床構造部３３を作業床等に利用して資材の搬出入等を行うことができ、第２工区でも先行工程を効率良く実施することができる。 In addition, when carrying out the preceding process in the second work area, the floor structure 33 constructed in the first work area near the ground surface can be used as a work floor, etc., for transporting materials in and out, and the preceding process can be carried out efficiently in the second work area as well.

（２）本建築方法は、前述の実施形態で示した直接基礎建物部ｂ１と杭基礎建物部ｂ２を有する建物に限らず、直接基礎建物部ｂ１のみを有する建物を構築する建物など、少なくとも直接基礎建物部ｂ１を有する建物を構築するのに好適に適用することができる。 (2) This construction method is not limited to buildings having the direct foundation building portion b1 and pile foundation building portion b2 shown in the above embodiment, but can be suitably applied to constructing buildings having at least the direct foundation building portion b1, such as buildings having only the direct foundation building portion b1.

（３）上記実施形態では、床付け面ｇ１に施す地盤改良が、柱状改良体５を格子状に配置して構成される地盤改良を例に挙げて説明したが、表層改良や深層改良等の各種の地盤改良を採用することができる。また、床付け面ｇ１の地盤強度等によっては地盤改良を省くことができる。 (3) In the above embodiment, the ground improvement applied to the bedding surface g1 was described as being configured by arranging columnar improvement bodies 5 in a grid pattern, but various types of ground improvement, such as surface improvement and deep improvement, can be adopted. In addition, depending on the ground strength of the bedding surface g1, ground improvement can be omitted.

（４）上記実施形態では、建方用支柱６の支柱幅よりも幅広のベース部６Ｂを建方用支柱６の下端に設ける場合を例に挙げて説明したが、床付け面ｇ１の地盤強度等によってはベース部６Ｂを省くことができる。 (4) In the above embodiment, an example was given of a case in which a base portion 6B wider than the support width of the construction support 6 is provided at the lower end of the construction support 6, but the base portion 6B can be omitted depending on the ground strength of the floor attachment surface g1, etc.

２地下躯体
３地上躯体
６建方用支柱
６Ｂベース部
２１基礎
２２地下柱
２３，３３床構造部
Ｇ地盤
ｇ１床付け面
ｂ１直接基礎建物部
ｂ２杭基礎建物部 2 Underground structure 3 Aboveground structure 6 Construction support 6B Base 21 Foundation 22 Underground columns 23, 33 Floor structure G Ground g1 Flooring surface b1 Direct foundation building section b2 Pile foundation building section

Claims

基礎が直接基礎構造である直接基礎建物部を逆打ち工法を用いて構築する建築方法であって、
地盤を前記基礎の下の床付け面まで掘削し、当該床付け面との間に建方用支柱を介在させる状態で前記直接基礎建物部の地下躯体における地下柱を建て込む地下柱の建方を行い、その建て込んだ地下柱に荷重を支持させる状態で前記直接基礎建物部の地表面近くの階の床構造部を構築する先行工程と、
前記先行工程の実行後、前記基礎を含む前記地下躯体の構築と前記直接基礎建物部の地上躯体の構築を並行実施する後行工程と、を備え、
前記基礎は、前記後行工程において、当該基礎に前記建方用支柱が埋め込まれる状態で構築されて、その構築後に前記地下柱の下端を上面で支持するものであり、
前記建方用支柱が、前記地下柱よりも軸耐力の小さなもので、水平方向の一方向のみに延びる幅広のベース部と、当該ベース部の幅方向の中間部位から前記地下柱の柱幅よりも小さな支柱幅で鉛直方向に延びる支柱部とから構成され、
前記先行工程において、前記床付け面以深の地盤中に地盤改良を施して平面視で格子状の地盤改良体を構成し、前記ベース部が、その水平方向の一方向のみに延びる幅方向が前記地盤改良体の延在方向に沿って延びる姿勢で前記地盤改良体の上に設置され、かつ、前記支柱部が前記地下柱と上下に一直線状で直列に並ぶ配置で前記地下柱を仮支持する状態で、前記建方用支柱が前記地下柱の建方に使用される建築方法。 A construction method for constructing a building part having a foundation structure using a top-down construction method,
a preceding process of excavating the ground to a flooring surface below the foundation, erecting underground columns in the underground framework of the spread-foundation building section with construction supports interposed between the ground and the flooring surface, and constructing a floor structure section of the spread-foundation building section for a floor near the ground surface while the erected underground columns support the load;
A subsequent process of constructing the underground structure including the foundation and the above-ground structure of the spread foundation building part in parallel after the preceding process is performed ,
The foundation is constructed in the subsequent process with the construction support pillar embedded in the foundation, and after the construction, the lower end of the underground pillar is supported on the upper surface,
The erection support pillar has a smaller axial strength than the underground pillar and is composed of a wide base portion extending in only one horizontal direction and a support portion extending vertically from a middle portion of the base portion in the width direction with a support width smaller than the column width of the underground pillar;
In the preceding step, ground improvement is performed in the ground deeper than the bedding surface to form a lattice-shaped ground improvement body in a planar view, the base portion is installed on the ground improvement body in an attitude in which its width direction, which extends in only one horizontal direction, extends along the extension direction of the ground improvement body, and the construction support is used to erect the underground column in a state in which the support portion temporarily supports the underground column in an arrangement in which it is lined up in series in a straight line above and below the underground column .

前記先行工程を実施するにあたり、前記地盤改良体のうち、建設地の周囲の地盤中に構築される山留め壁の近傍に位置する地盤改良体を、前記床付け面よりも上方に余盛して延伸させて、前記山留め壁を支える掘削法面を略鉛直に自立させる請求項１記載の建築方法。 A construction method as described in claim 1, wherein, when carrying out the preceding step, the ground improvement body located near a retaining wall constructed in the ground surrounding the construction site is extended with an excess above the flooring surface, so that the excavation slope supporting the retaining wall is made to stand approximately vertically.

前記先行工程を平面視で複数の工区に分けてタイミングをずらして実施するにあたり、前記地盤改良体のうち、後で工事する後工区の地山部分の周囲に位置する地盤改良体を、前記床付け面よりも上方に余盛して延伸させて、前記後工区の地山部分の周囲の掘削法面を略鉛直に自立させておき、先に工事する先工区にて先行工程を実行する際、前記後工区の地山部分の上面を地山構台として利用して資材の搬出入を行う請求項１又は２記載の建築方法。 A construction method as described in claim 1 or 2, in which when the preceding process is divided into multiple work sections in a plan view and carried out at staggered timing, the ground improvement bodies located around the natural ground portion of the subsequent work section to be constructed later are extended with an excess above the bedding surface, so that the excavation slope around the natural ground portion of the subsequent work section is made to stand independently approximately vertically, and when the preceding process is carried out in the previous work section to be constructed first, the upper surface of the natural ground portion of the subsequent work section is used as a natural ground platform for transporting and unloading materials .