JP2007177407A - Underground story extension method under the foundation of existing building - Google Patents

Underground story extension method under the foundation of existing building Download PDF

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JP2007177407A
JP2007177407A JP2005374027A JP2005374027A JP2007177407A JP 2007177407 A JP2007177407 A JP 2007177407A JP 2005374027 A JP2005374027 A JP 2005374027A JP 2005374027 A JP2005374027 A JP 2005374027A JP 2007177407 A JP2007177407 A JP 2007177407A
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slab
foundation slab
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JP4879582B2 (en
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Tomio Tsuchiya
富男 土屋
Junji Hamada
純次 濱田
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Takenaka Komuten Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an underground story extension method capable of constructing a piled raft foundation by tightly binding the existing pile and a new foundation slab. <P>SOLUTION: The ground under the existing foundation slab 3 of the existing building 1 excavates directly under the ground up to a layer and a depth having a small amount of settlement in a state to temporarily receive axial force by the existing pile 4, the new foundation slab 5 is constructed to the excavation bottom and, at the same time, the piled raft foundation is constructed by tightly binding the existing pile 4 and the new foundation slab 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

この発明は、杭基礎構造の既存建物の基礎下に地下階を増築施工する方法の技術分野に属し、更に云うと、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築し支持力を増強する地下階増築方法に関する。   The present invention belongs to the technical field of a method of extending an underground floor under the foundation of an existing building with a pile foundation structure.More specifically, an existing pile and a newly established foundation slab are connected to construct a piled raft foundation. The present invention relates to a method for extending a basement to increase support.

従来から杭基礎構造の既存建物の基礎下に地下階を増築施工する方法として、例えば、図４に示すように、既存建物４０の既存杭４１で軸力を仮受けした状態で既存基礎スラブ４２の下の地盤を掘削し、前記既存杭４１の周りに新設杭４３を打設し、同新設杭４３と既存杭４１とをフーチング４４で一体化することで支持力を増強し増築施工する方法がある。   Conventionally, as a method of extending an underground floor under the foundation of an existing building having a pile foundation structure, for example, as shown in FIG. 4, the existing foundation slab 42 in a state where an axial force is temporarily received by the existing pile 41 of the existing building 40. Excavating the ground below, placing a new pile 43 around the existing pile 41, and integrating the new pile 43 and the existing pile 41 with a footing 44 to increase the supporting force and extend the construction There is.

また、図５に示すように、既存建物５０の既存杭５１で軸力を仮受けしながら既存基礎スラブ５２の下の地盤を沈下量が少ない地層まで掘削し、前記掘削底面に全荷重を支持可能な新設の基礎スラブ５３を打設して、杭基礎構造を最終的に直接基礎構造に代えることで支持力を補強し増築施工する方法もある。   Further, as shown in FIG. 5, the ground under the existing foundation slab 52 is excavated to a formation with a small amount of subsidence while temporarily receiving the axial force with the existing pile 51 of the existing building 50, and the entire load is supported on the bottom of the excavation. There is also a method in which a new foundation slab 53 is placed and the pile foundation structure is finally replaced directly with the foundation structure to reinforce the support force and to perform the extension construction.

特許文献１には、杭基礎構造の既存建物の外周に山留め壁を構築し、既存杭の外周に仮受けサポートを建てた上でジャッキを設置して建物の軸力を同サポートへ盛り換えて既存杭を解体し、新たに同位置に本設鉄骨造の新設柱を設置することで支持力を増強し地下階を増築施工する方法が開示されている。   In Patent Document 1, a retaining wall is constructed on the outer periphery of an existing building of a pile foundation structure, a temporary support is built on the outer periphery of the existing pile, a jack is installed, and the axial force of the building is changed to the same support. A method is disclosed in which an existing pile is dismantled and a new steel pillar is installed at the same position to reinforce the bearing capacity and expand the basement floor.

また、特許文献２には、既存杭に支持された既存建物の外周に山留め壁（連続壁）を構築すると共に、前記山留め壁と既存基礎の地中梁とを接合して既存建物を支持し、しかる後に既存杭の周りへコンクリートを打設し、地下用の新設柱及び新設の基礎スラブを構築することで支持力を増強し地下階を増築施工する方法が開示されている。   In Patent Document 2, a retaining wall (continuous wall) is constructed on the outer periphery of an existing building supported by an existing pile, and the existing building is supported by joining the retaining wall and the underground beam of the existing foundation. After that, a method is disclosed in which concrete is placed around existing piles and a new pillar for basement and a new foundation slab are constructed to increase the bearing capacity and expand the basement floor.

特許第２６５０９６９号公報Japanese Patent No. 2650969 特公平６−８４６９０号公報Japanese Examined Patent Publication No. 6-84690

図４に示した方法は、基礎形式を変更せず杭基礎構造のまま増築施工するため、増築分の鉛直支持力を増強する新設杭４３を新たに打設しなければならない。しかし、既存基礎スラブ４２の下は施工空間が狭く、使用できる機械が限られると共に、機械自体の搬入が困難となる。また、煩雑で危険な作業が要求されて作業効率や安全性が悪いという問題がある。のみならず、新設杭４３の築造による施工費と材料費が嵩む。   Since the method shown in FIG. 4 does not change the foundation form and performs the extension construction with the pile foundation structure, a new pile 43 that reinforces the vertical supporting force for the extension must be newly placed. However, under the existing foundation slab 42, the construction space is narrow, the machines that can be used are limited, and it is difficult to carry in the machines themselves. In addition, there is a problem that work efficiency and safety are poor because complicated and dangerous work is required. Not only that, construction costs and material costs due to the construction of the new piles 43 increase.

図５に示した杭基礎構造を最終的に直接基礎構造に変更する方法は、既存杭５１の利用が仮設のみとなり合理的ではない。また、直接基礎を構築するためには支持力の増強と沈下の許容範囲内となる地層まで基礎下端を下げる必要がある。したがって、新設の基礎スラブ５３を荷重に耐えるに足りる相当の厚みに構築しなければならないし、適用地盤も限定されることになる。   The method of finally changing the pile foundation structure shown in FIG. 5 to a direct foundation structure is not rational because the use of the existing pile 51 is only temporary. In order to build the foundation directly, it is necessary to lower the lower end of the foundation to a stratum that is within the allowable range of reinforcement and settlement. Therefore, the new foundation slab 53 must be constructed with a thickness sufficient to withstand the load, and the applicable ground is also limited.

上記特許文献１に記載された技術は、既存杭を解体し新設柱を構築するべく仮受けサポート材による軸力の盛り換え作業が必要であるため、非常に面倒な構築工程が追加され工期の長期化とコスト高が懸念される。   Since the technique described in the above-mentioned patent document 1 requires the work of changing the axial force with the temporary support material in order to disassemble the existing pile and construct a new pillar, a very troublesome construction process is added. There are concerns about the lengthening and high costs.

上述したいずれの従来技術も、杭基礎構造とする既存建物を最終的にパイルド・ラフト基礎構造に構築して支持力を増強する既存建物の基礎下の地下階増築方法ないしそれを示唆する内容ではない。   Any of the above-mentioned conventional techniques is based on the method of extending the underground floor under the foundation of the existing building, which will eventually build a piled raft foundation structure into a piled raft foundation structure to enhance the bearing capacity, or suggests it. Absent.

特許文献２に記載された技術は、杭基礎構造とする既存建物に、基礎下を掘削したのち既存杭間に新設の基礎スラブが構築されるもので、一見するとパイルドラフト基礎と誤認されるが、この技術は新設の基礎スラブと既存杭又は基礎梁とを剛接又は緊結するとの記載は一切なく、そもそも新設の基礎スラブの支持力を期待していないものである。したがって、基礎形式は杭基礎構造のままで、やはりパイルド・ラフト基礎構造に変更して支持力を増強するものではない。のみならず、新たに地下用の新設柱を限られた狭い場所で複数構築することは至難で作業効率が悪くコストも嵩む。   The technology described in Patent Document 2 is that a new foundation slab is constructed between existing piles after excavation under the foundation in an existing building with a pile foundation structure. In this technology, there is no description that the newly established foundation slab and the existing pile or foundation beam are rigidly connected or tightly connected, and the support force of the newly established foundation slab is not expected in the first place. Therefore, the foundation form remains the pile foundation structure, and it is not changed to the piled raft foundation structure to enhance the bearing capacity. Not only that, it is extremely difficult to construct a plurality of new underground pillars in a limited narrow space, resulting in poor work efficiency and high cost.

本発明の目的は、杭基礎構造の既存建物における基礎下に地下階を増築する際に、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築して支持力を増強し、新設杭及び新設柱の築造の必要が無く、合理的で経済的な既存建物の基礎下の地下階増築方法を提供することにある。   The purpose of the present invention is to build a piled raft foundation by connecting an existing pile and a newly-founded foundation slab when expanding the basement floor under the foundation of an existing building with a pile foundation structure, There is no need to construct new piles and pillars, and it is to provide a reasonable and economical method for extending the basement under the foundation of existing buildings.

上述した従来技術の課題を解決するための手段として、請求項１に記載した発明に係る既存建物の基礎下の地下階増築方法は、
杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
前記既存建物の既存基礎スラブ下の地盤を、既存杭で軸力を仮受けした状態で沈下量の少ない地層及び深度まで直下地盤を掘削する工程と、
前記掘削底面に新設の基礎スラブを築造すると共に、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築する工程と、
から成ることを特徴とする。 As a means for solving the above-described problems of the prior art, the basement extension method under the foundation of the existing building according to the invention described in claim 1 is:
In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
Excavating the ground beneath the existing foundation slab of the existing building, and excavating the direct foundation to the depth and depth of the subsidence in a state where the axial force is temporarily received by the existing pile;
Constructing a new foundation slab on the bottom of the excavation and constructing a piled raft foundation by binding the existing pile and the new foundation slab;
It is characterized by comprising.

請求項２に記載した発明に係る既存建物の基礎下の地下階増築方法は、
杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
前記既存建物の既存基礎スラブ下の地盤を、沈下量の少ない地層及び深度まで地盤改良し、その後、既存杭で軸力を仮受けした状態で地下階増築分の階高深度まで直下地盤を掘削し、前記掘削底面に新設の基礎スラブを築造すると共に、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築することを特徴とする。 The basement extension method under the foundation of the existing building according to the invention described in claim 2,
In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
Improving the ground under the existing foundation slab of the existing building to a stratum and depth with less subsidence, and then excavating the direct groundbed to the deeper floor depth of the basement extension with provisional axial force received by the existing pile In addition, a new foundation slab is constructed on the bottom of the excavation, and a piled raft foundation is constructed by tightly connecting an existing pile and a new foundation slab.

請求項３に記載した発明に係る既存建物の基礎下の地下階増築方法は、
杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
既存建物の既存基礎スラブ下の地盤を、既存杭で軸力を仮受けした状態で地下階増築分の階高深度まで掘削したのち、前記掘削底面から沈下量の少ない地層及び深度まで地盤改良を行ない、前記改良地盤の上面へ新設の基礎スラブを築造し、同既存杭と新設の基礎スラブとを緊結し、パイルド・ラフト基礎を構築することを特徴とする。 The basement extension method under the foundation of the existing building according to the invention described in claim 3,
In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
After excavating the ground under the existing foundation slab of the existing building to the depth of the basement extension with the axial force temporarily received by the existing pile, improve the ground from the excavation bottom to the stratum and depth with less subsidence. And a new foundation slab is constructed on the upper surface of the improved ground, and the existing pile and the new foundation slab are joined together to construct a piled raft foundation.

請求項４記載の発明は、請求項１〜３のいずれか一に記載した既存建物の基礎下の地下階増築方法において、
既存杭を増築階の柱に仕上げ、外周壁を構築することを特徴とする。 Invention of Claim 4 is the basement extension method under the foundation of the existing building as described in any one of Claims 1-3,
It is characterized by finishing the existing piles as pillars on the extension floor and constructing the outer wall.

請求項１又は４に記載した発明に係る既存建物の基礎下の地下階増築方法は、以下のような効果を奏する。
（１）杭基礎構造とする既存建物の既存基礎スラブ下を沈下量の少ない地層又は深度まで掘削し、新設の基礎スラブを構築した後、既存杭と新設の基礎スラブとを緊結して所謂パイルド・ラフト基礎を構築するので、既存基礎地盤が軟弱であっても支持力を合理的に増強して地下階の増築を実施することができる。
（２）既存杭を増築階の柱に仕上げて利用するので、新たに新設柱を構築する作業やその材料費を削減できる。
（３）既存杭を有効的に利用するので、既存杭の解体、搬入作業、新設杭の設置作業を一切無用にして作業効率の向上とコストの低減を実現できる。
（４）既存基礎スラブは解体せず、その下の地盤から掘削するので、同既存基礎スラブの解体や、搬出作業を無くして作業効率を向上させると共に、既存基礎スラブが掘削時に切梁としての機能を発揮する。 The basement extension method under the foundation of the existing building according to the invention described in claim 1 or 4 has the following effects.
(1) After excavating the existing foundation slab of an existing building with a pile foundation structure to a low formation or depth of subsidence and constructing a new foundation slab, the existing pile and the newly established foundation slab are joined together to form a so-called pile. -Since the raft foundation is constructed, even if the existing foundation ground is soft, the bearing capacity can be increased reasonably and the basement can be expanded.
(2) Since the existing pile is used as a pillar of the extension floor, it is possible to reduce the work for building a new pillar and the material cost.
(3) Since existing piles are used effectively, dismantling of existing piles, carrying-in work, and installation work of new piles can be dispensed with, improving work efficiency and reducing costs.
(4) Since the existing foundation slab is excavated from the ground below it, dismantling the existing foundation slab and removing it will improve work efficiency, and the existing foundation slab will be used as a beam during excavation. Demonstrate the function.

請求項２〜４に記載した発明は、沈下量の少ない地層（支持層）までの深度が非常に深い場合であっても、新設の基礎スラブの下から前記沈下量の少ない地層及び深度まで地盤改良を施工する構成としたので、地層の如何に左右されずパイルドラフト基礎を構築して地下階の増築を施工できる。   In the invention described in claims 2 to 4, even if the depth to the formation (support layer) with a small amount of subsidence is very deep, the ground from the bottom of the newly-founded foundation slab to the formation and the depth with a small amount of subsidence Since it is configured to improve, it can build a piled raft foundation and extend the basement floor regardless of the formation.

本発明は、杭基礎構造の既存建物１における既存杭４と既存基礎スラブ３とで支持された基礎下に地下階を増築する方法である。
前記既存建物１の既存基礎スラブ３下の地盤を、既存杭４で仮受けした状態で沈下量の少ない地層及び深度まで直下地盤を掘削する。
前記掘削底面に新設の基礎スラブ５を築造すると共に、既存杭４と新設の基礎スラブ５とを緊結しパイルド・ラフト基礎を構築する。
前記既存杭４を増築階の柱に仕上げ、外周壁７を構築する。 The present invention is a method of extending an underground floor under a foundation supported by an existing pile 4 and an existing foundation slab 3 in an existing building 1 having a pile foundation structure.
The direct foundation board is excavated to the formation and depth with less subsidence while the ground under the existing foundation slab 3 of the existing building 1 is temporarily received by the existing pile 4.
A new foundation slab 5 is built on the bottom of the excavation, and an existing pile 4 and the new foundation slab 5 are joined together to construct a piled raft foundation.
The existing pile 4 is finished as a pillar of the extension floor, and the outer peripheral wall 7 is constructed.

以下、本発明に係る既存建物の基礎下の地下階増築方法の実施例を、図面に基づいて説明する。
本発明を実施する既存建物１は、図１に示すように、既存杭４と既存基礎スラブ３とから成る杭基礎構造の上に構築されている。基礎地盤Ｂが軟弱で増築階の重量が付加されると直接基礎構造では沈下が大きくなり成立せず、また杭基礎構造のみでも支持力が不足して成立しない場合に好適に実施される。 Hereinafter, the Example of the basement extension method under the foundation of the existing building which concerns on this invention is described based on drawing.
The existing building 1 which implements this invention is constructed | assembled on the pile foundation structure which consists of the existing pile 4 and the existing foundation slab 3, as shown in FIG. If the foundation ground B is soft and the weight of the extension floor is added, subsidence will not be established directly in the foundation structure, and it will not be established.

本発明の方法は、先ず、既存建物１の既存地下階２の底版として備えられた既存基礎スラブ３下の基礎地盤Ｂを、前記既存杭４で軸力を仮受けした状態で、沈下量の少ない地層Ｈまで、しかも地層Ｈ内で増築階分を十分に支持可能な深度まで掘削する。   In the method of the present invention, first, the foundation ground B under the existing foundation slab 3 provided as the bottom slab of the existing basement 2 of the existing building 1 is subjected to the amount of subsidence in a state in which the axial force is temporarily received by the existing pile 4. Excavation is carried out to a small number of formations H, and to the depth at which the extension floors can be sufficiently supported in the formations H

掘削する方法としては、例えば図示することは省略したが既存基礎スラブ３に作業用の孔を開設し、この作業孔を通して掘削機等を挿入し同スラブ３下の地盤が逐次掘削される。したがって、既存地下階２及び既存基礎スラブ３を解体することがないので余計な準備の必要が無く、作業効率が良い他、同既存地下階２と既存基礎スラブ３が切梁としての機能を発揮する効果がある。また、掘削時に既存杭４の支持力を有効利用できる効果もある。勿論この方法の限りではなく、既存建物１の外壁に沿って所定の深度に達する縦孔を設けたのち、横方向から掘削を進める方法で実施しても良い。   As an excavation method, for example, although illustration is omitted, a work hole is opened in the existing foundation slab 3, and an excavator or the like is inserted through the work hole to sequentially excavate the ground below the slab 3. Therefore, since the existing basement 2 and the existing foundation slab 3 are not dismantled, there is no need for extra preparation and work efficiency is improved, and the existing basement 2 and the existing foundation slab 3 function as a beam. There is an effect to. Moreover, there exists an effect which can utilize effectively the support force of the existing pile 4 at the time of excavation. Of course, the method is not limited to this method, and a method may be used in which a vertical hole reaching a predetermined depth is provided along the outer wall of the existing building 1 and then excavation is performed from the lateral direction.

次に、沈下量の少ない支持層Ｈまでの直下地盤の掘削が完了した段階で、図２に示すように、掘削底面上に配筋を行い、コンクリートを打設して新設の基礎スラブ５を築造する。前記新設の基礎スラブ５は、増築分の不足支持力を補強するに足りる厚さに施工される。具体的には上部と下部の２枚版として実施することが好ましい。   Next, at the stage where the excavation of the direct base plate to the support layer H with a small amount of subsidence has been completed, as shown in FIG. Build. The newly established foundation slab 5 is constructed to a thickness sufficient to reinforce the insufficient supporting force for the extension. Specifically, it is preferable to carry out as an upper and lower two-plate version.

そして、前記既存杭４と新設の基礎スラブ５とを緊結してパイルド・ラフト基礎構造を構築する。緊結方法としては、図示することは省略したが既存杭４にアンカーを打設する方法や、既存杭４の主筋をはつりだして新設の基礎スラブ５と筋束する方法とされる。この際、新設の基礎スラブ５と基礎梁とも緊結する。斯くすると、新設の基礎スラブ５と既存杭４との両方で合理的に既存建物１の鉛直軸力を支持できる。   Then, the existing pile 4 and the newly established foundation slab 5 are joined together to construct a piled raft foundation structure. Although not shown in the drawings, the tightening method includes a method of placing an anchor on the existing pile 4 or a method of sticking the main reinforcement of the existing pile 4 to the newly-found foundation slab 5. At this time, the newly established foundation slab 5 and the foundation beam are also tightly coupled. Thus, the vertical axial force of the existing building 1 can be reasonably supported by both the newly-founded foundation slab 5 and the existing pile 4.

しかる後に、前記既存杭４の外周面に化粧材６を取り付けて増築階の柱として仕上げる。更に、既存杭４…間に配筋を行い、壁型枠を組み立て、コンクリートを打設して外周壁７を構築し新築地下階８を完成する（請求項４記載の発明）。上記のように前記既存杭４を言わば構真柱としても利用するので、新たに新設柱を構築する作業やその材料費を削減できて経済的である。勿論、別途柱を増築することを適宜行われる。   After that, the decorative material 6 is attached to the outer peripheral surface of the existing pile 4 and finished as a pillar of the extension floor. Further, bar arrangement is performed between the existing piles 4..., A wall formwork is assembled, concrete is placed, an outer peripheral wall 7 is constructed, and a newly built basement floor 8 is completed (invention of claim 4). As described above, since the existing pile 4 is also used as a true pillar, it is economical because it is possible to reduce the work for building a new pillar and its material cost. Of course, it is appropriate to add a pillar separately.

図示例では地下階を１階分増築する場合の補強方法について説明したが、支持層Ｈが更に深い場合や地下階を更にもう１階分増やしたいときには、新設の基礎スラブ５を上面だけの一枚版に構築すると共にその上面から作業用の孔を開設したのち、上述した各工程を繰り返すことにより実施することができる。   In the illustrated example, the reinforcing method when the basement floor is extended by one floor has been described. However, when the support layer H is deeper or when the basement floor is to be increased by one more floor, the newly-founded basic slab 5 is provided only on the upper surface. After constructing a plate and opening a working hole from its upper surface, the above steps can be repeated.

次に、請求項２に記載した既存建物の基礎下の地下階増築方法について図３に基づいて説明する。実施例３は上述した実施例１と略同様の技術思想とされているため、以下にその相違点を中心に説明する。
実施例３は特に沈下量の少ない地層Ｈまでの深度が非常に深く、地下階増築分の階高深度より更に深い場合に好適に実施されるものである。
先ず前記既存建物１の既存基礎スラブ３下の地盤を、沈下量の少ない地層Ｈ内まで地盤改良を施工し地盤改良体９を構築する。前記地盤改良体９の構築は公知の深層混合処理工法或いはソイルセメント工法により構築される。そして、前記既存杭４で軸力を仮受けした状態で新築地下階８の階高深度（図示では地層Ｂ内）まで直下地盤（地盤改良体９の上層部）を掘削し、前記掘削底面に新設の基礎スラブ５を築造すると共に、既存杭４と新設の基礎スラブ５とを緊結してパイルド・ラフト基礎を構築する。 Next, the basement extension method under the foundation of the existing building described in Claim 2 is demonstrated based on FIG. Since the third embodiment has substantially the same technical idea as the first embodiment described above, the difference will be mainly described below.
The third embodiment is preferably carried out particularly when the depth to the formation H where the subsidence amount is small is very deep and deeper than the depth of the underground floor extension.
First, the ground improvement body 9 is constructed by constructing the ground under the existing foundation slab 3 of the existing building 1 to the ground H where the subsidence amount is small. The ground improvement body 9 is constructed by a well-known deep mixing method or a soil cement method. Then, in a state where the axial force is temporarily received by the existing pile 4, a direct foundation board (upper part of the ground improvement body 9) is excavated to the floor depth of the newly constructed basement 8 (in the formation B in the figure), A new foundation slab 5 is built, and a piled raft foundation is constructed by connecting the existing pile 4 and the new foundation slab 5 together.

この実施例に限らず、上記実施例１と同様に先ず前記既存建物１の既存基礎スラブ３下の基礎地盤Ｂを、既存杭４で軸力を仮受けした状態で新築地下階８の階高深度まで掘削する。その後、前記掘削底面から沈下量の少ない地層Ｈ内まで地盤改良を施工して地盤改良体９を構築する。
しかる後に改良地盤（地盤改良体９）の上面に新設の基礎スラブ５を築造すると共に、既存杭４と新設の基礎スラブ５とを上述した要領で緊結してパイルド・ラフト基礎を構築することもできる（請求項３記載の発明）。 Not only in this embodiment but also in the same manner as in the first embodiment, the height of the newly constructed basement 8 is first set in the state where the foundation ground B under the existing foundation slab 3 of the existing building 1 is temporarily received axial force by the existing pile 4. Drill to depth. Then, the ground improvement body 9 is constructed by constructing the ground improvement from the bottom of the excavation to the inside of the formation H where the subsidence amount is small.
After that, a new foundation slab 5 is built on the upper surface of the improved ground (ground improvement body 9), and the existing pile 4 and the new foundation slab 5 are joined together as described above to construct a piled raft foundation. (Invention of claim 3)

本発明は、杭基礎構造とする基礎形式を最終的にパイルド・ラフト基礎構造に変更して合理的な鉛直支持力の増強を行なった上で増築施工を実施できる。また、既存杭４を有効的に利用するので、既存杭４の解体や、搬出作業、新設杭の設置作業を一切無用として作業効率の向上とコストの低減も実現できるのである。   In the present invention, extension work can be carried out after the foundation type used as a pile foundation structure is finally changed to a piled raft foundation structure and a rational vertical bearing force is increased. Moreover, since the existing pile 4 is used effectively, the dismantling of the existing pile 4, the carrying-out work, and the installation work of the new pile are unnecessary, and the work efficiency can be improved and the cost can be reduced.

以上に実施形態を図面に基づいて説明したが、本発明は、図示例の実施形態の限りではなく、その技術的思想を逸脱しない範囲において、当業者が通常に行う設計変更、応用のバリエーションの範囲を含むことを念のために付言する。例えば、既存基礎スラブ３の下の地盤を掘削する際に、既存地下階２及び基礎スラブ３の面外変形を抑制するため、既存建物１の外周に山留め壁を構築することも行われる。   The embodiments have been described with reference to the drawings. However, the present invention is not limited to the illustrated embodiments, and design modifications and application variations that are usually made by those skilled in the art are within the scope of the technical idea of the invention. I will add a note to include the range. For example, when excavating the ground below the existing foundation slab 3, a retaining wall is also constructed on the outer periphery of the existing building 1 in order to suppress the out-of-plane deformation of the existing basement 2 and the foundation slab 3.

本発明に係る既存建物の基礎下の地下階増築方法において、既存基礎スラブ下を所定の地層及び深度まで掘削した状態を示す立面図である。In the basement extension method under the foundation of the existing building which concerns on this invention, it is an elevation which shows the state which excavated under the existing foundation slab to the predetermined stratum and depth. 本発明に係る既存建物の基礎下の地下階増築方法を実施したパイルド・ラフト基礎の一例を示した立面図である。It is the elevation which showed an example of the piled raft foundation which implemented the basement extension method under the foundation of the existing building which concerns on this invention. 本発明に係る既存建物の基礎下の地下階増築方法を実施したパイルド・ラフト基礎の別の例を示した立面図である。It is the elevation which showed another example of the piled raft foundation which implemented the basement extension method under the foundation of the existing building which concerns on this invention. 従来例を示す参考図である。It is a reference figure which shows a prior art example. 他の従来例を示す参考図である。It is a reference figure which shows another prior art example.

符号の説明Explanation of symbols

１ 既存建物
２ 既存地下階
３ 既存基礎スラブ
４ 既存杭
５ 新設の基礎スラブ 1 Existing building 2 Existing basement 3 Existing foundation slab 4 Existing pile
5 New foundation slab

Claims (4)

杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
前記既存建物の既存基礎スラブ下の地盤を、既存杭で軸力を仮受けした状態で沈下量の少ない地層及び深度まで直下地盤を掘削する工程と、
前記掘削底面に新設の基礎スラブを築造すると共に、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築する工程と、
から成ることを特徴とする、既存建物の基礎下の地下階増築方法。 In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
Excavating the ground beneath the existing foundation slab of the existing building, and excavating the direct foundation to the depth and depth of the subsidence in a state where the axial force is temporarily received by the existing pile;
Constructing a new foundation slab on the bottom of the excavation and constructing a piled raft foundation by binding the existing pile and the new foundation slab;
A basement extension method under the foundation of an existing building, characterized by comprising: 杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
前記既存建物の既存基礎スラブ下の地盤を、沈下量の少ない地層及び深度まで地盤改良し、その後、既存杭で軸力を仮受けした状態で地下階増築分の階高深度まで直下地盤を掘削し、前記掘削底面に新設の基礎スラブを築造すると共に、既存杭と新設の基礎スラブとを緊結してパイルド・ラフト基礎を構築することを特徴とする、既存建物の基礎下の地下階増築方法。 In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
Improving the ground under the existing foundation slab of the existing building to a stratum and depth with less subsidence, and then excavating the direct groundbed to the deeper floor depth of the basement extension with provisional axial force received by the existing pile And constructing a piled raft foundation by linking the existing pile and the newly established foundation slab together with the newly constructed foundation slab on the bottom of the excavation, and a basement extension method under the foundation of the existing building . 杭基礎構造の既存建物における既存杭と既存基礎スラブとで支持された基礎下に地下階を増築する施工方法において、
既存建物の既存基礎スラブ下の地盤を、既存杭で軸力を仮受けした状態で地下階増築分の階高深度まで掘削したのち、前記掘削底面から沈下量の少ない地層及び深度まで地盤改良を行ない、前記改良地盤の上面へ新設の基礎スラブを築造し、同既存杭と新設の基礎スラブとを緊結し、パイルド・ラフト基礎を構築することを特徴とする、既存建物の基礎下の地下階増築方法。 In the construction method of expanding the basement floor under the foundation supported by the existing pile and the existing foundation slab in the existing building of the pile foundation structure,
After excavating the ground under the existing foundation slab of the existing building to the depth of the basement extension with the axial force temporarily received by the existing pile, improve the ground from the excavation bottom to the stratum and depth with less subsidence. A basement floor under the foundation of the existing building, wherein a new foundation slab is built on the upper surface of the improved ground, the existing pile and the new foundation slab are connected, and a piled raft foundation is constructed. Extension method. 既存杭を増築階の柱に仕上げ、外周壁を構築することを特徴とする、請求項１〜３のいずれか一に記載した既存建物の基礎下の地下階増築方法。   The basement extension method under the foundation of the existing building as described in any one of Claims 1-3 characterized by finishing an existing pile into the pillar of an extension floor and constructing an outer peripheral wall.
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JPH0220768A (en) * 1988-07-08 1990-01-24 Takenaka Komuten Co Ltd Basement extension method for existing building
JP2000160551A (en) * 1998-11-27 2000-06-13 Takenaka Komuten Co Ltd Ground improving method applying top-down construction method
JP2000192479A (en) * 1998-12-28 2000-07-11 Tenox Corp Earthquake resistant reinforcing method for existing pile foundation
JP2002146809A (en) * 2000-11-07 2002-05-22 Taisei Corp Construction method for structure
JP2007169992A (en) * 2005-12-21 2007-07-05 Takenaka Komuten Co Ltd Bearing power increasing method in extension or reconstruction of upper structure of existing building

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS62288269A (en) * 1986-06-05 1987-12-15 株式会社間組 Method for extending underground stair of building
JPH0220768A (en) * 1988-07-08 1990-01-24 Takenaka Komuten Co Ltd Basement extension method for existing building
JP2000160551A (en) * 1998-11-27 2000-06-13 Takenaka Komuten Co Ltd Ground improving method applying top-down construction method
JP2000192479A (en) * 1998-12-28 2000-07-11 Tenox Corp Earthquake resistant reinforcing method for existing pile foundation
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JP2007169992A (en) * 2005-12-21 2007-07-05 Takenaka Komuten Co Ltd Bearing power increasing method in extension or reconstruction of upper structure of existing building

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