JP3884754B2 - Ground reinforcement method - Google Patents
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- JP3884754B2 JP3884754B2 JP2005144502A JP2005144502A JP3884754B2 JP 3884754 B2 JP3884754 B2 JP 3884754B2 JP 2005144502 A JP2005144502 A JP 2005144502A JP 2005144502 A JP2005144502 A JP 2005144502A JP 3884754 B2 JP3884754 B2 JP 3884754B2
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- 238000000034 method Methods 0.000 title claims description 56
- 230000002787 reinforcement Effects 0.000 title claims description 18
- 238000005259 measurement Methods 0.000 claims description 15
- 238000010276 construction Methods 0.000 claims description 10
- 238000009412 basement excavation Methods 0.000 claims description 8
- 229910000831 Steel Inorganic materials 0.000 description 50
- 239000010959 steel Substances 0.000 description 50
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000009424 underpinning Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 230000003014 reinforcing effect Effects 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 208000019901 Anxiety disease Diseases 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000036506 anxiety Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000011900 installation process Methods 0.000 description 1
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- 238000012360 testing method Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
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- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
Description
本発明は、地盤を補強するために使用される地盤補強工法に関し、特に、戸建住宅，集合住宅又は工場その他の既設構造物を支持している地盤を補強するために使用される地盤補強工法に関するものである。 The present invention relates to a ground reinforcement construction method used to reinforce the ground, and in particular, a ground reinforcement construction method used to reinforce a ground supporting a detached house, an apartment house, a factory or other existing structures. It is about.
戸建住宅，集合住宅又は工場その他の既設構造物は、強靭な地盤により支持されていることが好ましいが、必ずしもこうした強靭な地盤ではなく、軟弱な地盤に支持されている場合も少なくない。例えば、盛土で地盤が形成されている場合や、沼地に盛土された地盤により構造物が支持されている場合には、構造物の自重又は地震等の発生により不同沈下し、構造物が傾斜する危険性が高い。また、こうした軟弱地盤に建設された構造物が傾斜している場合も多い。そこで、こうした既設構造物を支持している地盤を改良・補強する工法として、アンダーピニング工法が採用されている。このアンダーピニング工法は、既設構造物を支持している地盤を補強する際にこれまで使用されている工法であり、先ず、既設構造物の基礎の下側を掘削し、所定の空間を形成した上で、該空間内において、該戸建住宅を反力として用いながら、所定の本数の杭を下方に打設し、これらの杭により上記基礎の下方から戸建住宅を支持させるものである。 Detached houses, apartment houses, factories and other existing structures are preferably supported by a strong ground, but they are not necessarily a strong ground, but are often supported by a soft ground. For example, when the ground is formed by embankment or when the structure is supported by the ground embanked in a swamp, the structure will sink due to the weight of the structure or the occurrence of an earthquake, etc., and the structure will incline High risk. In addition, there are many cases where structures constructed on such soft ground are inclined. Therefore, an underpinning method is adopted as a method for improving and reinforcing the ground supporting such existing structures. This underpinning method is a method that has been used so far to reinforce the ground supporting the existing structure. First, the underside of the foundation of the existing structure was excavated to form a predetermined space. In the space, while using the detached house as a reaction force, a predetermined number of piles are driven downward, and the detached house is supported by the piles from below the foundation.
しかしながら、上記従来の技術では、アンダーピニング工法による杭の打設は、該杭が支持地盤に到達するか否かに拘らず、傾斜した既設構造物が水平状態に復帰されたり、既設構造物の基礎にクラックが発生したりした場合に停止している。こうした上述した従来のアンダーピニング工法では、十分地盤を補強することができず、地震の発生による不同沈下により既設構造物が傾き、或いは、傾いた既設構造物を上記従来の工法により水平に補正した後に、地震等の発生を原因として、再び傾く危険性がある。こうした危険性が生ずる主な原因は、打設された杭の下端が支持地盤（強靭な地盤）に支持されていないことによるものが殆どである。なお、こうした事態の発生を防止するために、予め既設構造物の近傍からボーリング調査を行い、支持地盤の深度を測定し、この測定された深度に届くまで杭を打設する方法が採用されているが、施工現場によっては、支持地盤が傾斜していたり、不規則な状態で支持地盤が形成されていたりする場合には、やはり打設された杭の下端が支持地盤に支持されず、上記危険性は回避できない。 However, in the above-described conventional technology, the pile placement by the underpinning method is performed regardless of whether the pile reaches the support ground or not. It stops when a crack occurs in the foundation. In the conventional underpinning method described above, the ground cannot be sufficiently reinforced, and the existing structure is tilted due to the unsettled settlement due to the occurrence of an earthquake, or the tilted existing structure is corrected horizontally by the conventional method. Later, there is a risk of tilting again due to the occurrence of an earthquake or the like. The main cause of such danger is mostly that the lower end of the pile that has been laid is not supported by the supporting ground (tough ground). In addition, in order to prevent the occurrence of such a situation, a method of conducting a boring survey from the vicinity of an existing structure in advance, measuring the depth of the supporting ground, and driving a pile until it reaches this measured depth is adopted. However, depending on the construction site, if the supporting ground is inclined or the supporting ground is formed in an irregular state, the lower end of the placed pile is not supported by the supporting ground. The danger cannot be avoided.
そこで、本発明は、上述した地盤補強工法が有する課題を解決するために提案されたものであって、支持地盤が傾斜していたり不規則な状態で形成されていたりする場合であっても、打設される杭の下端を確実に支持地盤に支持させることができ、より一層確実に地盤を補強することができる新規な地盤補強工法を提案することを目的とするものである。 Therefore, the present invention has been proposed to solve the problems of the ground reinforcement method described above, and even if the support ground is inclined or formed in an irregular state, An object of the present invention is to propose a new ground reinforcement method that can reliably support the lower end of the pile to be placed on the supporting ground and can reinforce the ground more reliably.
本発明は、上述した目的を達成するために提案されたものであり、第１の発明（請求項１記載の発明）は、戸建住宅，集合住宅又は工場その他の既設構造物に近接した位置において、支持地盤の深度を測定する深度測定工程と、上記既設構造物の基礎の下側を掘削し、空間を形成する掘削工程と、上記掘削工程により形成された空間内において、上記既設構造物を支持しながら、複数の杭を、それぞれ該杭の長さ方向に徐々に継ぎ足しながら地中に打設する杭打設工程と、を備えた地盤補強工法において、上記杭の下端が、上記深度測定工程で得た深度に到達する以前に、継ぎ足した杭の上端と上記既設構造物の基礎との間に荷重計測器を介在させ、該荷重計測器による荷重の数値が所定の値を超えた場合に、上記杭打設工程を中止することを特徴とするものである。 The present invention has been proposed in order to achieve the above-mentioned object, and the first invention (the invention described in claim 1) is a position close to a detached house, an apartment house, a factory or other existing structures. The depth measurement step of measuring the depth of the supporting ground, the excavation step of excavating the lower side of the foundation of the existing structure to form a space, and the existing structure in the space formed by the excavation step A pile placing step of placing a plurality of piles into the ground while gradually adding the piles in the length direction of the piles. Before reaching the depth obtained in the measurement process, a load measuring instrument was interposed between the upper end of the added pile and the foundation of the existing structure, and the numerical value of the load by the load measuring instrument exceeded a predetermined value. In case, stop the above pile driving process It is an feature.
なお、この第１の発明において、改良する地盤上に設けられた構造物は、戸建住宅や集合住宅，工場等の建築物ばかりではなく屋外のプラント，鉄塔，タンク等であっても良い。また、補強すべき地盤は、必ずしも地震などにより傾斜した構造物を支持しているものばかりではなく、正常な水平レベルを維持している構造物が支持された地盤も含む。また、最初の工程である深度測定工程では、既設構造物の周囲の環境により、例えば、ボーリング，スウェーデン式サウンディング等の方法が採用される。なお、こうした深度測定工程で行われる支持地盤の深度の特定位置は、可能な限り既設構造物の近傍で行うことが好ましく、また、測定回数は特に限定されない。例えば、ボーリングによる場合、これを複数回実施することは高コストとなることから、既設構造物が住宅などである場合には、スウェーデン式サウンディング試験を行う場合が多い。また、上記掘削工程においては、既設構造物の外周側から地盤を掘削し、該構造物の基礎の下側に空間を形成するものであり、必ずしも構造物の基礎の下側全てを掘削する必要はない。なお、こうした掘削工程は後述する杭打設工程と共に行われる。すなわち、先ずは、既設構造物の外周側の適当な位置から部分的に掘削し、既設構造物の下側に杭を打設するに十分な空間を形成し、この空間内において、上方に位置する基礎の下面で反力をとりながら（又は、打撃等による杭打ち込み方法を採用することにより）杭を地中に打設するとともに、該杭により既設構造物を支持し、この状態でさらに掘削することにより、横方向に上記空間を広げ、杭の打設により既設構造物を支持して行く。こうした掘削工程と杭打設工程を交互に経ながら、既設構造物の全部又は一部を上記杭により支持する。なお、この杭は、鉛直方向の長さが、少なくとも上記空間の高さよりも短尺に成形されたものであり、これを継ぎ足しながら下方に打設されるものであって、該杭の材質，形状，外径は特に限定されるものではなく、さらに杭と杭とを継ぎ足す方法も、溶接方法，ボルト及びナットによる締結方法，嵌合方法，係合方法等種々の方法を採用することができる。 In the first invention, the structure provided on the ground to be improved may be an outdoor plant, a steel tower, a tank, or the like as well as a building such as a detached house, an apartment house, or a factory. Further, the ground to be reinforced does not necessarily support a structure inclined due to an earthquake or the like, but also includes a ground on which a structure maintaining a normal horizontal level is supported. Also, in the depth measurement process, which is the first process, methods such as boring and Swedish sounding are employed depending on the environment around the existing structure. In addition, it is preferable to perform the specific position of the depth of the support ground performed in such a depth measurement process as close to the existing structure as possible, and the number of times of measurement is not particularly limited. For example, in the case of boring, it is costly to perform this multiple times. Therefore, when the existing structure is a house, a Swedish sounding test is often performed. In the excavation process, the ground is excavated from the outer peripheral side of the existing structure to form a space below the foundation of the structure, and all the lower side of the foundation of the structure must be excavated. There is no. Such excavation process is performed together with a pile driving process described later. That is, first, a part of the existing structure is excavated from an appropriate position on the outer periphery side to form a space sufficient to drive a pile below the existing structure. The pile is placed in the ground while taking the reaction force on the lower surface of the foundation to be struck (or by adopting a pile driving method such as hitting), and the existing structure is supported by the pile, and further excavation is performed in this state By doing so, the space is expanded in the lateral direction, and the existing structure is supported by driving the piles. The excavation process and the pile driving process are alternately performed, and all or part of the existing structure is supported by the pile. The pile has a length in the vertical direction that is at least shorter than the height of the space, and is driven downward while adding the material. The outer diameter is not particularly limited, and various methods such as a welding method, a fastening method using bolts and nuts, a fitting method, and an engaging method can be adopted as a method for adding the piles to each other. .
そして、この第１の発明においては、上述した杭打設工程において、杭の下端が、上記深度測定工程で得た深度に到達する以前に、継ぎ足した杭の上端と上記既設構造物の基礎との間に荷重計測器を介在させ、該荷重計測器による荷重の数値が所定の値を超えた場合に、上記杭打設工程を中止するものである。この杭の下端とは、特定の位置において最初に打設された杭の下端である。また、上記荷重測定器は、上記既設構造物の下方に形成された空間において継ぎ足された杭と、該既設構造物の基礎との間に介在・配置されるものであり、荷重測定器と継ぎ足された杭の上端との間や、荷重測定器と基礎との間に木片，繊維などの緩衝材を配置しても良い。また、この荷重計測器は、少なくと、該荷重計測器に作用した荷重を計測できるものであれば、デジタル式でもアナログ式でも良く、その大きさや形状が問われるものではない。また、上記荷重測定装置を、継ぎ足した杭の上端と上記既設構造物の基礎との間に介在させるタイミングは、少なくと、杭の下端が、上記深度測定工程で得た深度に到達する以前であれば足り、最初の杭を打設する当初から荷重測定器を介在させても良い。 And in this 1st invention, before the lower end of a pile reaches | attains the depth obtained by the said depth measurement process in the pile placing process mentioned above, the upper end of the pile piled up and the foundation of the said existing structure A load measuring device is interposed between the piles, and when the numerical value of the load by the load measuring device exceeds a predetermined value, the pile driving process is stopped. The lower end of the pile is the lower end of the pile that is initially placed at a specific position. Further, the load measuring device is interposed and disposed between a pile added in a space formed below the existing structure and a foundation of the existing structure, A cushioning material such as a piece of wood or fiber may be disposed between the upper ends of the piles or between the load measuring device and the foundation. The load measuring device may be digital or analog as long as it can measure the load acting on the load measuring device, and its size and shape are not limited. In addition, the timing of interposing the load measuring device between the upper end of the added pile and the foundation of the existing structure is at least before the lower end of the pile reaches the depth obtained in the depth measurement step. If necessary, a load measuring device may be interposed from the beginning of placing the first pile.
そして、この発明においては、上記荷重計測器による荷重の数値が所定の値を超えた場合に、上記杭打設工程を中止するものであり、この所定の数値とは、地表と支持地盤との間に形成された地層や、該支持地盤の硬度にもよるが、例えば、杭打設工程中において、上記深度測定工程において得られた深度に達する前段階における荷重と比較することによって得られた大きな荷重を指す。すなわち、こうした荷重が荷重測定器により測定された場合には、支持地盤に杭の下端が当接したものと判断し、杭打設工程を終了する。なお、上記荷重計測器による荷重の数値が所定の値に達する以前の作業中に、既設構造物に異常が発生した場合においては、その時点において、その近辺において打設する杭を増加させ（増し打ちし）、また、こうした作業途中での杭の増し打ちの必要性がないように、既設構造物の構造や老朽化の程度に応じて、必要十分な杭の本数を予め決定する。 And in this invention, when the numerical value of the load by the load measuring instrument exceeds a predetermined value, the pile driving process is stopped, and the predetermined numerical value is the difference between the ground surface and the supporting ground. Depending on the stratum formed in between and the hardness of the supporting ground, for example, in the pile placing process, it was obtained by comparing with the load in the previous stage reaching the depth obtained in the depth measurement process Refers to a large load. That is, when such a load is measured by a load measuring device, it is determined that the lower end of the pile is in contact with the support ground, and the pile driving process is terminated. If an abnormality occurs in the existing structure during the work before the numerical value of the load measured by the load measuring instrument reaches a predetermined value, the piles to be placed in the vicinity are increased (increased) at that time. In addition, the necessary and sufficient number of piles is determined in advance according to the structure of the existing structure and the degree of aging so that there is no need for additional piles during the work.
本発明に係るに係る地盤補強工法によれば、打設される杭により地盤が補強され、構造部の健全性が確保されるばかりではなく、打設された杭の下端は必ず支持地盤（硬質地盤）に当接し支持されることから、地震等の発生に伴う不同沈下を有効に防止することができる。特に、上記不同沈下により既に傾斜した構造物を、本発明に係る地盤補強工法により補強した場合には、例えば、支持地盤が傾斜している場合であって、全ての杭の下端は該支持地盤に当接し支持されることから、上記傾斜した構造物を水平状態に補正することができるばかりではなく、所謂二次沈下の発生により再び傾斜してしまうという事態を有効に回避することができる。すなわち、この地盤補強工法によれば、ボーリング等の方法により限定された位置で且つ計算により求められた支持地盤の深度と、実際に打設された杭の支持状態との齟齬の結果から生ずる不安定性又は二次沈下の発生を有効に解消し又は防止することができる。 According to the ground reinforcement method according to the present invention, the ground is reinforced by the piles to be placed, and not only the soundness of the structural portion is ensured, but also the lower ends of the piles to be placed are always supported ground (hard Since it is in contact with and supported by the ground, it is possible to effectively prevent uneven settlement due to the occurrence of an earthquake or the like. In particular, when a structure that has already been inclined due to the above-mentioned uneven settlement is reinforced by the ground reinforcement method according to the present invention, for example, when the supporting ground is inclined, the lower ends of all the piles are the supporting ground. In addition to being able to correct the inclined structure to a horizontal state, it is possible to effectively avoid a situation in which it is inclined again due to the occurrence of so-called secondary settlement. That is, according to this ground reinforcement construction method, the anxiety arising from the result of the dredging between the depth of the support ground obtained by calculation at a position limited by a method such as boring and the support state of the actually placed pile. The occurrence of qualitative or secondary settlement can be effectively eliminated or prevented.
そして、上記荷重測定器としてロードセルを用いた場合には、精度も高く取り扱いも簡便であることから、作業性を向上することができる。 When a load cell is used as the load measuring instrument, the workability can be improved because it is highly accurate and easy to handle.
以下、本発明を実施するための最良の形態に係る地盤補強工法を、図面を参照しながら工程順に詳細に説明する。 Hereinafter, the ground reinforcement method according to the best mode for carrying out the present invention will be described in detail in the order of steps with reference to the drawings.
この実施の形態に係る地盤補強工法は、本発明を、図１に示すように、圧密沈下又は地震等の発生により傾斜した戸建住宅１を正常な状態に復帰（復元）させるとともに、該戸建住宅１を支持する地盤を改良する際の工法に適用したものである。そこで、以下、この地盤補強工法に付いて工程順に説明すると、先ず、図１に示す傾斜した戸建住宅１の近傍において、図示しないボーリング装置等を使用して後述する支持地盤（硬質地盤）１０の深度（距離）Ｌを測定する（深度測定工程）。また、こうした深度測定工程により、使用する杭（鋼管杭）の使用予定本数、油圧ジャッキの個数や油圧ジャッキの最大荷重などを算出する。 As shown in FIG. 1, the ground reinforcement construction method according to this embodiment restores (restores) a detached house 1 inclined by the occurrence of consolidation subsidence or an earthquake as shown in FIG. This is applied to a construction method for improving the ground supporting the built house 1. Therefore, in the following, the ground reinforcement method will be described in the order of steps. First, in the vicinity of the inclined detached house 1 shown in FIG. 1, a supporting ground (hard ground) 10 described later using a boring device (not shown) or the like. The depth (distance) L is measured (depth measurement step). In addition, the depth measurement step calculates the planned number of piles (steel pipe piles) to be used, the number of hydraulic jacks, the maximum load of the hydraulic jack, and the like.
そして、上記震度測定工程が終了すると、次いで、上記戸建住宅１の近傍から地盤３を掘削し、図２に示すように、（戸建住宅Hの）基礎４の下方を掘削し、空間（作業空間）５を形成する。次いで、上記空間５内に、油圧ジャッキ６及び鋼管杭７を搬入し、この油圧ジャッキ６を基礎４の下方に配置し、上記鋼管杭７を下方に（地盤３に）打設する（杭打設工程）。この鋼管杭７の打設方法を説明すると、上記基礎４の下方に油圧ジャッキ６を配置し、この油圧ジャッキ６の下方に鋼管杭７を鉛直方向に配置する。そして、上記油圧ジャッキ６を、該油圧ジャッキ６を構成するシリンダー６ａが伸張するよう駆動させ、上記戸建住宅１の荷重を反力として利用し、図３に示すように、上記鋼管杭７を下方に打設する。なお、上記空間５内において、こうした鋼管杭７を、例えば１本打設することにより、上記戸建住宅１の一部を支持した場合には、上記空間５を更に拡張し、同じ要領で別の箇所で鋼管杭７を打設する。こうした手順により、上記戸建住宅１の全部（又は一部）を上記要領にて最初に打設した鋼管杭７Ａにより支持する。なお、上記鋼管杭７の打設方法は、上述したように、戸建住宅１の荷重を反力として利用する方法ばかりではなく、機械的な打撃により打設する方法であっても良い。 Then, when the seismic intensity measurement process is finished, the ground 3 is excavated from the vicinity of the detached house 1 and the lower part of the foundation 4 (of the detached house H) is excavated as shown in FIG. Working space) 5 is formed. Next, the hydraulic jack 6 and the steel pipe pile 7 are carried into the space 5, the hydraulic jack 6 is arranged below the foundation 4, and the steel pipe pile 7 is driven downward (on the ground 3) (pile driving). Installation process). The method for placing the steel pipe pile 7 will be described. The hydraulic jack 6 is disposed below the foundation 4, and the steel pipe pile 7 is disposed below the hydraulic jack 6 in the vertical direction. And the said hydraulic jack 6 is driven so that the cylinder 6a which comprises this hydraulic jack 6 expand | extends, The load of the said detached house 1 is utilized as reaction force, As shown in FIG. Drive down. In addition, when a part of the detached house 1 is supported by placing one such steel pipe pile 7 in the space 5, for example, the space 5 is further expanded and separated in the same manner. The steel pipe pile 7 is driven at the location. By such a procedure, the whole (or a part) of the detached house 1 is supported by the steel pipe pile 7A initially placed in the above manner. In addition, as described above, the method of placing the steel pipe pile 7 is not limited to a method of using the load of the detached house 1 as a reaction force, but may be a method of placing by mechanical impact.
そして、このようにそれぞれ１本の鋼管杭７Ａにより戸建住宅１を支持すると、次いで、再び次の（２番目の）鋼管杭７Ｂを、油圧ジャッキ６と既に打設した鋼管杭７Ａとの間に配置し、油圧ジャッキ６のシリンダー６ａが伸張するよう駆動させ、図４に示すように、順番に他の位置においても次の（２番目の）鋼管杭７Ｂを打設する。なお、上記１番目の鋼管杭７Ａと２番目の鋼管杭７Ｂとは、互いに溶接することにより固定する。こうした作業を繰り返すことにより、徐々に鋼管杭７（７Ａ，７Ｂ・・・７Ｎ）が継ぎ足されながら打設されることにより、上記１番目の鋼管杭７Ａの下端は、下方に形成された支持地盤１０に近づく。なお、こうして打ち込まれた鋼管杭７の数により、１番目の鋼管杭７Ａの下端位置は、上記深度測定工程で特定された支持地盤１０の形成予想位置との関係で、把握されていることから、該支持地盤１０の形成予想位置に上記１番目の鋼管杭７Ａの下端が近づいたと判断した場合には、最も上方に配置された（例えば、３番目の）鋼管杭７Ｃの上部の油圧ジャッキ６と基礎４との間にロードセル９を配置し、この状態で上記油圧ジャッキ６を駆動させる。そして、こうした油圧ジャッキ６の駆動による、上記ロードセル９は、上端の着力点に作用した荷重が内部の歪ゲージを変位させ、この出力が該ロードセル９を構成する表示装置９ａに荷重として表示される。したがって、作業者は、この表示装置９ａに表示された荷重の値を目視しながら、途中で大きく荷重数値が上昇した場合には、図５に示すように、支持地盤１０に上記１番目の鋼管杭７Ａの下端が当接した（又はさらに打設された）ものと判断する。なお、この実施の形態においては、上記ロードセル９と基礎４との間には、該ロードセル９の安定性や破損を防止するために、平板１１を配置している。また、本実施の形態においては、上記３番目の鋼管杭７Ｃの側方に、該鋼管杭７Ｃの上面と面一とされた受台１２を支持板１３とともに溶接する。 And if the detached house 1 is each supported by one steel pipe pile 7A in this way, then, the next (second) steel pipe pile 7B is again placed between the hydraulic jack 6 and the already placed steel pipe pile 7A. The cylinder 6a of the hydraulic jack 6 is driven so as to extend, and the next (second) steel pipe pile 7B is driven in order at other positions as shown in FIG. In addition, the said 1st steel pipe pile 7A and the 2nd steel pipe pile 7B are fixed by welding each other. By repeating these operations, the steel pipe pile 7 (7A, 7B,... 7N) is gradually placed while being added, so that the lower end of the first steel pipe pile 7A is formed on the supporting ground formed below. Approach 10 In addition, from the number of the steel pipe piles 7 driven in in this way, the lower end position of the first steel pipe pile 7A is grasped in relation to the formation predicted position of the supporting ground 10 specified in the depth measurement step. When it is determined that the lower end of the first steel pipe pile 7A has approached the expected formation position of the support ground 10, the upper hydraulic jack 6 on the uppermost (for example, third) steel pipe pile 7C is disposed. The load cell 9 is arranged between the base 4 and the hydraulic jack 6 in this state. The load cell 9 driven by the hydraulic jack 6 displaces the internal strain gauge due to the load acting on the force applied to the upper end, and the output is displayed as a load on the display device 9a constituting the load cell 9. . Therefore, when the load value is greatly increased on the way while observing the load value displayed on the display device 9a, the operator places the first steel pipe on the supporting ground 10 as shown in FIG. It is determined that the lower end of the pile 7A is in contact (or further driven). In this embodiment, a flat plate 11 is disposed between the load cell 9 and the foundation 4 in order to prevent the load cell 9 from being stable or damaged. Moreover, in this Embodiment, the receiving stand 12 made flush with the upper surface of this steel pipe pile 7C is welded with the support plate 13 to the side of said 3rd steel pipe pile 7C.
そして、特定の部位において、上記ロードセル９を用いて特定の鋼管杭７の下端（１番面の鋼管杭７Ａの下端）が支持地盤１０により支持されたことが確認されると、それまで駆動させていた油圧ジャッキ６の駆動を停止させるとともに、図６に示すように、上記油圧ジャッキ６を上記受台１２上に移動させることにより、該油圧ジャッキ６により戸建住宅１（の一部）を支持させ、次いで、上記３番目の鋼管杭７Ｃの上端に４番目の鋼管杭７Ｄを溶接する。なお、この４番目の鋼管杭７Ｄの上端は、上記基礎４の下面に当接することはなく僅かな隙間が空くことから、図７に示すように、この隙間内に、（本実施の形態では）鉄板１４を配置させ、次いで上記油圧ジャッキ６を撤去する。 And when it is confirmed that the lower end of the specific steel pipe pile 7 (the lower end of the first steel pipe pile 7A) is supported by the support ground 10 using the load cell 9 in the specific portion, the load cell 9 is driven until then. The driving of the hydraulic jack 6 that has been stopped is stopped, and the hydraulic jack 6 is moved onto the cradle 12 as shown in FIG. Then, the fourth steel pipe pile 7D is welded to the upper end of the third steel pipe pile 7C. Since the upper end of the fourth steel pipe pile 7D does not contact the lower surface of the foundation 4 and a slight gap is formed, as shown in FIG. ) Place the iron plate 14 and then remove the hydraulic jack 6.
そして、このような要領で特定の位置における作業が終了すると、その位置の近傍（又は離間した位置）において、上記ロードセル９を使用しながら、それぞれの位置において荷重を測定し支持地盤１０に１番目の鋼管杭７Ａの下端が支持されたことを確認した上で、上記４番目の鋼管杭７Ｄを含めた全ての鋼管杭７（７Ａ・・・７Ｄ）により戸建住宅１を支持させる。なお、傾いた戸建住宅１を正常な状態に復帰させる場合には、最も下方に位置する部位における４番目の鋼管杭７Ｄと基礎４とが傾きの程度に応じて大きく離間するよう油圧ジャッキ６の駆動により、正常な状態となるまで復帰させるとともに、その傾きの程度に応じた肉厚の鉄板１４を該４番目の鋼管杭７Ｄと基礎４との間に配置させる。 Then, when the work at a specific position is completed in such a manner, the load cell 9 is used in the vicinity of the position (or a separated position), the load is measured at each position, and the first on the support ground 10. After confirming that the lower end of the steel pipe pile 7A is supported, the detached house 1 is supported by all the steel pipe piles 7 (7A... 7D) including the fourth steel pipe pile 7D. In addition, when returning the inclined detached house 1 to a normal state, the hydraulic jack 6 so that the 4th steel pipe pile 7D and the foundation 4 in the site | part located in the lowest part may space | separate greatly according to the grade of inclination. By returning to the normal state, the steel plate 14 having a thickness corresponding to the degree of the inclination is disposed between the fourth steel pipe pile 7D and the foundation 4.
なお、このように全ての鋼管杭７の下端が硬質な支持地盤１０に支持された場合には、上記受台１２及び支持板１２を取り除き、スラリー１５を上記空間５内に充填するとともに、掘削工程において発生した残土１６を地表に敷設する。こうした一連の作業により地盤補強作業は終了する。 In addition, when the lower ends of all the steel pipe piles 7 are supported by the hard support ground 10 in this way, the cradle 12 and the support plate 12 are removed, and the slurry 15 is filled in the space 5 and excavated. The remaining soil 16 generated in the process is laid on the ground surface. The ground reinforcement work is completed by such a series of work.
このように、上述した実施の形態に係る地盤補強工法では、ロードセル９を用いた荷重の測定により、全ての鋼管杭７の下端は、硬質な支持地盤１０に支持されるとともに、戸建住宅１は、これらの鋼管杭７により安定的に支持されるものであり、支持地盤１０に支持されない鋼管杭７が打設されることがない。したがって、この地盤補強工法によれば、傾斜状態から正常な状態に復帰された戸建住宅１が、圧密沈下又は地震等の発生により、二次沈下し再度傾斜してしまう事態を有効に防止することができる。特に、上記実施の形態では、最初の（１番目の）鋼管杭７の打設工程においてはロードセル９を使用せず、深度測定工程において得た支持地盤１０の深度（地表からの距離）に継ぎ足しながら打設した鋼管杭７Ｃが近接した状態から使用を開始することから、鋼管杭７を打設する位置の数に応じた数のロードセル９を用意する必要が無く、１つのロードセル９の使用で足りる。 Thus, in the ground reinforcement construction method according to the above-described embodiment, the lower ends of all the steel pipe piles 7 are supported by the hard supporting ground 10 by the measurement of the load using the load cell 9, and the detached house 1 Is stably supported by these steel pipe piles 7, and the steel pipe piles 7 not supported by the supporting ground 10 are not driven. Therefore, according to the ground reinforcement method, the detached house 1 that has been restored from the inclined state to the normal state effectively prevents the secondary subsidence due to the consolidation subsidence or the occurrence of an earthquake or the like, and the tilting again. be able to. In particular, in the above embodiment, the load cell 9 is not used in the placing process of the first (first) steel pipe pile 7, and the depth (distance from the ground surface) of the supporting ground 10 obtained in the depth measuring process is added. However, it is not necessary to prepare the number of load cells 9 according to the number of positions where the steel pipe piles 7 are placed because the steel pipe piles 7 </ b> C that are placed are close to each other. It ’s enough.
なお、上記実施の形態では、戸建住宅１を支持する地盤を補強する工法について説明したが、本発明は、こうした戸建住宅１に限定されず、集合住宅，工場，プラント，タンク等の構造物を支持する地盤を補強するために使用されても良い。また、上記実施の形態では、傾斜した戸建住宅１を支持する地盤を補強する工法について説明したが、本発明は、傾斜することなく正常な状態で構造物を支持している地盤を補強するために使用されても良い。また、本発明は、上述したロードセル９を用いることなく、他の荷重測定器を使用しても良いし、杭として鋼管杭を使用することなく、例えば、所謂コンクリート杭や硬質樹脂を素材とした杭を使用しても良い。 In the above embodiment, the method of reinforcing the ground supporting the detached house 1 has been described. However, the present invention is not limited to such a detached house 1 and is a structure of an apartment house, a factory, a plant, a tank, or the like. It may be used to reinforce the ground that supports the object. Moreover, in the said embodiment, although the construction method which reinforces the ground which supports the inclined detached house 1 was demonstrated, this invention reinforces the ground which is supporting the structure in a normal state, without inclining. May be used for In addition, the present invention may use other load measuring devices without using the load cell 9 described above, and without using a steel pipe pile as a pile, for example, a so-called concrete pile or hard resin is used as a material. Pile may be used.
１ 戸建住宅
３ 地盤
４ 基礎
５ 空間
６ 油圧ジャッキ
７（７Ａ，７Ｂ，７Ｃ，７D） 鋼管杭
９ ロードセル
１０ 支持地盤
1 Detached house 3 Ground 4 Foundation 5 Space 6 Hydraulic jack 7 (7A, 7B, 7C, 7D) Steel pipe pile 9 Load cell 10 Support ground
Claims (3)
上記既設構造物の基礎の下側を掘削し、空間を形成する掘削工程と、
上記掘削工程により形成された空間において、上記既設構造物を支持しながら、複数の杭をそれぞれ該杭の長さ方向に徐々に継ぎ足しながら地中に打設する杭打設工程と、
を備えた地盤補強工法において、
上記杭の下端が、上記深度測定工程で得た深度に到達する以前に、前記既設構造物の基礎の下方に油圧ジャッキを配置し、前記油圧ジャッキの下方に前記杭を鉛直方向に配置し、前記基礎と前記油圧ジャッキとの間に荷重計測器を介在させ、上記杭にかかる荷重を計測することを特徴とする、地盤補強工法。 A depth measurement step for measuring the depth of the supporting ground at a position close to a detached house, an apartment house or a factory or other existing structure;
Excavating the lower side of the foundation of the existing structure to form a space;
In the space formed by the excavation process, while supporting the existing structure, a pile driving process of driving a plurality of piles into the ground while gradually adding the piles in the length direction of the piles,
In the ground reinforcement method with
Before the lower end of the pile reaches the depth obtained in the depth measurement step, a hydraulic jack is arranged below the foundation of the existing structure, and the pile is arranged vertically below the hydraulic jack, A ground reinforcement construction method, wherein a load measuring instrument is interposed between the foundation and the hydraulic jack to measure a load applied to the pile.
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| JP5090804B2 (en) * | 2007-07-02 | 2012-12-05 | 株式会社Ｗａｓｃ基礎地盤研究所 | Construction method and foundation support structure of ready-made piles |
| JP2014040703A (en) * | 2012-08-21 | 2014-03-06 | Leafair Co Ltd | Existent construction ground improvement structure |
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