JP2004150032A - Foundation structure for building, and its design method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily take a measure to cope with repairing in case the subsidence of foundation structure has occurred in the foundation structure for a building. <P>SOLUTION: Predetermined instrumentation is carried out to the ground on which the foundation for the building is to be constructed, and whether improved foundation structure should be constructed also in the ground in addition to the foundation on the ground is determined according to the measured result. In the case of determining the construction of the improved foundation structure in the ground, improving bodies 40 with depth Z, width X and spacing Y are formed in a grated shape in the ground where the improved foundation structure is to be constructed, to partition the ground into a plurality of regions, and a mat foundation 30 is formed on the improving bodies so as not to cause mutual constraint between the improving bodies and the mat foundation 30. <P>COPYRIGHT: (C)2004,JPO

Description

第２のステップでは、レイリー波速度Ｖｒ１ を用いて、以下の式（２）により圧密降伏応力Ｐｙ１ （ｋＮ／ｍ^２ ）を算出する。
【００８０】

第３のステップでは、算出された一軸圧縮応力度ｑｕ１を用いて、下記の式（３）により土の粘着力Ｃ１を算出する。
【００８１】
Ｃ１＝ｑｕ１／２ （３）
第４のステップでは、あらかじめ知られているレイリー波速度Ｖｒと土質との対応関係表から土の単位体積重量γｔ１を特定する。この対応関係を図１１に示す。なお、この対応関係表は、清水昭男著、『土質地盤の調査・試験とその応用』
（理工図書出版）に示されている。
【００８２】
第５のステップでは、特定された単位体積重量γｔ１（ｋＮ／ｍ^３ ）とレイリー波速度Ｖｒ１ とを用いて、以下の式（４）により剛性率Ｇ１を算出する。
【００８３】
Ｇ１＝γｔ１×Ｖｒ１ ^２ ／９．８ （４）
第６のステップでは、算出された粘着力Ｃ１を用いて、以下の式（５）により体積圧縮係数ｍｖ１を算出する。
【００８４】
ｍｖ１＝１／（８０×Ｃ１） （５）
第７のステップでは、算出された剛性率Ｇ１とあらかじめ知られている地盤のポアンソン比νとを用いて、以下の式（６）により地盤の弾性係数Ｅ１（ｋＮ／ｍ^２ ）を算出する。
【００８５】
Ｅ１＝２×Ｇ１×（１＋ν） （６）
なお、弾性係数Ｅ１は、体積圧縮係数ｍｖ１を用いて、Ｅ１＝１／ｍｖ１で求められても良い。
【００８６】
第８のステップでは、第１層の層厚ｈ１ （地盤面から第１層と第２層の境目までの深さ）（ｍ）と、特定された単位体積重量γｔ１と、地盤面から基礎底までの深さｔとから、以下の式（７）により建屋建設前の有効地中応力σｚ１を算出する。
【００８７】
σｚ１＝｛ｔ＋［（ｈ１ −ｔ）／２］｝×γｔ１ （７）
なお、地盤面から基礎底までの深さｔというのは、地盤上の基礎として厚さｔのベタ基礎が設けられることを前提としている。このため、基礎底の無い状態で計算する場合には、ｔ＝０とされる。
【００８８】
第９のステップでは、単位面積当たりの建屋荷重ΣＷ（ｋＮ／ｍ^２ ）を算出する。これは、建屋の設計段階で計算することができる。
【００８９】
第１０のステップでは、第１層の層厚ｈ１ と深さｔとを用いて、建屋の基礎底から沈下量を算出されるべき位置までの深さｈｊ （ｍ）を決定する。
【００９０】
この深さｈｊ の決定は、第１層における特性曲線の傾きパターンが図９で説明した第１〜第３のパターンのいずれであるかにより変わる。すなわち、第１のパターンの場合、以下の式（８）による基礎底から（ｈ１ ／２）までの深さに設定され、第２、第３のパターンの場合、基礎底から第１の層と第２の層の境目までの深さ（ｈｊ ＝ｈ１ −ｔ）に設定される。
【００９１】
ｈｊ ＝（ｈ１ −ｔ）／２ （８）
図８の場合、第３のパターンであるので、ｈｊ ＝ｈ１ −ｔが採用される。
【００９２】
第１１のステップＳ１１では、あらかじめ知られている建屋のベタ基礎の長辺方向の長さＬと短辺方向の長さＢとの比Ｌ／Ｂを用いて、図１２に示すあらかじめ知られている対応関係から測定点の沈下係数Ｉｓを特定する。なお、図１２に示されている沈下係数Ｉｓは、ベタ基礎の平面形状が多角形の場合であって、測定点が多角形のコーナ部に近い領域に設定される場合を示している。測定点は、コーナ部の他にベタ基礎の中心部（多角形の中心部）にも設定する必要があり、この場合の沈下係数Ｉｓは図１２に示されている値の２倍の値とすることが知られている。
【００９３】
第１２のステップでは、算出された建屋荷重ΣＷと、長さＬ及びＢと、深さｈｊ とを用いて、以下の式（９）により地中増加応力Δσｚ１（ｋＮ／ｍ^２ ）を算出する。
【００９４】
Δσｚ１＝ΣＷ×Ｂ×Ｌ／｛（Ｌ＋ｈｊ ）×（Ｂ＋ｈｊ ）｝ （９）
第１３のステップでは、算出された有効地中応力σｚ１と地中増加応力Δσｚ１とを用いて、下記の式（１０）により建屋建設後の有効地中応力σｚ２１ （ｋＮ／ｍ^２ ）を算出する。
【００９５】
σｚ２１ ＝σｚ１＋Δσｚ１ （１０）
第１４のステップでは、第１層の層厚ｈ１ と深さｔとを用いて、以下の式（１１）により圧密層の層厚Ｈｊを算出する。
【００９６】
Ｈｊ＝ｈ１ −ｔ （１１）
第１５のステップでは、前記ポアソン比νと、算出された弾性係数Ｅ１と、建屋荷重ΣＷと、長さＢと、特定された沈下係数Ｉｓとから、下記の式（１２）により即時沈下量Ｓｉ１ （ｃｍ）を算出する。
【００９７】
Ｓｉ１ ＝｛ΣＷ×Ｂ×（１−ν^２ ）×Ｉｓ｝×１００／Ｅ１ （１２）
第１６のステップでは、算出された圧密降伏応力Ｐｙ１ と、算出された体積圧縮係数ｍｖ１と、算出された有効地中応力σｚ２１ と、算出された圧密層の層厚Ｈｊとを用いて、下記の式（１３）により圧密沈下量Ｓｃ１ （ｃｍ）を算出する。
【００９８】
Ｓｃ１ ＝｛ｍｖ１×（σｚ２１ −Ｐｙ１ ）×Ｈｊ｝×１００ （１３）
第１７のステップでは、算出された即時沈下量Ｓｉ１ と圧密沈下量Ｓｃ１ に対し、特性曲線の変動パターンに応じて少なくとも一方を採用して第１層の沈下量Ｓ１を得る。
【００９９】
ここで、特性曲線の変動パターンというのは、図８で説明したように、地盤が複数の層から成る場合に、レイリー波平均速度が深さに応じて大きく変動する層を示すパターンと、深さが変わってもレイリー波平均速度の変動の割合がほぼ一定である層を示すパターンがあることを意味している。そして、図８の第１層のように、レイリー波平均速度が深さによって大きく変動するパターンの場合には、均質でない造成地盤層や砂層であることから、建屋を建てることで地盤が沈下するので、即時沈下量Ｓｉ１ を採用する。一方、深さが変わってもレイリー波平均速度の変動の割合がほぼ一定であるパターンの場合には、均質である粘土層のような層であることから、即時沈下量よりむしろ圧密沈下量Ｓｃ１ を採用すべきである。勿論、これは原則であり、層の土質によっては即時沈下量Ｓｉ１ と圧密沈下量Ｓｃ１ の両方を加算して採用する場合もある。
【０１００】
また、上記の各式では、レイリー波速度Ｖｒを用いているが、これまではＳ波速度Ｖｓが用いられている。これに対し、本発明者は、レイリー波速度ＶｒとＳ波速度Ｖｓとの間には、Ｖｒ＝ａ・Ｖｓ（ａは係数）の関係があり、係数ａの値は０．８〜０．９９の値が好ましいことを確認している（特許第３０５２２２４号）。そこで、本形態では、レイリー波速度ＶｒとＳ波速度Ｖｓとが実質上等しいものとして、Ｓ波速度Ｖｓに代えてレイリー波速度Ｖｒを用いている。これは、後述する第２層以降の計算でも同じである。
【０１０１】
次に、第２層以降の即時沈下量、圧密沈下量の計算方法を、第２層（ｋ＝２）の場合について説明する。
【０１０２】
第２１のステップでは、第２層に関して求められたレイリー波速度Ｖｒ２ を用いて、以下の式（２１）により一軸圧縮応力度ｑｕ２（ｋＮ／ｍ^２ ）を算出する。
【０１０３】

第ｋ層について言えば、ｑｕｋ＝１０^{｛（ｌｏｇＶｒｋ −２．１２７）／０．４４３｝} ×１０×９．８となる。
【０１０４】
第２２のステップでは、レイリー波速度Ｖｒ２ を用いて、以下の式（２２）により圧密降伏応力Ｐｙ２ （ｋＮ／ｍ^２ ）を算出する。
【０１０５】

第ｋ層について言えば、Ｐｙｋ ＝１０^{｛（ｌｏｇＶｒｋ −１．９９８）／０．５１｝}×１０×９．８となる。
【０１０６】
第２３のステップでは、算出された一軸圧縮応力度ｑｕ２を用いて、下記の式（２３）により土の粘着力Ｃ２を算出する。
【０１０７】
Ｃ２＝ｑｕ２／２ （２３）
第ｋ層について言えば、Ｃｋ＝ｑｕｋ／２となる。
【０１０８】
第２４のステップでは、図１１に示されたレイリー波速度Ｖｒと土質との対応関係表から土の単位体積重量γｔ２を特定する。
【０１０９】
第２５のステップでは、特定された単位体積重量γｔ２とレイリー波速度Ｖｒ２ とを用いて、以下の式（２４）により剛性率Ｇ２を算出する。
【０１１０】
Ｇ２＝γｔ２×Ｖｒ２ ^２ ／９．８ （２４）
第ｋ層について言えば、Ｇｋ＝γｔｋ×Ｖｒｋ ^２ ／９．８となる。
【０１１１】
第２６のステップでは、算出された粘着力Ｃ２を用いて、以下の式（２５）により体積圧縮係数ｍｖ２を算出する。
【０１１２】
ｍｖ２＝１／（８０×Ｃ２） （２５）
第ｋ層について言えば、ｍｖｋ＝１／（８０×Ｃｋ）となる。
【０１１３】
第２７のステップでは、算出された剛性率Ｇ２とあらかじめ知られている地盤のポアソン比νとを用いて、以下の式（２６）により地盤の弾性係数Ｅ２（ｋＮ／ｍ^２ ）を算出する。
【０１１４】
Ｅ２＝２×Ｇ２×（１＋ν） （２６）
第ｋ層について言えば、
Ｅｋ＝２×Ｇｋ×（１＋ν）となる。
【０１１５】
なお、第２層の弾性係数Ｅ２は、Ｅ２＝１／ｍｖ２で、第ｋ層の弾性係数Ｅｋは、Ｅｋ＝１／ｍｖｋで算出されても良い。
【０１１６】
第２８のステップでは、第１層の層厚ｈ１ と、特定された単位体積重量γｔ１と、第２層の層厚ｈ２ （第１層と第２層の境目から第２層と第３層の境目までの深さ）（ｍ）と、特定された単位体積重量γｔ２とから、以下の式（２７）により建屋建設前の有効地中応力σｚ２を算出する。
【０１１７】
σｚ２＝γｔ１×ｈ１ ＋γｔ２×（ｈ２ ／２） （２７）
なお、第３層（ｋ＝３）の場合には、その層厚をｈ３ 、単位体積重量をγｔ３とすると、σｚ３＝γｔ１×ｈ１ ＋γｔ２×ｈ２ ＋γｔ３（ｈ３ ／２）で表され、従って第ｋ層の場合には、σｚｋ＝γｔ１×ｈ１ ＋γｔ２×ｈ２ ＋…＋γｔｋ（ｈｋ ／２）となることは言うまでも無い。
【０１１８】
第２９のステップでは、第１層の層厚Ｈｊと、第２層の層厚ｈ２ とを用いて、建屋の基礎底から沈下量を算出されるべき位置までの深さｈｓ２（ｍ）を決定する。
【０１１９】
この深さｈｓ２の決定も、第２層の特性曲線のパターンに応じて決められる。すなわち、第１のパターンの場合、以下の式（２８）で表される第２層の中間部分になるように決定される。
【０１２０】
ｈｓ２＝Ｈｊ＋（ｈ２ ／２） （２８）
勿論、第３層の場合には、ｈｓ３＝Ｈｊ＋ｈ２ ＋（ｈ３ ／２）で表され、第ｋ層の場合には、ｈｓｋ＝Ｈｊ＋ｈ２ ＋…＋（ｈｋ ／２）となる。
【０１２１】
一方、第２、第３のパターンの場合、基礎底から第２層と第３層の境目までの深さ（ｈｓ２＝Ｈｊ＋ｈ２ ）になるように決定される。第３層の場合には、ｈｓ３＝Ｈｊ＋ｈ２ ＋ｈ３ となり、第ｋ層の場合には、ｈｓｋ＝Ｈｊ＋ｈ２ ＋…＋ｈｋ となる。図２０の場合、第３のパターンであるので、（２８）式ではない方の式が用いられる。
【０１２２】
第３０のステップでは、建屋荷重ΣＷと長さＬ及びＢと深さｈｓ２とを用いて、以下の式（２９）により地中増加応力Δσｚ２（ｋＮ／ｍ^２ ）を算出する。
【０１２３】
Δσｚ２＝ΣＷ×Ｂ×Ｌ／｛（Ｌ＋ｈｓ２）×（Ｂ＋ｈｓ２）｝ （２９）
第ｋ層の場合、Δσｚｋ＝ΣＷ×Ｂ×Ｌ／｛（Ｌ＋ｈｓｋ）×（Ｂ＋ｈｓｋ）｝となる。
【０１２４】
第３１のステップでは、算出された有効地中応力σｚ２と地中増加応力Δσｚ２とを用いて、下記の式（３０）により建屋建設後の有効地中応力σｚ２２ （ｋＮ／ｍ^２ ）を算出する。
【０１２５】
σｚ２２ ＝σｚ２＋Δσｚ２ （３０）
第ｋ層の場合、σｚ２ｋ ＝σｚｋ＋Δσｚｋとなる。
【０１２６】
第３２のステップでは、第２層の層厚ｈ２ を圧密層の層厚Ｈｓ２とする。
【０１２７】
第３３のステップでは、前記ポアソン比νと、算出された弾性係数Ｅ２と、建屋荷重ΣＷと、長さＢと、特定された沈下係数Ｉｓとから、下記の式（３１）により即時沈下量Ｓｉ２ （ｃｍ）を算出する。
【０１２８】
Ｓｉ２ ＝｛ΣＷ×Ｂ×（１−ν^２ ）×Ｉｓ｝×１００／Ｅ２ （３１）
第ｋ層の場合、Ｓｉｋ ＝｛ΣＷ×Ｂ×（１−ν^２ ）×Ｉｓ｝×１００／Ｅｋとなる。
【０１２９】
第３４のステップでは、算出された圧密降伏応力Ｐｙ２ と、算出された体積圧縮係数ｍｖ２と、算出された有効地中応力σｚ２２ と、算出された圧密層の層厚Ｈｓ２とを用いて、下記の式（３２）により圧密沈下量Ｓｃ２ （ｃｍ）を算出する。
【０１３０】
Ｓｃ２ ＝｛ｍｖ２×（σｚ２２ −Ｐｙ２ ）×Ｈｓ２｝×１００ （３２）
勿論、第ｋ層の場合、Ｓｃｋ ＝｛ｍｖｋ×（σｚ２ｋ −Ｐｙｋ ）×Ｈｓｋ｝×１００となる。
【０１３１】
第３５のステップでは、算出された即時沈下量Ｓｉ２ と圧密沈下量Ｓｃ２ に対し、特性曲線の変動パターンに応じて少なくとも一方を採用して第１層の沈下量Ｓｊ２ を得る。通常、第２層以降では、自然地盤であることが多いので圧密沈下量が採用される。
【０１３２】
図１３は、レイリー波平均速度ＭＶｒと深さＨの実測値を示す。この測定は、図１４に示されるような五角形の平面形状のベタ基礎の場合について、そのコーナ部に近い領域に測定点Ｎｏ．１〜Ｎｏ．５（中央部は省略）を設定して行われたものである。
【０１３３】
図１５は、図１３の実測値に対して行われた第１層〜第４層の即時沈下量の計算結果と、上記の各式における諸元の値とを示している。例えば、諸元の値のうち、Ｈ０ ＝０．１、ΣＷ＝１．５、Ｌ／Ｂ＝１．０、Ｉｓ＝０．５６、土質は普通土、ポアソン比ν＝０．４５である。
【０１３４】
図１６は、図１３の実測値に対して行われた第１層〜第４層の圧密沈下量の計算結果と、上記の各式における諸元の値とを示している。
【０１３５】
図１７は、図１５の即時沈下量、図１６の圧密沈下量から各層の沈下量を決定した総括結果を示す。ここでは、第１層については即時沈下量のみを採用し、第２層〜第４層については圧密沈下量のみを採用している。Ｎｏ．１〜Ｎｏ．５の沈下量（ｃｍ）はそれぞれ、１．２、１１．８、１．３、５．１、０．４という結果が得られている。
【０１３６】
なお、上記の実測値を使用した計算では、第１層〜第４層のすべてを普通土として図１１における土の単位体積重量を特定しているが、単位体積重量は層毎に土質を判定し、判定した土質に基づいて図１１から各層の単位体積重量を特定するのが好ましい。このような土質の判定は、各層の深さがわかっているので、ボーリングにより各層毎に土をサンプリングして行うことができる。
【０１３７】
ここで、図１３のＮｏ．１及びＮｏ．５の第１層の場合について、図９において説明した特性曲線の傾きパターン別のレイリー波速度の計算例を説明する。
【０１３８】
Ｎｏ．１の第１層は、右傾斜の第１のパターンであるので、二乗法とエネルギー法とを用いる。
【０１３９】
二乗法の場合、Ｖｒ１ ＝｛［１．３４×（８０）^２ −０．１０×（８０）^２ ］／（１．３４ −０．１０） ｝^１／２ ＝８０．０
エネルギー法の場合、Ｖｒ１ ＝（１．３４ ×８０−０．１０×８０） ／（１．３４ −０．１０） ｝＝８０．０
両者の値が等しく、かつ第１層の測定値８０（ｍ／ｓｅｃ）とも等しいので、ここでは第１層のレイリー波速度として２乗法による計算値である８０（ｍ／ｓｅｃ）を採用（図１５のＮｏ．１の表面波速度Ｖｒ１ の項参照）している。
【０１４０】
Ｎｏ．５の第１層は、左傾斜の第３のパターンであるので、時間法と二乗法とを用いる。
【０１４１】
時間法の場合、
Ｔ０ ＝０．１／７５＝０．００１
Ｔ１ ＝１．３２／６５＝０．０２
Ｖｒ１ ＝（１．３２ −０．１）／（０．０２ −０．００１）＝６４．３
二乗法の場合、Ｖｒ１ ＝｛［１．３２×（６５）^２ −０．１０×（７５）^２ ］／（１．３２−０．１０） ｝^１／２ ＝６４．１
両者の値がほぼ等しいので、ここでは第１層のレイリー波速度として時間法による計算値である６４（ｍ／ｓｅｃ）を採用（図１５のＮｏ．５の表面波速度Ｖｒ１ の項参照）している。
【０１４２】
図１８は、参考のために、図１３のＮｏ．１〜Ｎｏ．５の測定点のそれぞれにおける第１層〜第４層について、二乗法、エネルギー法あるいは時間法によりレイリー波速度を計算した結果を示す。
【０１４３】
以上、本発明者により提案されている測定方法及び装置の一例を順をおって説明したが、上記の各種の計算はパーソナルコンピュータのような装置を使用して自動的に計算できることは言うまでも無い。すなわち、パーソナルコンピュータは、レイリー波速度、土の単位体積重量、ポアソン比等のデータ入力用のキーボード、入力されたデータを使用して演算を行う演算装置、演算結果表示用のディスプレイ、演算結果出力用のプリンタ等を備えている。特に、演算装置においては、上記の手順毎に計算式を導入したソフトウエアプログラムを用意することにより、自動計算が可能となる。また、表計算ソフトウエアを利用し、図１５〜図１７に示されるような表を作成しておいて、これらの表の必要箇所にデータを入力することで自動計算を行うこともできる。その一例として、本出願人により 「地盤探査装置及びそれに使用される解析プログラム」が提案（特願２００１−１５１９６１号）されている。勿論、特性曲線の傾きパターン、変動パターンの別に応じて計算式を変える必要があるが、これは、これらのパターンの種別に応じた計算式を設定しておき、どのパターンを採用するのかをユーザに選択入力させるようにすれば良い。あるいはまた、特性曲線の傾きパターン、変動パターンの別を自動判別するプログラムを用意しておいて、どのパターンを採用するのかについても自動的に選択させるようにすることもできる。
【０１４４】
いずれにしても、上記の測定方法により、図１７に示すような測定結果が得られた場合、図１の第１ステップにおける予想最大沈下量は、最も大きい値である１１．８ｃｍが採用される。一方、沈下による傾斜というのは、例えば図１４のＮｏ．１〜Ｎｏ５において、図１７に示されたように、Ｎｏ．１（＝１．２ｃｍ）、Ｎｏ．２（＝１１．８ｃｍ）、Ｎｏ．３（＝１．３ｃｍ）、Ｎｏ．４（＝５．１ｃｍ）、Ｎｏ５（＝０．４ｃｍ）である場合、例えばＮｏ．１とＮｏ．２との間の沈下による傾斜は、（１１．８−１．２）／１０００＝１０．６／１０００として算出される。そして、図１の第２ステップにおける判定に際しては、Ｎｏ．１〜Ｎｏ５の間における傾斜の最大値、図１７で言えば、１０．６／１０００が採用される。
【０１４５】
次に、図１の第１ステップにおける地盤の支持力度を測定する方法について説明する。この測定方法も、本発明者により提案されている（前記特許第３０５２２２４号）。つまり、前述した測定装置を用い、測定対象地盤上におけるレイリー波速度Ｖｒを測定し、このレイリー波速度Ｖｒと係数ａを用いてＳ波速度ＶｓをＶｒ＝ａ・Ｖｓとする。係数ａの値は前述したように、０．８〜０．９９である。そして、Ｓ波速度Ｖｓにより地盤の一軸圧縮強度ｑ_ｕ１を以下の式を用いて求める。
【０１４６】
Ｖｓ＝１３４ｑ_ｕ１ ^{０．４４３}
続いて、ベタ基礎底面下の地盤の粘着力Ｃ１を前述した式（３）、つまりＣ１＝ｑ_ｕ１／２により求める。
【０１４７】
更に、粘着力Ｃ１を用いて以下の式により地盤の支持力度ｑａを算出する。
【０１４８】
ｑａ＝（α・Ｃ１・Ｎｃ＋β・γ_ｔ１・Ｂ・Ｎｒ）／３
但し、上記式においてα、βはベタ基礎の形状係数、Ｎｃ、Ｎｒは支持力係数、γ_ｔ１はベタ基礎の下にある土の単位体積重量、Ｂはベタ基礎の最小幅、つまり短辺方向の長さである。
【０１４９】
次に、改良体４０の幅Ｘ、間隔Ｙ、深さＺの決定方法について説明する。図１の第２−３ステップＳ２−３、第２−４ステップＳ２−４、第２−５ステップＳ２−５、第２−６ステップＳ２−６において肯定の場合に、地盤中に改良体４０が造成されることは前述した通りである。
【０１５０】
図１９を参照して、間隔Ｙの決定方法について説明する。図４で説明したような改良体４０を造成するものと想定した場合、改良体４０において互いに対向し合う壁の間隔、いわゆる接地幅Ｂａを決定する際にはコグラー（Ｋｏｇｌｅｒ）の理論が良く利用される。つまり、コグラーの理論は、帯状荷重を受ける地盤内王力が、ある閉合した領域内で直線的な分布を示す場合に良く利用され、以下の式で表される。
【０１５１】
ｑ´＝（ｑ×Ｂａ）／（２×Ｚ）＜ｑａ
但し、ｑ´は地中応力（ｋＮ／ｍ^２ ）、ｑは接地圧（ｋＮ／ｍ^２ ）、ｑａは地盤の支持力度（ｋＮ／ｍ^２ ）である。
【０１５２】
上記式より、以下の不等式が導かれる。
【０１５３】
ｑ＜（２×Ｚ×ｑａ）／Ｂａ
Ｂ＜（２×Ｚ×ｑａ）／ｑ
ここで、Ｘ＝０．４５ｍ、ｑ＝１４ｋＮ／ｍ^２ 、ｑａ＝１５ｋＮ／ｍ^２ 、Ｚ＝０．７ｍとすると、
Ｂａ＝（２×０．７×１５）／１４＝１．５ｍ
Ｙ＝１．５＋０．４５＝１．９５（約２．０ｍ）
Ｘ＝０．４５ｍ、ｑ＝１４ｋＮ／ｍ^２ 、ｑａ＝１５ｋＮ／ｍ^２ 、Ｚ＝１．２ｍとすると、
Ｂａ＝（２×１．２×１５）／１４＝２．６ｍ
Ｙ＝２．６＋０．４５＝３．０５（約３．０ｍ）
Ｘ＝０．４５ｍ、ｑ＝１４ｋＮ／ｍ^２ 、ｑａ＝１５ｋＮ／ｍ^２ 、Ｚ＝１．７ｍとすると、
Ｂａ＝（２×１．７×１５）／１４＝３．６ｍ
Ｙ＝３．６＋０．４５＝４．０５（約４．０ｍ）
上記のように、改良体４０の幅Ｘ、深さＺが決まると、それに応じて間隔Ｙが算出される。つまり、幅Ｘ＝０．４５ｍ、深さＺ＝０．７ｍの場合、間隔Ｙ＝２．０ｍとされ、幅Ｘ＝０．４５ｍ、深さＺ＝１．２ｍの場合、間隔Ｙ＝３．０ｍとされ、幅Ｘ＝０．４５ｍ、深さＺ＝１．７ｍの場合、間隔Ｙ＝４．０ｍとされる。そして、上記の計算に基づいて改良体４０の幅Ｘ＝０．４５ｍとした場合の、改良体４０の壁の間隔Ｙと深さＺとの関係を図２０に示す。図１のフローチャートでは、例えば第２−３ステップＳ２−３において肯定、つまり連続壁４５工法の場合、改良体４０の壁の間隔Ｙと深さＺとの関係を３種類示している。しかし、これは説明をわかり易くするためであり、好ましい組み合わせではあるが、改良体４０の幅Ｘをある値を設定してしまえば、改良体４０の壁の間隔Ｙと深さＺとの関係は図２０に示すような特性に基づいて任意に設定されて良いことを意味する。
【０１５４】
次に、図２１を参照して、改良体４０の幅Ｘの決定方法について説明する。以下では、建物の重量と安定処理工の重量との合計重量を荷重（ここでは６０ｋＮ／ｍ^２ ）としてその下部地盤に起こり得る円弧すべりを考え、改良体４０のせん断抵抗力と幅の関係から改良体４０を構成する幅Ｘについて検討する。なお、安定処理工というのは、図１９で言えば、ベタ基礎３０の底壁に対応する部分のことであり、安定処理工の荷重はベタ基礎全体の重量である。また、円弧すべりの計算については、例えば「わかり易い土木講座６土木学会編集『土質工学』箭内寛治、浅川美利共著、彰国社発行、２１９頁〜２２５頁」に詳しく述べられているので、ここでは詳細な説明は省略する。
【０１５５】
１）せん断力Ｓの算出
最小安全率の円弧すべりを用いて、安全率１．２０となる抵抗力Ｐｒを算出し、その抵抗力Ｐｒに対抗する土圧Ｐによるせん断力Ｓを算出する。
【０１５６】
最小安全率の円弧すべりを改良体４０に当てはめると、図２１のようになる。図２１において、円弧すべりの部分を底辺長Ｌ_Ｓ １の第１のスライス部と、底辺長Ｌ_Ｓ ２の第２のスライス部とに分ける。第１のスライス部の重量をＷ_Ｓ １、底面の水平角をθ１とし、第２のスライス部の重量をＷ_Ｓ ２、底面の水平角をθ２とすると、円弧すべりにおける安全率Ｆｓは以下の式で求められる。
【０１５７】
Ｆｓ＝｛Σ（Ｃ・Ｌ_Ｓ ＋Ｗ_Ｓ ・ｃｏｓθ・ｔａｎφ）＋Ｐｒ｝／ΣＷ_Ｓ ・ｓｉｎθ
但し、Ｃは地盤を構成している土の粘着力（ｋＮ／ｍ^２ ）であり、例えば粘土では３ｋＮ／ｍ^２ 前後、砂では０ｋＮ／ｍ^２ である。一方、φは土の内部摩擦角であり、例えば砂では１０〜３０°、粘土では０°である。
【０１５８】
図２１における諸元は図２２の通りであるとする。
【０１５９】
図２２の数値と粘着力Ｃとして１．８ｋＮ／ｍ^２ 、内部摩擦角φ＝０°を上記式に代入し、安全率Ｆｓを１．２として抵抗力Ｐｒを逆算すると以下のようになる。
【０１６０】
Ｆｓ＝（１．８×１．５＋６９．２８×０＋Ｐｒ）／４５．２５＝１．２０
Ｐｒ＝１．２０×４５．２５−１．８×１．５＝５１．６０ｋＮ／ｍ^２
ここで、Ｐｒ＝Ｐであるので、土圧Ｐを水平成分Ｐ_Ｈ 、垂直成分Ｐ_Ｖ に分けると、δ＝（２／３）φ＝０°であるので、
Ｐ_Ｈ ＝Ｐ・ｃｏｓθ＝５１．６０・ｃｏｓ０°＝５１．６０ｋＮ／ｍ^２
Ｐ_Ｖ ＝Ｐ・ｓｉｎθ＝５１．６０・ｓｉｎ０°＝０ｋＮ／ｍ^２
なお、δは改良体に及ぼす力の水平からの角度である。
【０１６１】
上記の値によりせん断力を決定する。改良体の壁にかかるせん断力Ｓは土圧Ｐによる水平力であるので、せん断力Ｓは、Ｓ＝Ｐ_Ｈ ＝５１．６０ｋＮ／ｍ^２ となる。
【０１６２】
２）改良体４０の壁の幅Ｘの検討
改良体４０の壁のせん断力Ｓに対する抵抗力は、土の粘着力Ｃより求められるせん断応力度Ｓａである。せん断応力度Ｓａは粘着力Ｃに壁の幅Ｘを乗じた式で表せるので、前述のせん断力Ｓとの検討により、最小の幅Ｘを算出する。
【０１６３】
粘着力Ｃは安定処理工の一軸圧縮強度管理値ｑｕ ＝３．０ｋｇｆ／ｃｍ^２ より、
Ｃ＝（１／２）・ｑｕ ＝１．５０ｋｇｆ／ｃｍ^２ ＝１４７ｋＮ／ｍ^２
となる。
【０１６４】
せん断応力度Ｓａは、壁の幅Ｘにより、
Ｓａ＝Ｃ×Ｘ＝１４７×Ｘ（ｋＮ／ｍ）
となる。
【０１６５】
ここで、安全率Ｆｓ＝１．２であるので、
Ｆｓ＝Ｓａ／Ｓ＝（１４７×Ｘ）／５１．６０＝１．２
ゆえに、幅Ｘは、
Ｘ＝（１．２×５１．６０）／１４７＝０．４２１（ｍ）
となる。よって、最小壁幅Ｘを０．４５ｍとする。
【０１６６】
以上のような幅Ｘ、間隔Ｙ、深さＺの決定方法は、特に図１の連続４５工法に適している。
【０１６７】
次に、図１の連続（４５〜１００）工法に適した幅Ｘ、間隔Ｙ、深さＺの決定方法について説明する。（４５〜１００）というのは、幅Ｘとして０．４５〜１．０ｍの範囲が設定されることを意味するが、これは一例であり、幅Ｘが必ず０．４５〜１．０ｍの範囲内に制限されなければならないということではない。
【０１６８】
ここでも、建物の重量と安定処理工の重量との合計重量を荷重（ここでは６５ｋＮ／ｍ^２ ）としてその下部地盤に起こり得る円弧すべりを考え、改良体４０のせん断抵抗力と幅の関係から改良体４０を構成する幅Ｘについて検討する。なお、ここでは改良体４０の深さを３．４５ｍとする。
【０１６９】
１）せん断力Ｓの算出
最小安全率の円弧すべりを用いて、安全率１．２０となる抵抗力Ｐｒを算出し、その抵抗力Ｐｒに対抗する土圧Ｐによるせん断力Ｓを算出する。
【０１７０】
最小安全率の円弧すべりを改良体４０に当てはめると、図２３のようになる。図２３において、ここでは円弧すべりの部分が底辺長Ｌ_Ｓ １の第１のスライス部と、底辺長Ｌ_Ｓ ２の第２のスライス部と、底辺長Ｌ_Ｓ ３の第３のスライス部とに分けられる。第１のスライス部の重量をＷ_Ｓ １、底面の水平角をθ１、第２のスライス部の重量をＷ_Ｓ ２、底面の水平角をθ２、第３のスライス部の重量をＷ_Ｓ ３、底面の水平角をθ３とすると、円弧すべりにおける安全率Ｆｓは、前にも述べたように以下の式で求められる。
【０１７１】
Ｆｓ＝｛Σ（Ｃ・Ｌ_Ｓ ＋Ｗ_Ｓ ・ｃｏｓθ・ｔａｎφ）＋Ｐｒ｝／ΣＷ_Ｓ ・ｓｉｎθ
図２３における諸元は図２４の通りであるとする。
【０１７２】
図２４の数値と粘着力Ｃとして３．４３ｋＮ／ｍ^２ 、内部摩擦角φ＝０°を上記式に代入し、安全率Ｆｓを１．２として抵抗力Ｐｒを逆算すると以下のようになる。
【０１７３】
Ｆｓ＝（３．４３×３．１８＋１６．７０×０＋Ｐｒ）／１０．８０＝１．２０
Ｐｒ＝１．２０×１０．８０−３．４３×３．１８＝１１６．１３ｋＮ／ｍ^２
ここで、Ｐｒ＝Ｐであるので、土圧Ｐを水平成分Ｐ_Ｈ 、垂直成分Ｐ_Ｖ に分けると、δ＝（２／３）φ＝０°であるので、
Ｐ_Ｈ ＝Ｐ・ｃｏｓθ＝１１６．１３・ｃｏｓ０°＝１１６．１３ｋＮ／ｍ^２ Ｐ_Ｖ ＝Ｐ・ｓｉｎθ＝１１６．１３・ｓｉｎ０°＝０ｋＮ／ｍ^２
上記の値によりせん断力を決定する。改良体の壁にかかるせん断力Ｓは土圧Ｐによる水平力であるので、せん断力Ｓは、Ｓ＝Ｐ_Ｈ ＝１１６．１３ｋＮ／ｍ^２ となる。
【０１７４】
２）改良体４０の壁の幅Ｘの検討
改良体４０の壁のせん断力Ｓに対する抵抗力は、土の粘着力Ｃより求められるせん断応力度Ｓａである。せん断応力度Ｓａは粘着力Ｃに壁の幅Ｘを乗じた式で表せるので、前述のせん断力Ｓとの検討により、最小の幅Ｘを算出する。
【０１７５】
粘着力Ｃは安定処理工の一軸圧縮強度管理値ｑｕ ＝３．０ｋｇｆ／ｃｍ^２ より、
Ｃ＝（１／２）・ｑｕ ＝１．５０ｋｇｆ／ｃｍ^２ ＝１４７ｋＮ／ｍ^２
となる。
【０１７６】
せん断応力度Ｓａは、壁の幅Ｘにより、
Ｓａ＝Ｃ×Ｘ＝１４７×Ｘ（ｋＮ／ｍ）
となる。
【０１７７】
ここで、安全率Ｆｓ＝１．２であるので、
Ｆｓ＝Ｓａ／Ｓ＝（１４７×Ｘ）／１１６．１３＝１．２
ゆえに、幅Ｘは、
Ｘ＝（１．２×１１６．１３）／１４７＝０．９４８（ｍ）
となる。よって、最小壁幅Ｘを１．０ｍとする。
【０１７８】
このようにして、幅Ｘを決めたら、深さＺ＝３．４５ｍとして、前述したコグラーの理論を利用した算出方法により、間隔Ｙを算出すれば良い。なお、深さＺは前述した地盤調査の結果に基づいて決められるものであるので３．４５ｍ以外の値をとる場合もあり、この値に応じて間隔Ｙが変化する。
【０１７９】
次に、図２５を参照して、連続壁４５工法の設計手順について説明する。図２５において、ステップＳ１１では改良体４０の改良深さＺが決定される。改良深さＺは、Ｚ＝（掘削深度−根切深度）（ｍ）で表される。ステップＳ１２では可改良体４０の間隔Ｙの決定が行われる。つまり、前述したように、深さＺ＝０．７ｍの場合は間隔Ｙは２．０ｍ（ステップＳ１３）、深さＺ＝１．２ｍの場合は間隔Ｙは３．０ｍ（ステップＳ１４）、深さＺ＝１．２ｍの場合は間隔Ｙは３．０ｍ（ステップＳ１５）とされる。
【０１８０】
続いて、ステップＳ１６では、改良体４０の施工延長量（ｍ）の算出、つまり施工図の作成が行われると共に、以下の式に基づいて改良対象土量の算出が行われる。
【０１８１】
改良対象土量（ｍ^３ ）＝幅Ｘ（＝０．４５）×深さＺ×施工延長量
ステップＳ１７では、ソイルセメントを造る際のセメント系固化材の添加量が決定される。具体的には、建屋を構築すべき地盤内の５ポイントについて水素イオン濃度（ｐＨ）を測定し、得られた水素イオン濃度に基づいて添加量を決定する。特に、強酸性土壌においては、セメント系固化材添加量の割増しの他に、混和材添加の検討を実施する。
【０１８２】
ステップＳ１８においては、ステップＳ１７の決定に基づいてセメント系固化材の数量を以下の式により算出する。
【０１８３】
固化材数量（ｋｇ）＝改良対象土量×セメント添加量（ｋｇ／ｍ^３ ）
図２６を参照して、連続壁（４５〜１００）工法の設計手順について説明する。ステップＳ２１では、改良体４０の深さＺの検討が行われる。つまり、図７で説明した測定装置を用いて行われた地盤調査の結果に基づいて深さＺが決められる。併せて、円弧すべり計算の検討が行われる。
【０１８４】
ステップＳ２２では、改良体４０の幅Ｘの検討が行われ、その結果に基づいてステップＳ２３において間隔Ｙが算出される。以降のステップＳ２４〜Ｓ２６は、図２５で説明したステップＳ１６〜Ｓ１８とまったく同じである。
【０１８５】
図２７には、上記の連続４５工法あるいは連続（４５〜１００）工法による改良体４０の施工例を示す。
【０１８６】
図２８は、本発明による建屋用基礎構造の他の実施の形態を示す。この実施の形態においても、地盤上に形成されるベタ基礎３０と改良体４０とは相互に拘束し合わないようにされるが、ベタ基礎３０に面している改良体４０の上端部であって最も外側となる改良体４０の上端部の複数箇所に、必要に応じて第１の空間部を形成することのできる補強コンクリートブロック（第１の部材）４１が着脱自在に設けられている。この補強コンクリートブロック４１は、万一、地盤に圧密沈下等による沈下が生じた場合に、これを取り外して沈下修正のためのジャッキアップ用の空間として利用するためのものである。
【０１８７】
この補強コンクリートブロック４１の設置個数は、ベタ基礎３０の重量と建屋の重量との合計重量による荷重と、ジャッキアップ用のジャッキの能力とを考慮して決められる。そして、改良体４０の外側だけでは設置個数が不十分である場合には、図２９に示すように、最も外側となる改良体４０の上端部に設けられた複数（ここでは８個）の補強コンクリートブロック４１に加えて、内側の改良体４０の上端部にも少なくとも１箇所（ここでは４箇所）に、必要に応じて第２の空間部を形成することのできる補強コンクリートブロック（第２の部材）４２が着脱自在に設けられる。この場合、補強コンクリートブロック４２の設置領域に対応するベタ基礎３０の底壁部分には、補強コンクリートブロック４２の取出し及び後述するジャッキアップ作業用の開口３０ａが形成される。
【０１８８】
いずれにしても、補強コンクリートブロック４１、４２は常時存在するものであり、これらが存在することによって改良体４０の機械的強度が低下することを防止するために、改良体４０と同等以上の機械的強度を持つ材料で造られれば良く、材料は限定されない。また、第１、第２の空間部は、ジャッキアップ作業を行うという観点から改良体４０の外側面に面した開口である必要がある。
【０１８９】
沈下修正のためのジャッキアップ作業は、図３０に示されるように、補強コンクリートブロック４１（及び４２）を取り外し、そこにできる第１の空間部（及び第２の空間部）の底部及び天井部に鋼板４３を介在させてジャッキ４４を置く。そして、沈下量に相当する分だけジャッキ４３でベタ基礎４３を嵩上げし、嵩上げにより生じたベタ基礎４３の底面と改良体４０の上端部との隙間に詰め物を充填することにより沈下の修正が行われる。このような補修作業が終了したら、第１の空間部（及び第２の空間部）には再び補強コンクリートブロック４１（及び４２）が充填される。
【０１９０】
なお、ジャッキアップに際して改良体４０に作用する荷重を考慮して、改良体保護のために改良体４０には、図２８に示されるように、補強コンクリートブロック４１、４２よりも下側となる、地盤面から所定深さ（例えば４０ｃｍ）の部分に板状あるいは格子状の連続繊維補強材４６を介在させるのが好ましい。
【０１９１】
図３１を参照して、第２の実施の形態の変形例を説明する。この変形例では、図２９に示された複数の補強コンクリートブロック４１、４２のすべてあるいは何個かを常設とせずに空間部のままとし、この空間部にそれぞれ、減震装置７０を設けるようにしたものである。減震装置７０は、ベタ基礎３０の底面側に固定されるスライダー７１と、第１の空間部（あるいは第２の空間部）の底面側に固定されるアンダースライドプレート７２とから成る。この減震装置７０は、地盤が所定の震度以上で揺れた場合には、スライダー７１がアンダースライドプレート７２の上で滑ることにより、ベタ基礎３０からの上の建屋部分の揺れを減少させる、つまり減震作用をするように機能する。
【０１９２】
図３２において、スライダー７１は、金属材料によるアッパープレート７１−１とスライド体７１−２とから成る。アッパープレート７１−１は、その下面側に球面状の凹部７１−１ａを有し、スライド体７１−２はこの凹部７１−１ａに嵌合する凸部を有する。スライド体７１−２における凸部と反対側の面はアンダースライドプレート７２の接する面であり、滑りを良くするために四フッ化エチレンのような滑り材が圧着されている。
【０１９３】
図３３において、アンダースライドプレート７２は、金属板によるプレート体７２−１とその下側に積層された減震緩衝ゴム板７２−２とから成る。
【０１９４】
なお、スライダー７１とアンダースライドプレート７２の位置関係は上下逆にして配置されても良い。
【０１９５】
この変形例においても、万一、地盤沈下による沈下が一定値以上を越えた場合には、減震装置７０を取り外し、これによりできる第１、第２の空間部を利用して第２の実施の形態と同様の沈下に対する補修を行うことができる。そして、補修が終了したら、再び減震装置７０を装着すれば良い。
【０１９６】
なお、上述したいずれの実施の形態においても、ベタ基礎３０は改良体４０との間で相互に拘束し合わないようにされているので、地震等による大きな揺れが発生した場合にはベタ基礎３０が改良体４０に対してずれることがある。この場合には、ベタ基礎３０に対して油圧装置等によりずれを元に戻す作業が行われる。あるいはまた、ベタ基礎３０と地盤との間にダンパ機構のようなものを設置することにより、ずれを発生させないようにすることもできる。
【０１９７】
図３４は、寒冷地、つまり地盤中に凍結の生じることが想定される地域に適した基礎構造を示す。寒冷地においては、地盤中に改良体のような基礎を形成する場合、地域別にその最小の深さＺがあらかじめ決められている場合がある。この最小の深さＺは凍結深度と呼ばれている。
【０１９８】
このような地域においては、はじめに凍結深度として要求されている深さＺを決めたうえで、前述した計算法を用いて幅Ｘ及び間隔Ｙを決める。また、改良体４０の材料としてはコンクリートが要求されることが多いが、軽量コンクリートやソイルセメントでも良い。
【０１９９】
図３５は、幅Ｘ＝０．４５ｍで、深さＺが０．７ｍ（図ａ）、１．２ｍ（図ｂ）１．７ｍ（図ｃ）の場合の基礎構造を示している。特に、ここでは補強コンクリートブロック４１、４２を設けるために、連続繊維補強材４６を介在させている。図３５（ａ）のように深さ０．７ｍの改良体４０を構築する場合、地盤に改良体４０を形成するための溝を掘る。次に、溝の底部においてタンピングランマー等の転圧機械により転圧を施して深さ０．７ｍの溝とする。そして、掘削により生じた土にセメント系固化材を所定量添加して混合撹拌し、ソイルセメントとして溝内に充填する。続いて、再び転圧機械により転圧を施して厚さ０．３ｍの改良体４０の第１の層を形成し、その上に連続繊維補強材４６を敷設する。そして、この上から再び上記のソイルセメントを充填し、第１、第２の空間部ができるようにした上で転圧を施して厚さ０．４ｍの改良体４０の第２の層を形成する。以上のようにして改良体４０が形成されたら、改良体４０の上部における壁の間に切込砕石による層４５を形成する。この後、これらの上にベタ基礎３０が形成される。
【０２００】
次に、図３５（ｂ）のように深さ１．２ｍの改良体４０を構築する場合、地盤に改良体４０を形成するための溝を掘る。次に、溝の底部においてタンピングランマー等の転圧機械により転圧を施して深さ１．２ｍの溝とする。そして、掘削により生じた土にセメント系固化材を所定量添加して混合撹拌し、ソイルセメントとして溝内に充填する。続いて、再び転圧機械により転圧を施して厚さ０．５ｍの改良体４０の第１の層を形成する。この上に、更に上記のソイルセメントを充填し、転圧機械により転圧を施して厚さ０．３ｍの改良体４０の第２の層を形成し、その上に連続繊維補強材４６を敷設する。そして、この上から再び上記のソイルセメントを充填し、第１、第２の空間部ができるようにした上で転圧を施して厚さ０．４ｍの改良体４０の第３の層を形成する。以上のようにして改良体４０が形成されたら、改良体４０の上部における壁の間に切込砕石による層４５を形成する。この後、これらの上にベタ基礎３０が形成される。
【０２０１】
更に、図３５（ｃ）のように深さ１．７ｍの改良体４０を構築する場合、地盤に改良体４０を形成するための深さ１．７ｍの溝を掘る。そして、掘削により生じた土にセメント系固化材を所定量添加して混合撹拌し、ソイルセメントとして溝内に充填する。続いて、転圧機械により転圧を施して厚さ０．５ｍの改良体４０の第１の層を形成する。この上に、更に上記のソイルセメントを充填し、転圧機械により転圧を施して厚さ０．５ｍの改良体４０の第２の層を形成する。この上に、更に上記のソイルセメントを充填し、転圧機械により転圧を施して厚さ０．３ｍの改良体４０の第３の層を形成し、その上に連続繊維補強材４６を敷設する。そして、この上から再び上記のソイルセメントを充填し、第１、第２の空間部ができるようにした上で転圧を施して厚さ０．４ｍの改良体４０の第４の層を形成する。以上のようにして改良体４０が形成されたら、改良体４０の上部における壁の間に切込砕石による層４５を形成する。この後、これらの上にベタ基礎３０が形成される。
【０２０２】
図３５（ｃ）において、はじめに地盤に形成した溝の底部に転圧を施さないのは、以下の理由による。つまり、タンピングランマー等の転圧機械は人が溝内で操作するものであり、溝の深さが１．７ｍ以上あると、万一、溝の壁が崩落した場合に埋まってしまうおそれがあるからである。
【０２０３】
なお、図３５においては、開口３０ａに対応する領域に切込砕石による層４５が存在するが、補強コンクリートブロック４２を外して必要な作業を行う場合には、開口３０ａに対応する層４５は掘り起こされる。
【０２０４】
以上、本発明を幾つかの実施の形態をあげて説明したが、本発明は上記の実施の形態に制限されるものではない。例えば、改良体４０の上に構築される基礎としてベタ基礎をあげたが、これに限定されるものではない。また、説明をわかり易くするために、ベタ基礎の平面形状を正方形に近い形状で示しているが、ベタ基礎の形状は建屋の平面形状に応じて決められるものであり、正方形に近い形状とは限らない。例えば、図３６に示すように、ベタ基礎３０が長方形のような形状にされる場合もある。このような場合には、改良体４０は複数に区画している各領域が正方形に近い形状であることが好ましいので、一部がベタ基礎３０からはみ出すように形成されるのが好ましい。更に、図３７に示すように、ベタ基礎３０の底壁部分が四角形状であってもその上の布基礎部分の全体形状がかぎ形形状にされる場合もある。この場合にも、改良体４０はベタ基礎３０の底壁部分の形状に合わせて複数に区画している各領域が正方形に近い形状になるように形成される。更に言えば、図３７のようにベタ基礎の上の布基礎部分の全体形状がかぎ形形状である場合、建屋の荷重をも考慮した場合の重心位置が偏ることがあり、このような場合には、ベタ基礎３０の底壁部分も重心の偏りを考慮して、図３７に示すような形状にならないこともある。この場合であっても、改良体４０はベタ基礎３０の底壁部分の形状に合わせて複数に区画している各領域が正方形に近い形状になるように形成されるのが好ましい。
【０２０５】
図３８は、図３１に示された変形例の更に別の例を示した図である。この例では、ベタ基礎３０の下面と改良体４０の上端面との間の複数箇所に防災基礎構造８０を介在させている。防災基礎構造８０の設置箇所は、図２９に示された補強コンクリートブロック４１、４２とは別の位置とする。この防災基礎構造８０は、ベタ基礎３０の下面と改良体４０の上端面の互いに対向する部分にそれぞれ所定大の鋼板あるいは樹脂製の板材８１、８２を固定してなる。板材８１、８２の対向面には四フッ化エチレン樹脂等の滑り材が圧着されている。板材８１、８２は以下のようにして取付けされる。図２９に示された補強コンクリートブロック４１、４２を除いてできる第１、第２の空間部を図３０で説明したジャッキアップ用の空間として利用し、ジャッキアップによりできるベタ基礎３０の下面と改良体４０の上端面との間の隙間を利用して、板材８１、８２を固定する。板材８１、８２の固定作業が終了したら、ジャッキをダウンして第１、第２の空間部から取り外し、第１、第２の空間部には再び補強コンクリートブロック４１、４２を装着する。
【０２０６】
この防災基礎構造８０は、板材８１、８２の表面に塗布された滑り材の摩擦係数を越える揺れの地震が発生した際に板材８１、８２が滑り合うことで揺れを軽減して建屋を保護する。摩擦係数について言えば、図３１に示したものは約０．０７前後であるのに対し、図３８のものは０．１１〜０．１５程度とすることができる。これは、図３８の防災基礎構造８０は、図３１のものに比べて地震によるより大きな揺れが発生した時に減震装置として作用するものとすることができることを意味する。
【０２０７】
【発明の効果】
以上説明してきたように、本発明によれば、万一、地盤沈下に起因した基礎の沈下が生じてしまった場合には、これを補修するための対処策を容易に講じることができる。
【０２０８】
また、基礎を構築すべき地盤に補強用の基礎構造が必要であるか否かを含めて、補強用の基礎構造が必要である場合には幅、深さ、間隔に関してどの程度の補強用の基礎を構築すれば良いかという条件を適切な値で提供できるので、補強用の基礎を構築する際の材料費を抑えることができる。
【０２０９】
更に、沈下に対する対処に加えて、補強用の基礎を含む建屋用基礎構造に免震あるいは減震機能を持たせることができる。
【図面の簡単な説明】
【図１】本発明による建屋用基礎構造の設計方法の設計手順を示したフローチャート図である。
【図２】図１の設計手順における判定結果に基づいて構築される布基礎の例を示した図である。
【図３】図１の設計手順における判定結果に基づいて構築されるベタ基礎の例を示した図である。
【図４】図１の設計手順における判定結果に基づいて構築される本発明による基礎構造の一例を示した図である。
【図５】図１の設計手順における判定結果に基づいて構築される基礎杭の例を示した図である。
【図６】図１の設計手順における判定結果に基づいて構築される浮基礎の例を示した図である。
【図７】本発明において地盤沈下量の計算を行う場合に適用される測定システムの構成を示した図である。
【図８】図７の測定システムにおいて得られるレイリー波平均速度と深さの関係を示す特性曲線の一例を示した図である。
【図９】図７の測定システムにおいて得られる特性曲線における層毎の傾きパターンの例を示した図である。
【図１０】図７の測定システムにおいて測定対象となったベタ基礎とその地盤の関係を示した図である。
【図１１】図７の測定システムにおいて使用される土の単位体積重量を特定するための土質とレイリー波速度の関係を示した図である。
【図１２】図７の測定システムにおいて使用される沈下係数と基礎のサイズとの関係を示した図である。
【図１３】図７の測定システムにおいて得られたレイリー波平均速度と深さの関係を示す特性曲線を５つの測定点について実績値に基づいて示した図である。
【図１４】図１３の特性曲線を得るためにベタ基礎に設定された５つの測定点を示した図である。
【図１５】図１３の特性曲線を使用して層毎に即時沈下量を計算するために使用された諸元及び即時沈下量を示した図である。
【図１６】図１３の特性曲線を使用して層毎に圧密沈下量を計算するために使用された諸元及び圧密沈下量を示した図である。
【図１７】図１５の即時沈下量及び図１６の圧密沈下量を用いて層毎の沈下量を得ることを説明するための図である。
【図１８】図１３の特性曲線を使用して層毎にレイリー波速度を計算した結果を示した図である。
【図１９】本発明により補強用の基礎として形成される第１の例の改良体の幅Ｘを決定する方法を説明するための図である。
【図２０】図１９の幅Ｘの決定に際して利用される、改良体の間隔Ｙと深さＺとの関係を示した図である。
【図２１】図１９の幅Ｘを決定するために利用される円弧すべりについて説明するための図である。
【図２２】図２１に示された諸元の数値例を示した図である。
【図２３】本発明により補強用の基礎として形成される第２の例の改良体の幅Ｘを決定する方法を説明するための図である。
【図２４】図２３に示された諸元の数値例を示した図である。
【図２５】本発明により補強用の基礎として形成される第１の例の改良体の形成作業の流れを説明するためのフローチャート図である。
【図２６】本発明により補強用の基礎として形成される第２の例の改良体の形成作業の流れを説明するためのフローチャート図である。
【図２７】本発明により構築された第１の例の改良体を含む基礎構造を部分的に示した図である。
【図２８】本発明の第２の実施の形態として構築された基礎構造を部分的に示した図である。
【図２９】図２８の基礎構造の全体を示した平面図である。
【図３０】図２８の基礎構造を利用して行われるジャッキアップ作業を説明するための図である。
【図３１】図２８の形態の変形例として減震装置を組合わせた基礎構造を部分的に示した図である。
【図３２】図３１の減震装置を構成するスライダーを説明するための図である。
【図３３】図３１の減震装置を構成するアンダースライドプレートを説明するための図である。
【図３４】本発明が寒冷地に適用される場合の基礎構造の例を部分的に示した図である。
【図３５】本発明により形成される改良体の実際の形成工程の流れを、３つの例について説明するための図である。
【図３６】本発明による基礎構造の他の変形例を説明するための平面図である。
【図３７】本発明による基礎構造の更に他の変形例を説明するための平面図である。
【図３８】図３１に示された例の更に別の例を部分的に示した図である。
【符号の説明】
１ 演算装置
２ 地震計
３ 起振信号器
４ 振動発生機
５ 第１受信機
６ 第２受信機
２０ 布基礎
３０ ベタ基礎
４０ 改良体
４１、４２ 補強コンクリートブロック
４３ 鋼板
４４ ジャッキ
４５ 切込砕石による層
４６ 連続繊維補強材
５１ 基礎杭
６１ 浮基礎
７０ 減震装置
７１ スライダー
７２ アンダースライドプレート[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a building foundation structure and a design method thereof, and more particularly to a building foundation structure suitable for a building such as a detached house and a design method thereof.
[0002]
[Prior art]
When a building such as a detached house is constructed, usually, a foundation structure based on a so-called cloth foundation or solid foundation is first formed on the ground. In normal natural ground, unless a very hard ground such as a bedrock is established, it is inevitable that a subsidence of about several centimeters will occur as a building is built over the years. If the amount of settlement is the same in any part of the ground area supporting the building load, so-called equal settlement, settlement of about 3 cm is allowable.
[0003]
However, the ground has almost no continuation of the same soil layer over several tens of meters from the surface, and often includes a plurality of layers even when viewed at a depth of about 10 m from the ground surface. In such a case, there is a case where so-called differential settlement is caused even if the settlement amount is different even if the size is about the foundation for a building such as a detached house. Uneven settlement causes distortion of the building above it and eventually causes damage to the building, so that measures must be taken to prevent uneven settlement.
[0004]
From the above viewpoint, when the ground to be constructed is soft, a foundation structure for reinforcement is formed in the ground in addition to the cloth foundation and the solid foundation. To briefly explain one example, the following basic structure has been proposed.
[0005]
In the ground that forms the foundation of the building, trenches for stabilizing materials whose width and depth are adjusted according to the strength of the ground are dug, and soil trenches mixed with soil cement mixed with reinforcing fibers and rolled into these trenches. Press to produce improved wall-like stabilizers. Next, after forming a small groove on the upper surface of the stabilizer and providing a reinforcing bar for ribs, the reinforcing member is bound to a solid basic reinforcing bar. Further, concrete is poured into the small groove and the solid foundation, and the rib formed by the small groove and the solid foundation are integrated. In particular, when viewed as a plan view, the stabilizer is formed in a substantially lattice shape in the ground area forming the foundation of the building (for example, Patent Document 1).
[0006]
[Patent Document 1]
JP-A-8-232273 (page 3, FIG. 1)
[0007]
[Problems to be solved by the invention]
In the case of the above-mentioned reinforced foundation structure, if the amount of settlement increases over a long period of time and it exceeds a certain range, it is not possible to take measures to repair it .
[0008]
In addition, although the above-mentioned reinforcing foundation structure exerts its effect to some extent on soft ground, it is not clear how to increase the depth and thickness of the stabilizer, so there is sufficient margin. Since both the depth and the thickness must be relatively large, there is a problem in that the material cost for forming the stabilizer increases.
[0009]
On the other hand, in recent detached houses, seismic isolation or seismic reduction structures have been adopted for the foundations thereof in order to reduce shaking due to earthquakes. Generally speaking, when a seismic isolation or seismic reduction structure is adopted, a detached house, including the foundation on the ground, is allowed to swing freely with respect to the ground if it is shaken by an earthquake of a certain seismic intensity or higher. There is a need to.
[0010]
However, the above-mentioned reinforced foundation structure has a problem that the above-described seismic isolation or seismic reduction structure cannot be adopted because the solid foundation portion and the wall-shaped stabilizer portion are integrated by the rib. is there.
[0011]
Therefore, a main problem of the present invention is to provide a foundation structure for a building that can easily take a countermeasure for repairing a settlement in the event that the settlement occurs.
[0012]
Another object of the present invention is to provide a building foundation structure capable of imparting a seismic isolation or seismic reduction function to a building foundation structure including a reinforcement foundation in addition to coping with settlement.
[0013]
Yet another object of the present invention is to provide an understanding of the extent to which a reinforcement foundation structure is required, including whether or not the ground on which the foundation is to be constructed requires a reinforcement foundation structure. It is an object of the present invention to provide a design method of a building foundation structure capable of providing a condition of whether to construct a foundation with an appropriate value.
[0014]
[Means for Solving the Problems]
The method for designing a foundation structure for a building according to the present invention performs a predetermined measurement on the ground on which a foundation for a building is to be constructed, and improves the foundation into the ground in addition to the foundation on the ground according to the measurement result. It is determined whether a structure is to be constructed, and if it is determined that an improved foundation structure is to be constructed in the ground, the depth is set so as to partition the ground into a plurality of areas in the ground where the improved foundation structure is to be constructed. An improved body having a Z, a width X, and an interval Y is formed in a lattice shape, and a foundation on the ground is formed on the improved body so that the ground and the improved body are not mutually restrained. And
[0015]
In the present design method, the determination as to whether or not to construct the improved foundation structure is based on the fact that the ground on which the foundation is to be constructed is a plurality of types of ground support strengths set in advance for each of a plurality of types of predetermined ground depths. A first step of determining which of the following, and a second step of determining which of the plurality of types of expected settlement amount and inclination due to settlement the ground on which the foundation is to be constructed Wherein the depth Z, the width X, and the interval Y of the improved body are selected according to the determination results of the first step and the second step.
[0016]
Note that the second step is performed according to the determination result of the first step.
[0017]
In the present design method, the first step may be such that the supporting force at a depth of 0.5 m or less is 30 kN / m.²If the result of the determination in the 1-1 step is negative, the supporting force at a depth of 1 m or less is 20 kN / m.²Step 1-2 for judging whether or not the above is true, and if the result of the step 1-2 is negative, the supporting force at a depth of 2 m or more is 15 kN / m.²1-3 step of determining whether or not the above is true.
[0018]
On the other hand, when the second step is affirmative in the 1-1 step, the 2-1 step of determining whether the expected settlement amount is less than 3 cm and the inclination due to the settlement is less than 3/1000, If the affirmative determination in the 1-2 step or the negative determination in the 2-1 step, a 2-2 step of determining whether the expected squat amount is less than 5 cm and the inclination due to the squat is less than 3/1000, If the determination in step -2 is negative, step 2-3 of determining whether the expected settlement amount is less than 7 cm and the inclination due to the settlement is less than 3/1000.
[0019]
The second step may further include a second-4 step of determining whether the inclination is less than 6/1000 due to settlement of the ground on which the foundation is to be built, if the result of the second-3 step is negative. If the result of the determination in the step 1-3 is affirmative, the step 2-5 for determining whether the expected amount of settlement is less than 7 cm and the inclination due to the settlement is less than 3/1000, and the step 1-3 is negative. Alternatively, when the result of the step 2-5 is negative, the method may include a step 2-6 of judging whether the inclination is less than 6/1000 due to the settlement of the ground on which the foundation is to be built.
[0020]
More specifically, in the present design method, when the result of the step 2-1 is affirmative, it is determined that the improved foundation structure is unnecessary and that only the cloth foundation is formed as the foundation on the ground. .
[0021]
If the result of the step 2-2 is affirmative, it is determined that the improved foundation structure is unnecessary and that only a solid foundation is formed as the foundation on the ground.
[0022]
Furthermore, when the result of the step 2-3 is affirmative, it is determined that the improved foundation structure is necessary, and the improved body has a depth Z = 0.7 m, a width X = 0.45 m, and a space Y = 2. 2.0 m, or a depth Z = 1.2 m, a width X = 0.45 m, an interval Y = 3.0 m, or a depth Z = 1.7 m, a width X = 0.45 m, an interval Y = 4.0 m is determined to be formed.
[0023]
Further, if the result of the step 2-4 is affirmative, it is determined that the improved basic structure is necessary, and the improved body has a width X = 0.45 to 1.0 m and is determined in advance. It is determined that an improved body of the depth Z and the interval Y calculated by the calculated method is formed.
[0024]
On the other hand, if the result of the step 2-4 is negative, it is determined that the improved foundation structure is necessary, and it is determined that a foundation pile or a floating foundation is formed as the improved body.
[0025]
Further, if the result of the step 2-5 is affirmative, it is determined that the improved basic structure is necessary, and the improved body has a depth Z = 0.7 m, a width X = 0.45 m, and a space Y = 2. 2.0 m, or a depth Z = 1.2 m, a width X = 0.45 m, an interval Y = 3.0 m, or a depth Z = 1.7 m, a width X = 0.45 m, an interval Y = 4.0 m is determined to be formed.
[0026]
Further, when the result in the step 2-6 is affirmative, it is determined that the improved basic structure is necessary, and the improved body has a width X = 0.45 to 1.0 m and is determined in advance. It is determined that an improved body of the depth Z and the interval Y calculated by the calculated method is formed.
[0027]
On the other hand, if the result of the step 2-6 is negative, it is determined that the improved foundation structure is necessary, and it is determined that a foundation pile or a floating foundation is formed as the improved body.
[0028]
According to the present invention, there is also provided a foundation structure for a building, comprising a foundation formed on the ground on which the building is to be constructed, and an improved foundation structure formed in the ground on which the building is to be constructed. In the foundation structure for a main building, the improved foundation structure is formed by forming an improved body having a depth Z, a width X, and an interval Y in a lattice shape so as to divide the ground on which the building is to be constructed into a plurality of regions, Moreover, the improved body is characterized in that it is formed so as not to mutually restrain with the foundation formed on the ground.
[0029]
In the foundation structure for the main building, the upper end of the improved body facing the foundation formed on the ground and the upper end of the outermost improved body may be provided at a plurality of locations as necessary. A first member capable of forming a first space is detachably provided.
[0030]
Further, in addition to the upper end portion of the outermost improvement, a second member capable of forming a second space as necessary is provided at at least one position at the upper end of the inner improvement. You may be. Here, when the foundation formed on the ground is a solid foundation, an opening for work is formed in the solid foundation corresponding to the installation area of the second member.
[0031]
In the improved body, a plate-shaped or lattice-shaped continuous fiber reinforcing material is interposed at a predetermined depth from the ground surface below the first and second members to protect the improved body. Preferably.
[0032]
In the foundation structure for a main building, the improved body is formed of soil cement or concrete.
[0033]
On the other hand, it is preferable that the first and second members are made of a material having a strength equal to or higher than that of the improved body.
[0034]
Further, the improved body is preferably composed of a single layer or a plurality of layers in the depth direction, and in the case of a plurality of layers, it is preferable that rolling is applied to the upper surface of the lower layer at the boundary between the layers.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
First, an embodiment of a method of designing a building substructure according to the present invention will be described with reference to FIG. The method for designing a building foundation structure according to the present invention is executed according to the flow shown in the flowchart of FIG. 1, but before that, a predetermined measurement is performed on the ground on which the building foundation is to be constructed. . This measurement is performed in order to know the bearing capacity of the ground on which the foundation for the building is to be built, the expected amount of settlement, the inclination due to settlement, and the like, and will be described in detail later.
[0036]
Based on the above measurement results, it is determined whether to construct an improved foundation structure in the ground in addition to the foundation on the ground, and if it is determined that the improved foundation structure is to be constructed in the ground, the improvement foundation An improved body having a depth Z, a width X, and an interval Y is formed in a lattice shape so as to partition the ground into a plurality of regions in the ground on which a structure is to be constructed. The foundation on the ground is formed on the improved body. In this embodiment, the foundation on the ground is formed so that the ground and the improved body are not mutually restrained. . In other words, the foundation on the ground is formed so as to be able to slide on the improved body when shaking due to an earthquake, particularly when shaking due to an earthquake of a predetermined seismic intensity or higher occurs. Hereinafter, the improved body formed in a lattice shape may be referred to as a continuous wall.
[0037]
The improved body is formed in a lattice shape for the following reason. It is thought that the main cause of land subsidence that occurs when a building is constructed is that "consolidation subsidence" occurs in that the water contained in the soil is eliminated by the load of the building applied to the ground surface and the land subsides and sinks. I have. This "consolidation subsidence" occurs near the surface of the earth and progresses deeper. On the other hand, the improved body is intended to prevent the water which is supposed to be removed by the load by the continuous wall, so that the ground does not cause "consolidation settlement". In other words, there is no lateral flow in the portion surrounded by the continuous wall, and the thickness including the portion surrounded by the continuous wall, that is, the depth of the continuous wall is the improved depth.
[0038]
Judgment of whether or not to construct an improved foundation structure is based on which of the plurality of types of pre-established ground bearing capacity the pre-established ground has for each of the predetermined types of subsurface depth A first step of determining and a second step of determining whether the ground on which the foundation is to be built corresponds to a plurality of predetermined types of expected subsidence amounts and inclinations due to subsidence. Then, when it is determined that the improved foundation structure is to be constructed in the ground, the depth Z, the width X, and the interval Y of the improved body are selected according to the determination results of the first step and the second step. .
[0039]
Referring to FIG. 1, a specific example will be described. In the first step, a long-term supporting force at a depth of 0.5 m or less is 30 kN / m.²If the result is negative in the 1-1 step S1-1 that determines whether or not the above is true, and the 1-1 step S1-1 is negative, the supporting force at a depth of 1 m or less is 20 kN / m.²If the result of the determination in the 1-2 step S1-2 and the 1-2 step S1-2 is negative, the supporting force at a depth of 2 m or more is 15 kN / m.²A first to third step S1-3 of determining whether or not the above is included.
[0040]
On the other hand, in the second step, when the result in step 1-1 is affirmative, it is determined whether or not the expected maximum settlement amount is less than 3 cm and the inclination due to the settlement is less than 3/1000. If S2-1 is positive in the 1-2 step S1-2 or negative in the 2-1 step S2-1, is the expected maximum subsidence amount less than 5 cm and the inclination due to subsidence less than 3/1000? In the 2-2 step S2-2 for determining whether or not the result is negative in the 2-2 step S2-2, it is determined whether or not the expected maximum subsidence amount is less than 7 cm and the inclination due to subsidence is less than 3/1000. And a second to third step S2-3.
[0041]
In the present embodiment, the second step further determines whether or not the slope due to settlement of the ground on which the foundation is to be built is less than 6/1000, if the second step is negative in step S2-3. -4 step S2-4 is included.
[0042]
Further, in the present embodiment, when the second step is affirmative in the first to third steps S1-3, it is determined whether or not the expected maximum subsidence amount is less than 7 cm and the inclination due to subsidence is less than 3/1000. When the result of the determination in step S2-5 and the step 1-3 is negative in the step S1-3, or the result in step 2-5 is negative, the inclination due to the settlement of the ground on which the foundation is to be built is less than 6/1000. The method includes a second-sixth step S2-6 for determining whether or not there is any.
[0043]
If the result of the above determination is affirmative in the 2-1 step S2-1, the improved foundation structure is unnecessary, and only the cloth foundation 10 as shown in FIG. It is determined to be formed.
[0044]
In FIG. 2, as is well known, a cloth foundation 20 is formed by forming reinforced concrete walls having a predetermined width and height in a lattice shape in a ground area where a foundation is to be constructed. In the present embodiment, the cloth foundation portion included in the cloth foundation 20 and the solid foundation described below has the simplest cross-shaped shape for convenience, but this shape depends on the planar shape of the building. It can be decided, and it goes without saying that there are various shapes other than the cross-shaped.
[0045]
Subsequently, when the result is affirmative in the 2-2 step S2-2 in FIG. 1, the improved foundation structure is unnecessary, and only the solid foundation 30 as shown in FIG. 3 is formed as the foundation on the ground. judge.
[0046]
In FIG. 3, a solid foundation 30 has a predetermined width and height on a reinforced concrete bottom wall having a constant thickness formed in an area including a ground area on which the foundation is to be built, as is well known. The reinforced concrete wall is integrally formed in a lattice shape.
[0047]
Subsequently, when the result is affirmative in the 2-3 step S2-3 in FIG. 1, it is determined that the improved foundation structure is necessary, and as the improved body, the depth Z = 0.7 m, the width X = 0.45 m, An improved body with an interval Y = 2.0 m or an improved body with a depth Z = 1.2 m, a width X = 0.45 m, an interval Y = 3.0 m, or an improved body with a depth Z = 1.7 m and a width X = 0. It is determined that one of the improved bodies having a length of 45 m and an interval Y of 4.0 m is formed. Hereinafter, the improved body formed based on this determination result is referred to as a continuous wall 45 method.
[0048]
FIG. 4 shows the improved body 40 and the solid foundation 30 formed thereon. In FIG. 4, an improved body 40 is formed in the shape of a cross in the ground where the foundation is to be constructed. The improved body 40 is made of soil cement or, in some cases, concrete, and the forming method will be described later. In any case, after the improved body 40 is formed, the solid base 30 is formed thereon while the area corresponding to the upper end of the improved body 40 is covered with a sheet or the like. When the solid foundation 30 has solidified, the sheet is removed. Here, before forming the solid foundation 30, a layer 45 of cut crushed stone having a constant thickness is formed in the inner region of the improved body 40, but this may be omitted. In this manner, the improved body 40 and the solid foundation 30 are formed so as not to be mutually restrained.
[0049]
In addition, as shown in FIG. 4, the space Y is defined as the area of the improved body 40 in which the ground is divided into a plurality of (four in FIG. 4) regions by the improved body 40 and one area is formed. This is the distance between the centers of the opposing walls in the width direction. The reason and method for determining the depth Z, width X, and interval Y of the improved body 40 as described above will be described later.
[0050]
Subsequently, when the result is affirmative in the second-fourth step S2-4 in FIG. 1, it is determined that the improved foundation structure is necessary, and the width X is in the range of 0.45 to 1.0m as the improved body. , It is determined that an improved body of the depth Z and the interval Y calculated by a predetermined calculation method is formed. In this case, the shape of the improved body and the solid foundation formed thereon is basically the same as that shown in FIG. Instead of the three combinations determined in step S2-3, the combinations vary in accordance with the calculation results. This calculation method will also be described later. Hereinafter, the improved body formed based on this determination result is referred to as a continuous wall (45 to 100) method.
[0051]
Further, if the result is negative in the second-fourth step S2-4 in FIG. 1, it is determined that the improved foundation structure is necessary. In this case, it is determined that the improved body forms a foundation pile or a floating foundation. I do. In particular, whether to use a foundation pile or a floating foundation is determined by whether or not there is a support layer in the ground that satisfies predetermined conditions. Here, the supporting force is 200 kN / m at a depth of 10 m or less.²If the above support layer is present, the foundation pile is used.
[0052]
FIG. 5 shows an example of an improved body using a foundation pile. In FIG. 5, a plurality of foundation piles 51 are driven into the ground on which a foundation is to be constructed, and solid foundations 30 are formed on these foundation piles 51 so as not to be mutually restrained.
[0053]
FIG. 6 shows an example of an improved body using a floating foundation. In FIG. 6, a plurality of floating foundations 61 called frame-type foundations are formed in the ground on which the foundation is to be constructed, and the solid foundations 30 are formed on these floating foundations 61 so as not to restrict each other. As another example of a floating foundation, one made of styrofoam is known.
[0054]
Next, when the result is affirmative in the 2-5 step S2-5 in FIG. 1, it is determined that the improved foundation structure is necessary, and the improved body is formed by the continuous 45 method in the 2-3 step S2-3 described above. Is determined to be performed. That is, as an improved body, an improved body having a depth Z = 0.7 m, a width X = 0.45 m, and an interval Y = 2.0 m, or a depth Z = 1.2 m, a width X = 0.45 m, and an interval Y = Either a 3.0 m improvement or an improvement having a depth Z = 1.7 m, a width X = 0.45 m and an interval Y = 4.0 m. Of course, the depth Z, the width X, and the interval Y may be calculated by a calculation method described later.
[0055]
On the other hand, if the result in step 2-6 of FIG. 1 is affirmative, it is determined that the improved foundation structure is necessary, and the improvement by the continuous (45-100) method in step 2-4 step S2-4 described above. It is determined to form a body. That is, it is determined that an improved body having a width X of 0.45 to 1.0 m and a depth Z and an interval Y calculated by a predetermined calculation method is formed.
[0056]
Further, if the result is negative in the second 2-6 step S2-6, it is determined that the improved foundation structure is necessary. However, as the improved body, the foundation pile 51 or the floating pile 51 described in FIGS. It is determined that the foundation 61 is formed.
[0057]
Next, a description will be given of a measurement method and a measurement apparatus proposed by the inventor for measuring the settlement amount at a plurality of locations in a certain area on an arbitrary ground (Japanese Patent Application No. 2000-183290). This is a method and apparatus for measuring the expected amount of settlement and the slope due to settlement in the first step of FIG. 1 described above.
[0058]
FIG. 7 is a conceptual diagram of a Rayleigh wave velocity measuring system using a vibration generator according to the above proposal. The measurement system includes a computing unit 1, a seismograph 2, a vibration signal 3, a vibration generator 4, a first receiver 5, and a second receiver 6. In this measurement system, a vibration signal is generated and amplified by a vibration signal device 3, and a vibration generator 4 is vibrated in a vertical direction to generate a Rayleigh wave, which is one of surface waves, on the ground surface. When the time when this Rayleigh wave passes between the first receiver 5 and the second receiver 6 is T, the Rayleigh wave is calculated by the time T and the distance S between the first and second receivers 5 and 6. Can be obtained as MVr = S / T.
[0059]
Further, the Rayleigh wave average velocity can be similarly obtained by changing the excitation frequency f, and the dispersion characteristic of the Rayleigh wave in the depth direction can be obtained. Assuming that the depth is H and the wavelength of the Rayleigh wave is λ, H = λ / 2 = MVr / 2 · f. That is, most of the Rayleigh waves travel in a region of approximately one wavelength depth in the semi-infinite elastic body, and the average property in this region is considered to be approximately equal to the property at a half wavelength depth. This is because it can be done.
[0060]
FIG. 8 shows an example of a characteristic curve indicating the relationship between the average Hv of Rayleigh wave MVr and the depth H obtained by the above method. This characteristic curve shows an example in which the relationship between the average Rayleigh wave velocity MVr and the depth H is measured for the first to fifth layers with respect to the ground composed of a plurality of layers. In this characteristic curve, the depth at which the average Rayleigh wave velocity is first observed is H0 = 0.3 (m), and the average Rayleigh wave velocity MVr0 is 140 (m / sec). In this characteristic curve, the region up to the depth H1 where the average Rayleigh wave velocity varies greatly according to the depth, and the depth region where the rate of variation of the average Rayleigh wave velocity is almost constant even when the depth changes. There is. The existence of such a region where the Rayleigh wave average speed greatly fluctuates is considered to be due to the fact that there is a gap between the soil particles and the region is not homogeneous. This tendency is often seen in so-called formation ground layers, sand layers, and the like in which untouched, so-called natural ground, soil from other lands is piled up to form a new ground.
[0061]
On the other hand, the fact that the rate of fluctuation of the Rayleigh wave average velocity is almost constant means that there is no gap between particles in the soil, which means that the soil is a natural ground such as a clay layer. Thereby, the depth of the region where the Rayleigh wave average speed fluctuates greatly is identified as the depth H1, and this depth H1 (= 1.6 m) is the boundary between the first layer and the second layer below it. Is determined. The average Rayleigh wave velocity MVr1 at this depth H1 is 100 (m / sec).
[0062]
In the depth region below the depth H1, the average Rayleigh wave velocity MVr tends to increase at a substantially constant rate as the depth H increases. There is a portion where the relationship between H and the average Rayleigh wave velocity MVr becomes irregular. The existence of such irregular portions is considered to be due to the Rayleigh wave being affected at the boundary between layers. Thereby, the depths H2 (= 2.3 m), H3 (= 4.2 m), and H4 (= 7.1 m) of the irregular portions are identified, and these depths H2, H3, and H4 are respectively It is determined to be the boundary between the second layer and the third layer below, the boundary between the third layer and the fourth layer below, and the boundary between the fourth layer and the fifth layer below. The average velocities of Rayleigh waves corresponding to the depths H2, H3, and H4 are MVr2 (= 110 m / sec), MVr3 (= 125 m / sec), and MVr4 (= 140 m / sec), respectively.
[0063]
Here, an irregular portion appearing at the boundary of each layer in the characteristic curve is called an inflection point. Such inflection points in the characteristic curve can be identified without special skill.
[0064]
After measuring the boundaries and depths of the layers and the average Rayleigh wave velocity MVr for the first to fifth layers as described above, calculating the Rayleigh wave velocity Vr necessary for calculating the amount of ground subsidence for each layer And whether the calculated value and the measured Rayleigh wave average velocity MVr are appropriate or not.
[0065]
The calculation method proposed by the inventor is used for calculating the Rayleigh wave velocity Vr. In particular, there are a plurality of calculation methods, and the calculation method to be used is determined according to the inclination pattern of the characteristic curve described below for each layer.
[0066]
FIG. 9 is a diagram showing the types of tilt patterns for the first layer. The slope pattern of the characteristic curve includes a first pattern (FIG. 9a) in which the Rayleigh wave average velocity MVr increases to the right as the depth H increases, and a Rayleigh wave average velocity MVr substantially independent of the depth H. There is a second pattern that is constant (FIG. 9b) and a third pattern that slopes to the left where the average Rayleigh wave velocity MVr decreases as the depth H increases (FIG. 9c).
[0067]
There are three methods for calculating the Rayleigh wave velocity Vr: an energy method, a time method, and a square method.
[0068]
The energy method is given by the following equation:
Vr1 = (H1 × MVr1−H0 × MVr0) / (H1−H0)
Given by
[0069]
The time method is given by the following equation:
T0 = H0 / MVr0
T1 = H1 / MVr1
Vr1 = (H1-H0) / (T1-T0)
Given by
[0070]
Further, the square method is given by the following equation:
Vr1 = ｛(H1 × MVr1²−H0 × MVr0²) / (H1-H0)^1/2
Given by
[0071]
However, all of the above equations are for the first layer. In the case of the second layer, H0 is replaced by H1, H1 is replaced by H2, MVr0 is replaced by MVr1, MVr1 is replaced by MVr2, T0 is T1, T1 may be replaced with T2 for calculation. The same applies to the third and subsequent layers.
[0072]
In the case of the first pattern, the Rayleigh wave velocity is calculated using the above-mentioned square method and the energy method, and the two calculation results are compared to calculate the calculated Rayleigh wave velocity and the measured Rayleigh wave average velocity. Is determined.
[0073]
Also in the case of the second pattern, the Rayleigh wave velocity is calculated using the square method and the energy method, and the two calculation results are compared to determine whether the calculated Rayleigh wave velocity is equal to the measured Rayleigh wave average velocity. Is determined. Whether the first and second patterns are appropriate or not is determined to be appropriate if the two calculation results are close to each other, and the appropriate value is adopted from the two calculation results. The appropriate value is determined in consideration of the ground condition, and is, for example, a value on the safe side (lower value). If the values of the two calculation results are far apart, a value on the safe side, for example, a lower value is adopted in consideration of the ground condition.
[0074]
On the other hand, in the case of the third pattern, the Rayleigh wave velocity is calculated using the above-mentioned time method and the square method, and the two calculation results are compared to calculate the calculated Rayleigh wave velocity and the measured Rayleigh wave average. Judgment of speed and suitability. The determination of suitability is the same as above.
[0075]
Calculation examples using these specific numerical values will be described later.
[0076]
The inflection point in the characteristic curve is determined as described above, and each boundary of the ground layers of the first to (n + 1) th layers (n is an integer of 2 or more) is specified by the depth H, and the specified first Calculate the immediate settlement amount and consolidation settlement amount of the first layer using the layer thickness of the layer. For the layers up to the specified n-th layer excluding the first layer, use the layer thickness to settle the immediate settlement amount and consolidation settlement amount for each layer. The amount is calculated, and at least one of the immediate settlement amount and the consolidation settlement amount is adopted for each layer in accordance with the variation pattern of the characteristic curve for each layer to determine the settlement amount for each layer.
[0077]
With reference to FIG. 10 as well, a method for calculating the immediate settlement amount and the consolidation settlement amount of the first layer will be described.
[0078]
In the first step, using the Rayleigh wave velocity Vr1 determined for the first layer by the above method, the uniaxial compressive stress qu1 (kN / m²) Is calculated.
[0079]

In the second step, using the Rayleigh wave velocity Vr1, the consolidation yield stress Py1 (kN / m²) Is calculated.
[0080]

In the third step, using the calculated uniaxial compressive stress qu1, the adhesive force C1 of the soil is calculated by the following equation (3).
[0081]
C1 = qu1 / 2 (3)
In the fourth step, the unit volume weight γt1 of the soil is specified from the correspondence table between the Rayleigh wave velocity Vr and the soil known in advance. FIG. 11 shows this correspondence. In addition, this correspondence table is written by Akio Shimizu, "Survey and examination of soil and its application"
(Science & Engineering Books Publishing).
[0082]
In the fifth step, the identified unit volume weight γt1 (kN / m³) And the Rayleigh wave velocity Vr1 to calculate the rigidity G1 by the following equation (4).
[0083]
G1 = γt1 × Vr1²/9.8 (4)
In the sixth step, a volume compression coefficient mv1 is calculated by the following equation (5) using the calculated adhesive force C1.
[0084]
mv1 = 1 / (80 × C1) (5)
In the seventh step, the elastic modulus E1 (kN / m) of the ground is calculated by the following equation (6) using the calculated rigidity G1 and the previously known Poisson's ratio ν of the ground.²) Is calculated.
[0085]
E1 = 2 × G1 × (1 + ν) (6)
Note that the elastic coefficient E1 may be obtained by E1 = 1 / mv1 using the volume compression coefficient mv1.
[0086]
In the eighth step, the layer thickness h1 of the first layer (depth from the ground surface to the boundary between the first and second layers) (m), the specified unit volume weight γt1, and the ground surface The effective underground stress σz1 before the construction of the building is calculated from the depth t up to the following equation (7).
[0087]
σz1 = {t + [(h1−t) / 2]} × γt1 (7)
The depth t from the ground surface to the foundation bottom is based on the assumption that a solid foundation having a thickness t is provided as a foundation on the ground. Therefore, when the calculation is performed without the base bottom, t = 0.
[0088]
In the ninth step, the building load per unit area ΣW (kN / m²) Is calculated. This can be calculated during the building design phase.
[0089]
In the tenth step, the depth hj (m) from the foundation bottom of the building to the position where the amount of settlement should be calculated is determined using the layer thickness h1 of the first layer and the depth t.
[0090]
The determination of the depth hj changes depending on whether the inclination pattern of the characteristic curve in the first layer is any of the first to third patterns described with reference to FIG. That is, in the case of the first pattern, the depth is set from the base bottom to (h1 / 2) according to the following equation (8), and in the case of the second and third patterns, the first layer is set from the base bottom. The depth to the boundary of the second layer (hj = h1-t) is set.
[0091]
hj = (h1-t) / 2 (8)
In the case of FIG. 8, since it is the third pattern, hj = h1−t is adopted.
[0092]
In the eleventh step S11, using the ratio L / B of the length L in the long side direction and the length B in the short side direction of the solid foundation of the building, which is known in advance, as shown in FIG. The sink coefficient Is of the measurement point is specified from the corresponding relationship. The settlement coefficient Is shown in FIG. 12 indicates a case where the plane shape of the solid foundation is a polygon and the measurement point is set in a region near a corner of the polygon. It is necessary to set the measurement point not only at the corner but also at the center of the solid foundation (the center of the polygon). In this case, the squat coefficient Is is twice the value shown in FIG. It is known to
[0093]
In the twelfth step, using the calculated building load ΣW, the lengths L and B, and the depth hj, the underground increasing stress Δσz1 (kN / m²) Is calculated.
[0094]
Δσz1 = {W × B × L / {(L + hj) × (B + hj)}} (9)
In the thirteenth step, the effective ground stress σz21 (kN / m) after the building is constructed by the following equation (10) using the calculated effective ground stress σz1 and the increased ground stress Δσz1.²) Is calculated.
[0095]
σz21 = σz1 + Δσz1 (10)
In the fourteenth step, the layer thickness Hj of the consolidation layer is calculated by the following equation (11) using the layer thickness h1 of the first layer and the depth t.
[0096]
Hj = h1−t (11)
In the fifteenth step, the instantaneous settlement amount Si1 is calculated from the Poisson's ratio ν, the calculated elastic modulus E1, the building load ΔW, the length B, and the specified settlement coefficient Is by the following equation (12). (Cm) is calculated.
[0097]
Si1 = ｛ΣW × B × (1-ν²) × Is｝ × 100 / E1 (12)
In the sixteenth step, using the calculated consolidation yield stress Py1, the calculated volume compression coefficient mv1, the calculated effective underground stress σz21, and the calculated layer thickness Hj of the consolidation layer, The consolidation settlement amount Sc1 (cm) is calculated by the equation (13).
[0098]
Sc1 = {mv1 × (σz21−Py1) × Hj} × 100 (13)
In the seventeenth step, at least one of the calculated instantaneous settlement amount Si1 and the consolidation settlement amount Sc1 is adopted in accordance with the variation pattern of the characteristic curve to obtain the settlement amount S1 of the first layer.
[0099]
Here, the variation pattern of the characteristic curve is, as described with reference to FIG. 8, a pattern indicating a layer in which the average Rayleigh wave velocity varies greatly according to the depth when the ground is composed of a plurality of layers, This means that there is a pattern indicating a layer in which the rate of fluctuation of the average Rayleigh wave velocity is almost constant even if the frequency changes. In the case of a pattern in which the average Rayleigh wave velocity greatly varies depending on the depth as in the first layer in FIG. 8, the ground subsides by building a building because the ground layer and sand layer are not homogeneous. Therefore, the immediate settlement amount Si1 is adopted. On the other hand, in the case of a pattern in which the rate of fluctuation of the Rayleigh wave average velocity is substantially constant even when the depth changes, the consolidation settlement amount Sc1 rather than the immediate settlement amount because the layer is a homogeneous clay layer like a clay layer. Should be adopted. Of course, this is a principle, and depending on the soil properties of the layer, both the immediate settlement amount Si1 and the consolidation settlement amount Sc1 may be added and adopted.
[0100]
In each of the above equations, the Rayleigh wave velocity Vr is used, but the S wave velocity Vs has been used so far. On the other hand, the present inventor has found that there is a relationship of Vr = a · Vs (a is a coefficient) between the Rayleigh wave velocity Vr and the S-wave velocity Vs, and the value of the coefficient a is 0.8 to 0. It has been confirmed that a value of 99 is preferable (Japanese Patent No. 3052224). Therefore, in the present embodiment, the Rayleigh wave velocity Vr is used instead of the S wave velocity Vs, assuming that the Rayleigh wave velocity Vr is substantially equal to the S wave velocity Vs. This is the same in the calculation of the second and subsequent layers described later.
[0101]
Next, a method of calculating the immediate settlement amount and the consolidation settlement amount of the second layer and thereafter will be described for the case of the second layer (k = 2).
[0102]
In the 21st step, using the Rayleigh wave velocity Vr2 determined for the second layer, the uniaxial compressive stress qu2 (kN / m²) Is calculated.
[0103]

For the k-th layer, quk = 10^{{(LogVrk-2.127) /0.443}}× 10 × 9.8.
[0104]
In the 22nd step, using the Rayleigh wave velocity Vr2, the consolidation yield stress Py2 (kN / m²) Is calculated.
[0105]

For the k-th layer, Pyk = 10^{{(LogVrk-1.998) /0.51}}× 10 × 9.8.
[0106]
In the twenty-third step, using the calculated uniaxial compressive stress qu2, the adhesive force C2 of the soil is calculated by the following equation (23).
[0107]
C2 = qu2 / 2 (23)
As for the k-th layer, Ck = quk / 2.
[0108]
In the twenty-fourth step, the unit volume weight γt2 of the soil is specified from the correspondence table between the Rayleigh wave velocity Vr and the soil shown in FIG.
[0109]
In the twenty-fifth step, the rigidity G2 is calculated by the following equation (24) using the specified unit weight γt2 and Rayleigh wave velocity Vr2.
[0110]
G2 = γt2 × Vr2²/9.8 (24)
For the k-th layer, Gk = γtk × Vrk²/9.8.
[0111]
In a twenty-sixth step, a volume compression coefficient mv2 is calculated by the following equation (25) using the calculated adhesive strength C2.
[0112]
mv2 = 1 / (80 × C2) (25)
For the k-th layer, mvk = 1 / (80 × Ck).
[0113]
In the twenty-seventh step, using the calculated rigidity G2 and the previously known Poisson's ratio ν of the ground, the elastic modulus E2 (kN / m²) Is calculated.
[0114]
E2 = 2 × G2 × (1 + ν) (26)
As for the k-th layer,
Ek = 2 × Gk × (1 + ν).
[0115]
The elastic coefficient E2 of the second layer may be calculated as E2 = 1 / mv2, and the elastic coefficient Ek of the k-th layer may be calculated as Ek = 1 / mvk.
[0116]
In the 28th step, the layer thickness h1 of the first layer, the specified unit volume weight γt1, and the layer thickness h2 of the second layer (from the boundary between the first layer and the second layer, From the depth to the boundary) (m) and the specified unit volume weight γt2, the effective underground stress σz2 before building construction is calculated by the following equation (27).
[0117]
σz2 = γt1 × h1 + γt2 × (h2 / 2) (27)
In the case of the third layer (k = 3), assuming that the layer thickness is h3 and the unit volume weight is γt3, σz3 = γt1 × h1 + γt2 × h2 + γt3 (h3 / 2). In the case of a layer, it goes without saying that σzk = γt1 × h1 + γt2 × h2 +... + Γtk (hk / 2).
[0118]
In a twenty-ninth step, a depth hs2 (m) from the foundation bottom of the building to a position where the amount of settlement should be calculated is determined using the layer thickness Hj of the first layer and the layer thickness h2 of the second layer. I do.
[0119]
The determination of the depth hs2 is also determined according to the pattern of the characteristic curve of the second layer. That is, in the case of the first pattern, it is determined to be an intermediate portion of the second layer represented by the following equation (28).
[0120]
hs2 = Hj + (h2 / 2) (28)
Of course, in the case of the third layer, hs3 = Hj + h2 + (h3 / 2), and in the case of the k-th layer, hsk = Hj + h2 +... + (Hk / 2).
[0121]
On the other hand, in the case of the second and third patterns, the depth is determined to be the depth (hs2 = Hj + h2) from the base bottom to the boundary between the second layer and the third layer. In the case of the third layer, hs3 = Hj + h2 + h3, and in the case of the k-th layer, hsk = Hj + h2 +... + Hk. In the case of FIG. 20, since it is the third pattern, an expression other than the expression (28) is used.
[0122]
In the thirtieth step, the underground increased stress Δσz2 (kN / m²) Is calculated.
[0123]
Δσz2 = {W × B × L / {(L + hs2) × (B + hs2)}} (29)
In the case of the k-th layer, Δσzk = {W × B × L / {(L + hsk) × (B + hsk)}}.
[0124]
In a thirty-first step, the effective underground stress σz22 (kN / m) after the building is constructed using the calculated effective underground stress σz2 and the increased underground stress Δσz2 by the following equation (30).²) Is calculated.
[0125]
σz22 = σz2 + Δσz2 (30)
In the case of the k-th layer, σz2k = σzk + Δσzk.
[0126]
In the 32nd step, the layer thickness h2 of the second layer is set to the layer thickness Hs2 of the consolidation layer.
[0127]
In the thirty-third step, the instantaneous settlement amount Si2 is calculated from the Poisson's ratio ν, the calculated elastic modulus E2, the building load ΔW, the length B, and the specified settlement coefficient Is by the following equation (31). (Cm) is calculated.
[0128]
Si2 = ｛ΣW × B × (1-ν²) × Is｝ × 100 / E2 (31)
In the case of the k-th layer, Sik = ｛ΣW × B × (1-ν²) × Is｝ × 100 / Ek.
[0129]
In a thirty-fourth step, using the calculated consolidation yield stress Py2, the calculated volume compression coefficient mv2, the calculated effective underground stress σz22, and the calculated consolidation layer thickness Hs2, The consolidation settlement amount Sc2 (cm) is calculated by the equation (32).
[0130]
Sc2 = {mv2 × (σz22−Py2) × Hs2} × 100 (32)
Of course, in the case of the k-th layer, Sck = {mvk × (σz2k−Pyk) × Hsk} × 100.
[0131]
In a thirty-fifth step, at least one of the calculated instantaneous settlement amount Si2 and the consolidation settlement amount Sc2 is adopted in accordance with the variation pattern of the characteristic curve to obtain the settlement amount Sj2 of the first layer. Usually, since the second and subsequent layers are often in the natural ground, the consolidation settlement amount is adopted.
[0132]
FIG. 13 shows measured values of the average Rayleigh wave velocity MVr and the depth H. This measurement is performed on a solid foundation having a pentagonal flat shape as shown in FIG. 1 to No. 5 (the central part is omitted).
[0133]
FIG. 15 shows the calculation results of the instantaneous settlement amounts of the first to fourth layers performed on the actually measured values in FIG. 13 and the values of the specifications in each of the above equations. For example, among the values of the specifications, H0 = 0.1, ΣW = 1.5, L / B = 1.0, Is = 0.56, the soil is ordinary soil, and Poisson's ratio ν = 0.45.
[0134]
FIG. 16 shows the calculation results of the consolidation settlement amounts of the first to fourth layers performed on the actually measured values of FIG. 13 and the values of the specifications in the above equations.
[0135]
FIG. 17 shows an overall result of determining the settlement amount of each layer from the immediate settlement amount in FIG. 15 and the consolidation settlement amount in FIG. Here, only the immediate settlement amount is used for the first layer, and only the consolidation settlement amount is used for the second to fourth layers. No. 1 to No. As a result, the settlement amounts (cm) of No. 5 were 1.2, 11.8, 1.3, 5.1, and 0.4, respectively.
[0136]
In the calculation using the measured values described above, the unit volume weight of the soil in FIG. 11 is specified using all of the first to fourth layers as ordinary soil. Then, it is preferable to specify the unit volume weight of each layer from FIG. 11 based on the determined soil quality. Since the depth of each layer is known, such soil determination can be performed by sampling the soil for each layer by boring.
[0137]
Here, No. 1 in FIG. 1 and No. 1 In the case of the first layer of No. 5, a calculation example of the Rayleigh wave velocity for each inclination pattern of the characteristic curve described in FIG. 9 will be described.
[0138]
No. Since the first layer of 1 is a first pattern inclined rightward, the square method and the energy method are used.
[0139]
In the case of the square method, Vr1 = ｛[1.34 × (80)²−0.10 × (80)²] / (1.34-0.10)｝^1/2= 80.0
In the case of the energy method, Vr1 = (1.34 × 80−0.10 × 80) / (1.34−0.10)｝ = 80.0
Since both values are equal and the measured value of the first layer is equal to 80 (m / sec), 80 (m / sec), which is a value calculated by the square method, is adopted here as the Rayleigh wave velocity of the first layer (FIG. No. 15 of No. 1).
[0140]
No. Since the first layer of No. 5 is the third pattern inclined leftward, the time method and the square method are used.
[0141]
In the case of the time method,
T0 = 0.1 / 75 = 0.001
T1 = 1.32 / 65 = 0.02
Vr1 = (1.32-0.1) / (0.02-0.001) = 64.3
In the case of the square method, Vr1 = ｛[1.32 × (65)²−0.10 × (75)²] / (1.32-0.10)｝^1/2= 64.1
Since both values are substantially equal, here, 64 (m / sec) calculated by the time method is adopted as the Rayleigh wave velocity of the first layer (see the item of the surface wave velocity Vr1 of No. 5 in FIG. 15). ing.
[0142]
FIG. 18 is No. in FIG. 13 for reference. 1 to No. The results of calculating the Rayleigh wave velocity by the square method, the energy method, or the time method for the first to fourth layers at each of the five measurement points are shown.
[0143]
In the above, an example of the measuring method and the apparatus proposed by the inventor has been described in order, but it goes without saying that the above various calculations can be automatically calculated using a device such as a personal computer. There is no. In other words, the personal computer includes a keyboard for inputting data such as Rayleigh wave velocity, unit weight of soil, Poisson's ratio, etc., an arithmetic device for performing calculations using the input data, a display for displaying calculation results, and a calculation result output. Printer and the like. In particular, in the arithmetic device, automatic calculation can be performed by preparing a software program in which a calculation formula is introduced for each procedure described above. In addition, automatic calculation can be performed by creating tables as shown in FIGS. 15 to 17 using spreadsheet software and inputting data to necessary portions of these tables. As one example, the applicant has proposed a “ground exploration apparatus and an analysis program used therein” (Japanese Patent Application No. 2001-151961). Of course, it is necessary to change the calculation formula according to the slope pattern and the variation pattern of the characteristic curve, but this is done by setting the calculation formula according to the type of these patterns, and determining which pattern to use. May be selected and input. Alternatively, it is possible to prepare a program for automatically discriminating between the inclination pattern and the fluctuation pattern of the characteristic curve, and to automatically select which pattern to adopt.
[0144]
In any case, when the measurement result as shown in FIG. 17 is obtained by the above-described measurement method, the largest value of 11.8 cm, which is the largest value, is adopted as the expected maximum subsidence amount in the first step of FIG. . On the other hand, the inclination due to the settlement is, for example, No. 1 in FIG. In Nos. 1 to 5, as shown in FIG. 1 (= 1.2 cm), No. 1 No. 2 (= 11.8 cm); No. 3 (= 1.3 cm), No. 4 (= 5.1 cm) and No. 5 (= 0.4 cm), for example, 1 and No. The slope due to settlement between 2 and 1 is calculated as (11.8-1.2) /1000=10.6/1000. In the determination in the second step of FIG. The maximum value of the inclination between 1 and No. 5, 10.6 / 1000 in FIG. 17, is adopted.
[0145]
Next, a method for measuring the ground support strength in the first step of FIG. 1 will be described. This measurement method has also been proposed by the present inventors (Japanese Patent No. 3052224). That is, the Rayleigh wave velocity Vr on the ground to be measured is measured using the above-described measuring device, and the S-wave velocity Vs is set to Vr = a · Vs using the Rayleigh wave velocity Vr and the coefficient a. The value of the coefficient a is 0.8 to 0.99 as described above. Then, the uniaxial compressive strength q of the ground is obtained by the S-wave velocity Vs._u1Is calculated using the following equation.
[0146]
Vs = 134q_u1 ^0.443
Subsequently, the adhesive force C1 of the ground under the solid foundation bottom surface is calculated by the above-mentioned formula (3), that is, C1 = q_u1/ 2.
[0147]
Further, the ground supporting force qa is calculated by the following equation using the adhesive force C1.
[0148]
qa = (α · C1 · Nc + β · γ_t1・ B ・ Nr) / 3
Here, in the above equation, α and β are the shape factors of the solid foundation, Nc and Nr are the bearing force coefficients, and γ_t1Is the unit volume weight of the soil under the solid foundation, and B is the minimum width of the solid foundation, that is, the length in the short side direction.
[0149]
Next, a method of determining the width X, the interval Y, and the depth Z of the improved body 40 will be described. In the case of affirmative in the 2-3 step S2-3, the 2-4 step S2-4, the 2-5 step S2-5, and the 2-6 step S2-6 of FIG. Is created as described above.
[0150]
A method for determining the interval Y will be described with reference to FIG. Assuming that the improved body 40 as described with reference to FIG. 4 is to be formed, the Kogler theory is often used to determine the distance between the opposing walls in the improved body 40, that is, the so-called ground width Ba. Is done. In other words, Kogler's theory is often used when the in-ground force receiving a zonal load shows a linear distribution in a certain closed region, and is expressed by the following equation.
[0151]
q ′ = (q × Ba) / (2 × Z) <qa
However, q 'is the underground stress (kN / m²), Q is the ground pressure (kN / m²), Qa is the ground support force (kN / m²).
[0152]
The following inequality is derived from the above equation.
[0153]
q <(2 × Z × qa) / Ba
B <(2 × Z × qa) / q
Here, X = 0.45 m, q = 14 kN / m², Qa = 15 kN / m², Z = 0.7 m,
Ba = (2 × 0.7 × 15) /14=1.5 m
Y = 1.5 + 0.45 = 1.95 (about 2.0m)
X = 0.45m, q = 14kN / m², Qa = 15 kN / m², Z = 1.2 m,
Ba = (2 × 1.2 × 15) /14=2.6 m
Y = 2.6 + 0.45 = 3.05 (about 3.0 m)
X = 0.45m, q = 14kN / m², Qa = 15 kN / m², Z = 1.7 m,
Ba = (2 × 1.7 × 15) /14=3.6 m
Y = 3.6 + 0.45 = 4.05 (about 4.0 m)
When the width X and the depth Z of the improved body 40 are determined as described above, the interval Y is calculated accordingly. That is, when the width X is 0.45 m and the depth Z is 0.7 m, the interval Y is 2.0 m. When the width X is 0.45 m and the depth Z is 1.2 m, the interval Y is 3. In the case where the width X is 0.45 m and the depth Z is 1.7 m, the interval Y is 4.0 m. FIG. 20 shows the relationship between the wall spacing Y and the depth Z of the improved body 40 when the width X of the improved body 40 is set to 0.45 m based on the above calculation. In the flowchart of FIG. 1, for example, in the second to third steps S2-3, the result is affirmative, that is, in the case of the continuous wall 45 method, three types of relationships between the wall interval Y and the depth Z of the improved body 40 are shown. However, this is for the sake of simplicity of explanation, and although it is a preferable combination, once the width X of the improved body 40 is set to a certain value, the relationship between the interval Y and the depth Z of the wall of the improved body 40 becomes This means that it can be set arbitrarily based on the characteristics as shown in FIG.
[0154]
Next, a method of determining the width X of the improved body 40 will be described with reference to FIG. In the following, the total weight of the weight of the building and the weight of the stabilization process is defined as the load (here, 60 kN / m²), Considering a possible arc slip on the lower ground, and examining the width X constituting the improved body 40 from the relationship between the shear resistance and the width of the improved body 40. In FIG. 19, the stabilizing process means a portion corresponding to the bottom wall of the solid foundation 30, and the load of the stabilizing process is the weight of the entire solid foundation. Further, the calculation of the arc slip is described in detail in, for example, "Easy-to-understand Civil Engineering Course 6 edited by Japan Society of Civil Engineers," Geological Engineering ", Kanji Yanai and Miri Asakawa, published by Shokokusha, pp. 219-225. A detailed description will be omitted.
[0155]
1) Calculation of shear force S
Using the arc slip with the minimum safety factor, a resistance Pr that provides a safety factor of 1.20 is calculated, and a shear force S due to the earth pressure P that opposes the resistance Pr is calculated.
[0156]
FIG. 21 shows an example in which the arc slip with the minimum safety factor is applied to the improved body 40. In FIG. 21, the portion of the arc slip is the base length L_S1 first slice portion and base length L_S2 and a second slice section. The weight of the first slice is W_S1. The horizontal angle of the bottom surface is θ1, and the weight of the second slice portion is W_S2. Assuming that the horizontal angle of the bottom surface is θ2, the safety factor Fs in arc sliding can be obtained by the following equation.
[0157]
Fs = ｛Σ (CL_S+ W_S・ Cosθ ・ tanφ) + Pr｝ / ΣW_S・ Sin θ
Here, C is the adhesive force of the soil constituting the ground (kN / m²), For example, 3 kN / m for clay.²Before and after, 0kN / m in sand²It is. On the other hand, φ is the internal friction angle of the soil, for example, 10 to 30 ° for sand and 0 ° for clay.
[0158]
It is assumed that the specifications in FIG. 21 are as shown in FIG.
[0159]
The value of FIG. 22 and the adhesive force C are 1.8 kN / m.², And the internal friction angle φ = 0 ° is substituted into the above equation, and the resistance Pr is back calculated with the safety factor Fs set to 1.2.
[0160]
Fs = (1.8 × 1.5 + 69.28 × 0 + Pr) /45.25=1.20
Pr = 1.20 × 45.25-1.8 × 1.5 = 51.60 kN / m²
Here, since Pr = P, the earth pressure P is calculated as the horizontal component P_H, The vertical component P_VΔ = (2/3) φ = 0 °
P_H= P · cos θ = 51.60 · cos 0 ° = 51.60 kN / m²
P_V= P · sin θ = 51.60 · sin0 ° = 0 kN / m²
Here, δ is the angle of the force exerted on the improved body from the horizontal.
[0161]
The shear force is determined by the above values. Since the shear force S applied to the wall of the improved body is a horizontal force due to the earth pressure P, the shear force S is given by S = P_H= 51.60 kN / m²Becomes
[0162]
2) Examination of the width X of the wall of the improved body 40
The resistance to the shearing force S of the wall of the improved body 40 is the degree of shearing stress Sa obtained from the adhesive force C of the soil. Since the shear stress Sa can be expressed by an equation obtained by multiplying the adhesive strength C by the width X of the wall, the minimum width X is calculated by examining the shear force S described above.
[0163]
The adhesive strength C is a uniaxial compressive strength control value qu = 3.0 kgf / cm for a stabilizing treatment.²Than,
C = (1/2) · qu = 1.50 kgf / cm²= 147 kN / m²
Becomes
[0164]
The shear stress Sa is determined by the width X of the wall.
Sa = C × X = 147 × X (kN / m)
Becomes
[0165]
Here, since the safety factor Fs = 1.2,
Fs = Sa / S = (147 × X) /51.60=1.2
Therefore, the width X is
X = (1.2 × 51.60) /147=0.421 (m)
Becomes Therefore, the minimum wall width X is set to 0.45 m.
[0166]
The method for determining the width X, the interval Y, and the depth Z as described above is particularly suitable for the continuous 45 method shown in FIG.
[0167]
Next, a method of determining the width X, the interval Y, and the depth Z suitable for the continuous (45 to 100) method shown in FIG. 1 will be described. (45 to 100) means that a range of 0.45 to 1.0 m is set as the width X, but this is an example, and the width X is always in a range of 0.45 to 1.0 m. It does not mean that you have to be restricted within.
[0168]
Again, the total weight of the weight of the building and the weight of the stabilizing work is the load (here, 65 kN / m²), Considering a possible arc slip on the lower ground, and examining the width X constituting the improved body 40 from the relationship between the shear resistance and the width of the improved body 40. Here, the depth of the improved body 40 is set to 3.45 m.
[0169]
1) Calculation of shear force S
Using the arc slip with the minimum safety factor, a resistance Pr that provides a safety factor of 1.20 is calculated, and a shear force S due to the earth pressure P that opposes the resistance Pr is calculated.
[0170]
FIG. 23 shows the result of applying the arc slip with the minimum safety factor to the improved body 40. In FIG. 23, here, the portion of the arc slip is the base length L_S1 first slice portion and base length L_S2, the second slice portion and the base length L_S3 and a third slice section. The weight of the first slice is W_S1. The horizontal angle of the bottom surface is θ1, and the weight of the second slice is W_S2, the horizontal angle of the bottom surface is θ2, and the weight of the third slice is W_S3. Assuming that the horizontal angle of the bottom surface is θ3, the safety factor Fs in arc sliding can be obtained by the following equation as described above.
[0171]
Fs = ｛Σ (CL_S+ W_S・ Cosθ ・ tanφ) + Pr｝ / ΣW_S・ Sin θ
It is assumed that the specifications in FIG. 23 are as shown in FIG.
[0172]
24 and 3.43 kN / m as the adhesive force C², And the internal friction angle φ = 0 ° is substituted into the above equation, and the resistance Pr is back calculated with the safety factor Fs set to 1.2.
[0173]
Fs = (3.43 × 3.18 + 1.70 × 0 + Pr) /10.80=1.20
Pr = 1.20 × 10.80-3.43 × 3.18 = 116.13 kN / m²
Here, since Pr = P, the earth pressure P is calculated as the horizontal component P_H, The vertical component P_VIf δ = (2/3) φ = 0 °, then
P_H= P · cos θ = 116.13 · cos 0 ° = 116.13 kN / m²P_V= P · sin θ = 116.13 · sin0 ° = 0 kN / m²
The shear force is determined by the above values. Since the shear force S applied to the wall of the improved body is a horizontal force due to the earth pressure P, the shear force S is given by S = P_H= 116.13 kN / m²Becomes
[0174]
2) Examination of the width X of the wall of the improved body 40
The resistance to the shearing force S of the wall of the improved body 40 is the degree of shearing stress Sa obtained from the adhesive force C of the soil. Since the shear stress Sa can be expressed by an equation obtained by multiplying the adhesive strength C by the width X of the wall, the minimum width X is calculated by examining the shear force S described above.
[0175]
The adhesive strength C is a uniaxial compressive strength control value qu = 3.0 kgf / cm for a stabilizing treatment.²Than,
C = (1/2) · qu = 1.50 kgf / cm²= 147 kN / m²
Becomes
[0176]
The shear stress Sa is determined by the width X of the wall.
Sa = C × X = 147 × X (kN / m)
Becomes
[0177]
Here, since the safety factor Fs = 1.2,
Fs = Sa / S = (147 × X) /116.13=1.2
Therefore, the width X is
X = (1.2 × 116.13) /147=0.948 (m)
Becomes Therefore, the minimum wall width X is set to 1.0 m.
[0178]
After the width X is determined in this manner, the distance Y may be calculated by setting the depth Z to 3.45 m and using the above-described calculation method using the Kogler theory. Since the depth Z is determined based on the result of the above-described ground survey, the depth Z may take a value other than 3.45 m, and the interval Y changes according to the value.
[0179]
Next, the design procedure of the continuous wall 45 method will be described with reference to FIG. In FIG. 25, the improvement depth Z of the improvement body 40 is determined in step S11. The improved depth Z is represented by Z = (digging depth−root cutting depth) (m). In step S12, the interval Y of the improveable body 40 is determined. That is, as described above, when the depth Z is 0.7 m, the interval Y is 2.0 m (step S13). When the depth Z is 1.2 m, the interval Y is 3.0 m (step S14). When the length Z is 1.2 m, the interval Y is set to 3.0 m (step S15).
[0180]
Subsequently, in step S16, the construction extension amount (m) of the improved body 40 is calculated, that is, the construction drawing is created, and the soil volume to be improved is calculated based on the following equation.
[0181]
Improvement target soil volume (m³) = Width X (= 0.45) × depth Z × construction extension
In step S17, the amount of the cement-based solidifying material added when producing soil cement is determined. Specifically, the hydrogen ion concentration (pH) is measured at five points in the ground where the building is to be constructed, and the amount to be added is determined based on the obtained hydrogen ion concentration. In particular, in the case of a strongly acidic soil, the addition of the cement-based solidifying material and the study of the addition of admixtures will be studied.
[0182]
In step S18, the quantity of the cement-based solidified material is calculated by the following equation based on the determination in step S17.
[0183]
Quantity of solidified material (kg) = amount of soil to be improved x amount of added cement (kg / m³)
The design procedure of the continuous wall (45-100) method will be described with reference to FIG. In step S21, the depth Z of the improved body 40 is examined. That is, the depth Z is determined based on the result of the ground survey performed using the measuring device described with reference to FIG. At the same time, the calculation of arc slip is considered.
[0184]
In step S22, the width X of the improved body 40 is examined, and based on the result, the interval Y is calculated in step S23. The subsequent steps S24 to S26 are exactly the same as steps S16 to S18 described in FIG.
[0185]
FIG. 27 shows a construction example of the improved body 40 by the above-described continuous 45 method or the continuous (45-100) method.
[0186]
FIG. 28 shows another embodiment of the building substructure according to the present invention. Also in this embodiment, the solid foundation 30 and the improved body 40 formed on the ground are not restricted to each other, but the upper end of the improved body 40 facing the solid foundation 30. Reinforced concrete blocks (first members) 41 capable of forming a first space as necessary are detachably provided at a plurality of locations on the upper end of the outermost improvement body 40. This reinforced concrete block 41 is intended to be used as a jack-up space for settlement correction in the event that settlement occurs due to consolidation settlement or the like in the ground.
[0187]
The number of the reinforced concrete blocks 41 to be installed is determined in consideration of the load based on the total weight of the solid foundation 30 and the weight of the building and the capacity of the jack-up jack. If the number of installations is not sufficient just outside the improved body 40, as shown in FIG. 29, a plurality of (eight in this case) reinforcements provided at the upper end of the outermost improved body 40 are provided. In addition to the concrete block 41, at the upper end of the inner improvement 40, at least one (here, four) reinforced concrete block (second concrete) capable of forming a second space as required. A member 42 is detachably provided. In this case, an opening 30a for taking out the reinforcing concrete block 42 and a jack-up operation described later is formed in the bottom wall portion of the solid foundation 30 corresponding to the installation area of the reinforcing concrete block 42.
[0188]
In any case, the reinforced concrete blocks 41 and 42 are always present, and in order to prevent the mechanical strength of the improved body 40 from being reduced due to the presence thereof, a mechanical machine equal to or higher than the improved body 40 is used. What is necessary is just to be made with the material which has a target strength, and a material is not limited. Further, the first and second space portions need to be openings facing the outer side surface of the improved body 40 from the viewpoint of performing jack-up work.
[0189]
As shown in FIG. 30, the jacking-up work for settlement settlement removes the reinforced concrete block 41 (and 42), and the bottom and ceiling of the first space (and the second space) formed there. The jack 44 is placed with the steel plate 43 interposed therebetween. Then, the solid foundation 43 is raised by the jack 43 by an amount corresponding to the settlement amount, and the settlement is corrected by filling the gap between the bottom surface of the solid foundation 43 and the upper end portion of the improved body 40 caused by the raising with the padding. Is When such repair work is completed, the first space (and the second space) is filled with the reinforced concrete blocks 41 (and 42) again.
[0190]
In addition, in consideration of the load which acts on the improved body 40 at the time of jacking up, as shown in FIG. 28, the improved body 40 is located below the reinforced concrete blocks 41 and 42 for protecting the improved body. It is preferable to interpose a plate-like or lattice-like continuous fiber reinforcement 46 at a predetermined depth (for example, 40 cm) from the ground surface.
[0191]
A modification of the second embodiment will be described with reference to FIG. In this modification, all or some of the plurality of reinforced concrete blocks 41 and 42 shown in FIG. 29 are not made permanent and are left in the space, and the vibration damping device 70 is provided in each of these spaces. It was done. The vibration damping device 70 includes a slider 71 fixed to the bottom surface of the solid foundation 30 and an under slide plate 72 fixed to the bottom surface of the first space (or the second space). When the ground shakes at a predetermined seismic intensity or more, the vibration damping device 70 reduces the shaking of the building above the solid foundation 30 by sliding the slider 71 on the under slide plate 72, that is, It works to reduce vibration.
[0192]
In FIG. 32, the slider 71 includes an upper plate 71-1 and a slide body 71-2 made of a metal material. The upper plate 71-1 has a spherical concave portion 71-1a on the lower surface side, and the slide body 71-2 has a convex portion that fits into the concave portion 71-1a. The surface of the slide body 71-2 on the side opposite to the projection is the surface in contact with the under slide plate 72, and a sliding material such as ethylene tetrafluoride is press-fitted to improve the sliding.
[0193]
In FIG. 33, the under slide plate 72 includes a plate body 72-1 made of a metal plate and an anti-vibration cushion rubber plate 72-2 laminated below the plate body 72-1.
[0194]
In addition, the positional relationship between the slider 71 and the under slide plate 72 may be arranged upside down.
[0195]
Also in this modification, if the subsidence due to land subsidence exceeds a certain value or more, the seismic mitigation device 70 is removed, and the second implementation is performed using the first and second space portions formed thereby. The same repair for settlement can be performed as in the embodiment. Then, when the repair is completed, the vibration damping device 70 may be mounted again.
[0196]
In any of the above-described embodiments, the solid foundation 30 is configured so as not to be mutually restrained between the solid foundation 30 and the improved body 40. Therefore, when a large shaking due to an earthquake or the like occurs, the solid foundation 30 is not used. May be shifted with respect to the improved body 40. In this case, an operation of returning the displacement to the solid foundation 30 by a hydraulic device or the like is performed. Alternatively, the displacement can be prevented from occurring by installing a device such as a damper mechanism between the solid foundation 30 and the ground.
[0197]
FIG. 34 shows a foundation structure suitable for a cold region, that is, a region where freezing is assumed to occur in the ground. In cold regions, when forming a foundation such as an improved body in the ground, the minimum depth Z may be predetermined for each region. This minimum depth Z is called the freezing depth.
[0198]
In such an area, first, the depth Z required as the freezing depth is determined, and then the width X and the interval Y are determined using the above-described calculation method. Concrete is often required as a material for the improved body 40, but lightweight concrete or soil cement may be used.
[0199]
FIG. 35 shows the basic structure when the width X = 0.45 m and the depth Z is 0.7 m (FIG. A), 1.2 m (FIG. B), and 1.7 m (FIG. C). In particular, the continuous fiber reinforcement 46 is interposed in order to provide the reinforced concrete blocks 41 and 42 here. When constructing the improved body 40 having a depth of 0.7 m as shown in FIG. 35A, a groove for forming the improved body 40 is dug in the ground. Next, rolling is performed at the bottom of the groove by a rolling machine such as a tamping rammer to form a groove having a depth of 0.7 m. Then, a predetermined amount of cement-based solidifying material is added to the soil generated by excavation, mixed and stirred, and filled into the trench as soil cement. Subsequently, rolling is again performed by a rolling machine to form a first layer of the improved body 40 having a thickness of 0.3 m, and a continuous fiber reinforcement 46 is laid thereon. Then, the above-mentioned soil cement is filled again from above, and after the first and second spaces are formed, rolling is performed to form a second layer of the improved body 40 having a thickness of 0.4 m. I do. When the improved body 40 is formed as described above, a layer 45 made of cut crushed stones is formed between the upper walls of the improved body 40. Thereafter, the solid foundation 30 is formed on these.
[0200]
Next, when constructing the improved body 40 having a depth of 1.2 m as shown in FIG. 35B, a groove for forming the improved body 40 is dug in the ground. Next, rolling is applied to the bottom of the groove by a rolling machine such as a tamping rammer to form a groove having a depth of 1.2 m. Then, a predetermined amount of cement-based solidifying material is added to the soil generated by excavation, mixed and stirred, and filled into the trench as soil cement. Subsequently, rolling is again performed by a rolling machine to form a first layer of the improved body 40 having a thickness of 0.5 m. On top of this, the above-mentioned soil cement is further filled, and the compact is subjected to compaction by a compacting machine to form a second layer of the improved body 40 having a thickness of 0.3 m, and a continuous fiber reinforcing material 46 is laid thereon. I do. Then, the above-mentioned soil cement is filled again from above, the first and second spaces are formed, and rolling is performed to form a third layer of the improved body 40 having a thickness of 0.4 m. I do. When the improved body 40 is formed as described above, a layer 45 made of cut crushed stones is formed between the upper walls of the improved body 40. Thereafter, the solid foundation 30 is formed on these.
[0201]
Further, when constructing the improved body 40 having a depth of 1.7 m as shown in FIG. 35C, a groove having a depth of 1.7 m for forming the improved body 40 is dug in the ground. Then, a predetermined amount of cement-based solidifying material is added to the soil generated by excavation, mixed and stirred, and filled into the trench as soil cement. Subsequently, rolling is performed by a rolling machine to form a first layer of the improved body 40 having a thickness of 0.5 m. On top of this, the above-mentioned soil cement is further filled and subjected to compaction by a compacting machine to form a second layer of the improved body 40 having a thickness of 0.5 m. On top of this, the above-mentioned soil cement is further filled, and the compact is pressed by a compacting machine to form a third layer of the improved body 40 having a thickness of 0.3 m, and a continuous fiber reinforcing material 46 is laid thereon. I do. Then, the above-mentioned soil cement is filled again from above, and after forming the first and second spaces, rolling is performed to form a fourth layer of the improved body 40 having a thickness of 0.4 m. I do. When the improved body 40 is formed as described above, a layer 45 made of cut crushed stones is formed between the upper walls of the improved body 40. Thereafter, the solid foundation 30 is formed on these.
[0202]
In FIG. 35 (c), the reason why rolling is not applied to the bottom of the groove initially formed in the ground is as follows. That is, a rolling machine such as a tamping rammer is operated by a person in the groove, and if the depth of the groove is 1.7 m or more, the groove may be buried if the wall of the groove collapses. Because.
[0203]
In FIG. 35, there is a layer 45 made of cut crushed stones in a region corresponding to the opening 30a. However, when the reinforced concrete block 42 is removed and necessary work is performed, the layer 45 corresponding to the opening 30a is excavated. It is.
[0204]
As described above, the present invention has been described with reference to some embodiments, but the present invention is not limited to the above embodiments. For example, a solid foundation has been described as a foundation built on the improved body 40, but the present invention is not limited to this. In addition, for simplicity of explanation, the plane shape of the solid foundation is shown as a shape close to a square, but the shape of the solid foundation is determined according to the plane shape of the building, and is not limited to a shape close to a square. Absent. For example, as shown in FIG. 36, the solid foundation 30 may be shaped like a rectangle. In such a case, it is preferable that each of the plurality of divided regions has a shape close to a square, so that the improved body 40 is preferably formed so as to partially protrude from the solid foundation 30. Further, as shown in FIG. 37, even when the bottom wall portion of the solid foundation 30 has a square shape, the overall shape of the cloth foundation portion thereabove may be in a hook shape. Also in this case, the improved body 40 is formed so that each area divided into a plurality of shapes according to the shape of the bottom wall portion of the solid foundation 30 has a shape close to a square. Furthermore, if the overall shape of the cloth foundation on the solid foundation is a hook shape as shown in FIG. 37, the position of the center of gravity in consideration of the load of the building may be biased. In some cases, the bottom wall portion of the solid foundation 30 may not be shaped as shown in FIG. 37 in consideration of the deviation of the center of gravity. Even in this case, it is preferable that the improved body 40 is formed so that each of the plurality of divided regions has a shape close to a square according to the shape of the bottom wall portion of the solid foundation 30.
[0205]
FIG. 38 is a diagram showing still another example of the modification shown in FIG. In this example, the disaster prevention basic structure 80 is interposed at a plurality of locations between the lower surface of the solid foundation 30 and the upper end surface of the improved body 40. The installation location of the disaster prevention basic structure 80 is different from the reinforced concrete blocks 41 and 42 shown in FIG. The disaster prevention basic structure 80 is formed by fixing steel plates 81 and 82 of a predetermined size to a lower surface of the solid foundation 30 and an upper end surface of the improved body 40, respectively, at opposing portions. A sliding material such as tetrafluoroethylene resin is pressure-bonded to the facing surfaces of the plate members 81 and 82. The plate members 81 and 82 are attached as follows. The first and second spaces formed by removing the reinforced concrete blocks 41 and 42 shown in FIG. 29 are used as the space for jacking-up described with reference to FIG. 30, and the lower surface of the solid foundation 30 formed by jacking-up is improved. The plate members 81 and 82 are fixed by utilizing a gap between the upper end surface of the body 40 and the upper surface. When the work of fixing the plate members 81 and 82 is completed, the jack is lowered and removed from the first and second spaces, and the reinforced concrete blocks 41 and 42 are mounted in the first and second spaces again.
[0206]
This disaster prevention basic structure 80 protects the building by reducing the shaking by sliding the plate members 81 and 82 when a shaking earthquake exceeding the friction coefficient of the sliding material applied to the surfaces of the plate members 81 and 82 occurs. . Speaking of the coefficient of friction, the one shown in FIG. 31 is about 0.07, while the one shown in FIG. 38 can be about 0.11 to 0.15. This means that the disaster prevention basic structure 80 of FIG. 38 can act as a vibration damping device when a greater shaking due to an earthquake occurs than that of FIG.
[0207]
【The invention's effect】
As described above, according to the present invention, if the foundation subsidence occurs due to the land subsidence, a countermeasure for repairing the subsidence can be easily taken.
[0208]
In addition, if a foundation structure for reinforcement is required, including whether the foundation on which the foundation is to be constructed requires a foundation structure for reinforcement, how much width, depth, and spacing are required for reinforcement Since it is possible to provide the condition of whether to construct the foundation with an appropriate value, it is possible to suppress the material cost when constructing the foundation for reinforcement.
[0209]
Further, in addition to dealing with the settlement, the building foundation structure including the reinforcement foundation can be provided with a seismic isolation or seismic reduction function.
[Brief description of the drawings]
FIG. 1 is a flowchart showing a design procedure of a method for designing a building substructure according to the present invention.
FIG. 2 is a diagram illustrating an example of a cloth foundation constructed based on a determination result in the design procedure of FIG. 1;
FIG. 3 is a diagram showing an example of a solid foundation constructed based on a determination result in the design procedure of FIG. 1;
FIG. 4 is a diagram showing an example of a basic structure according to the present invention constructed based on a determination result in the design procedure of FIG. 1;
5 is a diagram showing an example of a foundation pile constructed based on a determination result in the design procedure of FIG.
FIG. 6 is a diagram illustrating an example of a floating foundation constructed based on a determination result in the design procedure of FIG. 1;
FIG. 7 is a diagram showing a configuration of a measurement system applied when calculating the amount of land subsidence in the present invention.
8 is a diagram illustrating an example of a characteristic curve showing a relationship between a Rayleigh wave average velocity and a depth obtained in the measurement system of FIG. 7;
9 is a diagram showing an example of a gradient pattern for each layer in a characteristic curve obtained by the measurement system of FIG. 7;
10 is a diagram showing a relationship between a solid foundation that has been measured in the measurement system of FIG. 7 and its ground.
11 is a diagram showing the relationship between soil properties and Rayleigh wave velocity for specifying the unit weight of soil used in the measurement system of FIG. 7;
FIG. 12 is a diagram showing a relationship between a settlement coefficient and a base size used in the measurement system of FIG. 7;
FIG. 13 is a diagram showing a characteristic curve showing a relationship between a Rayleigh wave average velocity and a depth obtained in the measurement system of FIG. 7 at five measurement points based on actual values.
14 is a diagram showing five measurement points set on a solid basis to obtain the characteristic curve of FIG.
FIG. 15 is a diagram showing specifications and an instantaneous settlement amount used to calculate an instantaneous settlement amount for each layer using the characteristic curve of FIG. 13;
16 is a diagram showing specifications and consolidation settlement amounts used to calculate the consolidation settlement amount for each layer using the characteristic curve of FIG. 13;
17 is a diagram for explaining that a subsidence amount for each layer is obtained by using the immediate subsidence amount of FIG. 15 and the consolidation subsidence amount of FIG. 16;
18 is a diagram showing a result of calculating a Rayleigh wave velocity for each layer using the characteristic curve of FIG.
FIG. 19 is a diagram for explaining a method of determining the width X of the improved body of the first example formed as a reinforcing base according to the present invention.
FIG. 20 is a diagram showing a relationship between an interval Y and a depth Z of an improved body used in determining the width X in FIG. 19;
FIG. 21 is a diagram for describing an arc slip used for determining a width X in FIG. 19;
FIG. 22 is a diagram showing a numerical example of specifications shown in FIG. 21;
FIG. 23 is a view for explaining a method of determining the width X of the improved body of the second example formed as a reinforcing base according to the present invention.
FIG. 24 is a diagram showing a numerical example of specifications shown in FIG. 23;
FIG. 25 is a flowchart for explaining a flow of a forming operation of an improved body of the first example formed as a reinforcing base according to the present invention.
FIG. 26 is a flowchart illustrating a flow of a forming operation of an improved body of the second example formed as a reinforcing base according to the present invention.
FIG. 27 is a diagram partially showing a substructure including a modification of the first example constructed according to the present invention.
FIG. 28 is a diagram partially showing a basic structure constructed as a second embodiment of the present invention.
FIG. 29 is a plan view showing the entire basic structure of FIG. 28;
30 is a diagram for explaining a jack-up operation performed using the basic structure of FIG. 28.
FIG. 31 is a view partially showing a foundation structure in which a vibration damping device is combined as a modification of the embodiment of FIG. 28;
FIG. 32 is a view for explaining a slider constituting the vibration reduction device of FIG. 31.
FIG. 33 is a view for explaining an under slide plate constituting the vibration reduction device of FIG. 31.
FIG. 34 is a diagram partially showing an example of a basic structure when the present invention is applied to a cold region.
FIG. 35 is a view for explaining three examples of the flow of an actual forming process of an improved body formed according to the present invention.
FIG. 36 is a plan view for explaining another modification of the basic structure according to the present invention.
FIG. 37 is a plan view for explaining still another modified example of the basic structure according to the present invention.
FIG. 38 is a diagram partially showing still another example of the example shown in FIG. 31;
[Explanation of symbols]
1 arithmetic unit
2 Seismograph
3 Excitation signal
4 Vibration generator
5 First receiver
6 Second receiver
20 Cloth foundation
30 solid foundation
40 Improvement
41, 42 Reinforced concrete block
43 steel plate
44 Jack
45 Layer by cut crushed stone
46 Continuous fiber reinforcement
51 Foundation pile
61 Floating Foundation
70 Vibration reduction device
71 Slider
72 Under slide plate

Claims (23)

Perform predetermined measurements on the ground on which the building foundation should be built,
According to the measurement result, in addition to the foundation on the ground, it is determined whether an improved foundation structure should be built in the ground,
When it is determined that the improved foundation structure is to be constructed also in the ground, the depth Z, width X, and interval Y are improved so as to partition the ground into a plurality of areas in the ground where the improved foundation structure is to be constructed. Form your body in a grid,
A method for designing a foundation structure for a building, wherein a foundation on the ground is formed on the improved body so that the foundation and the improved body are not mutually restrained. The method of designing a building substructure according to claim 1,
The determination as to whether the improved foundation structure should be constructed is based on which of the plurality of types of ground supporting strengths the ground on which the foundation should be constructed corresponds to each of the plurality of types of predetermined ground depths. A first step of determining
A second step of determining whether the ground on which the foundation is to be built corresponds to a plurality of predetermined types of expected settlement amounts and inclination due to settlement,
A design method of a building substructure, wherein a depth Z, a width X, and an interval Y of the improved body are selected according to the determination results of the first step and the second step. In the method for designing a building substructure according to claim 2,
The method of designing a substructure for a building, wherein the second step is performed according to a determination result of the first step. The method for designing a building substructure according to claim 2 or 3,
The first step is
A 1-1 step of determining whether the supporting force at a depth of 0.5 m or less is 30 kN / m ² or more;
If the result of the 1-1 step is negative, a 1-2 step of determining whether the supporting force at a depth of 1 m or less is 20 kN / m ² or more;
A step of determining whether the supporting force at a depth of 2 m or more is 15 kN / m ² or more when the result of the step 1-2 is negative. Method. In the method for designing a building substructure according to claim 4,
The second step includes:
If the result of the step 1-1 is affirmative, a step 2-1 of determining whether the expected amount of settlement is less than 3 cm and the inclination due to the settlement is less than 3/1000,
If the affirmative determination in the 1-2 step or the negative determination in the 2-1 step, a 2-2 step of determining whether the expected settlement amount is less than 5 cm and the inclination due to the settlement is less than 3/1000,
A step of determining whether the expected settlement amount is less than 7 cm and an inclination due to the settlement is less than 3/1000, if the answer in the step 2-2 is negative, the step 2-3. Design method. The method for designing a building substructure according to claim 5,
The second step further includes:
If the result of the step (2-3) is negative, the method includes a step (2-4) of judging whether the slope is less than 6/1000 due to the settlement of the ground on which the foundation is to be built. Design method. In the method for designing a building substructure according to claim 6,
The second step further includes:
A step of determining whether the expected settlement amount is less than 7 cm and an inclination due to the settlement is less than 3/1000, if affirmative in the 1-3 step,
If the result of the step 1-3 is negative or the result of the step 2-5 is negative, a step 2-6 of judging whether the inclination is less than 6/1000 due to the settlement of the ground on which the foundation is to be built is included. A method for designing a foundation structure for a building. The method for designing a building substructure according to claim 5,
If the result of the step 2-1 is affirmative, it is determined that the improved foundation structure is unnecessary and that only a cloth foundation is formed as the foundation on the ground. . The method for designing a building substructure according to claim 5,
If the result of the step 2-2 is affirmative, it is determined that the improved foundation structure is unnecessary and that only the solid foundation is formed as the foundation on the ground. . The method for designing a building substructure according to claim 5,
If the result of the step 2-3 is affirmative, it is determined that the improved substructure is necessary;
As the improved body, an improved body having a depth Z = 0.7 m, a width X = 0.45 m, and an interval Y = 2.0 m, or a depth Z = 1.2 m, a width X = 0.45 m, and an interval Y = 3 And an improved body having a depth of Z = 1.7 m, a width of X = 0.45 m, and an interval of Y = 4.0 m. Design method. In the method for designing a building substructure according to claim 6,
If affirmative in the step 2-4, it is determined that the improved substructure is necessary,
As the improved body, it is determined that an improved body having a width X = 0.45 to 1.0 m and a depth Z and an interval Y calculated by a predetermined calculation method is formed. Design method of building substructure. In the method for designing a building substructure according to claim 6,
If the result of the step 2-4 is negative, it is determined that the improved substructure is necessary,
A method for designing a foundation structure for a building, characterized in that it is determined that the improved body forms a foundation pile or a floating foundation. The method of designing a building substructure according to claim 7,
If the result of the step 2-5 is affirmative, it is determined that the improved foundation structure is necessary;
As the improved body, an improved body having a depth Z = 0.7 m, a width X = 0.45 m, and an interval Y = 2.0 m, or a depth Z = 1.2 m, a width X = 0.45 m, and an interval Y = 3 And an improved body having a depth of Z = 1.7 m, a width of X = 0.45 m, and an interval of Y = 4.0 m. Design method. The method of designing a building substructure according to claim 7,
If affirmative in step 2-6, it is determined that the improved substructure is necessary,
As the improved body, it is determined that an improved body having a width X = 0.45 to 1.0 m and a depth Z and an interval Y calculated by a predetermined calculation method is formed. Design method of building substructure. The method of designing a building substructure according to claim 7,
If the result of the step 2-6 is negative, it is determined that the improved foundation structure is necessary, and
A method for designing a foundation structure for a building, characterized in that it is determined that the improved body forms a foundation pile or a floating foundation. In a foundation structure for a building composed of a foundation formed on the ground on which a building is to be constructed and an improved foundation structure formed in the ground on which the building is to be constructed, the improved foundation structure includes a ground on which the building is to be constructed. Are formed in a lattice shape so as to divide the area into a plurality of areas, and the improved bodies are mutually interposed between the ground formed on the ground and the improved bodies. A foundation structure for a building, which is formed so as not to bind to each other. The foundation structure for a building according to claim 16,
Forming a first space portion at a plurality of locations as needed at the upper end of the outermost improved body which is the upper end of the improved body facing the foundation formed on the ground A base structure for a building, wherein a first member capable of being mounted is detachably provided. The foundation structure for a building according to claim 17,
In addition to the upper end of the outermost improvement, a second member capable of forming a second space portion is provided at at least one position at the upper end of the inner improvement as well. Base structure for buildings. The foundation structure for a building according to claim 18,
The foundation formed on the ground is a solid foundation,
An opening for working is formed in the solid foundation corresponding to an installation region of the second member, wherein the solid foundation has a working opening. 20. The building substructure according to claim 18 or 19, wherein the improved body has a plate-like or lattice-like shape at a predetermined depth from the ground surface, which is lower than the first and second members. Basic structure for buildings characterized by interposing continuous fiber reinforcement. The foundation structure for a building according to any one of claims 16 to 20,
The said improved body is formed from soil cement or concrete, The foundation structure for buildings characterized by the above-mentioned. The foundation structure for a building according to any one of claims 18 to 21,
The first and second members are made of a material having a strength equal to or higher than that of the improved body. The foundation structure for a building according to any one of claims 16 to 22,
The building is characterized in that the improved body is composed of a single layer or a plurality of layers in the depth direction, and in the case of a plurality of layers, the upper surface of the lower layer at the boundary of each layer is subjected to rolling compaction. Foundation structure.

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