JP2002285536A - Ground improvement method supposing liquefaction resulting from earthquake - Google Patents
Ground improvement method supposing liquefaction resulting from earthquakeInfo
- Publication number
- JP2002285536A JP2002285536A JP2001128427A JP2001128427A JP2002285536A JP 2002285536 A JP2002285536 A JP 2002285536A JP 2001128427 A JP2001128427 A JP 2001128427A JP 2001128427 A JP2001128427 A JP 2001128427A JP 2002285536 A JP2002285536 A JP 2002285536A
- Authority
- JP
- Japan
- Prior art keywords
- ground
- liquefaction
- settlement
- earthquake
- improvement method
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
Description
【０００１】[0001]
【発明が属する技術分野】本発明は、地震時の液状化を
前提にした地盤改良工法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground improvement method on the premise of liquefaction during an earthquake.
【０００２】[0002]
【従来の技術】従来、軟弱地盤に直接基礎構造物を構築
する場合の液状化対策としての地盤改良の一般的な考え
方は、「液状化しない地盤に改良する」ことにあった
が、近年、兵庫県南部地震を契機に、液状化して沈下が
発生しても構造物の最低限の機能だけは保持されるよう
にするという、液状化を前提とした考え方に変わってき
ている。2. Description of the Related Art Conventionally, the general idea of soil improvement as a countermeasure against liquefaction when constructing a foundation structure directly on soft ground was to "improve the ground to a non-liquefied state". In the wake of the Hyogoken-Nanbu Earthquake, the concept of liquefaction has been changed so that even if liquefaction and subsidence occur, only the minimum functions of the structure are maintained.
【０００３】[0003]
【発明が解決しようとする課題】本発明が解決しようと
する課題（本発明の目的）は、前記趨勢に鑑み、液状化
した後の地表面の沈下量を予測し、この予測沈下量が許
容沈下量を上回った場合に許容沈下量になるように地盤
改良を行う地震時の液状化を前提にした地盤改良工法を
提供することにある。SUMMARY OF THE INVENTION The problem to be solved by the present invention (object of the present invention) is to, in view of the above trend, predict the amount of settlement of the ground surface after liquefaction, and the estimated amount of settlement is allowable. It is an object of the present invention to provide a soil improvement method on the premise of liquefaction at the time of an earthquake, in which the soil is improved so that the allowable settlement amount is exceeded when the settlement amount is exceeded.
【０００４】なお、本発明が改良の対象とする地盤は、
地震時に液状化する地盤の内、締め固めによる改良効果
が期待できる砂質土地盤もしくは礫質土地盤である。The ground to be improved by the present invention is:
It is sandy or gravel ground that can be expected to improve by compaction among the ground that liquefies during an earthquake.
【０００５】[0005]
【課題を解決するための手段】前記課題を解決するため
に、本発明の液状化を前提にした地盤改良工法（以下、
本発明の工法という）では、地盤の初期間隙比から液状
化後の地表面の沈下量を予測し、この予測沈下量が許容
沈下量を上回る場合に、締め固め工法で許容沈下量に対
応する間隙比になるように地盤を締め固めるようにして
いる。Means for Solving the Problems In order to solve the above-mentioned problems, a soil improvement method based on liquefaction according to the present invention (hereinafter referred to as a soil improvement method).
According to the method of the present invention), the amount of settlement of the ground surface after liquefaction is predicted from the initial gap ratio of the ground, and if the predicted settlement exceeds the allowable settlement, the compaction method corresponds to the allowable settlement. The ground is compacted so as to achieve a void ratio.
【０００６】本発明の工法は、室内実験で得られた、液
状化による地盤の体積ひずみ（圧縮ひずみ）が地盤の初
期間隙比にのみ依存するという新規知見に基づくもので
あって、下記の式（１）で表される地盤の初期間隙比と
液状化後の体積ひずみとの関係を利用して、初期間隙比
から沈下量を予測したり、許許容沈下量から間隙比を求
めたりしている。The method of the present invention is based on a novel finding that the volumetric strain (compression strain) of the ground due to liquefaction obtained only in the laboratory experiment depends only on the initial gap ratio of the ground. Using the relationship between the initial void ratio of the ground expressed in (1) and the volumetric strain after liquefaction, the settlement amount is predicted from the initial clearance ratio, or the clearance ratio is calculated from the allowable settlement amount. I have.
【０００７】[0007]
【数１】 (Equation 1)
【０００８】なお、本発明の工法において、締め固め工
法で許容沈下量に対応する間隙比になるように地盤を締
め固める際の改良率は例えば、下記の式（２）で定める
ことができる（特開２０００−３４５５５３号公報参
照）。[0008] In the method of the present invention, the improvement rate when compacting the ground so as to obtain a gap ratio corresponding to the allowable settlement amount in the compacting method can be determined by, for example, the following formula (2) ( See JP-A-2000-345553).
【０００９】[0009]
【数２】 (Equation 2)
【００１０】[0010]
【発明の実施の形態】本発明の工法では、先ず、地盤の
初期間隙比（原地盤の間隙比）から原地盤が液状化した
ときの地表面の沈下量を予測するが、それには、本件発
明者らが発見した地盤の間隙比ｅと地盤が液状化したと
きの地盤の体積ひずみεとの関係を示す前記式（１）も
しくは図１から、原地盤土の間隙比ｅ０に対応する体積
ひずみε０を求め、これに液状化層厚Ｈをかけて予測沈
下量Ｓを求めればよい。DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, firstly, the amount of settlement of the ground surface when the original ground is liquefied is estimated from the initial void ratio of the ground (gap ratio of the original ground). From the above equation (1) or FIG. 1 showing the relationship between the gap ratio e of the ground discovered by the inventors and the volumetric strain ε of the ground when the ground liquefies, the volume corresponding to the gap ratio e0 of the original ground soil. The expected settlement amount S may be obtained by obtaining the strain ε0 and multiplying this by the liquefied layer thickness H.
【００１１】なお、原地盤土の間隙比ｅ０が不明の場合
は、原地盤の強度Ｎ値と細粒分含有率Ｆｃを検知して、
既知の経験式を用いて算出することができる。When the gap ratio e0 of the original ground is unknown, the strength N value of the original ground and the fine grain content Fc are detected.
It can be calculated using a known empirical formula.
【００１２】以上のようにして得られた予測沈下量Ｓと
許容沈下量Ｓａとを比較して、後者の方が大きい場合は
地盤改良の必要はないが、前者の方が大きい場合は、以
下の手法で求めた改良率ａｓで締め固め砂杭を造成して
地盤を改良をする。When the predicted settlement amount S obtained as described above and the allowable settlement amount Sa are compared, no ground improvement is necessary if the latter is larger, but if the former is larger, The compacted sand pile is formed at the improvement rate as obtained by the method described in the above to improve the ground.
【００１３】すなわち、許容沈下量Ｓａを液状化層厚Ｈ
で割って、許容沈下量Ｓａに見合う体積ひずみε１を求
め、それから、前記式（１）もしくは図１を用いて体積
ひずみε１に対応する間隙比ｅ１を求め、それから前記
式（２）もしくは図２により所要の改良率ａｓを求め
る。That is, the allowable subsidence amount Sa is determined by the liquefied layer thickness H.
2 to obtain a volumetric strain ε1 corresponding to the allowable settlement amount Sa. Then, a gap ratio e1 corresponding to the volumetric strain ε1 is obtained by using the above equation (1) or FIG. To obtain the required improvement rate as.
【００１４】なお、図２は、改良率ａｓから改良後の間
隙比ｅ１を算出する従来公知の経験式と式（１）とから
求めた改良率ａｓと体積ひずみεとの関係図である。FIG. 2 is a diagram showing the relationship between the improvement ratio as and the volumetric strain ε obtained from the conventionally known empirical formula for calculating the gap ratio e1 after improvement from the improvement ratio as and equation (1).
【００１５】前述のようにして改良率ａｓが求められた
ら、これを満足するように砂杭径と砂杭ピッチを定めて
締め固め砂杭を造成し、地盤を締め固めるが、その施工
態様は従来と同様であるのでこれ以上の説明は省略す
る。When the improvement ratio as is obtained as described above, the sand pile diameter and the pitch of the sand pile are determined so as to satisfy the conditions, the compacted sand pile is formed, and the ground is compacted. Since it is the same as the conventional one, further description is omitted.
【図１】地盤の間隙比と液状化による地盤の体積ひずみ
との関係図である。FIG. 1 is a diagram showing the relationship between the gap ratio of the ground and the volumetric strain of the ground due to liquefaction.
【図２】液状化による地盤の体積ひずみと改良率との関
係図である。FIG. 2 is a diagram showing the relationship between the volumetric strain of the ground due to liquefaction and the improvement rate.
【図３】本発明の工法のフロー図である。FIG. 3 is a flowchart of the method of the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 大林 淳 神奈川県横浜市南区永田東２−20−18 Ｆターム(参考） 2D043 CA00 EB02 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsushi Obayashi 2-20-18 Nagatahigashi, Minami-ku, Yokohama-shi, Kanagawa F-term (reference) 2D043 CA00 EB02
Claims (1)
の沈下量を予測し、この予測沈下量が許容沈下量を上回
る場合に、締め固め工法で許容沈下量に対応する間隙比
になるように地盤を締め固めることを特徴とする地震時
の液状化を前提にした地盤改良工法。1. The amount of settlement of the ground surface after liquefaction is predicted from the initial gap ratio of the ground, and when the predicted settlement amount exceeds the allowable settlement amount, the compaction method is used to determine the gap ratio corresponding to the allowable settlement amount. A ground improvement method based on liquefaction during an earthquake, characterized by compacting the ground as much as possible.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001128427A JP2002285536A (en) | 2001-03-23 | 2001-03-23 | Ground improvement method supposing liquefaction resulting from earthquake |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001128427A JP2002285536A (en) | 2001-03-23 | 2001-03-23 | Ground improvement method supposing liquefaction resulting from earthquake |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002285536A true JP2002285536A (en) | 2002-10-03 |
Family
ID=18977116
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001128427A Pending JP2002285536A (en) | 2001-03-23 | 2001-03-23 | Ground improvement method supposing liquefaction resulting from earthquake |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2002285536A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006291572A (en) * | 2005-04-11 | 2006-10-26 | Shimizu Corp | Method of predicting amount of deformation of ground and structure and program |
| JP2007262813A (en) * | 2006-03-29 | 2007-10-11 | Toda Constr Co Ltd | Construction method for foundation for soil improvement and reduction in ground subsidence |
| JP2009002007A (en) * | 2007-06-20 | 2009-01-08 | Shimizu Corp | Soil improving method |
| JP2018059310A (en) * | 2016-10-04 | 2018-04-12 | 株式会社大林組 | Design method of press-in pile in liquefied ground |
| JP2018199985A (en) * | 2017-05-30 | 2018-12-20 | 株式会社不動テトラ | Specification setting method of sandy ground compaction method |
-
2001
- 2001-03-23 JP JP2001128427A patent/JP2002285536A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006291572A (en) * | 2005-04-11 | 2006-10-26 | Shimizu Corp | Method of predicting amount of deformation of ground and structure and program |
| JP4640671B2 (en) * | 2005-04-11 | 2011-03-02 | 清水建設株式会社 | Ground / structure deformation prediction method and program |
| JP2007262813A (en) * | 2006-03-29 | 2007-10-11 | Toda Constr Co Ltd | Construction method for foundation for soil improvement and reduction in ground subsidence |
| JP2009002007A (en) * | 2007-06-20 | 2009-01-08 | Shimizu Corp | Soil improving method |
| JP2018059310A (en) * | 2016-10-04 | 2018-04-12 | 株式会社大林組 | Design method of press-in pile in liquefied ground |
| JP2018199985A (en) * | 2017-05-30 | 2018-12-20 | 株式会社不動テトラ | Specification setting method of sandy ground compaction method |
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