JPH0932005A - Method of preventing liquefaction of ground - Google Patents

Method of preventing liquefaction of ground

Info

Publication number
JPH0932005A
JPH0932005A JP20847395A JP20847395A JPH0932005A JP H0932005 A JPH0932005 A JP H0932005A JP 20847395 A JP20847395 A JP 20847395A JP 20847395 A JP20847395 A JP 20847395A JP H0932005 A JPH0932005 A JP H0932005A
Authority
JP
Japan
Prior art keywords
ground
tensile
liquefaction
hole
tension
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
Application number
JP20847395A
Other languages
Japanese (ja)
Inventor
Shinji Fukushima
伸二 福島
Original Assignee
Fujita Corp
株式会社フジタ
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fujita Corp, 株式会社フジタ filed Critical Fujita Corp
Priority to JP20847395A priority Critical patent/JPH0932005A/en
Publication of JPH0932005A publication Critical patent/JPH0932005A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To provide a method for effectively preventing liquefaction of the ground upon occurrence of an earthquake, which is inexpensive and which can have a short construction period. SOLUTION: Several tension members 1 are extended downward from the lower part 2a of a structure 2 built on the ground G1 . The tension members 1 are anchored with their lower end parts in the bottom parts of insertion holes by means of a solidifier 11, and are engaged on their upper end parts 1a with nuts 12. By fastening the nuts 12, an tensile axial force is exerted to the tension members 1 so as to increase the constraint pressure of the ground G1 between the each adjacent tension members 1, thereby it is possible to enhance liquefaction-resistant strength.

Description

【発明の詳細な説明】Detailed Description of the Invention
【0001】[0001]
【発明の属する技術分野】本発明は、地下水位以下にあ
る砂地盤等の軟質地盤が、地震発生時に液状化するのを
防止して、地上構造物あるいは地中構造物を地盤液状化
による災害から保護するための方法に関するものであ
る。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention prevents soft ground such as sand ground below the groundwater level from liquefying in the event of an earthquake, and damages ground structures or underground structures by ground liquefaction. It is about a way to protect against.
【0002】[0002]
【従来の技術】埋立地の地盤や、大量の砂や粘土分等を
含む砂質の土層からなる地盤(以下、砂地盤という)
は、水平変位に対する剪断抵抗力が小さいため、大地震
の発生時には、地下水位以下の土粒子間に過剰間隙水圧
が発生して地表へ土砂や地下水が噴き上げるといった地
盤の液状化現象が起こることがあり、建物等の構造物に
倒壊等の災害を招来する恐れがある。従来、このような
地盤の液状化を防止するため、次のような方法が採用さ
れている。 (1) 構造物及びその周辺の下部地盤に排水性の良い礫材
等のドレーン材を一定間隔で杭のように挿入して(サン
ドコンパクションパイル)、地震時に地盤中に発生する
過剰間隙水圧を消散させる、排水を基本原理とする方
法。 (2) 地盤中に杭や鋼矢板、シートパイル等を一定間隔又
は連続的に打設して、地震時の地盤の変形を抑制する方
法。
2. Description of the Related Art The ground of reclaimed land and the ground composed of a sandy soil layer containing a large amount of sand and clay (hereinafter referred to as sand ground)
Since the shear resistance to horizontal displacement is small, when a large earthquake occurs, excessive pore water pressure may occur between soil particles below the groundwater level, causing soil and groundwater liquefaction phenomena such as eruption of soil and groundwater. Yes, there is a risk of causing a disaster such as a collapse of structures such as buildings. Conventionally, the following method has been adopted in order to prevent such liquefaction of the ground. (1) Drain material such as gravel material with good drainage is inserted like a pile at a constant interval into the structure and the lower ground around it (sand compaction pile) to prevent excess pore water pressure generated in the ground during an earthquake. A method that uses water as a basic principle to dissipate. (2) Pile, steel sheet pile, sheet pile, etc. are placed in the ground at regular intervals or continuously to suppress deformation of the ground during an earthquake.
【0003】[0003]
【発明が解決しようとする課題】しかしながら、上記従
来の方法によれば、ドレーン材の挿入間隔や、杭、鋼矢
板、シートパイル等の打設間隔を密にする必要があり、
これらの資材コストが高く、しかもその挿入や打ち込み
に時間がかかり、専用の大型重機を必要とするため、施
工費用が膨大になり、工期も長くなるといった問題があ
る。
However, according to the above-mentioned conventional method, it is necessary to make the intervals of inserting drain material and the intervals of placing piles, steel sheet piles, sheet piles, etc. close,
The cost of these materials is high, and it takes a long time to insert and drive them, and a dedicated large heavy machine is required, resulting in a huge construction cost and a long construction period.
【0004】本発明は、上記のような事情のもとになさ
れたもので、その技術的課題とするところは、低コスト
かつ短い工期の施工によって、地震発生時の地盤の液状
化を有効に防止するための方策を講じることのできる方
法を提供することにある。
The present invention has been made under the above circumstances, and its technical problem is to effectively liquefy the ground in the event of an earthquake by constructing at a low cost and with a short construction period. It is to provide a method capable of taking measures to prevent it.
【0005】[0005]
【課題を解決するための手段】上述した技術的課題は、
本発明によって有効に解決することができる。すなわち
本発明に係る地盤の液状化防止方法は、構造物の下部か
らこの構造物の荷重を支持する地盤中に所定間隔で引張
材を挿入し、この引張材の下端部を前記地盤に定着し、
前記引張材の上端部から引張り方向の軸力を導入してこ
の引張材周囲の地盤に拘束圧を付与し、これによって、
以下に述べるとおり、地盤の拘束圧及び剪断抵抗を上昇
させ、地震による変位力を受けた時の土粒子間の過剰間
隙水圧の発生による地盤の液状化現象を抑制することが
できるものである。
The above-mentioned technical problems are as follows.
This can be effectively solved by the present invention. That is, the method for preventing liquefaction of the ground according to the present invention, the tensile material is inserted at a predetermined interval into the ground supporting the load of the structure from the lower part of the structure, and the lower end of the tensile material is fixed to the ground. ,
An axial force in the pulling direction is introduced from the upper end of the tensile member to apply a restraining pressure to the ground around the tensile member, thereby,
As described below, it is possible to increase the constraining pressure and shear resistance of the ground, and to suppress the liquefaction phenomenon of the ground due to the generation of excessive pore water pressure between soil particles when subjected to the displacement force due to an earthquake.
【0006】すなわち、地盤に挿入され下端部を地盤に
定着された引張材は、上端部から引張り方向の軸力を導
入されることによって、その周囲の地盤の拘束圧を上昇
させるものである。ある地盤が地震動を受けた場合、そ
の地盤内の深さzの位置にある土の要素の液状化に対す
る抵抗力(以下、液状化強度という)τL は、地盤の単
位体積当たりの重量をγとすると、地盤の拘束圧σz
(=γ・z)にほぼ比例することから、 τL =C・σz で表される(Cは比例定数)。したがって、前記拘束圧
を引張材に導入した軸力によってσz からσz +Δσに
増加させると、その増加に応じて、液状化強度はτL
ら τL +ΔτL =C・(σz +Δσ) に上昇する。一方、深さzの位置にある土の要素に地震
動によって作用する動的剪断応力τD は、剛体理論によ
れば、地震による地表水平加速度をαH 、重力加速度を
gとすると、 τD =γ・z・αH /g=σz ・αH /g となるので、その土の要素の液状化強度と地震による剪
断応力との比は、引張材による拘束圧増加前は、 FS =τL /τD =C・g/αH であるのに対し、引張材による拘束圧増加後は、 FSR=(τL +ΔτL )/τD =C・g[1+(Δσ/
σz )]/αH に増加する。
That is, the tensile member, which is inserted into the ground and has the lower end fixed to the ground, increases the binding pressure of the surrounding ground by introducing an axial force in the tensile direction from the upper end. When a ground is subjected to an earthquake motion, the resistance to liquefaction of the soil element at the depth z in the ground (hereinafter referred to as liquefaction strength) τ L is the weight per unit volume of the ground γ Then, the ground restraint pressure σ z
Since it is almost proportional to (= γ · z), it is represented by τ L = C · σ z (C is a proportional constant). Therefore, when the binding pressure is increased from σ z to σ z + Δσ by the axial force introduced into the tensile material, the liquefaction strength is changed from τ L to τ L + Δτ L = C · (σ z + Δσ) in accordance with the increase. Rise to. On the other hand, according to the rigid body theory, the dynamic shear stress τ D acting on the soil element at the position of depth z by the earthquake motion is α H and the gravity acceleration is h, and τ D = Since γ · z · α H / g = σ z · α H / g, the ratio between the liquefaction strength of the soil element and the shear stress due to the earthquake is F S = τ L / τ D = C · g / α H , whereas after increasing the confining pressure by the tensile material, F SR = (τ L + Δτ L ) / τ D = C · g [1+ (Δσ /
σ z )] / α H.
【0007】[0007]
【発明の実施の形態】本発明の実施の形態としては、例
えば引張材は、構造物の下部から地盤中に穿孔した引張
材挿入孔に挿入すると共にその下端部を前記引張材挿入
孔の底部に固結材を介して定着し、引張材への軸力の導
入は、引張材の上端部に螺合したナットにより行うこと
ができる。また、引張材への軸力導入後は、この引張材
全体をその周囲の地盤に固結材を介して定着することに
よって、この引張材と周辺地盤との摩擦力が増大するの
で、この摩擦力によって、地震動による地盤の変形が抑
制され、液状化の原因である過剰間隙水圧の発生が抑制
される。
BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, for example, a tensile member is inserted from a lower portion of a structure into a tensile member insertion hole drilled in the ground, and its lower end portion is a bottom portion of the tensile member insertion hole. The axial force can be introduced into the tensile member by fixing it to the tensile member via a solid material by a nut screwed to the upper end portion of the tensile member. Further, after the axial force is introduced to the tensile member, by fixing the entire tensile member to the surrounding ground through the solidifying material, the frictional force between the tensile member and the surrounding ground increases, so that this friction The force suppresses the deformation of the ground due to the earthquake motion, and suppresses the generation of excess pore water pressure that causes liquefaction.
【0008】図1及び図2は、本発明による地盤の液状
化防止方法の実施形態を概略的に示すものであり、参照
符号G1 は砂地盤等のような軟質の上層地盤、G2 はこ
の軟質地盤G1 の下側に存在する強度の大きい下層地
盤、WLは地下水位をそれぞれ示している。上層地盤G
1 上には建物等の構造物2があり、この構造物2の下部
2aからは鉛直下方へ延びる多数の引張材1が配置され
ている。引張材1は、構造物2及びその周囲の下部2a
に、水平方向所定ピッチで設定した格子点位置から、上
層地盤G1 内の所定の深さまで、あるいはこの上層地盤
1 を貫いてその下にある強度の大きい下層地盤G2
で穿孔された引張材挿入孔に挿入され、下端部1aが、
固結材11を介して前記引張材挿入孔の底部に定着され
ている。そしてこの引張材1に、上端部1bに螺合した
ナット12を締め付けて引張り方向の軸力を導入するこ
とによって、引張材1の外周、言い換えれば各引張材1
の間に存在する上層地盤G1 の拘束圧を増大させてい
る。
1 and 2 schematically show an embodiment of a method for preventing liquefaction of ground according to the present invention. Reference numeral G 1 is a soft upper layer ground such as sand ground, and G 2 is Under the soft ground G 1 , there is a high-strength lower ground, WL indicates the groundwater level, respectively. Upper ground G
A structure 2 such as a building is located on the top of the structure 1 , and a number of tensile members 1 extending vertically downward are arranged from a lower portion 2a of the structure 2. The tensile member 1 includes a structure 2 and a lower portion 2a around the structure 2.
In a horizontal direction from a grid point position set at a predetermined pitch, to a predetermined depth in the upper ground G 1, or through the upper ground G 1 Tensile drilled to large lower ground G 2 of intensity on the underlying The lower end 1a is inserted into the material insertion hole,
It is fixed to the bottom portion of the tensile material insertion hole through the solidifying material 11. Then, the nut 12 screwed to the upper end portion 1b is tightened on the tensile member 1 to introduce an axial force in the tensile direction, so that the outer periphery of the tensile member 1, in other words, each tensile member 1
The confining pressure of the upper ground G 1 existing between the two is increased.
【0009】[0009]
【実施例】図3乃至図11は、砂地盤G上へのコンクリ
ート建築物等の構造物の構築に際して、本発明による地
盤の液状化防止方法を適用した場合の典型的な一実施例
を施工順に示すものである。
EXAMPLE FIG. 3 to FIG. 11 show a typical example in which the method for preventing ground liquefaction according to the present invention is applied when constructing a structure such as a concrete building on the sand ground G. They are shown in order.
【0010】まず、図3に示すように、構造物の建設地
点となる地表面G’を整地し、構造物の下部に相当する
基礎コンクリート21を打設する。基礎コンクリート2
1の打設に際しては、予めラス網22や格子状に組み立
てた細い鉄筋23を配置しておく。
First, as shown in FIG. 3, the ground surface G ', which is the construction point of the structure, is leveled, and the foundation concrete 21 corresponding to the lower part of the structure is placed. Foundation concrete 2
At the time of placing 1, the lathe net 22 and the thin reinforcing bars 23 assembled in a lattice shape are arranged in advance.
【0011】次に図4に示すように、基礎コンクリート
21の表面に縦横所定ピッチで設定した格子点位置か
ら、砂地盤G内における所要の深さあるいはそれよりも
下層に存在するの硬質の地盤(図示省略,図1及び図2
におけるG2 に相当する)に達するまで、鉛直下方へそ
れぞれ引張材挿入孔3を穿孔する。この引張材挿入孔3
は、後述の引張材1よりも適宜大径の孔であるが、従来
工法におけるドレーン材の挿入孔等に比較すると極めて
小径であるため、小型の穿孔機によって短時間で穿孔す
ることができる。
Next, as shown in FIG. 4, from the lattice point positions set at a predetermined vertical and horizontal pitches on the surface of the foundation concrete 21, to the required depth in the sand ground G or to the hard ground existing in the lower layer than that. (Not shown, FIGS. 1 and 2
(Corresponding to G 2 in the above), each of the tensile member insertion holes 3 is drilled vertically downward. This tension material insertion hole 3
Is a hole having a diameter appropriately larger than that of the tensile member 1 described later, but since it has an extremely small diameter as compared with the insertion hole of the drain material in the conventional method, it can be drilled in a short time by a small punching machine.
【0012】次に図5に示すように、各引張材挿入孔3
の底部に、それぞれ固結材11を充填する。各引張材挿
入孔3には、周囲の砂地盤Gから流入した地下水が地下
水位WLの高さまで存在しているため、固結材11とし
ては、水和反応により経時的に硬化するモルタルが用い
られる。
Next, as shown in FIG. 5, each tension member insertion hole 3
The bottom part of each is filled with the solidifying material 11. In each tensile material insertion hole 3, since groundwater flowing from the surrounding sand ground G exists up to the height of the groundwater level WL, mortar that hardens with time due to a hydration reaction is used as the solidifying material 11. To be
【0013】次に図6に示すように、基礎コンクリート
21に開口した各引張材挿入孔3の上端部から、この引
張材挿入孔3内へそれぞれ引張材1を挿入し、その先端
部1aを引張材挿入孔3の底部に充填された未硬化の固
結材11内へ没入させる。引張材1は、その下端部1a
を引張材挿入孔3の底部まで挿入した場合に上端部1b
が基礎コンクリート21の上へ突出する長さを有するも
のであって、例えば鉄筋棒、鋼棒あるいは高分子材料か
らなる棒材等、引張強度の大きい材料が選定される。こ
れらの資材は、従来工法において大量に必要とする鋼矢
板やシートパイル等の資材に比較して、極めて低コスト
である。また、固結材11中に没入される下端部1aに
は、図11に示すように、定着力を高めるための多数の
凹凸13が形成されており、上端部1b近傍の外周面に
は、ナット12と螺合するための螺子溝14が形成され
ている。
Next, as shown in FIG. 6, the tension members 1 are inserted into the tension member insertion holes 3 from the upper ends of the tension member insertion holes 3 opened in the basic concrete 21, and the tips 1a thereof are inserted. It is immersed in the uncured solidified material 11 filled in the bottom of the tensile material insertion hole 3. The tensile member 1 has a lower end 1a.
1b when the tension member insertion hole 3 is inserted to the bottom
Has a length protruding above the basic concrete 21, and a material having a large tensile strength such as a reinforcing bar, a steel bar or a bar made of a polymer material is selected. These materials are extremely low in cost as compared with materials such as steel sheet piles and sheet piles that are required in large quantities in the conventional method. Further, as shown in FIG. 11, a large number of irregularities 13 for increasing the fixing force are formed on the lower end portion 1a immersed in the solidifying material 11, and the outer peripheral surface near the upper end portion 1b is A screw groove 14 for screwing with the nut 12 is formed.
【0014】固結材11は、時間の経過と共に硬化して
行き、引張材1の下端部1aはこの固結材11に定着さ
れる。一方、固結材11の外周部は、引張材挿入孔3の
底部内壁面、言い換えればこの底部周囲の砂地盤Gに接
触しており、しかもその一部は砂地盤Gの土粒子間に侵
入した状態で硬化する。したがって、引張材1の下端部
1aは、固結材11を介して砂地盤Gに強固に定着され
る。また、引張材挿入孔3の形状変更例として図7に示
すように、引張材挿入孔3の穿孔に際して、その底部3
aを特殊な拡幅掘削ビットを用いてやや大径に削孔する
ことによって、固結材11の十分な充填量を確保すると
共に、この固結材11が砂地盤G内に張り出した形状で
硬化するので、後述の軸力導入に際して拘束圧の付与範
囲を拡大することができる。
The solidifying material 11 hardens with the passage of time, and the lower end portion 1a of the tension material 1 is fixed to the solidifying material 11. On the other hand, the outer peripheral portion of the solidifying material 11 is in contact with the inner wall surface of the bottom portion of the tensile material insertion hole 3, in other words, the sand ground G around this bottom portion, and a part of it enters between the soil particles of the sand ground G. It cures in the condition. Therefore, the lower end portion 1 a of the tensile member 1 is firmly fixed to the sand ground G via the solidifying material 11. In addition, as shown in FIG. 7 as an example of changing the shape of the tension material insertion hole 3, when the tension material insertion hole 3 is drilled, its bottom portion 3 is formed.
By drilling a with a slightly larger diameter using a special widening excavating bit, a sufficient filling amount of the solidifying material 11 is secured, and the solidifying material 11 is hardened in a shape protruding into the sand ground G. Therefore, it is possible to expand the range in which the constraining pressure is applied when the axial force described below is introduced.
【0015】次に図8に示すように、基礎コンクリート
21上へ突出した引張材1の上端部1bに金属製のヘッ
ドプレート15を差し込み、更にその上から、前記上端
部1bに形成された螺子溝14にナット12を螺合す
る。そして、固結材11の硬化によって引張材1の下端
部1aが完全に定着されたら、ナット12を締め付ける
ことによって、この引張材1に引張り方向の軸力Pを導
入する。ここで、引張材1の下端部1aと上端部1bと
の間で周囲の砂地盤Gに作用する拘束圧Δσは、縦横方
向の引張材1の挿入ピッチをmL ×mT とすると、 Δσ=P/(mL ×mT ) である。したがって挿入ピッチ(格子点間隔)を密にす
るほど、また、ナット12の締め付けによる導入軸力を
大きくするほど、砂地盤Gに加えられる拘束圧が上昇す
る。そして、これにより、単位体積当たりの土の重量と
深さに比例する砂地盤Gの本来の拘束圧は、軸力Pの導
入によって強制的に上昇され、土粒子密度が増大し、先
に述べたように、砂地盤Gの液状化強度が増大し、地震
発生時の砂地盤Gの液状化を有効に防止することができ
る。
Next, as shown in FIG. 8, a metal head plate 15 is inserted into the upper end 1b of the tensile member 1 projecting onto the foundation concrete 21, and from above, a screw formed on the upper end 1b. The nut 12 is screwed into the groove 14. Then, when the lower end portion 1a of the tension member 1 is completely fixed by the hardening of the solidified material 11, the nut 12 is tightened to introduce the axial force P in the tension direction into the tension member 1. Here, the binding pressure Δσ acting on the surrounding sand ground G between the lower end portion 1a and the upper end portion 1b of the tensile member 1 is Δσ when the insertion pitch of the tensile members 1 in the vertical and horizontal directions is m L × m T. = P / (m L × m T ). Therefore, the closer the insertion pitch (lattice point interval) is made, and the larger the introduced axial force due to the tightening of the nut 12 is, the more the constraint pressure applied to the sand ground G is increased. As a result, the original binding pressure of the sand ground G, which is proportional to the weight and depth of soil per unit volume, is forcibly increased by the introduction of the axial force P, and the soil particle density is increased. As described above, the liquefaction strength of the sand ground G is increased, and the liquefaction of the sand ground G when an earthquake occurs can be effectively prevented.
【0016】また、図9及び図10に基礎コンクリート
21の形状変更例を示すように、基礎コンクリート21
を、必要に応じて格子状の基礎梁22を有するフレーム
構造とし、引張材1を前記基礎梁22の交差位置から挿
入して軸力を与えることによっても、砂地盤Gに対する
拘束圧を顕著に上昇させることができる。
Further, as shown in FIG. 9 and FIG. 10 as an example of changing the shape of the basic concrete 21, the basic concrete 21
Is a frame structure having a lattice-shaped foundation beam 22 as required, and the tension member 1 is inserted from the intersection position of the foundation beams 22 to give an axial force, thereby significantly restraining the sand ground G. Can be raised.
【0017】基礎コンクリート21の上面と、引張材1
の上端部1bに螺合したナット12との間に介在するヘ
ッドプレート15は、引張材挿通用の中央孔のほかに、
引張材挿入孔3に臨んで開設された固結材注入用の小孔
(図示省略)を有する。すなわち、引張材1に軸力Pを
導入することによって砂地盤Gの拘束圧を上昇させ、そ
の拘束圧に応じた地盤の圧縮が納まったら、前記ヘッド
プレート15の小孔を介して、引張材挿入孔3とその内
周の引張材1との間の隙間全体に、図11に示すように
固結材11’を充填する。この固結材11’は、引張材
1の下端部1aの定着のために用いた固結材11と同じ
もの(モルタル)である。
The upper surface of the foundation concrete 21 and the tensile member 1
The head plate 15 interposed between the nut 12 screwed to the upper end portion 1b of the
It has a small hole (not shown) for pouring the solidifying material, which is opened facing the tensile material inserting hole 3. That is, the restraining pressure of the sand ground G is increased by introducing the axial force P to the tensile member 1, and when the ground is compressed in accordance with the restraining pressure, the tensile member is passed through the small holes of the head plate 15. The entire gap between the insertion hole 3 and the tensile member 1 on the inner periphery thereof is filled with the solidifying material 11 'as shown in FIG. The solidifying material 11 ′ is the same as the solidifying material 11 (mortar) used for fixing the lower end portion 1 a of the tensile member 1.
【0018】固結材11’が硬化することによって、引
張材1のほぼ全体が、固結材11及び11’を介してそ
の周囲の砂地盤Gと定着されることになる。したがっ
て、砂地盤Gが地震動を受けた場合に、この砂地盤Gと
引張材1の相対変位に対する摩擦力が極めて大きくな
り、地震動による地盤変形を拘束するため、液状化現象
の直接の要因である過剰間隙水圧の発生が抑制され、先
に述べた砂地盤Gの拘束圧の上昇による液状化強度の増
大と合わせて、地震発生時の液状化を有効に防止するこ
とができる。
When the solidifying material 11 'is hardened, almost the entire tension material 1 is fixed to the sand ground G around it through the solidifying materials 11 and 11'. Therefore, when the sand ground G is subjected to an earthquake motion, the frictional force against the relative displacement between the sand ground G and the tensile member 1 becomes extremely large, and the ground deformation due to the earthquake motion is restrained, which is a direct factor of the liquefaction phenomenon. The generation of excess pore water pressure is suppressed, and together with the increase in the liquefaction strength due to the increase in the confining pressure of the sand ground G described above, the liquefaction at the occurrence of an earthquake can be effectively prevented.
【0019】なお、引張材1を構造物の基礎スラブ板か
ら直接挿入する場合には、図4以降の一連の作業は、こ
の基礎スラブ板の施工後に行われる。また、上記実施例
においては、地上構造物の構築について実施する場合に
ついて説明したが、本発明は地中構造物の構築にも適用
することができる。この場合は、地盤の液状化による地
中構造物の地中変位、例えば地中構造物が中空である等
によって周囲の地盤よりも比重が小さい場合の浮き上が
り変位を有効に防止することができる。また、引張材1
は、地盤への構造物の投影範囲だけでなく、例えば図1
及び図2に示すように、構造物2の外周における下部地
盤まで配置することによって、拘束圧の上昇領域が平面
的に拡大され、地震時における構造物2を安定性を向上
させることができる。
When the tensile member 1 is directly inserted from the basic slab plate of the structure, a series of operations after FIG. 4 is performed after the basic slab plate is constructed. Further, in the above-mentioned embodiment, the case where the construction of the aboveground structure is carried out has been described, but the present invention can be applied to the construction of the underground structure. In this case, it is possible to effectively prevent the underground displacement of the underground structure due to the liquefaction of the ground, for example, the floating displacement when the specific gravity is smaller than the surrounding ground due to the hollow underground structure. In addition, tension material 1
Is not only the projected range of the structure on the ground, but also, for example, in FIG.
Also, as shown in FIG. 2, by arranging up to the lower ground on the outer periphery of the structure 2, the region where the restraint pressure rises is enlarged in a plane, and the structure 2 can be improved in stability during an earthquake.
【0020】[0020]
【発明の効果】本発明の地盤の液状化防止方法による
と、次のような効果が実現される。 (1) 構造物の荷重を受ける地盤の拘束圧を上昇させるこ
とによって、液状化強度を増大させることができる。 (2) 地盤の拘束圧を上昇させるために挿入された引張材
とその周囲の地盤との摩擦を増大させることによって、
地盤の水平剪断抵抗を増大させ、過剰間隙水圧の発生を
抑制するので、上記液状化強度の増大との共働により、
地震時の地盤の液状化を有効に防止することができる。 (3) 前記引張材の挿入のための施工に際して、サンドコ
ンパクションパイル工法や鋼矢板等の打ち込みの場合の
ような大型の重機を必要とせず、引張材や固結材等の資
材費用も低廉であるため、施工費用を低減することがで
きる。 (4) 施工が容易であるため、工期を短縮することができ
る。
According to the ground liquefaction prevention method of the present invention, the following effects are realized. (1) The liquefaction strength can be increased by increasing the restraining pressure of the ground that receives the load of the structure. (2) By increasing the friction between the tension material inserted to increase the restraining pressure of the ground and the surrounding ground,
Since it increases the horizontal shear resistance of the ground and suppresses the generation of excess pore water pressure, in cooperation with the increase in the liquefaction strength,
Liquefaction of the ground during an earthquake can be effectively prevented. (3) The construction for inserting the tension material does not require a large heavy machine like the sand compaction pile method or the driving of steel sheet pile, and the material cost such as the tension material and the consolidation material is low. Therefore, the construction cost can be reduced. (4) Since the construction is easy, the construction period can be shortened.
【図面の簡単な説明】[Brief description of drawings]
【図1】本発明の実施形態を概略的に示す説明図であ
る。
FIG. 1 is an explanatory view schematically showing an embodiment of the present invention.
【図2】本発明の実施形態を概略的に示す説明図であ
る。
FIG. 2 is an explanatory view schematically showing an embodiment of the present invention.
【図3】本発明の一実施例において、構造物の荷重を受
ける地表面に基礎コンクリートを打設した状態を示す鉛
直断面図である。
FIG. 3 is a vertical cross-sectional view showing a state in which foundation concrete is placed on the ground surface receiving a load of a structure in one embodiment of the present invention.
【図4】本発明の一実施例において、基礎コンクリート
から砂地盤中へ向けて鉛直下方へ引張材挿入孔を穿孔し
た状態を示す鉛直断面図である。
FIG. 4 is a vertical cross-sectional view showing a state in which a tensile material insertion hole is vertically downwardly drilled from the basic concrete into the sand ground in the embodiment of the present invention.
【図5】本発明の一実施例において、引張材挿入孔の底
部に固結材を充填した状態を示す鉛直断面図である。
FIG. 5 is a vertical cross-sectional view showing a state in which the bottom portion of the tension material insertion hole is filled with a solidifying material in one embodiment of the present invention.
【図6】本発明の一実施例において、引張材挿入孔に引
張材を挿入しその下端部を固結材を介して引張材挿入孔
の底部に定着した状態を示す鉛直断面図である。
FIG. 6 is a vertical cross-sectional view showing a state in which the tensile material is inserted into the tensile material insertion hole and the lower end portion is fixed to the bottom portion of the tensile material insertion hole through the solidifying material in the embodiment of the present invention.
【図7】本発明の一実施例において、引張材挿入孔の形
状変更例を示す鉛直断面図である。
FIG. 7 is a vertical cross-sectional view showing an example of changing the shape of the tension member insertion hole in the embodiment of the present invention.
【図8】本発明の一実施例において、引張材挿入孔に挿
入した引張材の上端部にナットを螺合して前記引張材に
軸力を導入した状態を示す鉛直断面図である。
FIG. 8 is a vertical cross-sectional view showing a state in which a nut is screwed onto the upper end portion of the tension member inserted into the tension member insertion hole to apply an axial force to the tension member in one embodiment of the present invention.
【図9】本発明の一実施例において、基礎コンクリート
の形状変更例を示す斜視図である。
FIG. 9 is a perspective view showing an example of changing the shape of basic concrete in one embodiment of the present invention.
【図10】図9のA−A’線における鉛直断面図であ
る。
10 is a vertical cross-sectional view taken along the line AA ′ of FIG.
【図11】本発明の一実施例において、引張材挿入孔と
引張材の間の隙間に固結材を充填した状態を示す部分的
な鉛直断面図である。
FIG. 11 is a partial vertical cross-sectional view showing a state in which the gap between the tension material insertion hole and the tension material is filled with the solidifying material in the embodiment of the present invention.
【符号の説明】[Explanation of symbols]
1 引張材 1a 下端部 1b 上端部 11,11’ 固結材 12 ナット 2 構造物 2a 下部 3 引張材挿入孔 G 砂地盤 1 Tensile material 1a Lower end part 1b Upper end part 11,11 'Consolidation material 12 Nut 2 Structure 2a Lower part 3 Tensile material insertion hole G Sand ground

Claims (4)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 構造物の下部からこの構造物の荷重を支
    持する地盤中に所定間隔で引張材を挿入する工程と、 この引張材の下端部を前記地盤に定着する工程と、 前記引張材の上端部から引張り方向の軸力を導入してこ
    の引張材周囲の地盤に拘束圧を付与する工程と、を備え
    ることを特徴とする地盤の液状化防止方法。
    1. A step of inserting tensile members from a lower portion of a structure into a ground supporting a load of the structure at predetermined intervals, a step of fixing a lower end portion of the tensile material to the ground, and the tensile material. A step of introducing an axial force in the pulling direction from the upper end of the sheet to apply a restraining pressure to the ground around the tensile material, the method for preventing liquefaction of the ground.
  2. 【請求項2】 請求項1の記載において、 引張材は、構造物の下部から地盤中に穿孔した引張材挿
    入孔に挿入し、その下端部を固結材を介して前記引張材
    挿入孔の底部に定着することを特徴とする地盤の液状化
    防止方法。
    2. The tensile member according to claim 1, wherein the tensile member is inserted from a lower portion of a structure into a tensile member insertion hole formed in the ground, and a lower end portion of the tensile member is inserted into the tensile member insertion hole through a solidifying material. A method for preventing liquefaction of the ground, which is characterized by fixing to the bottom.
  3. 【請求項3】 請求項1の記載において、 引張材への軸力の導入は、引張材の上端部に螺合したナ
    ットにより行うことを特徴とする地盤の液状化防止方
    法。
    3. The method for preventing liquefaction of ground according to claim 1, wherein the axial force is introduced into the tensile member by a nut screwed to the upper end portion of the tensile member.
  4. 【請求項4】 請求項1の記載において、 引張材への軸力導入後、この引張材全体をその周囲の地
    盤に固結材を介して定着することを特徴とする地盤の液
    状化防止方法。
    4. The method for preventing liquefaction of ground according to claim 1, wherein after the axial force is applied to the tensile material, the entire tensile material is fixed to the surrounding ground through a solidifying material. .
JP20847395A 1995-07-25 1995-07-25 Method of preventing liquefaction of ground Pending JPH0932005A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP20847395A JPH0932005A (en) 1995-07-25 1995-07-25 Method of preventing liquefaction of ground

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP20847395A JPH0932005A (en) 1995-07-25 1995-07-25 Method of preventing liquefaction of ground

Publications (1)

Publication Number Publication Date
JPH0932005A true JPH0932005A (en) 1997-02-04

Family

ID=16556761

Family Applications (1)

Application Number Title Priority Date Filing Date
JP20847395A Pending JPH0932005A (en) 1995-07-25 1995-07-25 Method of preventing liquefaction of ground

Country Status (1)

Country Link
JP (1) JPH0932005A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008008047A (en) * 2006-06-29 2008-01-17 Penta Ocean Constr Co Ltd Liquefaction preventing structure and method of constructing the same
KR100899372B1 (en) * 2007-07-13 2009-05-26 김정인 Connection method of micropile cap to existing concrete footing structure, reinforced method using same and structure thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008008047A (en) * 2006-06-29 2008-01-17 Penta Ocean Constr Co Ltd Liquefaction preventing structure and method of constructing the same
KR100899372B1 (en) * 2007-07-13 2009-05-26 김정인 Connection method of micropile cap to existing concrete footing structure, reinforced method using same and structure thereof

Similar Documents

Publication Publication Date Title
US6280121B1 (en) Reinforced retaining wall
US6074133A (en) Adjustable foundation piering system
AU724933B2 (en) Method and apparatus for forming piles in-situ
US7326004B2 (en) Apparatus for providing a rammed aggregate pier
CA1335757C (en) Unit comprising mesh combined with geotextile
US4887691A (en) Modular wall construction using posts and panels
US6503024B2 (en) Concrete foundation pierhead and method of lifting a foundation using a jack assembly
US5582492A (en) Method and apparatus for an anchored earth restraining wall
US3541798A (en) Method and structure for shoring a lateral face of an excavation
US4572711A (en) Prestressed component retaining wall system
US6354766B1 (en) Methods for forming a short aggregate pier and a product formed from said methods
York et al. Setup and relaxation in glacial sand
US7033116B1 (en) Post-tensioned rammed earth construction
CA2809638C (en) Extensible shells and related methods for constructing a support pier
Matsuoka et al. A new earth reinforcement method using soilbags
JP4691690B2 (en) Joint structure and joining method of pedestal
US6659692B1 (en) Apparatus and method for supporting a structure with a pier and helix
CA3082307A1 (en) Cementitious foundation cap with post-tensioned helical anchors and method for making the same
US8221034B2 (en) Methods of providing a support column
US4592678A (en) Modular block retaining wall
US7578637B2 (en) Pile with an extended head and working method of its operation
US6503025B1 (en) Precast concrete beam element and methods of making and installing same
US4452028A (en) Structure and method for reinforcing a wall
US9243379B2 (en) Method of providing a support column
EP0533890A1 (en) Short aggregate piers and method and apparatus for producing same.

Legal Events

Date Code Title Description
A977 Report on retrieval

Effective date: 20041130

Free format text: JAPANESE INTERMEDIATE CODE: A971007

A131 Notification of reasons for refusal

Effective date: 20041208

Free format text: JAPANESE INTERMEDIATE CODE: A131

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20050406