JP6283485B2

JP6283485B2 - Ground improvement / pile structure for liquefaction countermeasures and ground improvement / liquefaction countermeasure construction method

Info

Publication number: JP6283485B2
Application number: JP2013186635A
Authority: JP
Inventors: 直樹廣瀬; 一喜久保; 正義鴫原
Original assignee: 株式会社アイ・シー・ジー; テクノハーツ株式会社
Priority date: 2013-09-09
Filing date: 2013-09-09
Publication date: 2018-02-21
Anticipated expiration: 2033-09-09
Also published as: JP2015052253A

Description

本発明は、液状化の可能性のある地盤に対して使用する為の地盤改良／液状化対策用杭構造体及び地盤液状化対策工法に関する。 The present invention relates to a ground improvement / liquefaction countermeasure pile structure and a ground liquefaction countermeasure construction method for use with ground that may be liquefied.

建築・住宅における液状化対策工法は多種の工法があるが、基本的に構造物を安定して支える地盤改良杭と、液状化を防止する為の杭を併用している。これらの工法において大規模建築物の場合はスケールメリットによる経済化を図ることができるが、小規模住宅においては経済的な課題がクローズアップしてくる。そのような中で多くの実績を上げている工法例として建築物を鋼管によって支持する地盤改良杭と液状化防止用ウエルパイプを併用し、地盤改良杭と液状化防止用ウエルパイプとを交互に土壌に打設する工法がある。しかしながら、この工法では地盤改良杭と液状化防止用ウエルパイプの２種類の杭を用いるため、煩雑であり、工事にも時間がかかり、品質面や経済的な面での大きな課題が残っている。 There are various methods of liquefaction countermeasures in buildings and houses. Basically, ground improvement piles that stably support structures and piles to prevent liquefaction are used in combination. In these construction methods, large-scale buildings can be economized by economies of scale, but economic problems are highlighted in small-scale houses. Under such circumstances, as an example of a construction method that has achieved many achievements, a ground improvement pile that supports a building with a steel pipe and a well pipe for preventing liquefaction are used in combination, and a ground improvement pile and a well pipe for preventing liquefaction are alternately used. There is a method of placing in the soil. However, since this method uses two types of piles, a ground improvement pile and a liquefaction-preventing well pipe, it is cumbersome, time-consuming to construct, and significant problems in terms of quality and economy remain. .

これに対して、このような課題を解消するために、地盤改良杭及び液状化防止杭の機能を備えた杭建造物が提案されている。特許文献１参照。特許文献１では、杭建造物を柱状の中実ポーラスコンクリートからなる杭本体とその中に埋設した軸方向及び周方向の鋼線等の補強材によって構成し、杭建造物は地中に直接打設している。従来の支持力杭と同様に、この杭建造物はプレキャストで一体化した中実プレストレスコンクリートで形成するか、あるいは現場で砕石を含むコンクリートを流し込むいわゆる現場打ちコンクリートにより形成する。特許文献１では、設計、施工が合理的に行え、工期短縮と建設費の低減が可能であるとしている。 On the other hand, in order to solve such a problem, a pile structure having functions of a ground improvement pile and a liquefaction prevention pile has been proposed. See Patent Document 1. In Patent Document 1, a pile structure is constituted by a pile body made of columnar solid porous concrete and reinforcing materials such as axial and circumferential steel wires embedded therein, and the pile structure is directly driven into the ground. Has been established. As with conventional bearing piles, this pile structure is made of solid prestressed concrete integrated by precast, or by so-called cast-in-place concrete poured with concrete containing crushed stone on site. According to Patent Document 1, design and construction can be performed rationally, and the construction period can be shortened and the construction cost can be reduced.

しかしながら、一体化したプレストレスコンクリートによる杭建造物は運搬するのに大型車両が必要であり、また地中に直接打ち込むため大型な打ち込み装置が必要であった。また、現場で穴を掘り砕石を含むコンクリートを流し込んで杭建造物を形成するのは煩雑であり、また均一な杭建造物を得るのには、均一な穴を掘り、均一なコンクリート構造を形成し、均一な品質の砕石を含むコンクリートを使用する等の現場での種々の作業を行う必要があった。したがって、工期短縮と建設費の低減という観点から十分とは言えなかった。さらに、外部から杭建造物に周囲の土壌が入り込んだ場合、入り込んだ土壌を外部に押し戻したり、あるいは杭建造物の内部に取り込んで当初の排水性を回復することは困難であった。また、中実もしくは中空の杭建造物を10数センチ〜20センチ径で数メートルの長さにすると、長期の使用により自重で折れてしまう可能性があることが懸念される。 However, a pile structure made of integrated prestressed concrete requires a large vehicle for transportation, and also requires a large driving device to drive directly into the ground. In addition, it is cumbersome to dig a hole on site and pour concrete containing crushed stone to form a pile structure. To obtain a uniform pile structure, dig a uniform hole to form a uniform concrete structure. However, it was necessary to perform various on-site operations such as using concrete containing crushed stone of uniform quality. Therefore, it was not sufficient from the viewpoint of shortening the construction period and reducing construction costs. Furthermore, when the surrounding soil entered the pile structure from the outside, it was difficult to restore the original drainage by pushing the introduced soil back to the outside or taking it into the pile structure. Moreover, when a solid or hollow pile building is made several tens of centimeters to 20 centimeters in diameter and several meters long, there is a concern that it may break due to its own weight due to long-term use.

特開平７−２８６３２３JP-A-7-286323

そこで、本発明者は、複数の中空の地盤改良杭と液状化対策用杭を一体のユニットに組み込んだ地盤改良／液状化対策用杭構造体とすることによって、１本の杭構造体で地盤改良と液状化対策を可能とし、連続的に内部に中空部を形成しているので良好な排水性を確保することを可能とし、また工場で適正な品質管理の下で地盤改良／液状化対策用杭ユニットを製造することができ、輸送が容易で、かつ現場で土中に地盤改良／液状化対策用杭ユニットを組み立てて製造することを可能にすることで、品質、工数、経済性の改善を図った地盤改良／液状化対策用杭構造体と、土中に地盤改良／液状化対策用杭構造体を形成する地盤改良／液状対策工法を提供することを目的とする。 Therefore, the present inventor made a ground structure with a single pile structure by making a ground improvement / liquefaction countermeasure pile structure in which a plurality of hollow ground improvement piles and a liquefaction countermeasure pile were incorporated into an integrated unit. Improvement and liquefaction countermeasures are possible, and continuous hollows are formed to ensure good drainage, and ground improvement / liquefaction countermeasures under proper quality control at the factory Pile units can be manufactured, transported easily, and it is possible to assemble and manufacture pile units for ground improvement / liquefaction countermeasures in the soil at the site. An object of the present invention is to provide a ground improvement / liquefaction countermeasure pile structure for improvement, and a ground improvement / liquid countermeasure method for forming a ground improvement / liquefaction countermeasure pile structure in the soil.

以下に、本発明の課題を解決するための手段を示す。
（請求項１）
地盤改良／液状化対策用杭構造体によって地盤改良／液状化対策を行う地盤改良／液状化対策工法であって、
該地盤改良／液状化対策用杭構造体は、多量の連続した空隙を有する透水性コンクリートからなる両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニットを複数個有し、それぞれの該中空円筒形状の地盤改良／液状化対策用杭ユニットの中空部は連通しかつ円筒形外周部がそれぞれ同心円状に配置され、該上下地盤改良／液状化対策用杭ユニットの端部を突き合わせた状態で上下に積み重ねることによって形成された地盤改良／液状化対策用杭構造体であって、上下に位置する該地盤改良／液状化対策用杭ユニットの端面間に、地盤改良／液状化対策用杭ユニットの外径に等しいか大きい外径を有し、非圧縮性の弾性素材からなる環状の緩衝材を介装しており、
前記地盤改良／液状化対策用杭構造体を地盤に貫入する際に、両端開口の円筒形中空金属ケーシング部と該円筒形中空金属ケーシング部の下端に着脱自在に設けられた蓋部とからなり、かつ該地盤改良／液状化対策用杭構造体の外周部に対して接触抵抗がない程度のクリアランスを有する内周面を備えた中空の金属ケーシングを準備し、
前記地盤改良／液状化対策用杭構造体を構成する前記複数の中空円筒形状の地盤改良／液状化対策用杭ユニットを、それらの端面間に弾性素材からなる環状の緩衝材を介装した状態で、該蓋の上でかつ該中空金属ケーシングの中空部内に収納し前記地盤改良／液状化対策用杭構造体を形成し、
該中空金属ケーシングを地中に貫入させる際には、
（１）地上の金属ケーシングの中空部に複数の地盤改良／液状化対策用杭ユニット及び緩衝材を積み重ねることにより地盤改良／液状化対策用杭ユニットを形成した状態で、これらを一緒に地盤に貫入させる場合、中空部に複数の地盤改良／液状化対策用杭ユニット及び緩衝材を積み重ねることにより地盤改良／液状化対策用杭ユニットを形成した状態で、これらを一緒に地盤に貫入させた後、若しくは、
（２）金属ケーシングのみを地盤に途中まで貫入させた後、地盤改良／液状化対策用杭構造体を金属ケーシング内に形成後、さらに金属ケーシングを所定の深さまで貫入させた後、若しくは、
（３）金属ケーシングのみを地盤に所定の最後の深さまで貫入させた後、地盤改良／液状化対策用杭構造体を金属ケーシング内に形成した後、
該蓋部は前記地盤改良／液状化対策用杭構造体の下端部に留まらせた状態で、該円筒形金属ケーシング部を地中から引き上げ、土中に前記地盤改良／液状化対策用杭構造体を埋設させることにより、地盤改良／液状化対策用杭構造体によって地盤改良／液状化対策を行う地盤改良／液状化対策工法。
Means for solving the problems of the present invention will be described below.
(Claim 1)
Ground improvement / Liquefaction countermeasure construction method for ground improvement / Liquefaction countermeasures by soil improvement / Liquefaction countermeasure pile structure,
The pile structure for soil improvement / liquefaction countermeasures has a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units having both ends open and made of water-permeable concrete having a large amount of continuous voids. The hollow part of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit is in communication and the cylindrical outer peripheral part is arranged concentrically, and the end of the upper foundation improvement / liquefaction countermeasure pile unit is abutted A pile structure for ground improvement / liquefaction countermeasures formed by stacking up and down at the bottom, and between the end faces of the pile unit for ground improvement / liquefaction countermeasures located above and below, a pile for ground improvement / liquefaction countermeasures It has an outer diameter that is equal to or larger than the outer diameter of the unit, and is equipped with an annular cushioning material made of an incompressible elastic material,
When penetrating the ground improvement / liquefaction countermeasure pile structure into the ground, it comprises a cylindrical hollow metal casing part with openings at both ends and a lid part detachably provided at the lower end of the cylindrical hollow metal casing part. and preparing a hollow metal casing with an inner peripheral surface having a degree of clearance is no contact resistance with respect to the outer peripheral portion of the ground improvement / liquefaction countermeasure pile structure,
The plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units constituting the ground improvement / liquefaction countermeasure pile structure are provided with an annular cushioning material made of an elastic material between their end faces. And forming the pile structure for ground improvement / liquefaction countermeasures on the lid and in the hollow part of the hollow metal casing,
When penetrating the hollow metal casing into the ground,
(1) In a state where a ground improvement / liquefaction countermeasure pile unit is formed by stacking a plurality of ground improvement / liquefaction countermeasure pile units and cushioning materials in the hollow portion of the ground metal casing, In the case of penetration, after a plurality of ground improvement / liquefaction countermeasure pile units and cushioning materials are stacked in the hollow portion to form a ground improvement / liquefaction countermeasure pile unit, these are penetrated into the ground together. Or
(2) After only the metal casing penetrates into the ground partway, after the ground improvement / liquefaction countermeasure pile structure is formed in the metal casing, and further, the metal casing is penetrated to a predetermined depth, or
(3) After only the metal casing is penetrated into the ground to a predetermined final depth, after the pile structure for ground improvement / liquefaction measures is formed in the metal casing,
The lid is held at the lower end of the soil improvement / liquefaction countermeasure pile structure, and the cylindrical metal casing is pulled up from the ground, and the soil improvement / liquefaction countermeasure pile structure is submerged in the soil. Ground improvement / liquefaction countermeasure construction method that performs ground improvement / liquefaction countermeasures by pile structure for ground improvement / liquefaction countermeasures by burying the body.

（請求項２）
地盤改良／液状化対策用杭構造体によって地盤改良／液状化対策を行う地盤改良／液状化対策工法であって、
該地盤改良／液状化対策用杭構造体は、多量の連続した空隙を有する透水性コンクリートからなる両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニットを複数個有し、それぞれの該中空円筒形状の地盤改良／液状化対策用杭ユニットの中空部は連通しかつ円筒形外周部がそれぞれ同心円状に配置され、該上下地盤改良／液状化対策用杭ユニットの端部を突き合わせた状態で上下に積み重ねることによって形成された地盤改良／液状化対策用杭構造体であって、上下に位置する該地盤改良／液状化対策用杭ユニットの端面間に、地盤改良／液状化対策用杭ユニットの外径に等しいか大きい外径を有し、非圧縮性の弾性素材からなる環状の緩衝材を介装しており、
前記地盤改良／液状化対策用杭構造体を地盤に貫入する際に、円筒形金属軸部と該円筒形金属軸部の下端に着脱自在に設けられかつ該地盤改良／液状化対策用杭構造体の外径より大きい外径を有する蓋部とからなり、かつ該地盤改良／液状化対策用杭構造体の内周部に対して接触抵抗がない程度のクリアランスを有する外周面を備えた円筒形金属軸を準備し、
前記地盤改良／液状化対策用杭構造体を構成する前記複数の地盤改良／液状化対策用杭ユニットを、それらの端面間に弾性素材からなる環状の緩衝材を介装した状態で、該蓋の上でかつ該金属軸部の外周に装着し前記地盤改良／液状化対策用杭構造体を形成し、
該中空金属軸を地中に貫入させる際には、
（１）予め複数の地盤改良／液状化対策用杭ユニットにより地盤改良／液状化対策用杭構造体を地上に位置する該蓋部の上でかつ金属軸部の外周に形成した状態で、これらを一緒に地盤に貫入させた後、若しくは、
（２）金属軸のみを地盤に途中まで貫入させた後、複数の地盤改良／液状化対策用杭ユニットにより地盤改良／液状化対策用杭構造体を該蓋部の上でかつ金属軸部の外周に配置し地盤改良／液状化対策用杭構造体を金属軸の外周に形成した状態で、さらに金属ケーシングを所定の深さまで貫入させ地中に埋設した後、
該蓋部は前記地盤改良／液状化対策用杭構造体の下端部に留まらせた状態で、該円筒形金属軸部を地中から引き上げ、土中に前記地盤改良／液状化対策用杭構造体を埋設させることにより、地盤改良／液状化対策用杭構造体によって地盤改良／液状化対策を行う地盤改良／液状化対策工法。
(Claim 2)
Ground improvement / Liquefaction countermeasure construction method for ground improvement / Liquefaction countermeasures by soil improvement / Liquefaction countermeasure pile structure,
The pile structure for soil improvement / liquefaction countermeasures has a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units having both ends open and made of water-permeable concrete having a large amount of continuous voids. The hollow part of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit is in communication and the cylindrical outer peripheral part is arranged concentrically, and the end of the upper foundation improvement / liquefaction countermeasure pile unit is abutted A pile structure for ground improvement / liquefaction countermeasures formed by stacking up and down at the bottom, and between the end faces of the pile unit for ground improvement / liquefaction countermeasures located above and below, a pile for ground improvement / liquefaction countermeasures It has an outer diameter that is equal to or larger than the outer diameter of the unit, and is equipped with an annular cushioning material made of an incompressible elastic material,
When the pile structure for ground improvement / liquefaction countermeasures penetrates into the ground, the pile structure for ground improvement / liquefaction countermeasures is provided detachably at the cylindrical metal shaft portion and the lower end of the cylindrical metal shaft portion. It consists of a lid having an outer diameter greater than the outer diameter of the body, and having an outer peripheral surface having a clearance of degree no contact resistance with the inner peripheral portion of the ground improvement / liquefaction countermeasure pile structure cylindrical Prepare a metal shaft,
The plurality of ground improvement / liquefaction countermeasure pile units constituting the ground improvement / liquefaction countermeasure pile structure are covered with an annular cushioning material made of an elastic material between their end faces. A pile structure for ground improvement / liquefaction measures is formed on the outer periphery of the metal shaft and
When penetrating the hollow metal shaft into the ground,
(1) With a plurality of ground improvement / liquefaction countermeasure pile units, a ground improvement / liquefaction countermeasure pile structure is formed on the outer periphery of the metal shaft part on the lid portion located on the ground. Or to penetrate the ground together, or
(2) After allowing only the metal shaft to penetrate partway into the ground, a plurality of ground improvement / liquefaction countermeasure pile units are used to place the ground improvement / liquefaction countermeasure pile structure on the lid and the metal shaft portion. With the pile structure for ground improvement / liquefaction countermeasures formed on the outer periphery and formed on the outer periphery of the metal shaft, the metal casing is further penetrated to a predetermined depth and buried in the ground.
The lid is held at the lower end of the soil improvement / liquefaction countermeasure pile structure, the cylindrical metal shaft is pulled up from the ground, and the soil improvement / liquefaction countermeasure pile structure is submerged in the soil. Ground improvement / liquefaction countermeasure construction method that performs ground improvement / liquefaction countermeasures by pile structure for ground improvement / liquefaction countermeasures by burying the body.

以下の態様は、本発明の好ましい態様である。
（請求項３）
前記緩衝材は上下の地盤改良／液状化対策用杭ユニットの端部の中空部に嵌合させる上下に延びる管状部と管状部の中央部半径方向外方に延びるフランジ部とからなり、該フランジ部の外径が前記地盤改良／液状化対策用杭ユニットの外径より大きい、請求項１または２に記載の地盤改良／液状化対策工法。
The following aspects are preferred aspects of the present invention.
(Claim 3)
The cushioning material includes a vertically extending tubular portion that fits into a hollow portion at an end of the upper and lower ground improvement / liquefaction countermeasure pile units, and a flange portion that extends radially outward from the central portion of the tubular portion. The ground improvement / liquefaction countermeasure construction method according to claim 1 or 2 , wherein the outer diameter of the portion is larger than the outer diameter of the pile unit for ground improvement / liquefaction countermeasures.

（請求項４）
前記地盤改良／液状化対策用杭構造体の中空部には、該中空部は確保されつつ軸方向に延びる長尺の剛性支持軸部材が挿入され、該長尺剛性支持軸部材は各々の前記地盤改良／液状化対策用杭ユニットの内周面に対して周方向に見て3箇所以上の箇所でかつ少なくとも該地盤改良／液状化対策用杭ユニットの内周面を支持するのに必要とされる長さに亘り接触・保持している、請求項１〜３のいずれかに記載の地盤改良／液状化対策工法。
（請求項５）
前記地盤改良／液状化対策用杭ユニットの内部に軸方向及び／又は周方向に延びる耐腐食性線状補強材を埋設している、請求項１乃至４のいずれかに記載の地盤改良／液状化対策工法。
(Claim 4)
A long rigid support shaft member extending in the axial direction while the hollow portion is secured is inserted into the hollow portion of the ground improvement / liquefaction countermeasure pile structure. Necessary to support at least three inner peripheral surfaces of the ground improvement / liquefaction countermeasure pile unit as viewed in the circumferential direction with respect to the inner peripheral surface of the soil improvement / liquefaction countermeasure pile unit. The ground improvement / liquefaction countermeasure construction method according to any one of claims 1 to 3, wherein the ground improvement / liquefaction prevention method is in contact with and held over the length of the ground.
(Claim 5)
The ground improvement / liquid state according to any one of claims 1 to 4, wherein a corrosion-resistant linear reinforcing material extending in the axial direction and / or the circumferential direction is embedded in the pile unit for soil improvement / liquefaction countermeasures. Chemical countermeasure construction method.

（請求項６）
前記中空円筒形状の地盤改良／液状化対策用杭ユニットの外周面には、上下に延びる導水溝が周方向に見て複数設けられ、該溝には多孔性排水路形成部材が設けられている、請求項１乃至５のいずれかに記載の地盤改良／液状化対策工法。
（請求項７）
前記地盤改良／液状化対策用杭ユニットの外周面が、目詰まりを低減させかつ該地盤改良／液状化対策用杭ユニットの外形を保持するための多孔性保形シートで覆われている、請求項１乃至６のいずれかに記載の地盤改良／液状化対策工法。
(Claim 6)
On the outer peripheral surface of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit, a plurality of vertically extending water guide grooves are provided in the circumferential direction, and a porous drainage forming member is provided in the groove. The ground improvement / liquefaction countermeasure construction method according to any one of claims 1 to 5.
(Claim 7)
The outer peripheral surface of the soil improvement / liquefaction countermeasure pile unit is covered with a porous shape retaining sheet for reducing clogging and maintaining the outer shape of the soil improvement / liquefaction countermeasure pile unit. Item 7. Ground improvement / liquefaction countermeasure method according to any one of Items 1 to 6.

本発明は、上記構成により以下の効果を有する。
（１）１本の地盤改良／液状化対策用杭構造体で地盤改良と液状化対策とを同時に可能とし、連続的に内部に中空部を形成しているので良好な排水性を確保することが可能であり、中空としたので重量及び材料費を大幅に削減できる。また、１本の地盤改良／液状化対策用杭構造体を複数の中空円筒形状の地盤改良／液状化対策用杭ユニットに分割形成しているので、製造から運搬、保管や操作時に不意に掛かる曲げ応力や自重で折れることはない。
（２）請求項１に記載するように、地盤改良／液状化対策用杭構造体は、蓋の上でかつ中空金属ケーシングの内部に確保された中空部に複数の中空円筒形状の地盤改良／液状化対策用杭ユニットを環状の緩衝材を介して上下に積み重ねて形成・埋設することが可能であるので、地盤改良／液状化対策用杭構造体が貫入される際に周囲の土が摩擦接触して地盤改良／液状化対策用杭構造体の表面に入り込むことを防止するとともに、軸方向に圧縮力が付加されることを防止することができる。
（３）請求項２に記載するような金属軸を用いる場合も、発明の効果（１）と同様に地盤改良／液状化対策用杭構造体が貫入される際に周囲の土が摩擦接触して地盤改良／液状化対策用杭構造体の表面に入り込むことを実質的に防止するとともに、捻じれ力や軸方向に過大な圧縮力が付加されることを防止することができる。 The present invention has the following effects by the above configuration.
(1) A single pile improvement / liquefaction countermeasure pile structure enables simultaneous ground improvement and liquefaction countermeasures, and a continuous hollow portion is formed to ensure good drainage. Since it is hollow, the weight and material cost can be greatly reduced. In addition, since one pile structure for soil improvement / liquefaction countermeasures is divided into a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units, it is unexpectedly suspended during manufacture, transportation, storage and operation. It does not break due to bending stress or its own weight.
(2) As described in claim 1, the pile structure for ground improvement / liquefaction countermeasures is provided with a plurality of hollow cylindrical ground improvements in the hollow portion secured on the lid and inside the hollow metal casing. The pile unit for liquefaction countermeasures can be formed and buried by stacking up and down with an annular cushioning material, so that the soil around the soil is rubbed when the pile structure for soil improvement / liquefaction countermeasures penetrates. While preventing contact and entering the surface of the pile structure for ground improvement / liquefaction measures, it is possible to prevent compressive force from being applied in the axial direction.
(3) In the case of using a metal shaft as described in claim 2, the surrounding soil is brought into frictional contact when the soil improvement / liquefaction countermeasure pile structure is penetrated as in the effect (1) of the invention. As a result, it is possible to substantially prevent the soil improvement / liquefaction countermeasure pile structure from entering the surface and to prevent the twisting force and the excessive compression force from being applied in the axial direction.

（４）一体に製造された杭構造体を現地環境下で埋設するのではなく、地盤改良／液状化対策用杭構造体を構成する中空円筒形状の短尺な地盤改良／液状化対策用杭ユニットを管理された工場内で製造できるので、寸法精度や品質の管理が十分に行われ、所望の規格化された当該杭ユニットが得られる。
従って、複数の中空円筒形状の地盤改良／液状化対策用杭ユニットを弾性素材からなる環状の緩衝材を介装した状態で上下に積み重ねて形成される杭構造体も、組み立て寸法精度が高く製品品質に優れる。
（５）中空円筒状の地盤改良／液状化対策用杭ユニットの外径、内径、その長さ、透水性コンクリートの性状等の構造を、地盤の状況に応じて適切に選んで規格化した複数種類の中空円筒状の地盤改良／液状化対策用杭ユニットを準備することが可能となる。
（６）短尺の中空円筒形状の地盤改良／液状化対策用杭ユニットの形状のまま現地まで運んで地盤改良／液状化対策用杭構造体を組み立てるので、地盤改良／液状化対策用杭ユニットの品質を維持し、容易に保管、輸送及び操作をすることができる。 (4) Rather than burying an integrally manufactured pile structure in the local environment, a hollow cylindrical short pile improvement / liquefaction countermeasure pile unit that constitutes a pile structure for ground improvement / liquefaction countermeasures Can be manufactured in a controlled factory, dimensional accuracy and quality can be sufficiently controlled, and a desired standardized pile unit can be obtained.
Therefore, a pile structure formed by stacking a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units vertically with an annular cushioning material made of an elastic material is also highly productive. Excellent quality.
(5) Plurality of hollow cylinder-shaped soil improvement / liquefaction countermeasure pile units that are appropriately selected and standardized according to the ground conditions, such as the outer diameter, inner diameter, length, and properties of permeable concrete It becomes possible to prepare a type of hollow cylindrical ground improvement / liquefaction countermeasure pile unit.
(6) Since the pile structure for ground improvement / liquefaction countermeasures is assembled in the form of a short hollow cylindrical ground improvement / liquefaction countermeasure pile unit, the pile structure for ground improvement / liquefaction countermeasures is assembled. Maintains quality and can be easily stored, transported and operated.

（７）現地で施工中に複数の中空円筒形状の地盤改良／液状化対策用杭ユニットを弾性素材からなる環状の緩衝材を介装して中空円筒状の地盤改良／液状化対策用杭ユニットの中空部あるいは金属軸部の外周に上下に積み重ねて地盤改良／液状化対策用杭構造体を形成するので、長尺脆性材料に対する不要な配慮もなくなり、作業労力及び作業面積を小さく出来る。
（８）地震による液状化現象を生じた際、地盤中の水圧は地盤改良／液状化対策用杭構造体の半径方向内側に向けてかかり、余剰の地下水は当該杭構造体の半径方向外側から内側の中空部に透水し、杭構造体の中空内部に入った地下水は中空部内部を通って地上へと導かれる構造となっているので、余剰地下水は効率的に地上へと排水される。
（９）地盤改良／液状化対策用杭構造体の空隙に多少土壌が侵入することも懸念されるが、杭構造体を中空構造とし中空部を大気に開放し大気圧としているので、地震の振動により目詰まりが解消され、また地震により地下水圧が上昇した場合には上昇した圧力を中空杭構造体の内外の圧力差により杭構造体の中空部に迅速に逃がすとともに、それに伴い土壌による杭構造体の目詰まりを解消することができる。 (7) Soil improvement / liquefaction countermeasure pile unit with a plurality of hollow cylinders during construction at the site with a hollow cylindrical ground improvement / liquefaction countermeasure pile unit with an annular cushioning material made of an elastic material Since the pile structure for ground improvement / liquefaction measures is formed by stacking up and down on the outer periphery of the hollow part or metal shaft part, unnecessary consideration for the long brittle material is eliminated, and the work labor and work area can be reduced.
(8) When a liquefaction phenomenon occurs due to an earthquake, the water pressure in the ground is applied radially inward of the pile structure for ground improvement / liquefaction countermeasures, and surplus groundwater flows from the radially outer side of the pile structure. Since the groundwater that has permeated into the inner hollow portion and entered the hollow interior of the pile structure is guided to the ground through the hollow portion, excess groundwater is efficiently drained to the ground.
(9) There is a concern that some soil may enter the voids of the pile structure for soil improvement / liquefaction countermeasures, but the pile structure is hollow and the hollow part is open to the atmosphere, so it is at atmospheric pressure. When clogging is eliminated by vibration and the groundwater pressure increases due to an earthquake, the increased pressure is quickly released to the hollow part of the pile structure due to the pressure difference between the inside and outside of the hollow pile structure, and the soil pile The clogging of the structure can be eliminated.

（１０）一方、バクテリアなどが繁殖して詰まってしまうバイオーケミカル的な目詰まり現象があり得るが、中空地盤改良／液状化対策用杭構造体の場合には、地盤より熱伝導係数が大きな中空部内部の温度は表面温度の変化を受け、温度上昇時に内圧が増加し、中空地盤改良／液状化対策用杭構造体におけるせん断力の弱い膜状の目詰まり部分は破壊される。この温度変化は周期的なもので、常に杭構造体内外の温度差の変動に依存する呼吸現象的な流体の移動によりバイオーケミカル的な目詰まり現象は解消される。
（１１）上下に位置する中空円筒形状の地盤改良／液状化対策用杭ユニットの端面間に、弾性素材からなる環状の緩衝材を介装しているので、各中空円筒形状の地盤改良／液状化対策用杭ユニットの突き当て端部における応力集中による微細破壊から適正に保護され、地盤改良／液状化対策用杭ユニット、ひいては地盤改良／液状化対策用杭構造体の形状安定性が図られる。
（１２）長尺剛性支持軸部材により、地盤改良／液状化対策用杭構造体の中空部を確実に確保するとともに、軸方向及び半径方向の耐圧縮強度を向上することが可能となり、杭構造体の構造安定性が高まる。
(10) On the other hand, there may be a bio-chemical clogging phenomenon where bacteria and the like propagate and clog, but in the case of a pile structure for hollow ground improvement / liquefaction countermeasures, the thermal conductivity coefficient is larger than that of the ground. The temperature inside the hollow part is affected by changes in the surface temperature, the internal pressure increases as the temperature rises, and the clogged part with weak shear force in the hollow ground improvement / liquefaction countermeasure pile structure is destroyed. This temperature change is periodic, and the bio-chemical clogging phenomenon is solved by the movement of the respiration phenomenon fluid that always depends on the fluctuation of the temperature difference inside and outside the pile structure.
(11) Ground improvement of the hollow cylindrical shape positioned above and below / Because an annular cushioning material made of an elastic material is interposed between the end faces of the liquefaction countermeasure pile unit, each hollow cylindrical ground improvement / liquid It is properly protected from microfracture due to stress concentration at the abutting end of the anti-liquefaction pile unit, and the shape stability of the ground improvement / liquefaction countermeasure pile unit and eventually the ground improvement / liquefaction countermeasure pile structure is achieved. .
(12) The long rigid support shaft member can surely secure the hollow portion of the pile structure for ground improvement / liquefaction countermeasures, and can improve the compressive strength in the axial direction and the radial direction. Increases the structural stability of the body.

（ａ）は中空円筒形状の地盤改良／液状化対策用杭ユニットの斜視図であり、（ｂ）と（ｃ）は中空円筒形状の地盤改良／液状化対策用杭ユニットの断面図である。(A) is a perspective view of a hollow cylindrical ground improvement / liquefaction countermeasure pile unit, and (b) and (c) are cross-sectional views of a hollow cylindrical ground improvement / liquefaction countermeasure pile unit. （ａ）は地上で中空金属ケーシングの内部に中空円筒形状の地盤改良／液状化対策用杭ユニットを緩衝材を介して積重ねる態様を説明する図であり、（ｂ）は3個の地盤改良／液状化対策用杭ユニットを収容した金属ケーシングを土中に貫入させた模式図であり、（ｃ）は蓋部を最下端の地盤改良／液状化対策用杭ユニットの下に残留させた状態で、中空金属ケーシングを引き抜いた図であり、（ｄ）は金属ケーシング引き抜き後周囲の土壌が金属ケーシング引き抜き穴から残留した当該杭の径まで戻った状態を示す図である。(A) is a figure explaining the aspect which piles up pile unit for a hollow cylindrical ground improvement / liquefaction countermeasure pile unit through a shock absorbing material inside a hollow metal casing on the ground, (b) is three ground improvement / Schematic view of a metal casing containing a liquefaction countermeasure pile unit inserted into the soil, (c) is a state in which the lid is left under the bottommost ground improvement / liquefaction countermeasure pile unit FIG. 6D is a diagram illustrating a state in which the hollow metal casing is pulled out, and (d) is a diagram illustrating a state in which the surrounding soil has returned to the diameter of the remaining pile from the metal casing pull-out hole after the metal casing is pulled out. （ａ）と（ｂ）は、それぞれ上下に位置する中空円筒形状の地盤改良／液状化対策用杭ユニットの端面間に介装される緩衝材を示す。(A) And (b) shows the shock absorbing material interposed between the end surfaces of the hollow cylinder-shaped ground improvement / liquefaction countermeasure pile unit located up and down, respectively. （ａ）は中空金属ケーシング内部に3個の下から上へと順に直径を大きくした地盤改良／液状化対策用杭ユニットを緩衝材を介して積層し地盤改良／液状化対策用杭構造体を形成し金属ケーシングと共に土中に貫入させた図であり、（ｂ）は蓋部を最下端の地盤改良／液状化対策用杭ユニットの下に残留させた状態で、金属ケーシングを引き抜いた後の状態図である。(A) In the hollow metal casing, piles of soil improvement / liquefaction countermeasure pile units with a diameter increasing in order from the bottom to the top are stacked with cushioning material, and the soil improvement / liquefaction prevention pile structure is formed. It is the figure which formed and penetrated into the soil with the metal casing, and (b) is the state after the metal casing was pulled out with the lid part remaining under the bottom soil improvement / liquefaction countermeasure pile unit. It is a state diagram. (ａ)、（ｂ）、（c）及び（d）は軸方向に延びる長尺の剛性支持軸部材が地盤改良／液状化対策用杭構造体の中空部に挿入された状態を示す断面図である。(a), (b), (c) and (d) are sectional views showing a state in which a long rigid support shaft member extending in the axial direction is inserted into the hollow portion of the pile structure for ground improvement / liquefaction measures It is. （ａ）及び（ｂ）はそれぞれ中空金属ケーシングの下端部に着脱自在に設ける蓋部の断面図を示す。(A) And (b) shows sectional drawing of the cover part detachably provided in the lower end part of a hollow metal casing, respectively. （ａ）及び（ｂ）は、内部に軸方向及び周方向に延びる耐腐食性線状補強材を埋設している前記中空円筒形状の地盤改良／液状化対策用杭ユニットを示す。(A) And (b) shows the said hollow cylindrical ground improvement / liquefaction countermeasure pile unit which has embed | buried the corrosion-resistant linear reinforcement extended in an axial direction and the circumferential direction inside. （ａ）は前記中空円筒形状の地盤改良／液状化対策用杭ユニットの外周面に、上下に導水する機能を有する溝が設けられていることを示す図、（ｂ）該溝には多孔性排水路形成部材が設けられていることを示す図、（ｃ）は多孔性排水路形成部材の一例を示す拡大斜視図である。(A) is a figure which shows that the groove | channel which has the function to conduct water up and down is provided in the outer peripheral surface of the said hollow cylindrical ground improvement / liquefaction countermeasure pile unit, (b) Porous in this groove | channel The figure which shows that the drainage channel formation member is provided, (c) is an expansion perspective view which shows an example of a porous drainage channel formation member. （ａ）は地上で金属軸の外周部に中空円筒形状の地盤改良／液状化対策用杭ユニットを緩衝材によって介装して積重ねる態様を説明する図であり、（ｂ）は3個の地盤改良／液状化対策用杭ユニットを外周部に積層した金属軸を土中に貫入させた模式図である。(A) is a figure explaining the aspect which piles up and piles the pile unit for ground improvement / liquefaction measures pile units of a hollow cylinder shape on the outer peripheral part of a metal shaft on the ground, with a cushioning material, (b) It is the schematic diagram which penetrated the metal shaft which laminated | stacked the pile unit for ground improvement / liquefaction countermeasures on the outer peripheral part in the soil.

図面を参照して、本発明を具体的に説明する。但し、本発明は図示されるものに限定されるものではなく、特許請求の範囲に包含されるのであれば、種々の変更が可能であり、それらのものも本発明の範囲内に含まれる。 The present invention will be specifically described with reference to the drawings. However, the present invention is not limited to what is shown in the drawings, and various modifications are possible as long as they are included in the scope of the claims, and such modifications are also included in the scope of the present invention.

本発明の地盤改良／液状化対策用杭構造体は、多量の連続した空隙を有する透水性コンクリートからなる両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニットを複数個有し、該地盤改良／液状化対策用杭ユニットの中空部は連通しかつ円筒形外周部がそれぞれ同心円状に配置され、上下地盤改良／液状化対策用杭ユニットの端部を緩衝材を介して突き合わせた状態で上下に積み重ねることによって形成された地盤改良／液状化対策用杭構造体である。 The pile structure for ground improvement / liquefaction countermeasures of the present invention has a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units having both ends open made of permeable concrete having a large amount of continuous voids, The hollow part of the ground improvement / liquefaction countermeasure pile unit communicates and the cylindrical outer peripheral part is arranged concentrically, and the end of the upper ground improvement / liquefaction countermeasure pile unit is abutted via a cushioning material. It is a pile structure for ground improvement / liquefaction measures formed by stacking up and down.

（１）両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニット
図１は、両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニット１の一実施例を示す。地盤改良／液状化対策用杭ユニット１は、多量の連続した空隙を有する透水性コンクリートから製造される。ここで、本実施例において、多量の連続した空隙を有する透水性コンクリートは、例えば、セメントを、山砂および硬質砂岩砕砂などの細骨材や硬質砂岩砕石などの粗骨材を用い、これに水と減水剤とを加え、配合し、混練り硬化したものを使用する。例えば、セメントＣとして普通ポルトランドセメントを、細骨材Ｓとして山砂および硬質砂岩砕砂を、粗骨材Ｇとして硬質砂岩砕石を用い、これに水Ｗと、混和剤としての減水剤とを加え、配合し、混練り硬化したものを使用する。配合割合としては、例えば以下のものがある（単位はｋｇ／ｃｍ３）。
Ｗ＝80 、Ｃ＝300 、Ｓ＝80 、Ｇ＝1500 、減水剤＝30 、
Ｗ／Ｃ（水セメント比）＝約30% (1) Soil Improvement / Liquefaction Countermeasure Pile Unit with Hollow Cylindrical Shape with Opening at Both Ends FIG. 1 shows an embodiment of a hollow cylindrical ground improvement / liquefaction countermeasure pile unit 1 with open ends. The soil improvement / liquefaction countermeasure pile unit 1 is manufactured from water-permeable concrete having a large amount of continuous voids. Here, in this embodiment, the permeable concrete having a large amount of continuous voids is made of, for example, cement using fine aggregates such as mountain sand and hard sandstone crushed sand, and coarse aggregates such as hard sandstone crushed stone. Add water, water reducing agent, blend, knead and harden. For example, ordinary Portland cement is used as cement C, mountain sand and hard sandstone crushed sand as fine aggregate S, hard sandstone crushed stone as coarse aggregate G, water W and a water reducing agent as an admixture are added thereto, A compounded, kneaded and cured product is used. Examples of the blending ratio include the following (unit: kg / cm3).
W = 80, C = 300, S = 80, G = 1500, water reducing agent = 30,
W / C (water cement ratio) = about 30%

多量の連続した空隙を有する透水性コンクリートについては、空隙率は主に細骨材比（細骨材／（細骨材＋粗骨）を適宜調整することによって変更することが出来る。また、空隙率が上がると、耐圧縮破壊荷重が小さくなり、空隙率が小さくなると耐圧縮荷重が大きくなる。耐圧縮破壊荷重は、ＡｘＢによって決まる（図１（ｂ）に示す中空円筒形状の地盤改良／液状化対策用杭ユニットの場合、断面積Ａ＝（Ｄ_１ ^２ーＤ_２ ^２）ｘ３．１４と単位面積あたりの圧縮強度Ｂｋｇｆ／ｃｍ^３の積）。地盤改良／液状化対策用杭ユニットに求められる圧縮強度Ｂｋｇｆ／ｃｍ^３）をもとに、中空円筒形状の地盤改良／液状化対策用杭ユニットの外径Ｄ１と内径Ｄ２を適宜選択する。なお、地盤改良／液状化対策用杭ユニットの壁厚Ｄ１−Ｄ２を薄くするとドレイン効果が大きくなり、厚くすると圧縮強度が大きくなる。地盤改良／液状化対策用杭ユニットの壁厚Ｄ１−Ｄ２は、ドレイン効果及び圧縮強度の観点から適宜設定する。 For water-permeable concrete having a large amount of continuous voids, the porosity can be changed mainly by appropriately adjusting the fine aggregate ratio (fine aggregate / (fine aggregate + coarse)). When the rate increases, the compressive fracture load decreases, and when the porosity decreases, the compressive load increases.The compressive fracture load is determined by AxB (see FIG. 1 (b)). In the case of a pile unit for anti-liquefaction measures, the cross-sectional area A = (D ₁ ² −D ₂ ² ) × 3.14 and the product of compressive strength Bkgf / cm ³ per unit area. The outer diameter D1 and the inner diameter D2 of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit are appropriately selected based on the compression strength Bkgf / cm ³ ). In addition, if the wall thickness D1-D2 of the pile unit for ground improvement / liquefaction measures is reduced, the drain effect is increased, and if it is increased, the compressive strength is increased. The wall thickness D1-D2 of the soil improvement / liquefaction countermeasure pile unit is appropriately set from the viewpoint of the drain effect and the compressive strength.

連続した空隙を有する透水性コンクリートについては、空隙率が上がると、耐圧縮破壊荷重が小さくなり、空隙率が小さくなると耐圧縮荷重が大きくなるとの相反する要求特性の組合せになる。従って、中空円筒形状の地盤改良／液状化対策用杭ユニットの外径Ｄ１と内径Ｄ２を適宜選択する必要が有る。
中空円筒形状の地盤改良／液状化対策用杭ユニットの寸法としては、例えば、外径Ｄ１を２００ｍｍ以下（例えば、１６０ｍｍ〜１４０ｍｍ）、内径Ｄ２を８０〜１００ｍｍとすれば圧縮強度は１０ｋｇｆを超える値が確保され、空隙率を１０〜３０％の範囲とすれば良好なドレイン効果が得られ、長さＬを１００ｍｍ（例えば、5本連結して５００ｍｍの地盤改良／液状化対策用杭構造体）とすれば取り扱いを容易にして品質良好な地盤改良／液状化対策用杭ユニットが得られる。 For water-permeable concrete having continuous voids, the compression fracture load decreases as the porosity increases, and there is a combination of conflicting required characteristics such that the compression load increases as the porosity decreases. Therefore, it is necessary to appropriately select the outer diameter D1 and the inner diameter D2 of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit.
As the dimensions of the pile unit for ground improvement / liquefaction countermeasures in the hollow cylindrical shape, for example, if the outer diameter D1 is 200 mm or less (for example, 160 mm to 140 mm) and the inner diameter D2 is 80 to 100 mm, the compressive strength exceeds 10 kgf. If the porosity is in the range of 10 to 30%, a good drain effect can be obtained, and the length L is 100 mm (for example, a pile structure for ground improvement / liquefaction countermeasures of 500 mm by connecting five pieces) Then, the pile unit for ground improvement / liquefaction measures with good quality can be obtained easily.

（２）両端開口の中空金属ケーシング、緩衝材、蓋部
図2（ａ）は地上で両端開口の中空金属ケーシング２の内部に緩衝材３を介して両端開口の中空円筒形状の地盤改良／液状化対策用杭ユニット１を積重ねる態様を示す。中空金属ケーシングは、鋼管等からなり、緩衝材３はゴム等の非圧縮性弾性材料からなる。４は中空金属ケーシング２の底部に着脱自在に配置した蓋部であり、蓋部４の外径は金属ケーシング２の外径とほぼ同一とされ、蓋部４は地盤改良／液状化対策用杭ユニット１で構成される地盤液状化対策用杭構造体を地中に安定して保持する。当該杭構造体を中空金属ケーシング２に挿着する場合、緩衝材の外周部と中空金属ケーシング２の内周部内径は、中空金属ケーシング２を土中から引き抜く際に接触抵抗がない程度のクリアランスが形成されるように構成されている。一方、地盤改良／液状化対策用杭構造体の外径は緩衝材外形より小さいかほぼ一致するように構成されている。 (2) Hollow metal casing, buffer material, lid part with openings at both ends Fig. 2 (a) shows a hollow cylindrical ground improvement with open ends at both ends via a buffer material 3 inside the hollow metal casing 2 with both ends opening on the ground. The aspect which piles up the pile unit 1 for crystallization countermeasures is shown. The hollow metal casing is made of a steel pipe or the like, and the cushioning material 3 is made of an incompressible elastic material such as rubber. Reference numeral 4 denotes a lid portion detachably disposed on the bottom of the hollow metal casing 2, the outer diameter of the lid portion 4 being substantially the same as the outer diameter of the metal casing 2, and the lid portion 4 is a pile for ground improvement / liquefaction measures The pile structure for ground liquefaction countermeasures composed of unit 1 is stably held in the ground. When the pile structure is inserted into the hollow metal casing 2, the outer peripheral portion of the cushioning material and the inner peripheral portion inner diameter of the hollow metal casing 2 are clearances that do not cause contact resistance when the hollow metal casing 2 is pulled out from the soil. Is formed. On the other hand, the outer diameter of the pile structure for ground improvement / liquefaction measures is configured to be smaller than or substantially coincide with the outer shape of the cushioning material.

図２（ｂ）は緩衝材３を介装して3個の地盤改良／液状化対策用杭ユニット１を入れた金属ケーシング２を土中に貫入させた模式図であり、図２（ｃ）は蓋部４を最下端の地盤改良／液状化対策用杭ユニット１の下に残留させた状態で、中空金属ケーシング２を引き抜いた図であり、図２（ｄ）は金属ケーシング２を引き抜き後周囲の土壌が地盤弾性により金属ケーシング２を引き抜いてできたクリアランスから残留した当該杭の径まで戻った状態を示す図である。 FIG. 2 (b) is a schematic view in which a metal casing 2 containing three soil improvement / liquefaction countermeasure pile units 1 with a buffer material 3 interposed is inserted into the soil, and FIG. 2 (c). FIG. 2D is a view of the hollow metal casing 2 pulled out with the lid 4 remaining under the bottom soil improvement / liquefaction countermeasure pile unit 1, and FIG. 2 (d) is after the metal casing 2 is pulled out. It is a figure which shows the state which the surrounding soil returned to the diameter of the said remaining pile from the clearance formed by extracting metal casing 2 by ground elasticity.

図２は地盤改良／液状化対策用杭ユニット１及び緩衝材３を全て地上に配置した中空金属ケーシング２中に挿入した後、金属ケーシング２を適当な貫入装置によって地中に貫入させたが、中空金属ケーシング２を途中まで地中に貫入させた後、全ての地盤改良／液状化対策用杭ユニット１及び緩衝材３を中空金属ケーシング２中に挿入し、その後中空金属ケーシング２を完全に地中に貫入することもできる。中空金属ケーシング２を途中まで地中に貫入させた場合には、地上に出ている中空金属ケーシング２の高さが低くなるので、地盤改良／液状化対策用杭ユニット１及び緩衝材３を中空金属ケーシング２中に挿入する作業が容易となる。あるいは、中空金属ケーシング２を完全に地中に貫入させた後、地盤改良／液状化対策用杭ユニット１及び緩衝材３を中空金属ケーシング２中に挿入することもできる。図２においては、金属ケーシング２の上端と一番上の地盤改良／液状化対策用杭ユニット１の上端の高さをほぼ同一として描いているが、一連の建設機械とのインタフェース構造に依存する部分であり多種構造が考えられる。更に、図２においては、強度のある地盤まで貫入するように描いているが、砂層における締固め効果による摩擦力が充分に確保される場合、特に小規模戸建住宅などの場合はその限りではない。 FIG. 2 shows that after the soil improvement / liquefaction countermeasure pile unit 1 and the cushioning material 3 are all inserted into the hollow metal casing 2 arranged on the ground, the metal casing 2 is penetrated into the ground by an appropriate penetration device. After the hollow metal casing 2 has been partially penetrated into the ground, all the ground improvement / liquefaction countermeasure pile units 1 and the cushioning material 3 are inserted into the hollow metal casing 2, and then the hollow metal casing 2 is completely grounded. It can also penetrate inside. When the hollow metal casing 2 is penetrated partway into the ground, the height of the hollow metal casing 2 that is exposed to the ground is lowered, so that the ground improvement / liquefaction countermeasure pile unit 1 and the cushioning material 3 are hollow. The operation of inserting into the metal casing 2 is facilitated. Alternatively, after the hollow metal casing 2 is completely penetrated into the ground, the ground improvement / liquefaction countermeasure pile unit 1 and the buffer material 3 can be inserted into the hollow metal casing 2. In FIG. 2, the height of the upper end of the metal casing 2 and the upper end of the uppermost ground improvement / liquefaction countermeasure pile unit 1 are depicted as substantially the same, but this depends on the interface structure with a series of construction machines. It is a part, and various structures can be considered. Furthermore, in FIG. 2, it is drawn so as to penetrate to a strong ground. However, in the case of a small detached house in particular, when the friction force due to the compaction effect in the sand layer is sufficiently secured, Absent.

図３（ａ）と（ｂ）は、それぞれ上下に位置する中空円筒形状の地盤改良／液状化対策用杭ユニットの端面間に介装されるゴム等の非圧縮性弾性材料からなる緩衝材を示す。緩衝剤は地盤改良／液状化対策用杭ユニットの端部の突き当て部における応力集中による微細破壊を防止する。図３（ａ）は環状の緩衝材３ａであり、上下の地盤改良／液状化対策用杭ユニット１の端面間に介設される。この場合環状緩衝材３ａの外径を地盤改良／液状化対策用杭ユニット１の外径より大きいか等しく、かつ中空金属ケーシング２の内径とほぼ同一としてあり、地盤改良／液状化対策用杭ユニット１から突出した環状緩衝材部分は、摩擦杭の役目を担うとともに、地盤改良／液状化対策用杭ユニット１は地中に安定して位置させる。図３（ｂ）は、上下に延びる管部と管部中央から半径方向外方に延びるフランジ部からなり、上下の管部は上下の地盤改良／液状化対策用杭ユニット１の端部の内径部に沿ってガイド・嵌合し、上下に位置する中空円筒の当該杭ユニットの中心軸を一致させ、フランジ部は上下の地盤改良／液状化対策用杭ユニット１の端部に当接しかつ外方に突出することによって、摩擦杭の役目を担うとともに、地盤改良／液状化対策用杭ユニット１を地中に安定して位置させる。なお、緩衝材は杭ユニットの端部の位置決めを容易とし、上下の杭ユニットが半径方向に相対的にずれるのを防止する手段を有すれば、図3（ｂ）のものに限定をされない。例えば、図3（ａ）に示す環状緩衝材の外周部に上下に延びる円筒状のフランジ部を設けることも出来る。

更に、図においては緩衝機能部とガイド機能部が同一素材で一体化された構造に描かれているが、両機能を最大限活用可能な素材の組合せ構造でも良いことは当然である。 3 (a) and 3 (b) show a cushioning material made of an incompressible elastic material such as rubber interposed between the end surfaces of a hollow cylindrical ground improvement / liquefaction countermeasure pile unit positioned above and below, respectively. Show. The buffering agent prevents microfracture due to stress concentration at the abutting portion of the end of the pile unit for soil improvement / liquefaction countermeasures. FIG. 3A shows an annular cushioning material 3 a interposed between the end surfaces of the upper and lower ground improvement / liquefaction countermeasure pile units 1. In this case, the outer diameter of the annular cushioning material 3a is greater than or equal to the outer diameter of the ground improvement / liquefaction countermeasure pile unit 1 and substantially the same as the inner diameter of the hollow metal casing 2, and the ground improvement / liquefaction countermeasure pile unit The annular cushioning material portion protruding from 1 serves as a friction pile, and the ground improvement / liquefaction countermeasure pile unit 1 is stably positioned in the ground. FIG. 3B shows a pipe part extending vertically and a flange part extending radially outward from the center of the pipe part. The upper and lower pipe parts are the inner diameters of the upper and lower ground improvement / liquefaction countermeasure pile units 1. Guide and fit along the part, align the center axis of the pile unit of the hollow cylinder located up and down, the flange part abuts the end of the pile unit 1 for upper and lower ground improvement / anti-liquefaction countermeasure unit 1 By projecting in the direction, it plays the role of a friction pile and the ground improvement / liquefaction countermeasure pile unit 1 is stably positioned in the ground. Note that the cushioning material is not limited to that shown in FIG. 3B as long as it has means for facilitating positioning of the end of the pile unit and preventing the upper and lower pile units from being relatively displaced in the radial direction. For example, a cylindrical flange portion extending vertically can be provided on the outer peripheral portion of the annular cushioning material shown in FIG.

Furthermore, in the drawing, the buffer function part and the guide function part are depicted as a structure integrated with the same material, but it is a matter of course that a combined structure of materials that can utilize both functions to the maximum is also possible.

なお、中空円筒形状の地盤改良／液状化対策用杭ユニット１の端面表面部に、弾性素材からなる「緩衝層」を設けることによって上下に位置する中空円筒形状の地盤改良／液状化対策用杭ユニット１の端面間に弾性素材からなる「緩衝層」が位置する場合も、請求項に記載する「上下に位置する中空円筒形状の地盤改良／液状化対策用杭ユニットの端面間に、弾性素材からなる環状の緩衝材を介装する」に含まれるものとする。この場合、緩衝層は上述の緩衝材３，３ａ、３ｂと同等の機能を示す厚みを有し、かつ上下の地盤改良／液状化対策用杭ユニット１から半径方向外方に延びる外延部を有することもある。 In addition, the hollow cylinder-shaped ground improvement / liquefaction countermeasure pile located above and below by providing a “buffer layer” made of an elastic material on the end surface of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit 1 Even when a “buffer layer” made of an elastic material is positioned between the end surfaces of the unit 1, the elastic material between the end surfaces of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit positioned above and below is described in the claims. It is assumed that the annular cushioning material consisting of In this case, the buffer layer has a thickness exhibiting the same function as the buffer materials 3, 3 a, and 3 b described above, and has an extended portion that extends radially outward from the upper and lower ground improvement / liquefaction countermeasure pile units 1. Sometimes.

図４に示す地盤改良／液状化対策用杭ユニット１ａ、１ｂ、１ｃは、下段から上段に向かって順に外径を大きくした摩擦杭構成を有する。図４（ａ）は地盤改良／液状化対策用杭ユニット１ａ、１ｂ、１ｃを緩衝材３、３を介して中空金属ケーシング２に挿入し、金属ケーシング２を土中に貫入した状態を示し、図４（ｂ）は土中から中空金属ケーシング２を引き抜いた後の状態を示す。緩衝材３の外径を当該杭ユニットの上端の外径より大きくし、金属ケーシング２の内径とほぼ等しくすると、緩衝材３の露出底部がより広い面積で土中に露出されるので、地盤液状化対策杭構造体がより安定して地中に保持される。 The ground improvement / liquefaction countermeasure pile units 1a, 1b, and 1c shown in FIG. 4 have a friction pile configuration in which the outer diameter is increased in order from the lower stage toward the upper stage. FIG. 4 (a) shows a state where the soil improvement / liquefaction countermeasure pile units 1a, 1b and 1c are inserted into the hollow metal casing 2 via the cushioning materials 3 and 3, and the metal casing 2 is penetrated into the soil. FIG. 4B shows a state after the hollow metal casing 2 is pulled out from the soil. If the outer diameter of the cushioning material 3 is made larger than the outer diameter of the upper end of the pile unit and substantially equal to the inner diameter of the metal casing 2, the exposed bottom of the cushioning material 3 is exposed in the soil in a wider area. The anti-pile pile structure is more stably held in the ground.

図５は、軸方向に延びる長尺の剛性支持軸部材が地盤改良／液状化対策用杭構造体の中空部に挿入された状態を示す断面図である。長尺剛性支持軸部材は、地盤改良／液状化対策用杭ユニットの中空部を確保し、かつ活用して配置され、杭構造の軸方向の耐圧縮強度を補強するとともに、杭ユニットを配置する場合のガイド構造として機能する。さらに、各地盤改良／液状化対策用杭ユニットの内周面に3箇所以上の箇所で軸方向に亘り接触・保持し、地盤改良／液状化対策用杭構造体を内方から支持し、杭構造体を構成する地盤改良／液状化対策用杭ユニットの相互のずれを防止し軸方向に一直線上に保持するとともにその半径方向の圧縮強度を高め、地盤改良効果をさらに高める。図５（ａ）は長尺剛性支持軸部材５ａが断面Ｈ形状を有する鋼材、図５（ｂ）は長尺剛性支持軸部材５ｂが断面Ｙ字形状を有する鋼材、図５（ｃ）では長尺剛性支持軸部材５ｃは断面Ｔ字形状を有する鋼材の例を示す。図５（ｄ）は、長尺の剛性支持軸部材として、例えば、メッシュ状の剛性樹脂素材による中空円筒形の排水材（例えば、西松建設株式会社の合成ポリプロピレン排水材を使用可能）５ｄを地盤改良／液状化対策用杭構造体の内周面に沿って接触させても良い。排水材はメッシュ状の中空円筒形状ではなくメッシュ状の中実円筒形状であってもよい。メッシュ材料であれば、メッシュ中の連続空隙によって地盤改良／液状化対策用杭ユニットの中空部を確保できる。 FIG. 5 is a cross-sectional view showing a state in which a long rigid support shaft member extending in the axial direction is inserted into the hollow portion of the pile structure for ground improvement / liquefaction countermeasures. The long rigid support shaft member secures and utilizes the hollow portion of the pile unit for soil improvement / liquefaction countermeasures and reinforces the compressive strength in the axial direction of the pile structure and arranges the pile unit. Functions as a guide structure. Furthermore, the pile improvement unit for soil improvement / liquefaction measures is contacted and held in the axial direction at three or more locations on the inner surface of the pile unit for improvement / liquefaction countermeasures in each area, and the pile structure for soil improvement / liquefaction countermeasures is supported from the inside. Prevents mutual displacement of pile units for soil improvement / liquefaction countermeasures constituting the structure and keeps them in a straight line in the axial direction, while increasing the radial compressive strength, further enhancing the ground improvement effect. 5A shows a steel material in which the long rigid support shaft member 5a has a H-shaped cross section, FIG. 5B shows a steel material in which the long rigid support shaft member 5b has a Y-shaped cross section, and FIG. 5C shows a long steel material. The scale rigid support shaft member 5c shows an example of a steel material having a T-shaped cross section. FIG. 5D shows a hollow cylindrical drainage material made of, for example, a mesh-like rigid resin material (for example, synthetic polypropylene drainage material from Nishimatsu Construction Co., Ltd.) 5d as the long rigid support shaft member. You may make it contact along the inner peripheral surface of the pile structure for improvement / liquefaction measures. The drainage material may have a mesh-like solid cylindrical shape instead of a mesh-like hollow cylindrical shape. If it is a mesh material, the hollow part of the pile unit for ground improvement / liquefaction measures can be ensured by the continuous space | gap in a mesh.

図６は、中空金属ケーシングの底端部に配置される蓋部の変形例の断面を示す。図６(ａ)は底部が円錐状とされた蓋部４ａであり、図６(ｂ)は底部が円錐状とされ、かつ上面の円周部に上方に立ち上げたフランジ部を有する蓋部４ｂを示す。蓋部４ｂにより、中空金属ケーシングの底端部をフランジ部内部に確実に位置決めすることができる。また、蓋部４の底面が平らな場合に比べて、底部を円錐状とした蓋部の場合には中空金属ケーシングをより小さな力で地中に貫入することができる。 FIG. 6 shows a cross section of a modified example of the lid disposed at the bottom end of the hollow metal casing. 6 (a) shows a lid portion 4a having a conical bottom portion, and FIG. 6 (b) shows a lid portion having a conical bottom portion and having a flange portion raised upward on the circumferential portion of the upper surface. 4b is shown. By the lid portion 4b, the bottom end portion of the hollow metal casing can be reliably positioned inside the flange portion. Moreover, compared with the case where the bottom face of the cover part 4 is flat, in the case of the cover part having a conical bottom, the hollow metal casing can be penetrated into the ground with a smaller force.

図７は、内部に適当な間隔で軸方向に線状の補強材７ａを、周方向に線状の補強材７ｂを埋設した中空円筒形状の地盤改良／液状化対策用杭ユニットを示す。これら補強材７ａ、７ｂは、耐食性を考慮した鉄線、鋼線または炭素繊維等の耐腐食性を有する材質から形成する。軸方向及び周方向に埋設された線状の補強材７ａ、７ｂによって、地盤改良／液状化対策用杭ユニットの軸方向及び半径方向の耐圧縮破壊強度は大きくなる。 FIG. 7 shows a hollow cylindrical ground improvement / liquefaction countermeasure pile unit in which linear reinforcing members 7a are embedded in the axial direction at appropriate intervals and linear reinforcing members 7b are embedded in the circumferential direction. These reinforcing members 7a and 7b are formed of a corrosion-resistant material such as an iron wire, a steel wire, or carbon fiber in consideration of corrosion resistance. The linear reinforcement members 7a and 7b embedded in the axial direction and the circumferential direction increase the compressive fracture resistance in the axial direction and the radial direction of the pile unit for ground improvement / liquefaction measures.

図８は、地盤改良／液状化対策用杭ユニット１１の外周面に排水手段を設けた実施例を示す。図８（ａ）に示すように、地盤改良／液状化対策用杭ユニット１１の外周面に縦方向に延びるＶ字状の溝部１２を周方向に所定の間隔で設け、図８（ｂ）に示すように、Ｖ字状溝部１２にほぼ断面三角形状の導水部材１３を嵌合している。図８（ｃ）に示すように、導水部材１３は断面三角形状の導水材１３ａと導水材１３ａを囲む通水囲い１３ｂとからなり、通水囲い１３ｂは導水材１３ａに水を通すための多数の開口部１３ｃが設けられている。導水材料としては、連続気泡を有する発泡樹脂あるいは硬質のメッシュ状の素材を用いることができ、また通水囲いとしてはパンチングメタル等を用いることができる。なお、溝部１２及び導水部材１３の断面形状は上記三角形状に限定されるものではなく、半円形状等任意の形状を取ることができる。 FIG. 8 shows an embodiment in which drainage means is provided on the outer peripheral surface of the soil improvement / liquefaction countermeasure pile unit 11. As shown in FIG. 8 (a), V-shaped groove portions 12 extending in the vertical direction are provided on the outer peripheral surface of the soil improvement / liquefaction countermeasure pile unit 11 at predetermined intervals in the circumferential direction. As shown, a water guide member 13 having a substantially triangular shape is fitted into the V-shaped groove 12. As shown in FIG. 8 (c), the water guide member 13 is composed of a water guide material 13a having a triangular cross section and a water flow enclosure 13b surrounding the water guide material 13a, and the water flow enclosure 13b is used to pass water through the water guide material 13a. The opening 13c is provided. As the water guiding material, a foamed resin having open cells or a hard mesh material can be used, and a punching metal or the like can be used as the water flow enclosure. In addition, the cross-sectional shape of the groove part 12 and the water conveyance member 13 is not limited to the said triangle shape, It can take arbitrary shapes, such as a semicircle shape.

積み重ねた地盤改良／液状化対策用杭ユニット１１のＶ字状溝部１２及び導水部材１３を一直線上に並ぶようにすることによって、地盤改良／液状対策用杭構造体の排水性を一層高めることができる。地盤に多量の水が発生した場合に、発生した水はＶ字状溝部１２中の導水部材１３を通って上方に排出され、過剰な水圧が地盤改良／液状化対策用杭構造体の外周面に付加されるのを防止し、杭構造体の圧縮破壊を防ぐ。したがって、特に瞬時の急激な水の流れを排水する必要がある場合には、該排水手段は好適に機能する。 By arranging the V-shaped groove portion 12 and the water guide member 13 of the pile improvement pile unit 11 for ground improvement / liquefaction countermeasures in a straight line, the drainage performance of the pile structure for ground improvement / liquid countermeasures can be further enhanced. it can. When a large amount of water is generated in the ground, the generated water is discharged upward through the water guide member 13 in the V-shaped groove 12, and excessive water pressure is generated on the outer peripheral surface of the pile structure for ground improvement / liquefaction measures To prevent the pile structure from being compressed. Therefore, especially when it is necessary to drain an instantaneous and rapid flow of water, the draining means functions suitably.

図示していないが、本発明においては、中空円筒形状の地盤改良／液状化対策用杭ユニットの外周面の目詰まりを低減させかつ該支持ユニットの外形を保持するための多孔性保形シートで覆うこともできる。 Although not shown, in the present invention, a porous cylindrical shape-retaining sheet for reducing clogging of the outer peripheral surface of a hollow cylindrical ground improvement / liquefaction countermeasure pile unit and maintaining the outer shape of the support unit. It can also be covered.

図９は、本発明の別の実施例である。図２及び図４においては、底部に蓋部４を備えた中空金属ケーシング２の内部に地盤改良／液状化対策用杭ユニットを緩衝材３を介して積重ねて地中に貫入し、中空金属ケーシング２を土中から引き抜いて地盤改良／液状化対策用杭ユニットで構成された地盤改良／液状化対策用杭構造体を土中に埋設する実施例を示したが、図９は地盤改良／液状化対策用杭ユニット１の内径よりも小さい外径を有する金属軸８を用いる実施例を示す。なお、金属軸８は中実構造、あるいは中空構造のいずれでもよい。 FIG. 9 is another embodiment of the present invention. 2 and 4, ground improvement / liquefaction countermeasure pile units are stacked through a cushioning material 3 in a hollow metal casing 2 having a lid 4 at the bottom, and penetrated into the ground. Fig. 9 shows an example in which the pile structure for soil improvement / liquefaction countermeasures is constructed in the soil by pulling 2 out of the soil, and FIG. The Example using the metal shaft 8 which has an outer diameter smaller than the internal diameter of the pile unit 1 for optimization is shown. The metal shaft 8 may be a solid structure or a hollow structure.

図９（ａ）に示すように、地上において蓋部４ｃの外周部のフランジ部の内部に金属軸８の下端部を配置させて、金属軸８の外周部に地盤改良／液状化対策用杭ユニット１をその外径が当該杭ユニットより大きいか同等の外径を有する緩衝材３を介して積み上げ、図８（ｂ）に示すように、外周面に地盤改良／液状化対策用杭ユニット１及び緩衝材３を積み上げた金属軸８及び蓋部４ｃを地中に貫入させて、地盤改良／液状化対策用杭構造体を土中に埋設する。その後、蓋部４ｃは土中に残して中空金属軸８のみを杭構造体から引き抜く。なお、地盤改良／液状化対策用杭構造体を金属軸の外周に挿入した場合、地盤改良／液状化対策用杭構造体の内周部と金属軸の外周部との間に、中空金属軸を土中の地盤改良／液状化対策用杭構造体から引き抜く際に接触抵抗がない程度のクリアランスが形成されるように構成されている。 As shown in FIG. 9 (a), the lower end portion of the metal shaft 8 is disposed inside the flange portion of the outer peripheral portion of the lid portion 4c on the ground, and the ground improvement / liquefaction countermeasure pile is disposed on the outer peripheral portion of the metal shaft 8. The unit 1 is piled up through a cushioning material 3 having an outer diameter larger than or equal to the pile unit, and as shown in FIG. 8 (b), the pile unit 1 for ground improvement / liquefaction countermeasures is provided on the outer peripheral surface. And the metal shaft 8 and the cover part 4c which piled up the buffer material 3 are penetrated in the ground, and the pile structure for ground improvement / liquefaction measures is embed | buried in soil. Thereafter, the lid 4c is left in the soil and only the hollow metal shaft 8 is pulled out from the pile structure. In addition, when the pile structure for ground improvement / liquefaction countermeasures is inserted on the outer periphery of the metal shaft, the hollow metal shaft is interposed between the inner periphery of the pile structure for ground improvement / liquefaction countermeasures and the outer periphery of the metal shaft. When pulling out from the soil improvement / liquefaction countermeasure pile structure in the soil, a clearance is formed so that there is no contact resistance.

本発明に係る地盤改良／液状化対策用杭構造体は液状化の可能性のある地盤に対して用いられ、地震による液状化現象に対し積極的に間隙水圧を抑制・消散することによって住宅等を液状化被害から保護する。 The pile structure for ground improvement / liquefaction countermeasures according to the present invention is used for ground that has the possibility of liquefaction, and houses, etc. by actively suppressing and dissipating pore water pressure against liquefaction caused by earthquakes. Protect from liquefaction damage.

１、１ａ、１ｂ、１ｃ、１１地盤改良／液状化対策用杭ユニット
２金属ケーシング
３、３ａ、３ｂ緩衝材
４、４ａ、４ｂ、４ｃ蓋部
５ａ、５ｂ、５ｃ剛性支持軸部材
７ａ、７ｂ線状補強材
８金属軸
１２Ｖ字状の溝部
１３導水部材
１３ａ導水材
１３ｂ通水囲い
１３ｃ開口部 1, 1a, 1b, 1c, 11 Pile unit for ground improvement / liquefaction measures 2 Metal casing 3, 3a, 3b Buffer material 4, 4a, 4b, 4c Lid 5a, 5b, 5c Rigid support shaft member 7a, 7b Wire Reinforcing material 8 Metal shaft 12 V-shaped groove 13 Water guide member 13a Water guide member 13b Water flow enclosure 13c Opening

Claims

Ground improvement / Liquefaction countermeasure construction method for ground improvement / Liquefaction countermeasures by soil improvement / Liquefaction countermeasure pile structure,
The pile structure for soil improvement / liquefaction countermeasures has a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units having both ends open and made of water-permeable concrete having a large amount of continuous voids. The hollow part of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit is in communication and the cylindrical outer peripheral part is arranged concentrically, and the end of the upper foundation improvement / liquefaction countermeasure pile unit is abutted A pile structure for ground improvement / liquefaction countermeasures formed by stacking up and down at the bottom, and between the end faces of the pile unit for ground improvement / liquefaction countermeasures located above and below, a pile for ground improvement / liquefaction countermeasures It has an outer diameter that is equal to or larger than the outer diameter of the unit, and is equipped with an annular cushioning material made of an incompressible elastic material,
When penetrating the ground improvement / liquefaction countermeasure pile structure into the ground, it comprises a cylindrical hollow metal casing part with openings at both ends and a lid part detachably provided at the lower end of the cylindrical hollow metal casing part. and preparing a hollow metal casing with an inner peripheral surface having a degree of clearance is no contact resistance with respect to the outer peripheral portion of the ground improvement / liquefaction countermeasure pile structure,
The plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units constituting the ground improvement / liquefaction countermeasure pile structure are provided with an annular cushioning material made of an elastic material between their end faces. And forming the pile structure for ground improvement / liquefaction countermeasures on the lid and in the hollow part of the hollow metal casing,
When penetrating the hollow metal casing into the ground,
(1) In a state where a ground improvement / liquefaction countermeasure pile unit is formed by stacking a plurality of ground improvement / liquefaction countermeasure pile units and cushioning materials in the hollow portion of the ground metal casing, In the case of penetration, after a plurality of ground improvement / liquefaction countermeasure pile units and cushioning materials are stacked in the hollow portion to form a ground improvement / liquefaction countermeasure pile unit, these are penetrated into the ground together. Or
(2) After only the metal casing penetrates into the ground partway, after the ground improvement / liquefaction countermeasure pile structure is formed in the metal casing, and further, the metal casing is penetrated to a predetermined depth, or
(3) After only the metal casing is penetrated into the ground to a predetermined final depth, after the pile structure for ground improvement / liquefaction measures is formed in the metal casing,
The lid is held at the lower end of the soil improvement / liquefaction countermeasure pile structure, and the cylindrical metal casing is pulled up from the ground, and the soil improvement / liquefaction countermeasure pile structure is submerged in the soil. Ground improvement / liquefaction countermeasure construction method that performs ground improvement / liquefaction countermeasures by pile structure for ground improvement / liquefaction countermeasures by burying the body.

Ground improvement / Liquefaction countermeasure construction method for ground improvement / Liquefaction countermeasures by soil improvement / Liquefaction countermeasure pile structure,
The pile structure for soil improvement / liquefaction countermeasures has a plurality of hollow cylindrical ground improvement / liquefaction countermeasure pile units having both ends open and made of water-permeable concrete having a large amount of continuous voids. The hollow part of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit is in communication and the cylindrical outer peripheral part is arranged concentrically, and the end of the upper foundation improvement / liquefaction countermeasure pile unit is abutted A pile structure for ground improvement / liquefaction countermeasures formed by stacking up and down at the bottom, and between the end faces of the pile unit for ground improvement / liquefaction countermeasures located above and below, a pile for ground improvement / liquefaction countermeasures It has an outer diameter that is equal to or larger than the outer diameter of the unit, and is equipped with an annular cushioning material made of an incompressible elastic material,
When the pile structure for ground improvement / liquefaction countermeasures penetrates into the ground, the pile structure for ground improvement / liquefaction countermeasures is provided detachably at the cylindrical metal shaft portion and the lower end of the cylindrical metal shaft portion. It consists of a lid having an outer diameter greater than the outer diameter of the body, and having an outer peripheral surface having a clearance of degree no contact resistance with the inner peripheral portion of the ground improvement / liquefaction countermeasure pile structure cylindrical Prepare a metal shaft,
The plurality of ground improvement / liquefaction countermeasure pile units constituting the ground improvement / liquefaction countermeasure pile structure are covered with an annular cushioning material made of an elastic material between their end faces. A pile structure for ground improvement / liquefaction measures is formed on the outer periphery of the metal shaft and
When penetrating the hollow metal shaft into the ground,
(1) With a plurality of ground improvement / liquefaction countermeasure pile units, a ground improvement / liquefaction countermeasure pile structure is formed on the outer periphery of the metal shaft part on the lid portion located on the ground. Or to penetrate the ground together, or
(2) After allowing only the metal shaft to penetrate partway into the ground, a plurality of ground improvement / liquefaction countermeasure pile units are used to place the ground improvement / liquefaction countermeasure pile structure on the lid and the metal shaft portion. With the pile structure for ground improvement / liquefaction countermeasures formed on the outer periphery and formed on the outer periphery of the metal shaft, the metal casing is further penetrated to a predetermined depth and buried in the ground.
The lid is held at the lower end of the soil improvement / liquefaction countermeasure pile structure, the cylindrical metal shaft is pulled up from the ground, and the soil improvement / liquefaction countermeasure pile structure is submerged in the soil. Ground improvement / liquefaction countermeasure construction method that performs ground improvement / liquefaction countermeasures by pile structure for ground improvement / liquefaction countermeasures by burying the body.

The cushioning material includes a vertically extending tubular portion that fits into a hollow portion at an end of the upper and lower ground improvement / liquefaction countermeasure pile units, and a flange portion that extends radially outward from the central portion of the tubular portion. The ground improvement / liquefaction countermeasure construction method according to claim 1 or 2 , wherein the outer diameter of the portion is larger than the outer diameter of the pile unit for ground improvement / liquefaction countermeasures.

A long rigid support shaft member extending in the axial direction while the hollow portion is secured is inserted into the hollow portion of the ground improvement / liquefaction countermeasure pile structure. Necessary to support at least three inner peripheral surfaces of the ground improvement / liquefaction countermeasure pile unit as viewed in the circumferential direction with respect to the inner peripheral surface of the soil improvement / liquefaction countermeasure pile unit. The ground improvement / liquefaction countermeasure construction method according to any one of claims 1 to 3, wherein the ground improvement / liquefaction prevention method is in contact with and held over the length of the ground.

The ground improvement / liquid state according to any one of claims 1 to 4, wherein a corrosion-resistant linear reinforcing material extending in the axial direction and / or the circumferential direction is embedded in the pile unit for soil improvement / liquefaction countermeasures. Chemical countermeasure construction method.

On the outer peripheral surface of the hollow cylindrical ground improvement / liquefaction countermeasure pile unit, a plurality of vertically extending water guide grooves are provided in the circumferential direction, and a porous drainage forming member is provided in the groove. The ground improvement / liquefaction countermeasure construction method according to any one of claims 1 to 5.

The outer peripheral surface of the soil improvement / liquefaction countermeasure pile unit is covered with a porous shape retaining sheet for reducing clogging and maintaining the outer shape of the soil improvement / liquefaction countermeasure pile unit. Item 7. Ground improvement / liquefaction countermeasure method according to any one of Items 1 to 6.