【発明の詳細な説明】[Detailed description of the invention]
〔産業上の利用分野〕
この発明は、軟弱地盤の改良に用いる地盤改良材に関す
る．
〔従来の技術〕
水分の多い軟弱な地盤を改良するには従来より各種の工
法が提案されている．
例えば、第４図に示すように、両面を波形面１に形成し
た帯状内部芯２の外側を透水性の筒状シ一ト３で覆った
ドレーン材４を用い、第５図（ａ）乃至（ロ）の如《、
マンドレル５とアンカープレート６を使用してドレーン
材４を軟弱地盤Ａに所定の深度まで押込み、この後マン
ドレル５のみを引き抜いてドレーン材４を軟弱地盤Ａ内
に残し、内部芯２の波形面１の凹溝と筒状シ一ト３の間
に形成された通水路７に軟弱地盤Ａ内の水分を集め、こ
の水分を地上に露出させるか地表のサンドマットＢに臨
ませた通水路７で蒸発させることにより、軟弱地盤Ａか
ら水分を除去して改良する工法が提案されている．
〔発明が解決しようとする課題〕
ところで、上記のようなドレーン工法に用いるドレーン
材４は、内部芯２０波形面１における凹溝によって通水
路７を形成する構造になっているため、通水路の断面積
を太き《するのが困難であり、排水効率が悪いと共に、
透水性の筒状シ一ト３は祇シートを用いて形成されてい
るため、目詰まりが生じやすく透水効果の低下が発生し
やすいという問題がある．
また、内部芯２の波形表面に透水性のシ一ト３が重なる
構造になっているため、土圧の作用でシ一ト３が波形面
１に押し付けられ、通水路７の断面積が減少し、排水効
率が低下することになる．この発明のｔｉｎは、上記の
ような問題点を解決するためになされたものであり、広
い断面積の通水路を形成することができ、土圧が作用し
ても通水路の断面減少の発生がなく、排水が効率的に行
なえる地盤改良材を提供することにある．〔課題を解決
するための手段〕
上記のような課題を解決するため、この発明の第１の手
段は、透水性を有する二枚の繊維シートを、両シート間
に所定の間隔を保つように多数の繊維で対向上に結合し
た構成としたものである．また、この発明の第２の手段
は、透水性を有する二枚の繊維シートを、両シート間に
所定の間隔を保つように多数の繊維で対向上に結合し、
両シート間に砂を充填した構成としたものである．〔作
用〕
第１の手段
地盤改良材を軟弱地盤に押込んで埋設すると、二枚の繊
維シートが土圧を受け、軟弱地盤中の水分は繊維シート
を透過して両繊維シート間に確保された間隔内に集めら
れ、この間隔が通水路となって排水される．
第２の手段
地盤改良材を軟弱地盤に押込んで埋設すると、二枚のシ
ートが土圧を受け、軟弱地盤中の水分は繊維シートを透
過して両繊維シート間に充填した砂に吸水され、この砂
によるサンドドレーンによって水分が排水される．[Industrial Application Field] This invention relates to a ground improvement material used for improving soft ground. [Conventional technology] Various construction methods have been proposed to improve soft ground with high moisture content. For example, as shown in FIG. 4, using a drain material 4 in which the outer side of a band-shaped inner core 2 with corrugated surfaces 1 on both sides is covered with a water-permeable cylindrical sheet 3, (b) As in《,
The drain material 4 is pushed into the soft ground A to a predetermined depth using the mandrel 5 and the anchor plate 6, and then only the mandrel 5 is pulled out, leaving the drain material 4 in the soft ground A, and the corrugated surface 1 of the internal core 2 is pushed. Moisture in the soft ground A is collected in the water passage 7 formed between the concave groove and the cylindrical seat 3, and this moisture is exposed to the ground or in the water passage 7 facing the sand mat B on the ground surface. A construction method has been proposed that removes moisture from soft ground A through evaporation. [Problems to be Solved by the Invention] By the way, the drain material 4 used in the above-mentioned drain construction method has a structure in which the water passage 7 is formed by grooves in the corrugated surface 1 of the inner core 20, It is difficult to make the cross-sectional area thick, and drainage efficiency is poor.
Since the water-permeable cylindrical sheet 3 is formed using a cylindrical sheet, there is a problem that it is easily clogged and the water-permeable effect is easily deteriorated. Also, since the structure is such that the water-permeable sheet 3 overlaps the corrugated surface of the inner core 2, the sheet 3 is pressed against the corrugated surface 1 by the action of earth pressure, reducing the cross-sectional area of the water passageway 7. This will reduce drainage efficiency. The tin of this invention was made to solve the above-mentioned problems, and it is possible to form a passageway with a wide cross-sectional area, and it does not cause the cross-sectional area of the passageway to decrease even when earth pressure is applied. The objective is to provide a ground improvement material that can efficiently drain water without any waste water. [Means for Solving the Problems] In order to solve the above-mentioned problems, the first means of the present invention is to prepare two water-permeable fiber sheets such that a predetermined distance is maintained between the two sheets. It has a structure in which a large number of fibers are bonded in pairs. Further, a second means of the present invention is to combine two water-permeable fiber sheets with a large number of fibers so as to maintain a predetermined distance between the two sheets,
The structure is such that sand is filled between both sheets. [Function] When the first means ground improvement material was pushed into soft ground and buried, the two fiber sheets were subjected to earth pressure, and the moisture in the soft ground permeated through the fiber sheets and was secured between the two fiber sheets. The water is collected within an interval, and this interval serves as a drainage channel for drainage. Second method: When the ground improvement material is pushed into soft ground and buried, the two sheets receive earth pressure, and the water in the soft ground permeates through the fiber sheet and is absorbed by the sand filled between the two fiber sheets. Water is drained away through sand drains.
【実施例】【Example】
以下、この発明の実施例を添付図面の第１図乃至第３図
に基づいて説明する．
第１図と第２図に示す第１の例において、地盤改良材１
１は、透水性を有する二枚の繊維シ一ト１２、１２を、
両シ一ト１２と１２間に所定の間隔を保つように多数の
繊維１３で対向状に結合して長尺の帯状に形成されてい
る．
前記繊維シ一ト１２、１２は、ポリエステル等の合成樹
脂を用いて織製され、同じくポリエステル等の合成樹脂
を使用した繊雄１３により両繊維シ一ト１２、１２は対
向状に結合され、両繊維シ一ト１２と１２間の間隔が通
水路１４になっている．
上記繊維１３は、十分に腰があり、両繊維シ一ト１２と
１２の外面から土圧が作用しても通水路１４を確保する
ように繊維径と配置間隔が設定されている．
第３図に示す地盤改良材１１ａの第２の例は、上記第１
の例で示した地盤改良材１１における繊維シ一ト１２と
１２間に砂１５を充填し、サンドドレーンタイプとした
ものである．
この第２の例においては、両繊維シ一ト１２、１２の両
側端部を、縫着や溶着、接着等の手段で閉じ、充填した
砂１５がこぼれ出ないようにすると共に、両繊維シ一ト
１２、１２に作用する土庄を砂１５によって支持するこ
とができるため、繊維１３の配置数を減らすことができ
、これにようて砂１５の充填も容易に行なえることにな
る．この発明の地盤改良材１１、ｌｌａは上記のような
構成であり、第５図に示した従来のドレーン材埋設と同
様に、マンドレルとアンカープレートを用いて軟弱地盤
の所要深度にまで垂直状態で壇設する．
第１の例においては、両繊維シ一ト１２、１２の外面に
土圧が作用し、軟弱地盤の水分は両繊維シ一ト１２、１
２を透過して通水路１４内に集められ、地上に排水され
ることになる．
また、第２の例においては、両繊維シ一ト１２、１２を
透過した水分が砂１５に吸収され、毛細管現象によって
地上に排水されることになる．何れの例においても、軟
弱地盤の土庄が作用する面は繊維シ一ト１２、１２で形
成されているため、十分な透水性と面積を確保すること
ができ、しかも目詰まりの発生が少なく、優れた排水効
率を維持できると共に、第１の例では繊維１３により、
土圧が作用しても通水路１４を確保できる．また、第２
の例では、繊維１３と砂１５によって土圧による変形を
防ぎ、サンドドレーンエ法と同様の排水が行なえる．
〔効果〕
以上のように、この発明によると、二枚の透水性を有す
る繊維シートを繊維で結合して両繊維シート間に通水路
用の間隔を保つようにしたので、繊維シートにより十分
な透水性を確保でき、目詰まりの発生も少なく、しかも
土圧による通水路の変形も生じないので、広い断面積の
通水路を維持することができ、集水効果が高く軟弱地盤
の改良が効率よく行なえる．
また、繊維シート間に砂を充填したので、土圧による変
形を砂によって防ぐことができ、しかもサンドドレーン
による毛細管現象によって排水が効率よく行なえる．Embodiments of the present invention will be described below with reference to FIGS. 1 to 3 of the accompanying drawings. In the first example shown in Figures 1 and 2, the ground improvement material 1
1 includes two water-permeable fiber sheets 12, 12,
A large number of fibers 13 are connected in opposite directions so as to maintain a predetermined distance between the two sheets 12 to form a long band. The fiber sheets 12, 12 are woven using a synthetic resin such as polyester, and the fiber sheets 12, 12 are joined in a facing manner by a weaving ring 13 also using a synthetic resin such as polyester, The space between the two fiber sheets 12 is a water passage 14. The fibers 13 have sufficient stiffness, and the fiber diameter and arrangement spacing are set so as to secure the water passage 14 even if earth pressure acts from the outer surfaces of both fiber sheets 12 and 12. The second example of the ground improvement material 11a shown in FIG.
Sand 15 is filled between the fiber sheets 12 in the ground improvement material 11 shown in the example above to form a sand drain type material. In this second example, both ends of both fiber sheets 12, 12 are closed by means such as sewing, welding, or gluing to prevent filled sand 15 from spilling out, and to prevent both fiber sheets 12, 12 from spilling out. Since the sand 15 can support the soil that acts on the sand 12, 12, the number of fibers 13 arranged can be reduced, and filling with the sand 15 can therefore be easily performed. The soil improvement materials 11 and lla of the present invention have the above-mentioned configuration, and similarly to the conventional drain material burying shown in FIG. Set up a platform. In the first example, earth pressure acts on the outer surfaces of both fiber sheets 12, 12, and moisture in the soft ground is absorbed by both fiber sheets 12, 1.
2, collected in the water passageway 14, and drained to the ground. In the second example, the water that has passed through both fiber sheets 12, 12 is absorbed by the sand 15 and drained to the ground by capillary action. In either example, the surface on which the soil of the soft ground acts is formed of the fiber sheets 12, 12, so that sufficient water permeability and surface area can be ensured, and clogging is less likely to occur. In addition to being able to maintain excellent drainage efficiency, in the first example, the fibers 13
Even if earth pressure acts, the water passage 14 can be secured. Also, the second
In this example, the fibers 13 and sand 15 prevent deformation due to earth pressure, allowing drainage similar to the sand drain method. [Effects] As described above, according to the present invention, two water-permeable fiber sheets are bonded together with fibers to maintain a space between the two fiber sheets for the passageway, so that the fiber sheets can provide sufficient water flow. Water permeability is ensured, clogging is less likely to occur, and the waterway does not deform due to earth pressure, so a waterway with a wide cross-sectional area can be maintained, with a high water collection effect and efficient improvement of soft ground. It works well. In addition, since sand is filled between the fiber sheets, deformation due to earth pressure can be prevented by the sand, and drainage can be carried out efficiently through capillary action caused by the sand drain.
【図面の簡単な説明】[Brief explanation of the drawing]
第１図はこの発明に係る地盤改良材の第１の例を示す横
断平面図、第２図は同上の斜視図、第３図は同第２の例
を示す横断平面図、第４図は従来のドレーン材を示す横
断面図、第５図の（ａ）乃至（ロ）は同上の施工工法を
示す説明図である．１１、ｌｌａ・・・・・・地盤改良
材、１２・・・・・・繊維シート、 １３・・・・・・
繊維、１４・・・・・・通水路、 １５・・・・
・・砂。FIG. 1 is a cross-sectional plan view showing a first example of the ground improvement material according to the present invention, FIG. 2 is a perspective view of the same, FIG. 3 is a cross-sectional plan view showing a second example of the same, and FIG. A cross-sectional view showing a conventional drain material, and FIGS. 5(a) to 5(b) are explanatory views showing the same construction method. 11, lla...ground improvement material, 12...fiber sheet, 13...
Fiber, 14... Conduit, 15...
··sand.