JP6335569B2 - Ground preparation method and ground structure - Google Patents
Ground preparation method and ground structure Download PDFInfo
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- JP6335569B2 JP6335569B2 JP2014060089A JP2014060089A JP6335569B2 JP 6335569 B2 JP6335569 B2 JP 6335569B2 JP 2014060089 A JP2014060089 A JP 2014060089A JP 2014060089 A JP2014060089 A JP 2014060089A JP 6335569 B2 JP6335569 B2 JP 6335569B2
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Description
本発明は、地盤の改良技術に関し、特に、地震動によって起こる地盤の液状化の影響を低減する地盤造成工法および地盤構造に関する。 The present invention relates to a ground improvement technique, and more particularly, to a ground construction method and a ground structure for reducing the influence of ground liquefaction caused by earthquake motion.
従来、緩い砂質土で形成された地盤上に道路を建設する場合、地盤の液状化による路面の変形や損傷を防止する種々の工法が提案されている。 Conventionally, when a road is constructed on the ground formed of loose sandy soil, various methods for preventing deformation and damage of the road surface due to liquefaction of the ground have been proposed.
このような工法の一例として、特許文献１が開示する道路変状防止方法は、土砂密度が不均等になるように路床部を造成することにより、液状化が生じた場合に、水が路肩側から路床部に流入するのに伴って、密度が均一になるように土砂が移動し、路面中央部が隆起して、地盤沈下による道路の変形や損傷を防止する。 As an example of such a construction method, the road deformation prevention method disclosed in Patent Document 1 is such that, when liquefaction occurs by creating a roadbed so that the sediment density becomes uneven, As it flows into the roadbed from the side, the earth and sand move so that the density becomes uniform, and the center of the road surface rises to prevent road deformation and damage due to land subsidence.
また、特許文献２が開示する地盤改良方法は、液状化層を貫いて支持層まで延在する地中壁を道路長に沿って構築することにより、地盤の液状化による道路の変形や損傷を抑制する。 In addition, the ground improvement method disclosed in Patent Document 2 constructs an underground wall that extends through the liquefied layer and extends to the support layer along the road length, thereby preventing deformation and damage of the road due to liquefaction of the ground. Suppress.
一方、近年、発生が懸念されている東海地震や東南海地震、南海地震等の巨大地震や連動地震では、地震動が数分間継続することが予想されている。このような地震動が液状化層に伝わると、液状化層に含まれる多量の間隙水が浮上して路床部の直下に集まり、地震動の継続時間に比例した時間、路床部の直下に滞留する。このため、過大な水圧が路床部に長時間かかると共に、路床部直下の液状化層が軟化する虞がある。 On the other hand, in recent years, earthquake motions are expected to continue for several minutes in Tokai earthquakes, Tonankai earthquakes, Nankai earthquakes, etc. When such ground motion is transmitted to the liquefied layer, a large amount of pore water contained in the liquefied layer rises and gathers directly under the road bed, and stays directly under the road bed for a time proportional to the duration of the ground motion. To do. For this reason, excessive water pressure is applied to the road bed for a long time, and the liquefied layer immediately below the road bed may be softened.
しかしながら、特許文献１が開示する道路変状防止工法で造成された地盤構造では、液状化によって生じた水が排出されないため、地震動が数分間継続した場合、多量の水が路床部やジオグリッドの直下に長時間に亘って滞留し、道路や路床部が不等沈下して、路面の変形や損傷が起こるという問題があった。 However, in the ground structure created by the road deformation prevention method disclosed in Patent Document 1, water generated by liquefaction is not discharged, so if earthquake motion continues for a few minutes, a large amount of water will flow into the roadbed or geogrid. There was a problem that the road surface and the roadbed portion settled unequally under the road, and the road surface and the roadbed subsided unevenly, resulting in deformation and damage to the road surface.
また、特許文献２が開示する地盤改良方法では、巨大な地中壁を道路長に沿って構築しなければならず、地盤改良に係る時間や費用が多大になることが懸念される。 Moreover, in the ground improvement method which patent document 2 discloses, a huge underground wall must be constructed along the road length, and there is a concern that the time and cost related to ground improvement will be great.
本発明は、上記従来技術の問題に鑑みてなされたものであり、地盤の液状化によって生じた水を速やかに排出可能な地盤造成工法および地盤構造を提供することを目的とするものである。 The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a ground construction method and a ground structure capable of quickly discharging water generated by liquefaction of the ground.
上記課題を解決するために、本発明の地盤造成工法は、含水土で形成された原地盤を掘削して開口を形成し、当該開口上に透水性の高い粒状物で構成される排水層を形成し、繊維混合処理土で構成される繊維含有層を排水層上に形成する。 In order to solve the above problems, the ground preparation method of the present invention excavates the original ground formed of hydrous soil to form an opening, and a drainage layer composed of highly permeable granular material on the opening. Forming and forming a fiber-containing layer composed of the fiber-mixed soil on the drainage layer
本発明の地盤造成工法および地盤構造を提供することにより、地盤の液状化によって生じた水を速やかに排出することができる。このため、地震によって地盤が液状化した場合でも、道路の不等沈下や地盤の側方流動、これらに伴う道路の変形や損傷を防止することができ、緊急輸送道路や重要幹線道路等の主要道路の通行を確保することができる。 By providing the ground preparation method and the ground structure of the present invention, water generated by liquefaction of the ground can be quickly discharged. For this reason, even when the ground is liquefied due to an earthquake, it is possible to prevent uneven subsidence of the road, lateral flow of the ground, and deformation and damage of the road caused by these subsidence. Road traffic can be secured.
また、本発明の地盤造成工法および地盤構造は、支持層まで延在する地中壁を設置する従来技術のような大規模な掘削作業を行う必要がなく、地盤造成に係る時間や費用を低減することができる。 In addition, the ground construction method and ground structure of the present invention do not require large-scale excavation work as in the prior art in which an underground wall extending to the support layer is installed, reducing the time and cost related to ground creation. can do.
図１は、本発明の地盤構造の第１の実施形態を示す図である。以下、図１を参照して、地盤構造１００と、地盤構造１００の造成工法について説明する。 FIG. 1 is a diagram showing a first embodiment of the ground structure of the present invention. Hereinafter, the ground structure 100 and the construction method of the ground structure 100 will be described with reference to FIG.
地盤構造１００は、液状化層１０と、排水層１１と、繊維含有層１２と、排水ドレーン１３と、舗装部１４とで構成される。 The ground structure 100 includes a liquefied layer 10, a drainage layer 11, a fiber-containing layer 12, a drainage drain 13, and a pavement 14.
液状化層１０は、水分を含んだ砂質土から成る飽和砂地盤で形成された層である。液状化層１０は、地震動によって砂質土が振動することにより、砂質土の粒子同士の係合が解かれて沈降し、粒子の間に散在していた水が集合および浮上して液状化現象が発生する。 The liquefied layer 10 is a layer formed of a saturated sand ground made of sandy soil containing moisture. When the sandy soil vibrates due to the earthquake motion, the liquefied layer 10 liquefies as the sandy soil particles are disengaged and settled, and the water scattered between the particles gathers and floats. The phenomenon occurs.
排水層１１は、透水性の高い砕石等の粒状物で構成される。図１に示す実施形態では、排水層１１は水平部１１０および垂直部１１１で構成され、液状化層１０と繊維含有層１２との間に形成される。排水層１１には、液状化によって生じた水が流入する。 The drainage layer 11 is composed of granular material such as crushed stone having high water permeability. In the embodiment shown in FIG. 1, the drainage layer 11 includes a horizontal portion 110 and a vertical portion 111, and is formed between the liquefied layer 10 and the fiber-containing layer 12. Water generated by liquefaction flows into the drainage layer 11.
排水層１１は、フレームおよびネットで構成された収容装置に砕石を充填したグラベルマットを用いて形成することができる。グラベルマットのフレームおよびネットは、砕石を保持する強度を有する限り、任意の素材を使用することができる。なお、フレームは、排水層１１の剛性を担保するため、鋼製フレームを使用するのが好適である。 The drainage layer 11 can be formed by using a gravel mat filled with crushed stone in a housing device constituted by a frame and a net. The gravel mat frame and net can be made of any material as long as it has strength to hold crushed stone. In addition, in order to ensure the rigidity of the drainage layer 11, it is preferable to use a steel frame.
排水層１１の粒状物は、排水層１１の透水性、すなわち液状化層１０から排水層１１への水の流入効率を高めるために、液状化層１０の砂質の径よりも大きい粒状物を使用することが好適である。また、排水層１１の透水性を繊維含有層１２よりも高くするために、繊維含有層１２に含まれる土砂よりも粒径が大きな粒状物を排水層１１に使用してもよい。 In order to increase the water permeability of the drainage layer 11, that is, the inflow efficiency of water from the liquefied layer 10 to the drainage layer 11, the particulate matter of the drainage layer 11 is a granule larger than the sandy diameter of the liquefied layer 10. It is preferred to use. Further, in order to make the water permeability of the drainage layer 11 higher than that of the fiber-containing layer 12, a granular material having a particle size larger than the earth and sand contained in the fiber-containing layer 12 may be used for the drainage layer 11.
繊維含有層１２は、短繊維を含む土砂（以下、「繊維混合処理土」とする。）で形成される。繊維混合処理土は、腐食に強い合成樹脂等の短繊維を土砂に入れて撹拌して生成される。短繊維の長さは、１〜１５０ｍｍとするのが好適である。また、短繊維の太さは、１〜１５０ｄｔｅｘとするのが好適である。なお、短繊維の材質や長さ、太さ、添加量は、土質条件に応じて所望の強度を発揮するものを採用すべきである。 The fiber-containing layer 12 is formed of earth and sand containing short fibers (hereinafter referred to as “fiber mixed treated soil”). The fiber-mixed treated soil is produced by putting short fibers such as synthetic resin resistant to corrosion into earth and sand and stirring them. The length of the short fiber is preferably 1 to 150 mm. The thickness of the short fiber is preferably 1 to 150 dtex. In addition, what should exhibit desired intensity | strength should be employ | adopted for the material, length, thickness, and addition amount of a short fiber according to soil conditions.
排水ドレーン１３は、排水層１１に流入した水を地表に排出する手段である。排水ドレーン１３は、垂直に延在する中空構造をしており、舗装部１４の長手方向に沿って排水層１１の垂直部１１１に設置される。排水ドレーン１３の上端部は、外部と連続しており、排水層１１に流入した水は、排水ドレーン１３を介して地表に排出される。 The drainage drain 13 is a means for discharging water that has flowed into the drainage layer 11 to the ground surface. The drainage drain 13 has a hollow structure extending vertically, and is installed in the vertical part 111 of the drainage layer 11 along the longitudinal direction of the pavement part 14. The upper end of the drainage drain 13 is continuous with the outside, and the water that flows into the drainage layer 11 is discharged to the ground via the drainage drain 13.
舗装部１４は、繊維含有層１２上に形成される路面である。舗装部１４は、アスファルト等の舗装部材を押圧して形成される。 The pavement 14 is a road surface formed on the fiber-containing layer 12. The pavement 14 is formed by pressing a pavement member such as asphalt.
液状化層１０が液状化すると、図１の矢印が示すように、水が排水層１１の周囲の液状化層１０から排水層１１に流入し、排水ドレーン１３を通って地表に排出される。また、水が繊維含有層１２に浸入した場合でも、自重によって排水層１１に流出し、排水ドレーン１３を介して地表に排出される。これにより、液状化によって発生した水を効率よく排出でき、水の滞留によって生じ得る舗装部１４の不等沈下や地盤の側方流動、これらに伴う舗装部１４の変形や損傷を防止することができる。 When the liquefied layer 10 is liquefied, water flows from the liquefied layer 10 around the drainage layer 11 into the drainage layer 11 and is discharged to the ground surface through the drainage drain 13 as indicated by the arrows in FIG. Even when water enters the fiber-containing layer 12, it flows out into the drainage layer 11 by its own weight and is discharged to the ground surface through the drainage drain 13. Thereby, the water generated by liquefaction can be efficiently discharged, and the uneven subsidence of the pavement 14 and the lateral flow of the ground, which can be caused by the retention of water, and the deformation and damage of the pavement 14 due to these can be prevented. it can.
ここで、図１に示す地盤構造１００の造成工法の一実施形態について説明する。まず、液状化層１０をショベルカー等の重機によって掘削して開口を形成する。次に、液状化層１０の開口にグラベルマットを敷設し、排水層１１の水平部１１０を形成する。次いで、排水ドレーン１３を舗装部１４の長手方向に沿って設置し、その周囲にグラベルマットを敷設して、排水層１１の垂直部１１１を形成する。そして、排水層１１の水平部１１０および垂直部１１１で規定される開口に繊維混合処理土を入れて繊維含有層１２を形成し、繊維含有層１２上に舗装部材を敷設して舗装部１４を形成する。なお、地表面を構成する垂直部１１１の上面は、排水ドレーン１３の開口部を除き、アスファルトコンクリート等の舗装部材で舗装される。 Here, an embodiment of a construction method for the ground structure 100 shown in FIG. 1 will be described. First, the liquefied layer 10 is excavated by a heavy machine such as an excavator to form an opening. Next, a gravel mat is laid in the opening of the liquefied layer 10 to form the horizontal portion 110 of the drainage layer 11. Next, the drainage drain 13 is installed along the longitudinal direction of the pavement 14, and a gravel mat is laid around the drainage drain 13 to form the vertical part 111 of the drainage layer 11. Then, the fiber-mixed treated soil is put into the openings defined by the horizontal portion 110 and the vertical portion 111 of the drainage layer 11 to form the fiber-containing layer 12, and a pavement member is laid on the fiber-containing layer 12 to form the pavement portion 14. Form. The upper surface of the vertical part 111 constituting the ground surface is paved with a paving member such as asphalt concrete except for the opening of the drainage drain 13.
図１に示す実施形態では、道路を挟んで２の垂直部１１１を形成するが、他の実施形態では、道路の片側に１の垂直部１１１を形成してもよい。また、３以上の垂直部１１１を道路の両側や中央部に形成してもよい。さらに、本実施形態では、１の垂直部１１１について１列の排水ドレーン１３を設置するが、他の実施形態では、１の垂直部１１１について複数列の排水ドレーン１３を設置してもよい。 In the embodiment shown in FIG. 1, two vertical portions 111 are formed across the road. However, in another embodiment, one vertical portion 111 may be formed on one side of the road. Further, three or more vertical portions 111 may be formed on both sides or the center of the road. Furthermore, in this embodiment, one row of drainage drains 13 is installed for one vertical portion 111, but in another embodiment, multiple rows of drainage drains 13 may be installed for one vertical portion 111.
図２は、本発明の地盤構造の第２の実施形態を示す図である。以下、図２を参照して、地盤構造２００と地盤構造２００の造成工法について、第１の実施形態との相違点を中心に説明する。 FIG. 2 is a diagram showing a second embodiment of the ground structure of the present invention. Hereinafter, with reference to FIG. 2, the ground structure 200 and the construction method of the ground structure 200 will be described focusing on differences from the first embodiment.
地盤構造２００は、液状化層１０と、排水層２１と、繊維含有層１２と、排水ドレーン２３と、舗装部１４と、排水管２５とで構成される。 The ground structure 200 includes a liquefied layer 10, a drainage layer 21, a fiber-containing layer 12, a drainage drain 23, a pavement 14, and a drainage pipe 25.
排水層２１は、液状化層１０と繊維含有層１２との間に形成される。排水層２１の基底部は、両端部が最下点となるように勾配が施されている。 The drainage layer 21 is formed between the liquefied layer 10 and the fiber-containing layer 12. The base of the drainage layer 21 is sloped so that both ends are at the lowest point.
排水ドレーン２３は、排水層２１に流入した水を排水管２５に排出する手段である。排水ドレーン２３は中空構造をしており、排水層２１の基底部の端部と排水管２５とを連結する。排水ドレーン２３は、舗装部１４の長手方向に沿って複数設置され、排水層２１に流入した水が、排水ドレーン２３を介して排水管２５に排出される。本実施形態では、排水ドレーン２３の流入口に目詰まり防止用のフィルターを設置することが好適である。 The drainage drain 23 is means for discharging water that has flowed into the drainage layer 21 to the drainage pipe 25. The drainage drain 23 has a hollow structure and connects the end of the base of the drainage layer 21 and the drainage pipe 25. A plurality of drainage drains 23 are installed along the longitudinal direction of the pavement 14, and the water flowing into the drainage layer 21 is discharged to the drainage pipe 25 through the drainage drain 23. In the present embodiment, it is preferable to install a filter for preventing clogging at the inlet of the drainage drain 23.
排水管２５は、液状化によって生じた水を排出する手段である。排水管２５は、舗装部１４の長手方向に沿って埋設される。排水管２５は、液状化によって生じた水や雨水を排出する専用の排出管でもよく、生活排水用の下水管でもよい。 The drain pipe 25 is a means for discharging water generated by liquefaction. The drain pipe 25 is embedded along the longitudinal direction of the pavement 14. The drainage pipe 25 may be a dedicated drainage pipe for discharging water or rainwater generated by liquefaction, or may be a sewage pipe for domestic drainage.
液状化層１０が液状化すると、図２の矢印が示すように、水が排水層２１の周囲の液状化層１０から排水層２１に直接または間接的に流入し、基底部の傾斜に沿って両側に流れ、排水ドレーン２３を通って排水管２５に排出される。これにより、液状化によって発生した水を効率よく排出でき、水の滞留によって生じ得る舗装部１４の不等沈下や地盤の側方流動、これらに伴う舗装部１４の変形や損傷を防止することができる。 When the liquefied layer 10 is liquefied, water flows directly or indirectly from the liquefied layer 10 around the drainage layer 21 into the drainage layer 21 as indicated by the arrows in FIG. It flows on both sides, passes through the drainage drain 23 and is discharged into the drainage pipe 25. Thereby, the water generated by liquefaction can be efficiently discharged, and the uneven subsidence of the pavement 14 and the lateral flow of the ground, which can be caused by the retention of water, and the deformation and damage of the pavement 14 due to these can be prevented. it can.
ここで、図２に示す地盤構造１００の造成工法の一実施形態について説明する。なお、排水管２５が既に埋設されている場合の造成工法について説明する。 Here, an embodiment of the construction method of the ground structure 100 shown in FIG. 2 will be described. In addition, the construction method when the drain pipe 25 is already embed | buried is demonstrated.
まず、基底部が傾斜を有するように液状化層１０を掘削して開口を形成する。次に、排水ドレーン２３を舗装部１４の長手方向に沿って設置し、排水管２５と連結する。次いで、液状化層１０の開口にグラベルマットを敷設して排水層２１を形成する。そして、液状化層１０と排水層２１で規定される開口に繊維混合処理土を入れて繊維含有層１２を形成し、繊維含有層１２上に舗装部材を敷設して舗装部１４を形成する。当然ではあるが、排水層２１の基底部の端部の高さは、排水管２５の流入口よりも高くすることに留意すべきである。なお、地表面を構成する繊維含有層１２の上面は、アスファルトコンクリート等の舗装部材で舗装される。 First, the liquefied layer 10 is excavated so that the base has an inclination to form an opening. Next, the drainage drain 23 is installed along the longitudinal direction of the pavement 14 and connected to the drainage pipe 25. Next, a gravel mat is laid in the opening of the liquefied layer 10 to form the drainage layer 21. Then, the fiber-mixed soil is put into the opening defined by the liquefied layer 10 and the drainage layer 21 to form the fiber-containing layer 12, and a pavement member is laid on the fiber-containing layer 12 to form the pavement portion 14. Of course, it should be noted that the height of the end of the base of the drainage layer 21 is higher than the inlet of the drainage pipe 25. The upper surface of the fiber-containing layer 12 constituting the ground surface is paved with a paving member such as asphalt concrete.
図２に示す実施形態では、液状化によって生じた水が、排水層２１の両側の設置された排水管２５に流れるよう、排水層２１の基底部に勾配が施されているが、他の実施形態では、排水層２１の片側にのみ排水管２５を設置し、当該排水管に水が流れるよう、排水層２１の基底部の勾配を片流れにしてもよい。 In the embodiment shown in FIG. 2, the base of the drainage layer 21 is sloped so that water generated by liquefaction flows into drainage pipes 25 installed on both sides of the drainage layer 21. In the embodiment, the drain pipe 25 may be installed only on one side of the drainage layer 21 and the gradient of the base of the drainage layer 21 may be one-sided so that water flows through the drainage pipe.
図３は、本発明の地盤構造の第３の実施形態を示す図である。以下、図３を参照して、地盤構造３００と地盤構造３００の造成工法について、第１の実施形態との相違点を中心に説明する。 FIG. 3 is a diagram showing a third embodiment of the ground structure of the present invention. Hereinafter, with reference to FIG. 3, the ground structure 300 and the construction method of the ground structure 300 will be described focusing on differences from the first embodiment.
地盤構造３００は、液状化層１０と、排水層３１と、繊維含有層１２と、舗装部１４と、集水管３６とで構成される。排水層３１は、液状化層１０と繊維含有層１２との間に形成される。排水層３１の基底部は、中心部が最下点となるように勾配が施される。 The ground structure 300 includes the liquefied layer 10, the drainage layer 31, the fiber-containing layer 12, the pavement 14, and the water collecting pipe 36. The drainage layer 31 is formed between the liquefied layer 10 and the fiber-containing layer 12. The base of the drainage layer 31 is given a gradient so that the center is the lowest point.
集水管３６は、排水層３１に流入した水を集水して排水する集排水手段である。集水管３６は中空構造をしており、壁面部が網目構造やハニカム構造等の透水構造をしている。集水管３６は、ポリプロピレン等の合成樹脂を用いて製造することができる。集水管３６は、排水層３１の中心部に舗装部１４の長手方向に沿って埋設される。 The water collection pipe 36 is a collection and drainage means for collecting and draining the water that has flowed into the drainage layer 31. The water collection pipe 36 has a hollow structure, and the wall surface portion has a water-permeable structure such as a mesh structure or a honeycomb structure. The water collecting pipe 36 can be manufactured using a synthetic resin such as polypropylene. The water collecting pipe 36 is embedded in the central portion of the drainage layer 31 along the longitudinal direction of the pavement 14.
図３に示す実施形態では、管状の集水管３６を使用するが、他の実施形態では、断面形状が多角形の集水部材を使用することができる。集水管３６の設置数や口径、幅、高さは、液状化層１０が含有する水分量や想定される地震動の継続時間等に応じて決定するのが好適である。 In the embodiment shown in FIG. 3, a tubular water collecting pipe 36 is used, but in other embodiments, a water collecting member having a polygonal cross-sectional shape can be used. The number, diameter, width, and height of the water collecting pipes 36 are preferably determined according to the amount of water contained in the liquefied layer 10 and the expected duration of earthquake motion.
液状化層１０が液状化すると、図３の矢印が示すように、水が排水層３１の周囲の液状化層１０から排水層３１に直接または間接的に流入し、基底部の傾斜に沿って中心部に流れ、集水管３６に排出される。集水管３６は、集水した水を外部に排出する。これにより、液状化によって発生した水を効率よく排出でき、水の滞留によって生じ得る舗装部１４の不等沈下や地盤の側方流動、これらに伴う舗装部１４の変形や損傷を防止することができる。 When the liquefied layer 10 is liquefied, water flows directly or indirectly from the liquefied layer 10 around the drainage layer 31 into the drainage layer 31 as indicated by the arrows in FIG. It flows to the center and is discharged to the water collecting pipe 36. The water collection pipe 36 discharges the collected water to the outside. Thereby, the water generated by liquefaction can be efficiently discharged, and the uneven subsidence of the pavement 14 and the lateral flow of the ground, which can be caused by the retention of water, and the deformation and damage of the pavement 14 due to these can be prevented. it can.
ここで、図３に示す地盤構造１００の造成工法の一実施形態について説明する。まず、基底部が傾斜を有するように液状化層１０を掘削して開口を形成する。次に、基底部の最下点に位置する中心部に集水管３６を設置する。次いで、液状化層１０の開口にグラベルマットを敷設して排水層３１を形成する。そして、液状化層１０と排水層３１で規定される開口に繊維混合処理土を入れて繊維含有層１２を形成し、繊維含有層１２上に舗装部材を敷設して舗装部１４を形成する。なお、地表面を構成する繊維含有層１２の上面は、アスファルトコンクリート等の舗装部材で舗装される。 Here, an embodiment of the construction method of the ground structure 100 shown in FIG. 3 will be described. First, the liquefied layer 10 is excavated so that the base has an inclination to form an opening. Next, the water collecting pipe 36 is installed at the center located at the lowest point of the base. Next, a gravel mat is laid in the opening of the liquefied layer 10 to form the drainage layer 31. Then, the fiber-mixed soil is put into the opening defined by the liquefied layer 10 and the drainage layer 31 to form the fiber-containing layer 12, and a pavement member is laid on the fiber-containing layer 12 to form the pavement portion 14. The upper surface of the fiber-containing layer 12 constituting the ground surface is paved with a paving member such as asphalt concrete.
図３に示す実施形態では、集水管３６を舗装部１４の長手方向に沿って埋設するが、他の実施形態では、１以上の集水管３６を舗装部１４の短手方向に沿って埋設してもよい。 In the embodiment shown in FIG. 3, the water collecting pipe 36 is embedded along the longitudinal direction of the pavement 14, but in another embodiment, one or more water collecting pipes 36 are embedded along the short direction of the pavement 14. May be.
図４は、本発明の地盤構造の第４の実施形態を示す図である。以下、図４を参照して、地盤構造４００と地盤構造４００の造成工法について、第３の実施形態との相違点を中心に説明する。 FIG. 4 is a diagram showing a fourth embodiment of the ground structure of the present invention. Hereinafter, with reference to FIG. 4, the ground structure 400 and the construction method of the ground structure 400 will be described focusing on differences from the third embodiment.
地盤構造４００は、液状化層１０と、排水層４１と、繊維含有層１２と、舗装部１４と、集水管３６とで構成される。排水層４１は、液状化層１０と繊維含有層１２との間に形成され、基底部の端部が最下点となるように勾配が施される。集水管３６は、排水層２１に流入した水を集水して排出する手段である。集水管３６は、排水層４１の両端部に舗装部１４の長手方向に沿って埋設される。 The ground structure 400 includes the liquefied layer 10, the drainage layer 41, the fiber-containing layer 12, the pavement 14, and the water collecting pipe 36. The drainage layer 41 is formed between the liquefied layer 10 and the fiber-containing layer 12, and is provided with a gradient so that the end of the base becomes the lowest point. The water collection pipe 36 is means for collecting and discharging the water flowing into the drainage layer 21. The water collection pipes 36 are embedded along the longitudinal direction of the pavement 14 at both ends of the drainage layer 41.
液状化層１０が液状化すると、図４の矢印が示すように、水が排水層４１の周囲の液状化層１０から排水層４１に直接または間接的に流入し、基底部の傾斜に沿って両端部に流れ、集水管３６に排出される。集水管３６は、集水した水を外部に排出する。これにより、液状化によって発生した水を効率よく排出でき、水の滞留によって生じ得る舗装部１４の不等沈下や地盤の側方流動、これらに伴う舗装部１４の変形や損傷を防止することができる。 When the liquefied layer 10 is liquefied, water flows directly or indirectly from the liquefied layer 10 around the drainage layer 41 into the drainage layer 41 as indicated by the arrows in FIG. It flows to both ends and is discharged to the water collecting pipe 36. The water collection pipe 36 discharges the collected water to the outside. Thereby, the water generated by liquefaction can be efficiently discharged, and the uneven subsidence of the pavement 14 and the lateral flow of the ground, which can be caused by the retention of water, and the deformation and damage of the pavement 14 due to these can be prevented. it can.
ここで、図４に示す地盤構造１００の造成工法の一実施形態について説明する。まず、基底部が傾斜を有するように液状化層１０を掘削して開口を形成する。次に、基底部の最下点に位置する両端部に集水管３６を設置する。次いで、液状化層１０の開口にグラベルマットを敷設して排水層４１を形成する。そして、液状化層１０と排水層４１で規定される開口に繊維混合処理土を入れて繊維含有層１２を形成し、繊維含有層１２上に舗装部材を敷設して舗装部１４を形成する。なお、地表面を構成する繊維含有層１２の上面は、アスファルトコンクリート等の舗装部材で舗装される。 Here, an embodiment of the construction method of the ground structure 100 shown in FIG. 4 will be described. First, the liquefied layer 10 is excavated so that the base has an inclination to form an opening. Next, the water collecting pipes 36 are installed at both ends located at the lowest point of the base. Next, a gravel mat is laid in the opening of the liquefied layer 10 to form a drainage layer 41. Then, the fiber-mixed soil is put into the opening defined by the liquefied layer 10 and the drainage layer 41 to form the fiber-containing layer 12, and a pavement member is laid on the fiber-containing layer 12 to form the pavement portion 14. The upper surface of the fiber-containing layer 12 constituting the ground surface is paved with a paving member such as asphalt concrete.
図４に示す実施形態では、液状化によって生じた水が、排水層４１の両側に設置された集水管３６に流れるよう、排水層４１の基底部に勾配が施されているが、他の実施形態では、排水層４１の基底部の一方に集水管３６を設置し、当該集水管に水が流れるよう、排水層４１の基底部の勾配を片流れにしてもよい。 In the embodiment shown in FIG. 4, the base of the drainage layer 41 is inclined so that the water generated by liquefaction flows into the water collecting pipes 36 installed on both sides of the drainage layer 41. In the embodiment, the water collecting pipe 36 may be installed on one side of the base of the drainage layer 41, and the slope of the base of the drainage layer 41 may be unidirectional so that water flows through the water collecting pipe.
図５は、路床部を繊維混合処理土で改良した事例と、路床部を低強度コンクリートで改良した事例と、路床部を改良していない事例の実験結果を示す図である。この実験では、液状化層を１０ｍ、路盤厚さを０．９ｍ、繊維混合処理土改良体の厚さを１．１ｍ、低強度コンクリート改良体の厚さを２．１ｍとした模型実験により、各事例について、一軸圧縮強度（ｑｕ）、変形係数（Ｅ５０）、曲げ引張強度（σｂ）について測定した。 FIG. 5 is a diagram showing experimental results of an example in which the roadbed part is improved with fiber-mixed soil, an example in which the roadbed part is improved with low-strength concrete, and an example in which the roadbed part is not improved. In this experiment, by a model experiment in which the liquefied layer was 10 m, the roadbed thickness was 0.9 m, the thickness of the fiber-mixed treated soil improved body was 1.1 m, and the thickness of the low-strength concrete improved body was 2.1 m. for each case, the uniaxial compressive strength (q u), deformation coefficient (E 50), were measured for flexural tensile strength (σ b).
これらの実験結果が示すように、繊維混合処理土改良体では、短繊維によって土砂同士の係合力が増大することにより、低強度コンクリート改良体よりも優れた曲げ強度や靱性を備えており、低強度コンクリート改良体よりも、路床部の厚さを抑えることができる。このため、地盤を深く掘削することなく排水層の厚さを十分に確保することができ、地盤改良に要する時間や経費を低減できる。 As these experimental results show, the fiber-mixed treated soil improved body has better bending strength and toughness than the low-strength concrete improved body by increasing the engaging force between the sand and sand due to short fibers. The thickness of the roadbed can be reduced as compared with the improved concrete. For this reason, the thickness of the drainage layer can be sufficiently secured without deeply excavating the ground, and the time and cost required for ground improvement can be reduced.
また、繊維混合処理土改良体は、優れた曲げ強度や靱性により、道路や路床部の不等沈下や地盤の側方流動を防止し、低強度コンクリート改良体よりも有利な変形抑制効果を奏する。 In addition, the fiber-mixed treated soil improvement body prevents uneven settlement of roads and roadbeds and lateral flow of the ground due to excellent bending strength and toughness, and has an advantageous deformation suppression effect over the low-strength concrete improvement body. Play.
さらに、本発明では、繊維混合処理土で形成された繊維含有層が、グラベルマットで構成された排水層で包囲または支持されることにより、排水層で包囲または支持されない繊維含有層と比べて、優れたな変形抑制効果を奏する。 Furthermore, in the present invention, the fiber-containing layer formed of the fiber-mixed treated soil is surrounded or supported by the drainage layer composed of the gravel mat, so that compared to the fiber-containing layer that is not surrounded or supported by the drainage layer, Excellent deformation suppression effect.
これまで本実施形態につき説明してきたが、本発明は、上述した実施形態に限定されるものではなく、上述した実施形態の構成要素を変更若しくは削除し、または上述した実施形態の構成要素に他の構成要素を追加するなど、当業者が想到することができる範囲内で変更することができる。特に、本発明の地盤造成工法は、緩い砂質土で形成された地盤のみならず、軟弱粘性土地盤等の含水土で形成された地盤にも応用でき、いずれの態様においても本発明の作用効果を奏する限り、本発明の範囲に含まれるものである。 Although the present embodiment has been described so far, the present invention is not limited to the above-described embodiment, and the constituent elements of the above-described embodiment are changed or deleted, or other than the constituent elements of the above-described embodiment. It is possible to make modifications within the range that can be conceived by those skilled in the art, such as adding the above-described components. In particular, the ground preparation method of the present invention can be applied not only to the ground formed of loose sandy soil but also to the ground formed of hydrous soil such as soft and viscous soil, and the operation of the present invention in any aspect. As long as there is an effect, it is included in the scope of the present invention.
１００…地盤構造、１１…排水層、１２…繊維含有層、１３…排水ドレーン、１４…舗装部、２００…地盤構造、２１…排水層、２３…排水ドレーン、２５…排水管、３００…地盤構造、３１…排水層、３６…集水管、４００…地盤構造、４１…排水層 DESCRIPTION OF SYMBOLS 100 ... Ground structure, 11 ... Drainage layer, 12 ... Fiber content layer, 13 ... Drainage drain, 14 ... Pavement part, 200 ... Ground structure, 21 ... Drainage layer, 23 ... Drainage drain, 25 ... Drainage pipe, 300 ... Soil structure 31 ... Drainage layer, 36 ... Catchment pipe, 400 ... Ground structure, 41 ... Drainage layer
Claims (4)
地盤を掘削して開口を形成する工程と、
液状化層の砂質の径よりも大きい粒状物で構成され、垂直部および水平部で形成される排水層を前記開口上に形成する工程と、
一端が外部と連続するように排水手段を前記垂直部に設置する工程と、
長さが１〜１５０ｍｍである短繊維を混合した繊維混合処理土で構成される繊維含有層を前記排水層上に形成する工程と、
前記繊維含有層上に舗装部を形成する工程と
を含む、地盤造成工法。 It is a ground construction method to create against the original ground formed with hydrous soil,
Excavating the ground to form an opening;
A step of forming a drainage layer formed of a granular material larger than the sandy diameter of the liquefied layer and formed in a vertical part and a horizontal part on the opening;
Installing the drainage means in the vertical part so that one end is continuous with the outside;
Forming a fiber-containing layer composed of a fiber-mixed treated soil mixed with short fibers having a length of 1 to 150 mm on the drainage layer;
And a step of forming a pavement on the fiber-containing layer .
地盤を掘削して開口を形成する工程と、
液状化層の砂質の径よりも大きい粒状物で構成され、基底部は勾配をつけて形成される排水層を前記開口上に形成する工程と、
前記排水層の基底部に排水手段を設置する工程と、
長さが１〜１５０ｍｍである短繊維を混合した繊維混合処理土で構成される繊維含有層を前記排水層上に形成する工程と、
前記繊維含有層上に舗装部を形成する工程と
を含む、地盤造成工法。 It is a ground construction method to create against the original ground formed with hydrous soil,
Excavating the ground to form an opening;
A step of forming a drainage layer formed on the opening , which is made of a granular material larger than the sandy diameter of the liquefied layer, and the base portion is formed with a gradient ;
Installing drainage means at the base of the drainage layer;
Forming a fiber-containing layer composed of a fiber-mixed treated soil mixed with short fibers having a length of 1 to 150 mm on the drainage layer;
And a step of forming a pavement on the fiber-containing layer .
前記排水層上に形成され、長さが１〜１５０ｍｍである短繊維を混合した繊維混合処理土で構成される繊維含有層とを含み、
前記排水層は排水手段を含み、
前記垂直部は、一端が外部と連続する排水手段が設置されていることを特徴とする、地盤構造。 A drainage layer composed of a granular material larger than the sandy diameter of the liquefied layer and formed in a vertical part and a horizontal part ;
A fiber-containing layer that is formed on the drainage layer and is composed of a fiber-mixed treated soil in which short fibers having a length of 1 to 150 mm are mixed;
The drainage layer includes drainage means;
The vertical structure is provided with a drainage means having one end continuous with the outside.
前記排水層上に形成され、長さが１〜１５０ｍｍである短繊維を混合した繊維混合処理土で構成される繊維含有層とを含み、
前記排水層は排水手段を含み、
前記排水層の基底部に排水手段を備えることを特徴とする、地盤構造。 The drainage layer is composed of granular materials larger than the sandy diameter of the liquefied layer, and the base portion is formed with a gradient ,
A fiber-containing layer that is formed on the drainage layer and is composed of a fiber-mixed treated soil in which short fibers having a length of 1 to 150 mm are mixed;
The drainage layer includes drainage means;
A ground structure comprising drainage means at the base of the drainage layer.
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| JP6854479B2 (en) * | 2017-03-15 | 2021-04-07 | 新高知重工株式会社 | Liquefaction countermeasure structure for underground structures |
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