JP2021008748A - Impermeable structure of slope and its construction method - Google Patents
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Abstract
Description
本発明は、斜面の表層として設けられる斜面の遮水構造及びその構築方法に関するものである。 The present invention relates to a slope impermeable structure provided as a surface layer of a slope and a method for constructing the same.
特許文献１，２に開示されているように、切土や盛土によって形成される斜面には、斜面崩壊の原因となる雨水の浸透などを防ぐために、コンクリートなどを使用して安定化を図ることが行われている。 As disclosed in Patent Documents 1 and 2, the slope formed by cutting or embankment should be stabilized by using concrete or the like in order to prevent the infiltration of rainwater that causes slope failure. Is being done.
例えば、特許文献１では、斜面にコンクリートを吹き付けることによって、表層に遮水構造が設けられることが開示されている。また、特許文献２には、鉄筋コンクリートによって縦梁を構築し、その縦梁間に露出する斜面を緑化吹付材によって被覆する斜面安定工が開示されている。 For example, Patent Document 1 discloses that a water-impervious structure is provided on a surface layer by spraying concrete on a slope. Further, Patent Document 2 discloses a slope stabilization work in which a vertical beam is constructed of reinforced concrete and the slope exposed between the vertical beams is covered with a greening spray material.
一方、特許文献３，４には、道路の簡易舗装材料として、製鋼スラグと高炉水砕スラグとを混合した材料が使用されることが記載されている。ここで、道路の舗装として使用するためには、車両の走行によって轍や摩耗が起き難いように、セメントやアスファルトなどの結合力の高い材料が添加されて、強度が高められる。 On the other hand, Patent Documents 3 and 4 describe that a material obtained by mixing steelmaking slag and blast furnace granulated slag is used as a simple pavement material for roads. Here, in order to use it as a road pavement, a material having a high binding force such as cement or asphalt is added so that ruts and wear are unlikely to occur due to the running of the vehicle, and the strength is increased.
しかしながら、セメントやアスファルトなどの結合材は、材料費が高く、特に斜面の表面積が広くなる長大のり面に施工する場合には、工事費が増大することになる。
そこで、本発明は、比較的安価な材料のみで構築できるうえに、遮水性能の高い斜面の遮水構造及びその構築方法を提供することを目的としている。
However, the material cost of the binder such as cement and asphalt is high, and the construction cost increases particularly when it is installed on a long slope where the surface area of the slope is large.
Therefore, an object of the present invention is to provide a water-impervious structure for a slope having high water-impervious performance and a method for constructing the same, in addition to being able to be constructed using only relatively inexpensive materials.
前記目的を達成するために、本発明の斜面の遮水構造は、斜面の表層として設けられる斜面の遮水構造であって、製鋼スラグと高炉水砕スラグとを混合したスラグ材を、締固め密度比が90％以上となるように締め固めたことを特徴とする。
ここで、前記スラグ材の締固め密度比が95％以上となるように締め固めることが好ましい。
In order to achieve the above object, the slope impermeable structure of the present invention is a slope impermeable structure provided as the surface layer of the slope, and compacts a slag material obtained by mixing steelmaking slag and blast furnace granulated slag. It is characterized by compaction so that the density ratio is 90% or more.
Here, it is preferable to compact the slag material so that the compaction density ratio is 95% or more.
例えば、前記製鋼スラグは粒径が40mm以下であって、前記高炉水砕スラグは前記スラグ材の全量に対する含有量が5質量％以上25質量％以下とすることができる。また、前記スラグ材によって形成される前記表層の厚さは、100mm−200mmとすることができる。さらに、前記スラグ材によって形成される前記表層の透水係数が3.0×10-6m/s以下となるようにすることが好ましい。 For example, the steelmaking slag has a particle size of 40 mm or less, and the content of the blast furnace granulated slag with respect to the total amount of the slag material can be 5% by mass or more and 25% by mass or less. Further, the thickness of the surface layer formed by the slag material can be 100 mm-200 mm. Further, it is preferable that the water permeability coefficient of the surface layer formed by the slag material is 3.0 × 10 -6 m / s or less.
また、斜面の遮水構造の構築方法の発明は、斜面の表層として設けられる斜面の遮水構造の構築方法であって、製鋼スラグと高炉水砕スラグとを混合したスラグ材を前記斜面に敷き均して、締固め密度比が90％以上となるように締め固めることを特徴とする。 Further, the invention of the method for constructing the water-impervious structure on the slope is a method for constructing the water-impervious structure on the slope provided as the surface layer of the slope, in which a slag material obtained by mixing steelmaking slag and blast furnace granulated slag is laid on the slope. It is characterized in that it is compacted so that the compaction density ratio is 90% or more.
このように構成された本発明の斜面の遮水構造は、製鋼スラグと高炉水砕スラグとを混合したスラグ材を、締固め密度比が90％以上となるように締め固めたことによって構築される。 The water-impervious structure of the slope of the present invention constructed in this way is constructed by compacting a slag material obtained by mixing steelmaking slag and blast furnace granulated slag so that the compaction density ratio is 90% or more. To.
要するに、製鋼工程で発生する製鋼スラグと高炉水砕スラグとを使用するだけなので、比較的安価な材料費にすることができる。また、締固め密度比が90％以上となるように締め固めることによって、高い遮水性能を確保することができる。特に、締固め密度比を95％以上とすることで、雨水の斜面への浸透率を大幅に低減させることができる。 In short, since only the steelmaking slag generated in the steelmaking process and the blast furnace granulated slag are used, the material cost can be relatively low. Further, high water-impervious performance can be ensured by compacting so that the compaction density ratio is 90% or more. In particular, by setting the compaction density ratio to 95% or more, the penetration rate of rainwater into the slope can be significantly reduced.
以下、本発明の実施の形態について図面を参照して説明する。図１は、本実施の形態で説明する斜面の遮水構造の構成を、部分的に拡大して示した説明図である。
まず図１を参照しながら全体的な構成を説明すると、斜面Ｓには、地山を掘削する切土の際に発生する傾斜面や、基礎地盤上に土を盛り上げて堤体や造成地などを構築する盛土の際に発生する傾斜面などが該当する。
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing a configuration of a water-impervious structure on a slope described in the present embodiment in a partially enlarged manner.
First, the overall structure will be explained with reference to FIG. 1. On the slope S, there are slopes generated when excavating the ground, levee bodies, embankments, etc. by raising the soil on the foundation ground. This applies to slopes that occur during embankment to construct.
以下では、1:2.0勾配の斜面、すなわち水平に対して約26°の傾斜角で傾く斜面Ｓの表層として設けられる、斜面の遮水構造となる遮水層１を例に説明する。このような斜面Ｓには、斜面崩壊の原因となる雨水の斜面Ｓの内部への浸透や表面の侵食などを防ぐために、遮水層１が設けられる。 In the following, an example will be described of a water-impervious layer 1 having a water-impervious structure of a slope provided as a surface layer of a slope having a slope of 1: 2.0, that is, a slope S having an inclination angle of about 26 ° with respect to the horizontal. An impermeable layer 1 is provided on such a slope S in order to prevent rainwater from penetrating into the slope S and eroding the surface, which causes slope failure.
この遮水層１に最も求められる性能は遮水性能であり、透水係数が小さくなるほど好ましい。さらに、遮水層１には、セメントやアスファルトなどの高価な材料を使用せずに、比較的に安価な材料だけで構築できることが好ましい。 The most required performance of the water-impervious layer 1 is water-impervious performance, and the smaller the water permeability coefficient, the more preferable. Further, it is preferable that the impermeable layer 1 can be constructed only with a relatively inexpensive material without using an expensive material such as cement or asphalt.
そこで、本実施の形態では、遮水層１を製鋼スラグと高炉水砕スラグとを混合したスラグ材によって形成することとする。製鋼スラグや高炉水砕スラグなどの鉄鋼スラグは、製鋼工程で発生する産業副産物であり、比較的安価に入手できるうえに、有効に利用することで環境負荷の低減にも貢献できるようになる。 Therefore, in the present embodiment, the impermeable layer 1 is formed of a slag material obtained by mixing steelmaking slag and blast furnace granulated slag. Steel slag such as steelmaking slag and blast furnace granulated slag is an industrial by-product generated in the steelmaking process, and can be obtained at a relatively low price, and by effectively using it, it can contribute to reducing the environmental load.
製鋼スラグ及び高炉水砕スラグは、酸化カルシウム、けい酸カルシウム、酸化鉄（II）、アルミナ等を主成分とする複合材料であって、潜在水硬性を有する。また、製鋼スラグ単体でも弱い水硬性があり強度を発現するが、製鋼スラグに高炉水砕スラグを混合することによって、強アルカリである製鋼スラグが更に強い水硬性を有する高炉水砕スラグを刺激し、水和物が生成して強度の高い固結体になる。 Steelmaking slag and blast furnace granulated slag are composite materials containing calcium oxide, calcium silicate, iron (II) oxide, alumina and the like as main components, and have latent hydraulic hardness. In addition, steelmaking slag alone has weak water hardness and exhibits strength, but by mixing blast furnace granulated slag with steelmaking slag, steelmaking slag, which is a strong alkali, stimulates blast furnace granulated slag with even stronger water hardness. , Hydrate is formed to form a strong solidified body.
さらに詳細に説明すると、高炉水砕スラグが製鋼スラグのアルカリ刺激を受け、シリカ(Si)とアルミニウム(Al)とが水分に溶け出し、製鋼スラグから溶け出すカルシウム(Ca)とポゾラン反応を起こして石灰シリカアルミナ(C-S-A-H:C=CaO,S=SiO2,A=Al2O3,H=H2O)系水和物が生成されると、粒子間隙を繋いでいくと同時に粒子間空隙が充填されることで固結が起きる。また、水中の過剰なCaイオンが空気中の炭酸イオンと反応して、炭酸カルシウム(CaCO3)も同時に生成して固結することになる。 More specifically, the blast furnace granulated slag is stimulated by the alkali of the steelmaking slag, and silica (Si) and aluminum (Al) dissolve in water, causing a pozolan reaction with calcium (Ca) dissolved from the steelmaking slag. When lime silica-alumina (CSAH: C = CaO, S = SiO 2 , A = Al 2 O 3 , H = H 2 O) -based hydrate is produced, it connects the interparticle gaps and at the same time creates interparticle voids. Caking occurs when filled. In addition, excess Ca ions in water react with carbonate ions in the air to simultaneously generate calcium carbonate (CaCO 3 ) and consolidate.
このような製鋼スラグと高炉水砕スラグとを混合したスラグ材によって遮水層１を構築するには、斜面Ｓにスラグ材を敷き均し、その上から水硬性を促進させるための水を散布し、転圧機などで転圧して締め固めることで形成することになる。 In order to construct the impermeable layer 1 with a slag material obtained by mixing such steelmaking slag and blast furnace granulated slag, the slag material is spread on the slope S and water for promoting water hardness is sprayed on the slag material. Then, it is formed by rolling and compacting with a compactor or the like.
製鋼スラグとしては、例えば目開き40mmの篩でふるって網目を通り抜けた粒径が40mm以下の製鋼スラグを使用することができる。また、高炉水砕スラグとしては、溶融した高炉スラグに加圧水を噴射するなどして、急激に冷却したままのガラス質の粒状スラグが使用できる。 As the steelmaking slag, for example, a steelmaking slag having a particle size of 40 mm or less that has passed through the mesh by sieving with a sieve having a mesh size of 40 mm can be used. Further, as the blast furnace granulated slag, glassy granular slag that has been rapidly cooled by injecting pressurized water onto the molten blast furnace slag can be used.
高炉水砕スラグは、例えばスラグ材の全量に対する含有量が5質量％以上25質量％以下となるように混合される。これに対して、製鋼スラグのスラグ材の全量に対する含有量は、95質量％以下75質量％以上となる。要するに、製鋼スラグと高炉水砕スラグとを併せたものが、スラグ材の全量となる。 The blast furnace granulated slag is mixed so that, for example, the content of the slag material with respect to the total amount is 5% by mass or more and 25% by mass or less. On the other hand, the content of the steelmaking slag with respect to the total amount of the slag material is 95% by mass or less and 75% by mass or more. In short, the total amount of slag material is the combination of steelmaking slag and blast furnace granulated slag.
一方において、遮水層１として要求される遮水性能を発揮させるためには、道路舗装以上の締め固めが必要となる。すなわち、道路舗装においては、透水性舗装のように積極的に雨水を基盤側に浸透させる舗装が存在するように、遮水性能はそれほど重要視されないこともあるが、斜面Ｓを安定化させるためには、所定以上の遮水性能を備えていることが要求される。 On the other hand, in order to exhibit the impermeable performance required for the impermeable layer 1, it is necessary to compact the road pavement or more. That is, in road pavement, the impermeable performance may not be so important as there is a pavement that actively infiltrates rainwater into the base side like a permeable pavement, but in order to stabilize the slope S. Is required to have a water-impervious performance equal to or higher than a predetermined value.
そこで、以下では、締固め度合と透水性との関係について説明するとともに、斜面Ｓの表層として設ける遮水層１に適した遮水構造について説明する。まず、図２−図６を参照しながら、遮水性能を確認するために行った散水実験について説明する。 Therefore, in the following, the relationship between the degree of compaction and the water permeability will be described, and the impermeable structure suitable for the impermeable layer 1 provided as the surface layer of the slope S will be described. First, a watering experiment conducted to confirm the impermeable performance will be described with reference to FIGS. 2 to 6.
この散水実験では、上記したスラグ材を使用した斜面Ｓ（のり面）の施工条件（含水比，乾燥密度）による遮水性能の違いを把握するために、のり面付近を模擬した傾斜地盤の地盤模型（図２参照）を作製して実施した。 In this watering experiment, in order to understand the difference in impermeable performance depending on the construction conditions (moisture content ratio, dry density) of the slope S (slope) using the above-mentioned slag material, the ground of the slope ground simulating the vicinity of the slope A model (see FIG. 2) was prepared and carried out.
この散水実験を実施するにあたり、含水比と密度（乾燥密度）を変えたスラグ材の供試体の透水試験を行い、含水比及び乾燥密度の大きさによる透水係数の変化を把握することにした。まず、図３に示すように、含水比7％−11％の範囲で締固め密度比が90％−99％の供試体の透水試験を行った。ここで、締固め密度比（Dc）とは、試料の乾燥密度と最大乾燥密度との比で、「締固め度」と言われることもある締固め度合を表す指標である。 In carrying out this watering experiment, it was decided to conduct a hydraulic conductivity test of the slag material specimens with different water content and density (dry density) to understand the change in hydraulic conductivity depending on the water content and the magnitude of the dry density. First, as shown in FIG. 3, a water permeability test of a specimen having a compaction density ratio of 90% to 99% in a water content ratio of 7% to 11% was performed. Here, the compaction density ratio (Dc) is a ratio between the dry density of a sample and the maximum dry density, and is an index indicating the degree of compaction, which is sometimes referred to as “compacting degree”.
一連の試験の結果、含水比が大きくなり最適含水比の11％に近くなるほど透水係数が小さくなること、また締固め密度比（乾燥密度）が大きくなるほど小さな透水係数が得られることがわかった。特に、最適含水比が11％に近くで締固め密度比が99％と大きい場合には、透水係数は1.0×10-8m/s以下の極めて小さな値になることを確認した。 As a result of a series of tests, it was found that the larger the water content ratio and the closer to 11% of the optimum water content ratio, the smaller the hydraulic conductivity, and the larger the compaction density ratio (dry density), the smaller the hydraulic conductivity. In particular, it was confirmed that when the optimum water content ratio is close to 11% and the compaction density ratio is as large as 99%, the hydraulic conductivity becomes an extremely small value of 1.0 × 10 -8 m / s or less.
また、最適含水比より大きな含水比の供試体に対して、含水比を変えたスラグ材の供試体の透水試験を行い、最適含水比より大きな範囲での含水比の大きさによる透水係数の変化を把握することにした。この供試体の作製密度は、締固め密度比を90％とし、含水比が11％、12％、13％となる３種類の供試体を用意した。 In addition, a hydraulic conductivity test was conducted on a specimen with a hydraulic conductivity larger than the optimum hydraulic conductivity of a slag material specimen with a different hydraulic conductivity, and the change in the hydraulic conductivity due to the magnitude of the hydraulic conductivity in a range larger than the optimum hydraulic conductivity. I decided to figure out. As for the preparation density of this specimen, three types of specimens having a compaction density ratio of 90% and a water content ratio of 11%, 12%, and 13% were prepared.
これらの３種類の供試体に対して透水試験をした結果、含水比が11％の供試体では1.11×10-5(m/s)、含水比が12％の供試体では1.76×10-5(m/s)、含水比が13％の供試体では2.24×10-5(m/s)という透水係数ｋの結果が得られた。要するに、いずれの含水比としても、ほぼ同程度の透水係数ｋとなり、最適含水比より大きな範囲では含水比が透水係数ｋに与える影響は小さいことがわかった。 As a result of water permeability tests on these three types of specimens, the specimen with a water content of 11% was 1.11 × 10 -5 (m / s), and the specimen with a water content of 12% was 1.76 × 10 -5. A hydraulic conductivity k of 2.24 × 10 -5 (m / s) was obtained for the specimen with (m / s) and a water content of 13%. In short, it was found that the hydraulic conductivity k was almost the same regardless of the water content ratio, and the influence of the hydraulic conductivity on the hydraulic conductivity k was small in the range larger than the optimum hydraulic conductivity k.
図２は、本実施の形態の斜面の遮水構造の効果を確認するために行った散水実験で使用した地盤模型の概要を示している。この地盤模型は、120mmの層厚で斜面Ｓを模したのり面地盤（東北硅砂6号で作製）に、スラグ材を使用したのり面工を敷設した構造である。 FIG. 2 shows an outline of the ground model used in the watering experiment conducted to confirm the effect of the impermeable structure on the slope of the present embodiment. This ground model has a structure in which a slope work using slag material is laid on a slope ground (made of Tohoku silica sand No. 6) that imitates a slope S with a layer thickness of 120 mm.
遮水層１は、150mmの層厚とし、斜面長は約1700mmとした。実際の斜面Ｓに遮水層１として施工する場合の層厚は、100mm−200mm程度となるように形成するのが好ましい。また、斜面Ｓののり尻側（表流水の下流側）となる位置には、透水平板を設置し、その近辺はのり面地盤ではない開口として、表流水量を測定できるようにした。さらに、斜面Ｓを模したのり面地盤には、複数の排水経路を下面に直交する方向で設け、浸透量を測定できるようにした。 The impermeable layer 1 has a layer thickness of 150 mm and a slope length of about 1700 mm. When the water-impervious layer 1 is applied to the actual slope S, the layer thickness is preferably about 100 mm to 200 mm. In addition, a transparent horizontal plate was installed at the position on the slope S on the side of the slope (downstream of the surface water) so that the amount of surface water could be measured by using an opening that is not the slope ground in the vicinity. Further, on the slope ground imitating the slope S, a plurality of drainage paths are provided in a direction orthogonal to the lower surface so that the permeation amount can be measured.
そして、地盤模型の構築後、1：2.0の斜面Ｓ（図１参照）を模擬するために、土槽ごと26度に傾けた。また、のり面地盤には、300mm間隔で土壌水分計と間隙水圧計とを設置した。ここで、土壌水分計にはのり尻側（表流水の下流側）から順にPWP01,PWP02,・・・という符号を付け、間隙水圧計にはのり尻側から順にM01,M02,・・・という符号を付けた。 Then, after the construction of the ground model, the entire soil tank was tilted at 26 degrees in order to simulate the 1: 2.0 slope S (see FIG. 1). In addition, soil moisture meters and pore water pressure gauges were installed at 300 mm intervals on the slope ground. Here, the soil moisture meter is labeled PWP01, PWP02, ... in order from the glue tail side (downstream side of surface water), and the pore water pressure gauge is labeled M01, M02, ... in order from the glue tail side. Signed.
散水実験は、降雨強度を変えて複数のパターンで行った。詳細には、降雨強度20mm/hrの場合と降雨強度90mm/hrの場合の散水実験を行った。また、遮水層１の模擬は、材料となるスラグ材の配合は同一とし、締固め度合を変えた複数のケース（Case1-Case3）で行った。 The watering experiment was carried out in multiple patterns with different rainfall intensities. Specifically, watering experiments were conducted when the precipitation intensity was 20 mm / hr and when the precipitation intensity was 90 mm / hr. Further, the simulation of the impermeable layer 1 was performed in a plurality of cases (Case1-Case3) in which the composition of the slag material used as the material was the same and the degree of compaction was changed.
スラグ材の配合は、全量に対する製鋼スラグの含有量が80質量％（粒径25mm以下）、高炉水砕スラグの含有量が20質量％（粒径2mm）とした。また、初期含水比は、いずれのケースも11.0％とした。 The composition of the slag material was such that the content of steelmaking slag was 80% by mass (particle size 25 mm or less) and the content of blast furnace granulated slag was 20% by mass (particle size 2 mm). The initial water content was 11.0% in all cases.
そして、Case1は、乾燥密度が2.263(g/cm3)となるように締め固めたケースである。この締固め度合は、最大乾燥密度との比で表す締固め密度比（Dc）で99％となる。このCase1の室内透水試験によって測定された透水係数ｋは、9.04×10-9(m/s)となった。 Case 1 is a case compacted so that the drying density is 2.263 (g / cm 3 ). This degree of compaction is 99% in terms of the compaction density ratio (Dc) expressed as a ratio to the maximum dry density. The hydraulic conductivity k measured by the indoor hydraulic conductivity test of Case 1 was 9.04 × 10 -9 (m / s).
また、Case2は、乾燥密度が2.057(g/cm3)となるように締め固めたケースである。この締固め度合は、最大乾燥密度との比で表す締固め密度比（Dc）で90％となる。このCase2の室内透水試験によって測定された透水係数ｋは、1.11×10-5(m/s)となった。 Case 2 is a case compacted so that the drying density is 2.057 (g / cm 3 ). This degree of compaction is 90% in terms of compaction density ratio (Dc) expressed as a ratio to the maximum dry density. The hydraulic conductivity k measured by the indoor hydraulic conductivity test of Case 2 was 1.11 × 10 -5 (m / s).
さらに、Case3は、乾燥密度が2.171(g/cm3)となるように締め固めたケースである。この締固め度合は、最大乾燥密度との比で表す締固め密度比（Dc）で95％となる。このCase3の室内透水試験によって測定された透水係数ｋは、3.19×10-6(m/s)となった。 In addition, Case 3 is a case compacted to a dry density of 2.171 (g / cm 3 ). This degree of compaction is 95% in terms of compaction density ratio (Dc) expressed as a ratio to the maximum dry density. The hydraulic conductivity k measured by the indoor hydraulic conductivity test of Case 3 was 3.19 × 10 -6 (m / s).
散水実験では、傾斜させた地盤模型の上から、降雨強度20mm/hr又90mm/hrとなる散水を行い、透水平板位置から排出される表流水量、のり面地盤の下面側から排出される浸透量、土壌水分計及び間隙水圧計の検出値を測定した。 In the watering experiment, water was sprinkled from the top of the inclined ground model to a rainfall intensity of 20 mm / hr or 90 mm / hr, and the amount of surface water discharged from the position of the permeable horizontal plate and the penetration discharged from the lower surface side of the slope ground. The amount, the detected values of the soil moisture meter and the pore water pressure gauge were measured.
図４−図６に、降雨強度毎の実験結果を示した。ここで、比較のために、遮水層１を設けない場合（無対策）の実験結果も示した。まず図４は、降雨強度20mm/hrの場合（図４（ａ））と降雨強度90mm/hrの場合（図４（ｂ））の浸透率の時刻歴を示している。 FIG. 4-Fig. 6 shows the experimental results for each rainfall intensity. Here, for comparison, the experimental results when the impermeable layer 1 is not provided (no countermeasures) are also shown. First, FIG. 4 shows the time history of the penetration rates when the precipitation intensity is 20 mm / hr (FIG. 4 (a)) and when the precipitation intensity is 90 mm / hr (FIG. 4 (b)).
ここで、浸透率（％）とは、表流水量と浸透量の合計に対する浸透量の割合を示す値で、浸透率＝浸透量／（表流水量＋浸透量）の式によって算定される。これらの結果を見ると、いずれの降雨強度においても、Case1では浸透率がほとんど見られず、斜面Ｓの内部への浸透が起きないことが確認された。 Here, the permeation rate (%) is a value indicating the ratio of the permeation amount to the total of the surface water amount and the permeation amount, and is calculated by the formula of permeation rate = permeation amount / (surface water amount + permeation amount). From these results, it was confirmed that the penetration rate was hardly observed in Case 1 at any rainfall intensity, and the penetration into the slope S did not occur.
その一方で、Case2は遮水効果がほとんど見られず、浸透率は無対策と同程度であった。これに対して、締固め密度比を95％としたCase3では、完全な遮水は実現できなかったが、かなりの降雨が浸透せずに表面水（表流水）として流下したと言える。 On the other hand, Case 2 showed almost no water-blocking effect, and the penetration rate was about the same as that of no measures. On the other hand, in Case 3 with a compaction density ratio of 95%, complete water impermeability could not be achieved, but it can be said that considerable rainfall did not permeate and flowed down as surface water (surface water).
そこで、降雨強度を20mm/hrとして、各ケースの斜面Ｓの位置による違いについて検証することとした。ここで、降雨強度20mm/hrは、気象庁の「雨の強さと降り方」の分類によれば、予報用語で「強い雨」、人の受けるイメージで「どしゃ降り」の雨となる。 Therefore, it was decided to set the rainfall intensity to 20 mm / hr and verify the difference depending on the position of the slope S in each case. Here, the rainfall intensity of 20 mm / hr is classified as "strong rain" in the forecast term and "rainfall" in the image received by people according to the classification of "rain intensity and how to get off" by the Japan Meteorological Agency.
図５は、飽和度（％）の時刻歴を示したグラフであり、図５（ａ）は斜面Ｓの下流地点（図２のPWP01地点）における飽和度を示し、図５（ｂ）は斜面Ｓの中央地点（図２のPWP03地点）における飽和度を示し、図５（ｃ）は斜面Ｓの上流地点（図２のPWP06地点）における飽和度を示している。 FIG. 5 is a graph showing the time history of the degree of saturation (%), FIG. 5 (a) shows the degree of saturation at the downstream point of the slope S (point PWP01 in FIG. 2), and FIG. 5 (b) is the slope. The degree of saturation at the central point of S (point PWP03 in FIG. 2) is shown, and FIG. 5 (c) shows the degree of saturation at the upstream point of slope S (point PWP06 in FIG. 2).
これらの結果を見ると、下流地点（図５（ａ））では、無対策のケースで飽和度が低く、スラグ材による遮水層１を設けたのり面工を施工したケース（Case1-Case3）では、比較的飽和度が高くなっていることがわかる。 Looking at these results, at the downstream point (Fig. 5 (a)), the saturation was low in the case of no countermeasures, and the case where the slope work was performed with the impermeable layer 1 made of slag material (Case1-Case3). Then, it can be seen that the degree of saturation is relatively high.
これは、無対策では、ほぼ均等に降雨が斜面Ｓの内部（盛土内）に浸透するのに対して、遮水層１を施工したケースでは、遮水層１の表面を流下する表流水が多くなり、下流地点（のり尻）付近でその一部が浸透するためと考えられる。要するに、のり尻における流入量が、無対策のケースよりも多くなると考えられる。 This is because, without countermeasures, rainfall permeates the inside of the slope S (inside the embankment) almost evenly, whereas in the case where the impermeable layer 1 is constructed, the surface water flowing down the surface of the impermeable layer 1 flows down. It is thought that this is because the number increases and a part of it penetrates near the downstream point (nori-jiri). In short, it is considered that the amount of inflow at the glue butt will be larger than in the case of no measures.
一方、中央地点（図５（ｂ））では、無対策とCase2の飽和度は同様の時刻歴となり、Case1とCase3では、ほとんど飽和度の増加が見られずに、図４で示した浸透率の結果と同様に、時間の経過による増加が見られない結果となった。 On the other hand, at the central point (Fig. 5 (b)), the saturation of Case 2 was the same as that of no countermeasures, and in Case 1 and Case 3, there was almost no increase in saturation, and the penetration rate shown in Fig. 4 was observed. Similar to the result of, the result showed no increase with the passage of time.
そして、上流地点（図５（ｃ））では、Case1，Case3，Case2，無対策の順に飽和度の増加が確認され、下流地点及び中央地点では無対策と同程度かそれ以上の浸透が確認されていたCase2についても、上流地点においては一定の遮水効果が見られることが確認された。 Then, at the upstream point (Fig. 5 (c)), an increase in saturation was confirmed in the order of Case1, Case3, Case2, and no countermeasures, and at the downstream and central points, penetration equal to or higher than that without countermeasures was confirmed. It was confirmed that Case 2 also had a certain water-blocking effect at the upstream point.
図６は、降雨強度を90mm/hrとして、各ケースの斜面Ｓの位置による違いについて、飽和度（％）の時刻歴によって検証した結果を示している。ここで、降雨強度90mm/hrは、気象庁の「雨の強さと降り方」の分類によれば、予報用語で「猛烈な雨」、人の受けるイメージで「息苦しくなるような圧迫感がある。恐怖を感ずる。」という雨になる。 FIG. 6 shows the result of verifying the difference depending on the position of the slope S of each case by the time history of the saturation degree (%), assuming that the rainfall intensity is 90 mm / hr. Here, according to the classification of "rain intensity and how to get off" by the Japan Meteorological Agency, the rainfall intensity of 90 mm / hr is "heavy rain" in the forecast term, and "a feeling of oppressive feeling that makes people suffocate." I feel afraid. "
そして、飽和度の時刻歴を示した図６のグラフにおいて、図６（ａ）は斜面Ｓの下流地点（図２のPWP01地点）における飽和度を示し、図６（ｂ）は斜面Ｓの中央地点（図２のPWP03地点）における飽和度を示している。 Then, in the graph of FIG. 6 showing the time history of the saturation degree, FIG. 6A shows the saturation degree at the downstream point of the slope S (PWP01 point of FIG. 2), and FIG. 6B is the center of the slope S. The degree of saturation at the point (PWP03 point in FIG. 2) is shown.
これらの結果を見ると、下流地点（図６（ａ））では、降雨強度20mm/hrの場合と同様の結果になったが、中央地点（図６（ｂ））では、Case2においても飽和度の増加が抑制されていることが確認された。 Looking at these results, the results were similar to those at the downstream point (Fig. 6 (a)) when the rainfall intensity was 20 mm / hr, but at the central point (Fig. 6 (b)), the saturation level was also high in Case 2. It was confirmed that the increase in was suppressed.
「猛烈な雨」に分類される降雨強度90mm/hrの場合のように、流入量が非常に大きくなる場合には、一定量が表流水として排水されて、斜面Ｓ内部の飽和度の増加が抑制されたものと考えられる。 When the inflow is very large, as in the case of a rainfall intensity of 90 mm / hr classified as "heavy rain", a certain amount is drained as surface water and the degree of saturation inside the slope S increases. It is considered to have been suppressed.
ところでスラグ材は、アルカリ性を示すため、参考までに各ケースのpHも測定した。いずれのケースにおいても、表流水のpHは平均値で7.8-8.5程度となり、浸透水のpHは8.2-11.7程度となった。但し、スラグ材の炭酸化が表面から進むことにより、これらのpHは時間の経過とともに徐々に低下していくことになる。 By the way, since the slag material is alkaline, the pH of each case was also measured for reference. In each case, the average pH of surface water was about 7.8-8.5, and the pH of osmotic water was about 8.2-11.7. However, as the carbonation of the slag material progresses from the surface, these pH gradually decrease with the passage of time.
次に、本実施の形態の斜面の遮水構造及びその構築方法の作用について説明する。
このように構成された本実施の形態の斜面の遮水構造は、製鋼スラグと高炉水砕スラグとを混合したスラグ材を斜面Ｓに敷き均して、締固め密度比が90％以上となるように締め固めることによって構築される。
Next, the operation of the water-impervious structure of the slope of the present embodiment and the method of constructing the same will be described.
In the water-impervious structure of the slope of the present embodiment configured in this way, a slag material obtained by mixing steelmaking slag and blast furnace granulated slag is spread evenly on the slope S, and the compaction density ratio becomes 90% or more. It is built by compacting so that
要するに、製鋼工程で発生する製鋼スラグと高炉水砕スラグとを使用するだけなので、比較的安価な材料費にすることができる。また、締固め密度比が90％以上となるように締め固めることによって、少なくとも斜面Ｓののり肩付近（表流水の上流側）の飽和度が増加することのない高い遮水性能を確保することができる。 In short, since only the steelmaking slag generated in the steelmaking process and the blast furnace granulated slag are used, the material cost can be relatively low. In addition, by compacting so that the compaction density ratio is 90% or more, high impermeable performance that does not increase the saturation of at least the vicinity of the glue shoulder of the slope S (upstream side of surface water) should be ensured. Can be done.
また、降雨強度が大きい場合には、斜面Ｓののり肩付近だけでなく、中央付近においても飽和度が増加するのを抑えることができる。さらに、締固め密度比を95％以上とすることで、雨水の斜面Ｓへの浸透率を大幅に低減させることができる。 Further, when the rainfall intensity is high, it is possible to suppress an increase in the degree of saturation not only in the vicinity of the shoulder of the slope S but also in the vicinity of the center. Further, by setting the compaction density ratio to 95% or more, the penetration rate of rainwater into the slope S can be significantly reduced.
このような遮水層１は、製鋼スラグの粒径が40mm以下であって、全量に対する高炉水砕スラグの含有量を5質量％以上25質量％以下にしたスラグ材を、転圧によって締め固めることで構築することができる。 In such an impermeable layer 1, a slag material having a steelmaking slag having a particle size of 40 mm or less and a blast furnace granulated slag content of 5% by mass or more and 25% by mass or less based on the total amount is compacted by rolling compaction. It can be built by.
また、スラグ材によって形成される遮水層１の厚さは、100mm−200mm程度にすることで、材料費を抑えたうえで、所望する遮水性能が得られるようになる。要するに、遮水層１の透水係数ｋが3.0×10-6m/s以下となるように締め固めることで、盛土や地山などの斜面Ｓの内部に雨水が浸透して崩壊を誘発することを防ぐことができる。 Further, by setting the thickness of the impermeable layer 1 formed of the slag material to about 100 mm-200 mm, the desired impermeable performance can be obtained while suppressing the material cost. In short, by compacting the impermeable layer 1 so that the hydraulic conductivity k is 3.0 × 10 -6 m / s or less, rainwater permeates the inside of the slope S such as embankment or ground and induces collapse. Can be prevented.
以上、図面を参照して、本発明の実施の形態を詳述してきたが、具体的な構成は、この実施の形態に限らず、本発明の要旨を逸脱しない程度の設計的変更は、本発明に含まれる。 Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes to the extent that the gist of the present invention is not deviated are described in the present invention. Included in the invention.
例えば、前記実施の形態では、1:2.0の勾配の斜面Ｓを例に説明したが、これに限定されるものではなく、任意の勾配の斜面を有する盛土や切土に対しても本発明を適用することができる。 For example, in the above-described embodiment, the slope S having a slope of 1: 2.0 has been described as an example, but the present invention is not limited to this, and the present invention is also applied to embankments and cuts having slopes of an arbitrary slope. Can be applied.
Ｓ 斜面
１ 遮水層（斜面の遮水構造）
S slope 1 Impermeable layer (impermeable structure of slope)
Claims (10)
製鋼スラグと高炉水砕スラグとを混合したスラグ材を、締固め密度比が90％以上となるように締め固めたことを特徴とする斜面の遮水構造。 It is a water-impervious structure of the slope provided as the surface layer of the slope.
A water-impervious structure on a slope characterized by compacting a slag material, which is a mixture of steelmaking slag and blast furnace granulated slag, so that the compaction density ratio is 90% or more.
製鋼スラグと高炉水砕スラグとを混合したスラグ材を前記斜面に敷き均して、締固め密度比が90％以上となるように締め固めることを特徴とする斜面の遮水構造の構築方法。 It is a method of constructing a water-impervious structure on a slope provided as the surface layer of the slope.
A method for constructing an impermeable structure on a slope, characterized in that a slag material obtained by mixing steelmaking slag and blast furnace granulated slag is spread evenly on the slope and compacted so that the compaction density ratio is 90% or more.
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