【発明の詳細な説明】[Detailed description of the invention]
本発明は、特に、道路、河川堤防、造成地、鉄
道等の法面や山腹の傾斜面等の浸食防止又は緑化
を行う際に用いて好適な地表面の安定化工法に関
する。
土壌又は岩盤が裸出した地表面は雨、風、霜等
による浸食作用を受け易いので、好ましくは緑化
工法により安定化されるが、場合によつては、安
定化しようとする地表面に酢酸ビニル等の合成樹
脂エマルジヨンが混入分散された客土を適用して
比較的厚い被覆層を設けることにより安定化する
ことが知られている。
しかしながら上記従来の客土を地表面に適用し
た場合には、特に被覆層が厚い程、客土の固結に
日数を要する為未乾燥の客土が降雨によつて流失
崩壊することが多かつた。
この為バインダーとしてセメントを用いること
により客土を急速に固化し、例えば数時間後の降
雨によつても流失崩壌しないようにすることが行
なわれている。しかしながら、この場合はセメン
トのアルカリ性が、例えば緑化する際の種子の発
芽を阻害する等、客土に悪影響を及ぼすものであ
つた。
本発明者等は上記従来の安定化工法の欠点を改
良する過程で、合成樹脂エマルジヨンと焼石膏と
を併用すると客土粒子の固結に要する時間が短縮
され、しかも客土中に種子を混入した場合に該種
子の発芽率の低下は極めて僅かであるという知見
を得て本発明を完成した。
即ち、本発明の目的とするところは、客土の団
結に要する時間が比較的短く従つて降雨により客
土が流失することの少い地表面の安定化工法を提
供することにあり、その要旨は、合成樹脂エマル
ジヨン、焼石膏が土中に混入分散されてなり、前
記焼石膏の量が0.3〜５重量％である客土を地表
面に適用することを特徴とする地表面の安定化工
法に存する。
本発明における合成樹脂エマルジヨンの好適な
例としては、ポリ酢酸ビニルエマルジヨン、酢酸
ビニル−アクリル酸エステル共重合体エマルジヨ
ン、エチレン−酢酸ビニル共重合体エマルジヨ
ン、酢酸ビニル−ビニルバーサテイツク酸共重合
体エマルジヨン、ポリアクリル酸エステルエマル
ジヨン、スチレン−アクリル酸エステル共重合体
エマルジヨン、スチレン−ブタジエン共重合体エ
マルジヨン、ポリクロロプレンエマルジヨン等が
挙げられ、特に、安価な点でポリ酢酸ビニルエマ
ルジヨンが、客土粒子の固結性を高める性質がす
ぐれている点で酢酸ビニル−アクリル酸エステル
共重合体エマルジヨンが好ましく用いられる。
これら合成樹脂エマルジヨンの使用量は、多過
ぎると乾燥固結した客土が不必要な程度に迄固く
なつたり、或いは客土の粒子表面を合成樹脂被膜
が完全に覆つてしまう為客土中に必要に応じて混
入した種子もしくは根莖の発芽の障害となり易
く、一方少な過ぎると客土中の粒子を相互に固結
させて保水性及び適度の柔軟性を付与する機能が
発現しにくく、例えば乾燥後の表層部に発生した
ひび割れ部分に降雨が侵入して客土の流失崩壊を
生じ易くなるので、一般に客土全体における樹脂
分の割合が0.1〜10重量％程度となる範囲とされ
る。
又焼石膏の使用量は客土に用いる土質等にも左
右されるが、客土全体の0.3〜５重量％とされる。
これは、余り少な過ぎると客土中の水分との反応
による凝結硬化作用が発現しにくく従つて客土の
乾燥固結時間の短縮化が達成されず、余り多過ぎ
ると客土が固くなり過ぎ、表層のヒビ割れや発芽
障害を来たす傾向があるからである。
本発明に用いる客土を調整する方法は何等特定
されるものではないが、一般に、前記合成樹脂エ
マルジヨンを必要に応じて水で希釈した後、焼石
膏を加えて得られた分散液と、土とを混合し、更
に必要により種子もしくは根莖を加えて均一に分
散させるのである。
この場合、更にピートモス、リンター等の繊維
類やセメント、ドロマイト等を本発明の目的達成
を妨げない範囲内で客土に混入分散させても良
い。又、地表面を緑化によつて安定させる場合に
は種子もしくは根茎を予め客土に混入しておいて
もよく、場合によつては地表面に適用された客土
に対して種子もしくは根茎を撒布してもよい。
かくして得られた客土を地表面に適用する方法
は何等限定されないが、好ましくは吹付工法が採
用される。
又本発明工法は法面や傾斜面の安定化に限ら
ず、平坦な海岸、河岸、造成地等における飛砂砂
止や鉱業地帯における鉄鉱石、石炭等の粉塵の浮
遊防止等にも使用され得る。
本発明地表面の安定化工法は上述の通りの構成
になされ、合成樹脂エマルジヨン及び焼石膏が土
中に混入分散されてなる客土を地表面に適用する
ので、焼石膏が混入されない場合に比して客土の
固結に要する時間が短縮され従つて安定化しよう
として地表面を被覆した客土が降雨によつて流失
崩壊することが殆んど無くなるのである。
又、本発明における客土中に種子もしくは根莖
を混入分散した場合は、客土の固結時間が短縮さ
れる一方、種子もしくは根莖の発芽率は焼石膏を
用いない場合に比して殆んど遜色が無いので、特
に降雨期、或いは降雨回数の多い地域における地
表面の緑化による安定工法として好適である。
以下に本発明の実施例を示す。
単に部とあるのは重量部を表わす。
実施例１及び比較例１
水10部に、種類及び量が第１表に示された濃度
50重量％の合成樹脂エマルジヨン及び第１表に示
された量の焼石膏を加え、これらと山土100部と
を混合して各成分が均一に分散した客土を得た。
一方水平面に対し30゜の角度に傾斜させたスレ
ート板を用意し、その900cm2に亘る部分を上記客
土によつて被覆し厚さ100mmの客土層を設けた。
次に30分又は48時間客土層を養生した後、毎分10
ｍ／ｍの人工雨を10分間降らせて流出土量を比較
したところ結果は第１表の通りであつた。
又、客土中に種子としてホワイトクローバーを
予め混入する以外は上記と同様にして調整した客
土を用いて、上記と同様にして厚さ100mmの客土
層を設けて播種７日後の発芽率の比較をしたとこ
ろ結果は第１表の通りであつた。ホワイトクロー
バーの量は客土層の100cm2当りに100粒存在するよ
うにした。
尚第１表においては、合成樹脂エマルジヨンの
種類及び量並びに焼石膏の量が同じ場合の上記二
種の実験を同一実験番号で表わした。（実験番号
１〜10）
更に比較の為に合成樹脂エマルジヨン及び焼石
膏を全く用いない場合、合成樹脂エマルジヨンの
みを用いた場合、焼石膏のみを用いた場合、セメ
ントのみを用いた場合の夫々について順次上記と
同様の実験を行つた。その結果は第１表の通りで
あつた。（比較例１、実験番号１〜４）
The present invention particularly relates to a ground surface stabilization method suitable for use in preventing erosion or greening slopes of roads, river embankments, reclaimed land, railways, etc. and mountainside slopes. Since bare soil or bedrock is easily eroded by rain, wind, frost, etc., it is preferably stabilized by greening methods, but in some cases, acetic acid may be applied to the ground surface to be stabilized. It is known that stabilization can be achieved by providing a relatively thick coating layer by applying soil in which a synthetic resin emulsion such as vinyl is mixed and dispersed. However, when the above-mentioned conventional soil cover is applied to the ground surface, the thicker the cover layer, the more days it takes for the soil to consolidate, so the undried soil is often washed away and collapsed by rain. Ta. For this reason, cement is used as a binder to rapidly solidify the soil so that it will not be washed away or crumbled even if, for example, it rains several hours later. However, in this case, the alkalinity of cement had an adverse effect on the soil, for example by inhibiting the germination of seeds during greening. In the process of improving the drawbacks of the conventional stabilization method described above, the present inventors discovered that by using synthetic resin emulsion and calcined gypsum in combination, the time required for consolidation of soil particles can be shortened, and that seeds can be mixed into soil. The present invention was completed based on the knowledge that the germination rate of the seeds decreases only slightly when the seed germination rate is reduced. That is, an object of the present invention is to provide a ground surface stabilization method that takes a relatively short time to consolidate soil and is less likely to be washed away by rain. is a ground surface stabilization method characterized by applying to the ground surface soil in which a synthetic resin emulsion and calcined gypsum are mixed and dispersed in the soil, and the amount of said calcined gypsum is 0.3 to 5% by weight. exists in Suitable examples of the synthetic resin emulsion in the present invention include polyvinyl acetate emulsion, vinyl acetate-acrylic acid ester copolymer emulsion, ethylene-vinyl acetate copolymer emulsion, and vinyl acetate-vinyl versatate copolymer. These include emulsion, polyacrylic ester emulsion, styrene-acrylic ester copolymer emulsion, styrene-butadiene copolymer emulsion, polychloroprene emulsion, etc. Among them, polyvinyl acetate emulsion is particularly popular due to its low cost. Vinyl acetate-acrylic acid ester copolymer emulsion is preferably used because it has an excellent property of enhancing the caking property of soil particles. If the amount of these synthetic resin emulsions used is too large, the dried and solidified soil will become unnecessarily hard, or the surface of the soil particles will be completely covered with a synthetic resin film. If necessary, it tends to hinder the germination of seeds or rhizomes mixed in, while if it is too small, it is difficult to express the function of coagulating the particles in the soil and imparting water retention and appropriate flexibility, for example, drying. Since rainwater can easily enter the cracks that occur in the surface layer and cause the soil to wash away and collapse, the proportion of resin in the entire soil is generally set at about 0.1 to 10% by weight. The amount of calcined gypsum used depends on the quality of the soil used for the soil, but it is generally 0.3 to 5% by weight of the total soil.
If this amount is too small, it will be difficult for the soil to set and harden due to the reaction with the moisture in the soil, and therefore the drying and compacting time of the soil will not be shortened, and if it is too large, the soil will become too hard. This is because they tend to cause surface cracks and germination problems. Although there is no particular method for preparing the soil used in the present invention, in general, after diluting the synthetic resin emulsion with water as necessary, the dispersion obtained by adding calcined gypsum and the soil Then, if necessary, seeds or rhizomes are added to ensure uniform dispersion. In this case, peat moss, fibers such as linters, cement, dolomite, etc. may be mixed and dispersed in the soil within a range that does not impede achievement of the objectives of the present invention. In addition, when stabilizing the ground surface by greening, seeds or rhizomes may be mixed into the soil in advance; in some cases, seeds or rhizomes may be mixed into the soil applied to the ground surface. May be sprayed. The method of applying the thus obtained soil to the ground surface is not limited in any way, but a spraying method is preferably employed. In addition, the method of the present invention is not limited to stabilizing slopes and slopes, but can also be used to prevent flying sand on flat coasts, riverbanks, developed areas, etc., and to prevent floating dust such as iron ore and coal in mining areas. obtain. The ground surface stabilization method of the present invention has the above-mentioned structure and applies soil made of synthetic resin emulsion and calcined gypsum mixed and dispersed in the soil to the ground surface, which is compared to the case where calcined gypsum is not mixed. As a result, the time required for consolidation of the soil is reduced, and the soil that covers the ground surface in an attempt to stabilize it is almost never washed away and collapsed by rain. Furthermore, when seeds or rhizomes are mixed and dispersed in the soil in the present invention, while the consolidation time of the soil is shortened, the germination rate of the seeds or rhizomes is almost negligible compared to when calcined gypsum is not used. Since there is no inferiority, it is suitable as a stable construction method by greening the ground surface, especially during the rainy season or in areas with frequent rainfall. Examples of the present invention are shown below. Parts simply refer to parts by weight. Example 1 and Comparative Example 1 In 10 parts of water, the concentration is as shown in Table 1.
50% by weight of synthetic resin emulsion and the amount of calcined gypsum shown in Table 1 were added, and these were mixed with 100 parts of mountain soil to obtain soil in which each component was uniformly dispersed. On the other hand, a slate plate tilted at an angle of 30° with respect to the horizontal plane was prepared, and a 900 cm 2 portion of the plate was covered with the above soil to form a layer of soil with a thickness of 100 mm.
Next, after curing the soil layer for 30 minutes or 48 hours,
When artificial rain of m/m was applied for 10 minutes and the amount of soil washed away was compared, the results are shown in Table 1. In addition, using soil prepared in the same manner as above except that white clover was mixed in advance as seeds in the soil, a layer of soil with a thickness of 100 mm was provided in the same manner as above, and the germination rate was determined 7 days after sowing. The results were as shown in Table 1. The amount of white clover was set so that 100 seeds were present per 100 cm 2 of the soil layer. In Table 1, the above two types of experiments in which the type and amount of synthetic resin emulsion and the amount of calcined gypsum were the same are represented by the same experiment number. (Experiment Numbers 1 to 10) Furthermore, for comparison, cases where no synthetic resin emulsion or calcined gypsum were used at all, cases where only synthetic resin emulsion was used, cases where only calcined gypsum was used, and cases where only cement were used were examined. Experiments similar to those described above were conducted one after another. The results were as shown in Table 1. (Comparative example 1, experiment numbers 1 to 4)
【表】
実施例２、比較例２
法面勾配35゜の岩盤の面積約20m2に対し第２表
中、実施例２の配合に示す客土を吹き付けて厚さ
80ｍ／ｍの被覆層を得た。
一方、該被覆層を設けた隣接区に、第２表中、
比較例２の配合に示す如くセメントをバインダー
として用いて得られた客土によつて厚さ80ｍ／ｍ
の被覆層を別途設けた。
施工終了直後から降雨状況と上記被覆層の安定
化状態を観察し続けたところ、その結果は第２表
に示す通りであつた。[Table] Example 2, Comparative Example 2 An area of approximately 20 m 2 of rock with a slope slope of 35° was sprayed with soil shown in the composition of Example 2 in Table 2, and the thickness was
A coating layer of 80 m/m was obtained. On the other hand, in the adjacent area where the coating layer was provided, in Table 2,
As shown in the formulation of Comparative Example 2, a thickness of 80 m/m was obtained using soil obtained using cement as a binder.
A separate coating layer was provided. Immediately after the completion of construction, we continued to observe the rainfall conditions and the stabilization state of the coating layer, and the results were as shown in Table 2.
【表】【table】
【表】【table】