JP2566420B2 - Lightweight embankment structure and construction method - Google Patents

Description

The present invention relates to a structure of an embankment having a polyurethane foam inside as a constituent element and a method for constructing the embankment.

[Conventional technology]

Conventionally, as the structure of the embankment made for the purpose of site construction or embankment, the whole structure has been mainly composed of only sand or earth and sand. However, in these conventional embankment structures, the soil pressure that is used is large due to the high density of the sand, sand, etc. that compose it, and the subsidence of the embankment causes consolidation settlement due to a large load, or the bottom of the embankment itself is There was a case where a so-called slip phenomenon that spreads outward was generated. Moreover, when constructing the embankment as backfilling for a retaining wall, for example, it was necessary to make the retaining wall large in cross section to support the large lateral pressure. Further, in constructing these conventional embankments, a method is used in which the sand or the like that constitutes the embankment is transported to the construction site while the sand and the like are evenly piled up from below.

As a means for reducing the large weight, which was one of the drawbacks of the conventional embankment, a banking structure using a lightweight material such as expanded polystyrene has been proposed in recent years, and some construction examples have already been seen in Norway and the like. Has been. This lightweight embankment structure has, for example, a block structure layer formed by laminating a large number of blocks made of expanded polystyrene inside, and the weight of the embankment can be reduced by partially replacing the conventional sand etc. with this block structure layer. In addition, it also exhibits excellent workability.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional lightweight embankment structure, the weight of the embankment is reduced by using the lightweight foam, and the block structure layer can be constructed simply by stacking ready-made blocks, which is excellent in workability. However, there is no integrity between each block, or between the block structure layer and the lower ground, etc.Therefore, when a large top load is applied, it may cause settlement due to block displacement, There was a drawback that the resistance to horizontal force was extremely weak.

The present invention has been made in view of the above circumstances, is lightweight and excellent in workability, and yet is a lightweight embankment structure capable of ensuring the integrity of the entire embankment and exhibiting a strong resistance to load and horizontal force. And its construction method.

[Means for solving problems]

A lightweight embankment structure according to a first aspect of the invention is a lightweight embankment including a lightweight structure layer, wherein the lightweight structure layer is integrally formed of a polyurethane foam.

A method of constructing a lightweight embankment according to a second aspect of the present invention comprises:
Formed by injecting polyurethane before foaming / curing into a frame assembled along the design side of the lightweight structure layer, foaming / curing it, and then removing the frame. Is.

[Action]

The lightweight structural layer is made of polyurethane at the construction site using a formwork, so that the lightweight structural layer is integrally and simply configured. By forming the lightweight structure layer as an integral structure, the lightweight structure layer can increase the deformation resistance against external force.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a lightweight embankment structure, and the whole is designated by reference numeral 1. The embankment 1 is composed of a lightweight structure layer 2 which constitutes the majority of the embankment 1 and a coating layer 3 which covers the outside of the lightweight structure layer 2. Reference C is the ground.

The lightweight structural layer 2 is integrally formed of the polyurethane foam 4, and the lightweight structural layer 2 made of the polyurethane foam 4 is formed as follows.

First, as shown in FIG. 2 (a), the ground G at the place where the embankment should be constructed is laid flat, and then the design slope F of the lightweight structure layer
A metal foam (metal frame) 5 is set along the line.

Subsequently, using a spraying machine or the like as shown in FIG. 3B, the polyurethane 4a before foaming and curing is sprinkled on the ground G until it has a predetermined thickness (about 30 cm in the embodiment). Polyurethane
4a starts to foam in about 5 minutes and hardens at the same time to become a polyurethane foam 4. Here, the polyurethane 4a has high adhesiveness (also used as an adhesive), and has low viscosity and large polarity, so that "wetting" on the coated surface is good.
Moreover, the adhesive usually dislikes water, and the adhesive performance tends to be significantly reduced when the water content is high, but the polyurethane foam 4 is formed by the reaction of an isocyanate and a compound having active hydrogen (for example, water). In this case, water does not become an inhibitory substance but becomes a factor that contributes to the adhesive action. Therefore, the polyurethane foam 4 and the ground G can be expected to be integrated.

When the polyurethane 4a in the mold has foamed / cured, sprinkle the polyurethane 4a before foaming / curing on the upper part of the polyurethane 4a until it reaches a predetermined thickness again, as shown in (c) of FIG. -It is cured, but at this time it becomes integrated with the polyurethane foam 4 already formed in the lower part ((d) of the same figure).

After that, by repeating the above steps, the polyurethane foam 4 having the target height is formed as shown in FIG. 8E, and then the metal foam 5 is removed. That is, as a result, the lightweight structure layer 2 is completed as shown in FIG.

By the way, there is concrete as a molding using a mold, but since polyurethane has an extremely low specific gravity and a low foaming pressure as compared with concrete, the mold (metal foam 5) used in the present invention is rigid. It can be small, and construction can be done easily. Here, the reason why the polyurethane foam 4 is formed in a predetermined thickness is that the polyurethane generates a high reaction heat when foaming, and this heat may cause the polyurethane foam 4 itself to be burned down, and the heat generation thereof is suppressed. This is also because the metal foam is used for the mold to improve heat dissipation.

After the lightweight structure layer 2 is formed as described above, the covering layer 3 is formed on the outer side thereof. The cover layer 3 may be made of sand or the like as in the conventional case, but the cover layer 3 may not be formed on the lightweight structure layer 2 and the lightweight structure layer 2 may be used as the embankment 1 as it is.

According to the embankment 1 configured as described above, it is possible to realize a significant weight reduction of the entire embankment by the lightweight structure layer 2 and prevent consolidation and settlement of the ground, and of course, by configuring the lightweight structure layer 2 with polyurethane, Integral configuration on site is possible. As a result, the lightweight structure layer 2 has a large resistance to external force such as load and horizontal force, and the deformation due to external force becomes much smaller than that of the block structure.

If the lightweight structural layer 2 made of the polyurethane foam 4 is formed by the above method, the lightweight structural layer 2 and the lightweight structural layer 2 and the ground G can be easily integrated.

When the coating layer 3 is formed on the outer side of the lightweight structure layer 2,
The polyurethane 4a before foaming and curing is again sprayed on the outer surface of the lightweight structure layer 2 and the substance constituting the coating layer 3 is attached thereto, whereby the covering layer 3 and the lightweight structure layer 2 are integrated. You can Further, the embankment structure and the method for constructing the embankment according to the present invention may be applied not only to the embankment of the form shown in the present embodiment but also to the embankment as backfilling of the retaining wall, for example.

〔The invention's effect〕

As described above, according to the lightweight embankment structure of the first invention, it is possible to reduce the weight of the entire embankment and to eliminate the consolidation phenomenon of the ground and the sliding phenomenon of the lower part of the embankment due to its own weight. By integrating these, it has a strong resistance to external force and can suppress deformation due to load or horizontal force. Moreover, by constructing this lightweight structure layer from polyurethane foam, it is possible to integrally form it on site and to carry out the construction extremely efficiently. Further, according to the method of constructing a lightweight embankment according to the second aspect of the present invention, the lightweight structural layer itself can be integrated with the lightweight structural layer itself and the lightweight structural layer and the ground can be integrated at the same time. Therefore, the construction of the lightweight structure layer is realized very efficiently. In particular, since the embankment has a very large volume, and in most cases has a single cross-sectional shape and is relatively simple, this method is extremely effective and can significantly reduce the construction period.

[Brief description of drawings]

FIG. 1 shows an embodiment of the first invention, which is a cross-sectional view of a lightweight embankment structure, and FIGS. 2 (a) to (f) illustrate a method for constructing the lightweight embankment of the second invention. FIG. 3 is a cross-sectional view of each step of lightweight embankment. G: ground, F: slope, 1 ... embankment, 2 ... lightweight structure layer, 3 ... coating layer, 4a ... polyurethane, 4 ... polyurethane foam, 5 ... metal foam.

Claims (2)

(57) [Claims] 1. A lightweight embankment structure comprising a lightweight structure layer, wherein the lightweight structure layer is formed of an integral polyurethane foam. 2. A method for constructing a lightweight embankment having at least a light weight structure layer therein, wherein the light weight structure layer is foamed in a formwork assembled along a design slope of the light weight structure layer.
A method for constructing a lightweight embankment, which comprises forming polyurethane by injecting polyurethane before curing, foaming and curing it, and then removing the form.