JPH0333322A - Earthy structure and reinforcing body therefor - Google Patents

Abstract

PURPOSE:To strengthen asphalt layer over the surface of a road by a method wherein belt-like substances are made of a plurality of polyoxymethelene linear substances that are laid in parallel and are coated with synthetic resin lamina and a reinforcing body is made thereby with intersections where the belt-like substances intersect at right angles each other bonded together and is extended and embedded at the middle of asphalt composite material. CONSTITUTION:Five polyoxymethelene linear substances 1 in 0.5mm diameter and having 40GPa of tensile modulus of elasticity are placed in parallel and are coated with synthetic resin lamina, and a belt-like substance 3 is formed thereby. The belt-like substances 3 are then placed in parallel at intervals in the two directions intersecting at right angles each other, and a reinforcing body 4 is made thereby with intersections bonded together. Then the reinforcing body 4 is extended and embedded roughly at the middle of a 10cm thick asphalt composite material and an asphalt layer is formed thereby as a surface layer of a road. As occasion demands, the reinforcing body 4 may be embedded in earthy structures other thant the asphalt, including bankings, retaining walls or roads, and positive reinforcement of soil layers can be made therewith. Thereby sliding collapses, cracks, ruttings and others can be prevented, resulting in practicable construction of strong earthy structures including bankings, roads and others.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reinforcing body for earth structures such as embankments and roads, and an earth structure reinforced using this reinforcing body.

[Traditional technique]

In conventional road construction, after the roadbed is created, a lower and upper roadbed is formed using crushed stone, earth and sand, etc., and then asphalt or concrete is used as the base and surface layer to pave the road.

However, in recent years, the density of vehicle traffic on roads and the weight of vehicles loaded have continued to rise, causing damage to many roads, and the reality is that road repairs using overlays and the like are frequently carried out before the end of their useful life.

In particular, the disadvantages of asphalt roads include not only asphalt deterioration due to repeated loading, but also problems such as excessive hardening (low temperature) or fluidization (high temperature) of asphalt due to temperature changes, and abnormalities such as subgrade subgrade and heave. Therefore, it is easy to cause cracks, ruts, and cave-ins in the pavement surface.

On the other hand, the stability of embankments in terms of earthwork rate is determined by the strength of the embankment itself and the strength of the foundation ground.

In order to make the embankment more stable, it is necessary to use better quality earth and sand, or to make the embankment a gentle slope, which poses problems in terms of construction costs and effective use of land. The emergence of a method was expected.

As a way to solve these problems with asphalt roads and embankment slopes, attempts have been made to spread synthetic fibers such as woven fabrics, non-woven fabrics, rope nets, etc. as reinforcing materials in asphalt and earth. There is. However, because conventional reinforcements have a low tensile modulus of elasticity of the synthetic fibers used as materials and large dimensional changes under load, they cannot be used to reinforce earth and sand with a small amount of fracture strain or asphalt at low temperatures. It had little effect as a material. For this reason, its use as a filter for treating soft ground and for separating crushed stone layers and sand and sand layers is popular, but in order to actively reinforce the asphalt and sand layers themselves, There was a need for a reinforcing body with a structure that could fully utilize the advantages of the new material.

[Object of the invention] This invention was made in view of the above circumstances. The purpose is to provide reinforcement for earth structures that can be buried in earth structures such as embankments, retaining walls, and roads to prevent sliding collapse, cracks, ruts, etc. We propose an earth structure buried within a layer.

[Structure of the invention]

This reinforcement for earth structures has a tensile modulus of elasticity of 20 GPa or more,
A strip of high elastic polymer linear material having a breaking elongation of 7% or more, or a plurality of linear members in parallel, coated with a synthetic resin layer, is arranged in two orthogonal directions with a gap between them. arranged,
It is characterized by having orthogonal intersections fixed and integrated. Another earth structure according to the invention is constructed by expanding and burying the above-mentioned reinforcing body in the embankment layer of the embankment main body or in the asphalt layer of the road surface layer, and on or under the surface of the reinforcing body. The embankment layer or asphalt layer is characterized in that it is integrated through the embankment or asphalt filled in the voids of the reinforcing body.

The highly elastic polymer linear body constituting this reinforcing body has an initial tensile modulus of 20 gigapascals (GPa) or more and a breaking elongation of 7.
Must be greater than or equal to %. Even if a reinforcing body constructed using a linear body of 20 GPa or less is buried in earth and sand or an asphalt layer, the force that opposes the deformation of the reinforcing body is small in the area where the strain of the earth and sand causes failure is 2% or less. Since the destructive limit deformation of the earth and sand is easily reached, the reinforcing effect cannot be fully exerted. When buried in a sand embankment layer of soil with poor self-adhesion, such as sandy soil, it is more preferable to have an initial tensile modulus of 30 GPa or more and to be able to exert stress intensively in a low elongation region. be.

On the other hand, the earth structure that was reinforced by burying this reinforcing body,
When a sudden impulsive load is applied, the reinforcement must absorb this impact energy in order to support this load. This energy is proportional to the critical amount of deformation under the same breaking strength. Therefore, the highly elastic polymer linear body constituting this reinforcing body has high elasticity and at least 7%
It must have an elongation at break of .

Such highly elastic polymer linear bodies can be obtained by superstretching polyoxymethylene, polyester, polyamide, polyolefin, and the like. For example, polyoxymethylene linear bodies can be drawn with an initial tensile modulus of 5 to 7 GPa by stretching (neck stretching) performed in normal melt spinning, but this can be further stretched several times to increase molecular orientation (neck stretching). (ultra-stretching), it can be increased to 20 to 40 GPa.

(Table 1) (Table 1) Examples of physical properties of highly elastic polymer linear bodies Describe.

If the purpose is only to increase the reinforcing effect, the amount of linear bodies used can be increased to increase the fracture resistance in the 2 to 3% range. However, with such means, the area of the linear body per unit area of the reinforcing body, that is, the area of the band-shaped body becomes large, the void surrounded by the band-shaped body decreases, and the soil on and below the surface of the reinforcing body increases. It becomes difficult to integrate the asphalt layers or asphalt layers, and sliding failure becomes more likely to occur.

In general, ropes, nets, woven and knitted fabrics, etc. have inherent structural deformation due to bending of the composition called twisting and weaving shrinkage, which significantly reduces the apparent modulus of elasticity.

Therefore, in order to obtain a reinforcing body with a high elastic modulus and a high reinforcing effect, it is necessary to make the reinforcing body by a method that does not cause twisting, weaving or shrinkage, etc. This reinforcing body is made by arranging one or more highly elastic polymer linear bodies 1 in parallel without bending them at all, and covering them with a synthetic resin layer 2 to form a band-shaped body 3, as shown in Fig. 1. The reinforcing body 4 is constructed by arranging them in parallel with a gap between them in two orthogonal directions and fixing and integrating the intersecting parts, so that the high elastic modulus of the linear body can be expressed in the reinforcing body without impairing it. Do it like this.

The total area of the voids surrounded by the strips of the reinforcing body is preferably 50% or more of the area of the reinforcing body. If it is less than 50%, the bond between the earth and sand or asphalt layer on and below the surface of the buried reinforcing body tends to be insufficient. More preferably it is 60% or more. In order to provide such a gap, it is preferable that the gap between the parallel strips be at least five times the width of the strips.

In order to bury this reinforcing body 1 in, for example, an embankment 5, as shown in Fig. 2, it is spread out over the lower earth and sand layer G without slack, and then the upper earth and sand layer 6° is placed on top of it, and the upper earth and sand layer is sufficiently covered. By compacting, the voids of the reinforcing body 1 are sufficiently filled with earth and sand, and the earth and sand layers above and below the surface are integrated by 6.6 degrees, and an earth structure consisting of the embankment 5 is constructed. The reinforcing bodies are buried in one or more layers, with intervals maintained, as necessary. It is also buried within the asphalt layer for reinforcement.

〔Example〕

As shown in Figure 1, tensile modulus 40 GPa, diameter 0
．． Five 5 mm polyoxymethylene linear bodies 1 are arranged in several rows and covered with a polyethylene resin layer 2 to form a width of 6 mm. Omm,
A strip 3 with a thickness of 2.0 mm was made, and the strip 3 was arranged in parallel in two orthogonal directions with a gap D=40 mm.
The orthogonal intersection points were partially heated to 100° C., and only the polyethylene resin layer 2 was melted and point-joined to form the reinforcing body 4.

The tensile strength of the polyoxymethylene linear body 1 is 30 kg and the elongation at break is 7%, the tensile strength of the strip 3 is 150 kg and the elongation at break is 7%, and the tensile strength of the reinforcing body 4 is about 110 kg per 3 cm width. The elongation at break was 7%, and it was found that the performance of the linear body 1 was exhibited in the reinforcing body without impairing it.

This reinforcing body 4 was spread and buried approximately in the center of an asphalt mixture having a thickness of 10 cm to form an asphalt layer for the road surface layer. The asphalt mixture is a dense-grained Ascon (13) according to the asphalt pavement guidelines established by the Japan Road Association
) was used.

The asphalt layer reinforced by embedding this reinforcing body was evaluated for thermal stability (O3) by a wheel tracking test. Under conditions of driving at a speed of 42 times for 71 minutes at 60° C., the number of driving times until deformation of 1 mm was defined as O5. Therefore, the larger the DS value, the greater the rutting prevention effect.

The results of Examples and Comparative Examples are shown in Table 2.

(Table 2) [Effects of the Invention] This invention is as described above, and this reinforcing body for earth structures can be buried in the embankment layer of the embankment main body or in the asphalt layer of the road surface layer, etc. to prevent sliding collapse, cracks, and ruts. It is highly effective in preventing digging, etc., and enables the construction of strong earth structures such as embankments and roads.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a reinforcing body for earth structures according to the present invention, and FIG. 2 is a sectional view schematically showing the structure of an embankment in which this reinforcing body is buried. 1... Highly elastic polymer linear body 2... Synthetic resin layer, 3... Band-shaped body 4.
... Reinforcement body, 5 ... Embankment 6.6° ...
...earth and sand

Claims (2)

[Claims] (1) A belt-shaped body made by covering one or multiple parallel high-elastic polymer linear bodies with a synthetic resin layer with a tensile modulus of elasticity of 20 GPa or more and a breaking elongation of 7% or more in two orthogonal directions. A reinforcing body for earth structures, characterized in that the reinforcing bodies are arranged in parallel with a gap between them, and the orthogonal intersections are fixed and integrated. (2) The reinforcing body described in claim (1) is expanded and buried within the embankment layer of the embankment main body or within the asphalt layer of the road surface layer, and is constructed on or under the surface of the reinforcing body. An earth structure characterized in that the embankment layer or asphalt layer is integrated with the embankment or asphalt filled in the voids of the reinforcing body.