JPH11247171A - Plastic sheet for ground reinforcement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently endure tensile strength applied on the collapse of filling by vertically and horizontally arranging the knife cutting part of the holes of circles or the like in zigzag in their direction to be cut on a plastic base plate and extending the base plate in the vertical direction. SOLUTION: Rectangular holes 12 are vertically and horizontally arranged on a polyethylene-made plastic base plate 11 in zigzag, and extended under heating to obtain a plastic sheet 110 . Rectangular holes 120 formed by extending the rectangular holes 12 drilled in the plastic base plate 11 comprise an edge part 13 molecular-oriented by continuously extending in the extension direction and an edge part 14 affected at the time of extending processing before and after it, extension force is dispersed for extending the part (b) of the intersection of both, and no crack occurs at the part. If a fin part is formed on the edge part of the extension direction, the part is bent at the time of pulling to be large resistance, and collapse of filling can be suppressed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a plastic sheet for reinforcing ground.

[0002]

2. Description of the Related Art In recent years, the construction of houses has rapidly increased, and therefore, residential areas are often prepared by embankment. In addition, there are many road constructions on steep embankments at civil engineering sites. These embankments do not allow landslides at all,
For this reason, various measures have been taken. That is, a method of arranging nets in layers in the embankment to prevent landslides and stabilize the embankment has been widely adopted, and a net made of corrosion-resistant plastic or the like has been used conventionally.

However, unstretched polyethylene nets, when buried in the ground, have a remarkably high tensile strength due to earth pressure or the like, that is, the elongation rate of the nets against landslides. No big effect can be expected.

Accordingly, in recent years, nets oriented uniaxially (or biaxially) and oriented in a molecule have been used as such a measure, but they are buried in the soil as a guide for landslides of embankments. It is also true that, despite the fact that nets having a high resistance to pulling out of the soil from the soil are preferred, they are not sufficiently satisfied.

As an example of a plastic sheet for reinforcing the ground, there is Japanese Patent Publication No. 1-32060. In this technique, a round hole is formed in a polyethylene substrate, and the hole is stretched uniaxially (or biaxially) to obtain a plastic sheet for ground reinforcement.
Here, the plastic sheet obtained by the uniaxial stretching will be further described. In general, the expanded sheet is fixed along the expanded metal along the slope of the embankment, and about 50 cm above the expanded sheet. Embankment,
Next, a plastic sheet is similarly placed on the sheet, and embankment is performed. This is sequentially repeated to complete the embankment. Of course, the embedding is performed by disposing the plastic sheet at a right angle to the inclined surface in the extending direction when viewed from above.

[0006] Since a building such as a detached house or a factory is to be constructed on the embankment, the embanked soil must not collapse even a little. This means that the embedded plastic sheet must be able to withstand the force of the embankment sliding down. That is, when viewed from the plastic sheet side, it must have enough strength to withstand the collapse of the embankment.

[0007]

SUMMARY OF THE INVENTION The present invention provides a plastic sheet having a novel structure which is buried in the ground, and more particularly, has a high strength enough to withstand the tensile strength applied to the collapse of the embankment. It is intended to provide a plastic sheet.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a first gist of the present invention is to form a circular (including oval) or rectangular hole on a plastic substrate. Ground reinforcement characterized in that knife-cut portions are engraved in a staggered manner and aligned in the vertical and horizontal directions, the substrate is stretched in the vertical direction, and the edges constituting the holes are stretched in the stretching direction and are molecularly oriented. Plastic sheet for use.

The second gist is that an H-shaped or U-shaped knife cut portion is engraved on a plastic substrate in a staggered manner and aligned in the vertical and horizontal directions, and the substrate is stretched in the vertical direction and the knife cut portion is formed. The present invention relates to a plastic sheet for ground reinforcement characterized in that a portion is stretched in a stretching direction and is molecularly oriented.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, as a means for stretching a plastic substrate, first, a perforated substrate is formed, and then this is stretched in a uniaxial direction under heating, and the stretched portion is molecularly oriented and has extremely excellent strength. Therefore, the embankment is buried in the soil by matching the expected collapse direction of the embankment with this extension direction.

However, in the conventional plastic sheet, an opening portion is mainly composed of an edge portion (extending direction) where the perforated hole is mainly extended, and an edge portion (extending direction perpendicular to the extending direction) which is hardly extended. However, cracks are likely to occur at the intersections of the two edges, and if a crack is found in any one place, the strength of the plastic sheet as a whole is weakened, resulting in a plastic sheet that cannot be used to prevent the collapse of the embankment. .

On the other hand, if holes and knife cut portions to be stretched are arranged vertically and horizontally in a zigzag pattern as in the present invention, the entire edge in the stretching direction of the opening obtained by stretching is subjected to stretching. Therefore, this portion is strengthened, and the tensile force at the time of stretching is dispersed without being concentrated at one place, so that a plastic sheet excellent in strength and free of cracks is obtained.

In the plastic sheet of the present invention,
A substrate made of a thermoplastic elastomer is preferable, for example, high-density polyethylene or polypropylene is used. Usually, a hole formed in a plastic substrate is rectangular, and a fin may be formed at an edge of the hole. If an H-shaped or U-shaped knife cut portion is formed on a plastic substrate, a fin portion is inevitably formed.

[0014] The fin portion greatly increases the resistance to pulling out of the soil, and has a large area that crosses the soil in the direction in which the soil tends to collapse when viewed from the embankment side. That is, a fin portion is formed in the direction in which the plastic sheet is pulled out, and the fin portion is bent upward or downward with respect to the pulling force, so that the area thereof increases and the pulling resistance increases. Becomes Preferably, the fin may be given an angle with respect to the plastic substrate (sheet) in advance.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the plastic sheet of the present invention will be described in more detail with reference to the drawings. First, a plastic sheet having no fin portion of the previously - when indicating the door 31 _0, 1 is a plan view of the plastic substrate 31 before the stretching, Figure 2 is a plastic sheet after stretching - is a plan view of a preparative 31 ₀ .

The plastic substrate 31 is made of polyethylene, and has a rectangular hole 32 (long side 3) formed by pressing.
2 ₁ , short side 32 ₂ ), which were pierced on the plastic substrate 31 vertically and horizontally. The plastic sheet was stretched under heating in the long side 32 _{in one} direction of the rectangular holes 32 - to give the door 31 _0.

The rectangular holes 32 formed in the substrate 31 is being stretched a rectangular hole 32 _0, the site of the long side 32 ₁ is extended arguments for stretching thin and thin sides 32 _11, and the molecular Due to the orientation, it is an extremely strong part. Incidentally, the short sides 32 ₂ remains in is the thickness of the most original size without being affected even when stretching is also substantially intact. However, the portion a in the figure is the intersection of the elongated long side 32 ₁ and the short side 32 ₂ at the original size, and the strain during the stretching is concentrated on this portion. Watch the break occur.

Hereinafter, the plastic sheet of the present invention will be described in more detail with reference to examples. FIGS. 3 and 4 show a first example of the plastic sheet of the present invention.
Is a rectangular hole 1 in a plastic substrate 11 made of polyethylene.
FIG. 2 is a plan view when 2 are arranged vertically and horizontally in a staggered manner. Then, by stretching under heating a plastic substrate 11 plastic sheets - are those obtained bets 11 _0, 4 plastic sheet after the stretching - is a plan view of a preparative 11 _0.

[0019] As can be seen in the figure, the hole 12 ₀ rectangular rectangular hole 12 drilled in the substrate 11 is formed by stretching is stretched continuously in the stretching direction molecularly oriented edge 1
3 and before and after the edge portion 14 which is also affected during the stretching process. At the intersection b of the two portions, the stretching force is dispersed because of stretching, and no crack is generated at this portion. There is a feature. If a fin portion is formed at the edge in the stretching direction, this portion is bent at the time of pulling out, resulting in a large resistance, thereby effectively suppressing the collapse of the embankment.

FIGS. 5 and 6 show the plastic seal of the present invention.
FIG. 5 is a plan view showing an H-shaped knife cut 22 in a plastic substrate 21 made of polyethylene, which shows a heated plastic substrate 2.
1, a cut or cut portion 22 is engraved vertically and horizontally in a zigzag manner by a press or a roll provided with a large number of H-shaped knives (not shown). Therefore, the engraved cut portion 22 is knife-cut into an H shape, and the center portion is cut to form the fin portion 25.

[0021] Then, the plastic sheet is stretched in a direction having the fin portion 25 of the plastic substrate 21 under heating - are those obtained bets 21 _0, 6 plastic sheet after the stretching - DOO 21 ₀ It is a top view. As can be seen in the figure, those knives cut portion 22 of the H-type cutting unit 22 other than the fin portion 25 is stretched, the rectangular holes 22 ₀ is formed in particular extending direction of the edge portion 23 are drawn in succession And the phenomenon of cracking at the intersection point b is reduced.

[0022]

As described above, the present invention has been found to reduce the occurrence of cracks at the intersections of the pieces constituting the opening of the plastic sheet obtained by stretching. Extremely high.

[Brief description of the drawings]

FIG. 1 is a plan view of a substrate when a conventional plastic sheet is manufactured.

FIG. 2 is a plan view of a plastic sheet when the substrate of FIG. 1 is stretched.

FIG. 3 is a plan view of a substrate of a first example of the plastic sheet of the present invention.

FIG. 4 is a plan view of the plastic sheet when the substrate of FIG. 3 is stretched.

FIG. 5 is a plan view of a substrate of a second example of the plastic sheet of the present invention.

FIG. 6 is a plan view of the plastic sheet when the substrate of FIG. 5 is stretched.

[Explanation of symbols]

11 and 21 ‥‥ plastic substrate, 11 _0, 21 ₀ ‥‥ plastic sheet - DOO, 12 ‥‥ plastic substrates drilled hole, 12 ₀ ‥‥ rectangular hole formed by stretching, is 13, 23 ‥‥ stretched edge molecularly oriented Te, 14 ‥‥ not stretched edge, 22 ‥‥ knife cut portion, 22 ₀ ‥‥ stretching rectangular hole formed by, 25 ‥‥ fin portion, the intersection of b ‥‥ edge.

Claims (2)

[Claims] 1. A method for forming a plurality of holes on a plastic substrate in a zigzag pattern in a vertical and horizontal direction, stretching the substrate in the vertical direction, and stretching the edges of the holes in the stretching direction to molecular orientation. A plastic sheet for reinforcing a ground, characterized in that: 2. An H-shaped or U-shaped knife cut portion is engraved on a plastic substrate in a staggered manner in the vertical and horizontal directions, the substrate is stretched in the vertical direction, and the knife cut portion is stretched in the stretching direction. A plastic sheet for ground reinforcement characterized by being molecularly oriented.