JP2799067B2 - Civil engineering sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet for civil engineering used for soil improvement in various types of civil engineering construction works such as hill control works, flood control works, construction of structures on soft ground, and the like.

2. Description of the Related Art It is desirable to improve the ground beforehand in order to prevent deformation and uneven settlement of the ground when constructing structures on mountainous works, flood control works, road construction or soft ground. In general, ground improvement works such as dispersion of applied load, densification by promoting consolidation of soft ground, spring water, drainage of groundwater, protection of slope, filter and separation of earth and sand, etc. are usually performed.

Conventionally, when performing these works, from the viewpoint of tensile strength, elasticity, water permeability and durability, a sheet for civil engineering made of synthetic resin woven fabric, nonwoven fabric or net or laminated with woven fabric and nonwoven fabric is used. In the construction site, civil engineering sheets are connected to each other in the vertical and horizontal directions, sized to a suitable size, installed several times at the construction site, and covered with earth and sand from above.

Conventionally, the connection of civil engineering sheets is performed by sewing a string at a suitable interval on a reinforcing fabric sewn to the ear so that work on the site can be performed, and tying this string, Tying the strings one by one requires a considerable amount of effort, resulting in poor work efficiency, and poor knotting makes it easy to unravel, and the strength of the connecting portion is relatively weak and easy to break.

In order to cope with the above-mentioned problem, there has been proposed a construction in which pipe pieces are connected to the periphery and pipes are alternately passed through adjacent pipe pieces of the civil engineering sheet so as to connect the civil engineering sheets (particularly, Japanese Patent Laid-Open Publication No. HEI 10-157556). Kaihei 2-43409).

According to this, the sheets can be connected only by passing the pipes through the tubular piece, and there is an advantage that the working efficiency is improved and the strength of the connecting portion is relatively strong.

SUMMARY OF THE INVENTION In the above method of connecting a pipe piece to the periphery of a sheet for civil engineering and connecting the pipe pieces by passing pipes, the pipe piece has a double structure in which an edge is turned over and a ground part is provided at an end thereof. However, when a woven cloth sheet is used, the seam at the edge of the cloth folded by the tensile load may slip off and come off from pipes. is there.

An object of the present invention is to solve the above-mentioned problem, that is, to strengthen the sewn portion of the tubular piece and increase the tensile strength so that slip-through does not occur.

Means for Solving the Problems In connecting civil engineering sheets having strength that can be used for ground improvement, the present inventors laminated nonwoven fabric on the knitted woven fabric at the edge, joined the nonwoven fabric together, and sewed. It has been found that the tensile strength of the bonded portion is increased, and the present invention has been completed.

Therefore, the present invention is a civil engineering sheet made of a synthetic resin knitted fabric in which tubular pieces for connecting pipes to the periphery are connected, and at least both sides of the sheet edge are formed as a laminate formed of a nonwoven fabric layer. After the edge is folded, the folded end is further folded inward to form a triple structure, and the triple structure portion is sewn with the nonwoven fabric layer joined.

ADVANTAGE OF THE INVENTION According to this invention, since the frictional force between nonwoven fabrics improves more than the frictional force between woven fabrics, the shift | offset | difference of a joining part decreases and the tensile strength of a sewing part increases.

The nonwoven fabric may be laminated only at the edge forming the tubular piece, but the sheet is composed of a woven fabric layer and a nonwoven fabric layer, and the strength, which is the property of the woven fabric, the drainage property, which is the property of the nonwoven fabric, and soil. It is desirable to have the follow-up capability. In any case, the knitted fabric used in the present invention has a tensile modulus of 20 GP.
a (gigapascal) or more, preferably 50 GPa or more,
Moreover, a multifilament having a tensile strength of 1.2 GPa or more, preferably 1.5 GPa or more, is used in at least one direction. As the monofilament constituting the multifilament, a filament using a synthetic resin such as polyamide, polyester, polyacrylonitrile, polyvinyl alcohol, polyolefin, and polystyrene can be used. Among them, polyolefin such as polyethylene and polypropylene can be used. Preferably, a stretched product of ultrahigh molecular weight polyethylene is suitable. The stretched product can be produced, for example, by the method described in JP-A-59-187614 or JP-A-59-130313.

Further, the multifilament may be formed of a defibrated yarn or a cilia yarn made of the synthetic resin.

The defibrated yarn as referred to herein is one obtained by regularly or irregularly defibrating a synthetic resin film and tape with a carding machine, and the cilia yarn does not have a mesh structure. It is a bulky yarn having a spun yarn-like feel obtained by controlling the fiber distribution.

The thickness of the multifilament is preferably 300 to 2500 denier, particularly preferably 500 to 2000 denier.

Such a multifilament is used in at least one direction of the structure of the textile fabric. This increases the strength in that direction. As the woven structure, various woven structures that apply these basic structures, such as plain weave, twill weave, and satin weave, can be used.

When the multifilament is used in one direction, another filament such as a multifilament or a monofilament outside the above range can be used as the filament in the other direction. Further, the multifilament in the above range can be used not only in one direction but also in a plurality of directions as a warp and a weft. By doing so, the strength in any arbitrary direction can be increased.

Also, the basis weight of a woven fabric using the above multifilaments in at least one direction is 50 to 1000 g / m ² , especially 100 to 5 g / m ² .
00 g / m ² is preferred.

As the non-woven fabric laminated on the knitted fabric, the synthetic resin is formed by randomly arranging long fibers or short fibers,
Such non-woven fabric is made of polyamide fiber, polyester fiber,
Any fibers made of long fibers (including continuous fibers) such as polyacrylonitrile fibers, polyvinyl alcohol fibers, polyvinyl chloride fibers, polyvinylidene chloride fibers, polyethylene fibers, polypropylene fibers, and polystyrene fibers, or any nonwoven fabric made of short fibers Good. Among them, nonwoven fabrics made of polyamide fibers, polyester fibers, polyvinyl alcohol fibers, polyethylene fibers, and polypropylene fibers are particularly preferable.

The fibers may be formed at various draft ratios or draw ratios, but those having high strength and low elongation are particularly preferable. In addition, long fibers are preferable to short fibers in view of a mechanical entanglement method such as a needle punch described later. The long fibers or short fibers of the nonwoven fabric are usually formed by melt spinning, and the randomized fiber group is collected by, for example, a screen to form a wave. If desired, a heat stabilizer,
An antioxidant, an ultraviolet absorber, a pigment, a heat-resistant agent, a surfactant, and the like may be added or surface-treated at the time of melting prevention, at the time of forming the web, and before and after the formation. 0.5 to 3 filaments or short fibers of the nonwoven fabric thus produced
0 denier, especially 3 to 15 denier is preferred. The basis weight of the nonwoven fabric is preferably 30 to 1000 g / m ² , particularly preferably 100 to 500 g / m ² .

As the laminated structure of the knitted fabric layer and the nonwoven fabric layer, (1) a three-layer structure in which the knitted fabric layer is used as an intermediate layer and a nonwoven fabric layer is laminated on both surfaces thereof, and (2) the woven fabric layer and the nonwoven fabric layer are alternately repeated. For example, a multilayer structure having a nonwoven fabric layer on both sides can be exemplified.

Examples of a method for joining the knitted fabric layer and the nonwoven fabric layer include a method using a needle punch, a water jet punch, an ultrasonic welder, a high-frequency welder, and heat embossing. When making a needle punch, the number of needle punches penetrating each layer is 20 to 150 times per cm ² , especially 3 times.
If the number is zero or more, the bonding between the layers is good, and the needle depth is preferably 6 to 15 mm, particularly preferably 8 to 14 mm.

The laminate obtained in this manner has a small reduction in the initial tensile strength due to needle punch since the knitted fabric layer is formed of multifilaments in at least one direction, and also has excellent water permeability. In addition, if each layer is surface-treated with a nonionic surfactant such as polyoxyethylene alkyl ether or polyoxyethylene alkyl phenyl ether before or while performing needle punching, each layer can be formed by needle punching. This is preferred because the fiber cutting can be reduced to further prevent a decrease in the initial tensile strength, and each layer becomes hydrophilic to improve water permeability.

In the case of using a heat fusion method such as each of the above welders or heat embossing, partial bonding may be used.

In order to increase the bonding strength of each layer, the knitted fabric layer and the nonwoven fabric layer are preferably made of the same or compatible synthetic resin material.

As a method for preventing slip-through, the inventors have also:
If a canvas is interposed between the nonwoven fabrics of the sewn portion, the tensile strength of the sewn portion is further increased, and the strength is doubled as compared to the one not using the canvas, as shown in FIG.
As shown in FIG. 2B or 2C, it was found that resistance to slip-through was stronger when the stitches were staggered a plurality of times at a suitable interval with a multi-needle sewing machine as shown in FIG. 2B or FIG. 2C.

Therefore, another invention is characterized in that, in the above invention, a canvas is interposed between the nonwoven fabrics of the sewn portions. Still another invention is a method in which a plurality of needle sewing machines are used to sew at an appropriate interval. It is characterized by wearing.

In order to prevent slip-through, it is desirable to further improve the strength of the sewn portion by impregnating the sewn portion with a polymerizable monomer such as methyl methacrylate or a coagulable resin and curing the sewn portion.

The present inventors have further found that inserting the edges into a double winding increases the strength of the sewn portion.

Therefore, another invention is characterized in that the edge portion is constituted by a laminate having a nonwoven fabric layer on both sides, the edge portion is wrapped, the nonwoven fabric layer is sewn in a joined state, and the tubular piece is double-wound. I do.

FIG. 1 shows an embodiment of the present invention, in which an edge of a three-layered civil engineering sheet in which a nonwoven fabric 2 is laminated on both sides of a woven fabric 1 and a canvas 3 is attached to one side thereof. After folded back inward so that the folded end is further turned inward, the triple structure portion is sewn at two places with a two-needle sewing machine at intervals larger than the interval between the needles, and pipes formed at the edge are inserted. Cuts 6 are made at appropriate intervals in the cylindrical piece 5 of FIG.

FIG. 3 shows another embodiment, in which a canvas 8 is attached to an edge portion of a civil engineering sheet 7 having a three-layer laminate structure in which a nonwoven fabric is laminated on both sides of a woven fabric to form a double winding. The triple structure portion is sewn at two places with a two-needle sewing machine at an interval larger than the interval between the needles, and a tubular piece 11 formed at the edge for inserting pipes is double-wound. In the figure, reference numeral 12 denotes a connecting pipe.

Effect of the Invention As described above, the present invention has a triple structure in which the edges provided with the nonwoven fabric layers on both sides are folded to form a triple structure, and in the sheet for civil engineering in which a tubular piece for passing pipes around the periphery is connected, the nonwoven fabric layers are separated from each other. A tubular piece is formed by sewing the triple structure part in the joined state, and by sewing the triple structure part in the state where the nonwoven fabrics are joined, the frictional force increases and the tensile strength of the sewn part is increased It is possible to increase slippage of the weft yarn due to slippage.

In addition, when sewing is performed with a canvas interposed between the nonwoven fabrics, the sewn portion can be further strengthened.

Further, the sewn portion can be further strengthened by sewing a plurality of times with a multi-needle sewing machine at appropriate intervals or by impregnating the sewn portion with a coagulable resin.

When the tubular piece is double-wound, the sewn portion can be further strengthened.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a main part of a sheet for civil engineering according to the present invention, FIG.
3C are views showing an example of suturing, and FIG. 3 is a schematic view of a main part of another embodiment. 1 ... woven cloth, 2 ... non-woven cloth, 3 ... canvas 4 ... seam, 5 ... cylinder piece, 6 ... cut

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-271513 (JP, A) JP-A-2-43408 (JP, A) JP-A-64-45866 (JP, A) 15336 (JP, U) Japanese Utility Model Hei 1-105643 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) E02D 3/00 102

Claims (7)

(57) [Claims] 1. A civil engineering sheet made of a synthetic resin knitted fabric in which a tubular piece for inserting pipes into the periphery is connected to a laminate having at least both sides of the sheet edge formed of a nonwoven fabric layer. A sheet for civil engineering, wherein an edge portion is folded, and then a folded end is further folded inward to form a triple structure, and the triple structure portion is sewn with the nonwoven fabric layer joined. 2. The sheet for civil engineering according to claim 1, wherein the knitted fabric uses a multifilament having a tensile modulus of not less than 20 GPa and a tensile strength of not less than 1.2 GPa in at least one direction. 3. The sheet for civil engineering according to claim 2, wherein the woven fabric has a tensile modulus of 50 GPa or more and a tensile modulus of 1.5 GPa or more. 4. The sheet for civil engineering according to claim 1, wherein a canvas is interposed between the nonwoven fabrics at the sewn portion. 5. The sheet for civil engineering according to claim 1, wherein the sewn portion is sewn a plurality of times at appropriate intervals by a plurality of needle sewing machines. 6. The sheet for civil engineering according to claim 1, wherein the sewn portion is impregnated with a setting resin. 7. A civil engineering sheet made of a synthetic resin knitted fabric in which cylindrical pieces for connecting pipes to the periphery are connected to each other, wherein at least both sides of the sheet edge are formed of a nonwoven fabric layer, and A sheet for civil engineering, wherein the edge portion is turned back and then further turned inward to form a triple structure, and the triple structure portion is sewn with the nonwoven fabric layers joined to each other to form a tubular piece into a double winding. .