Block Mat

Abstract

To provide a block mat capable of reducing the number of anchor pins required for construction of the block mat and reducing construction costs. [Solution] A block mat 100 having multiple concrete blocks 20 fixed to a flexible base sheet 10, in which the nonwoven fabric constituting the base sheet 10 is a mixture of 20 wt% to 75 wt% of fibers of 2.2 dtex or more and less than 4.4 dtex and 25 wt% to 80 wt% of fibers of 7.0 dtex or more and 20.0 dtex or less, based on 100 wt% of the entire nonwoven fabric.

Description

[Technical field]

[0001] The present invention relates to a block mat. [Background technology]

[0002] To protect the slopes of rivers, dams, retarding basins, etc., an erosion prevention material called a block mat has been used. A block mat is a material in which a large number of concrete blocks are integrated into a base sheet made of synthetic fiber nonwoven fabric, etc. Block mats are easy to install and have excellent durability. Conventional techniques relating to such block mats are disclosed in, for example, Patent Document 1 listed below. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-204918 A Summary of the Invention [Problem to be solved by the invention]

[0004] When fixing nonwoven fabric to a slope, anchor pins are inserted into the base sheet of the block mat to secure it to the slope, but there has been a demand to reduce the number of anchor pins in order to improve workability and reduce work costs.

[0005] Therefore, an object of the present invention is to provide a block mat which can reduce the number of anchor pins required when constructing the block mat and can reduce construction costs. [Means for solving the problem]

[0006] As a result of extensive investigations aimed at achieving the above object, the present inventors have discovered the following. If the frictional force of the base sheet that makes up the block mat against the slope is increased, the block mat can be prevented from slipping off the slope even if the number of anchor pins is reduced. By mixing fibers of a specific fineness with fibers of a specific fineness in the base sheet, it is possible to impart anti-slip properties while maintaining the function as a suction prevention material. Based on the above, the present inventors have completed the following invention.

[0007] [1] A block mat in which multiple concrete blocks are fixed to a flexible base sheet, The nonwoven fabric constituting the base sheet is a mixture of 20 wt% to 75 wt% of fibers having a diameter of 2.2 dtex or more and less than 4.4 dtex, and 25 wt% to 80 wt% of fibers having a diameter of 7.0 dtex or more and less than 20.0 dtex, with the entire nonwoven fabric being taken as 100 wt%.

[0008] [2] The block mat described in [1], wherein the opening diameter of the base sheet is 0.2 mm or less. [3] The block mat according to [1] or [2], wherein the base sheet is provided with reinforcing threads. Effect of the Invention

[0009] According to the block mat of the present invention, the base sheet constituting the block mat itself is prevented from slipping on slopes, so that it is possible to reduce the number of anchor pins required when installing the block mat, thereby reducing installation costs. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a plan view illustrating a block mat 100. [Diagram 2] 2 is a diagram showing a schematic cross section of the block mat 100 taken along the line II-II shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will be described in detail below. In this specification, the term "main component" refers to a component that accounts for the largest percentage by mass when the total of the target substance is 100% by mass, and is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more.

[0012] Furthermore, when it is written "X to Y" (X and Y are any numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", as well as "preferably greater than X" and "preferably smaller than Y".

[0013] <Block Mat> Fig. 1 is a plan view that shows a block mat 100. Fig. 2 is a view that shows a cross section of the block mat 100 taken along the line II-II shown in Fig. 1.

[0014] As shown in FIGS. 1 and 2, a block mat 100 includes a base sheet 10 and a plurality of concrete blocks 20, 20, . . . fixed to the base sheet 10.

[0015] The base sheet 10 is a flexible sheet, and is made of a specific nonwoven fabric, which will be described later.

[0016] The size of the base sheet 10 is not particularly limited, but typically, the width (length in the left-right direction in FIG. 1) is about 40 cm to 2 m, and the length (length in the up-down direction in FIG. 1) is about 1 m to 10 m. When laying the block mat 100 as described later, it is preferable that portions (clamping margins) 10a, 10b not provided with concrete blocks 20, 20, ... are provided at both longitudinal ends of the base sheet 10 in order to attach (clamp) an instrument for hoisting the block mat 100. The widths w1, w2 of the clamping margins 10a, 10b are not particularly limited as long as they are large enough to attach the instrument, but may be, for example, about 400 mm or more and 600 mm or less. Furthermore, when laying a plurality of block mats 100 side by side in the width direction (left and right direction in FIG. 1) as described later, it is preferable to lay them with parts of the base sheet 10 overlapping. Therefore, it is preferable that a portion (overlap) 10c where no concrete blocks 20, 20, ... are provided is provided at one end of the width direction of the base sheet 10. The width w3 of the overlap 10c is not particularly limited, but can be, for example, 200 mm or more and 400 mm or less.

[0017] The block mat of the present invention is a block mat having a plurality of concrete blocks fixed to a flexible base sheet, in which the nonwoven fabric constituting the base sheet is a mixture of 20 wt% to 75 wt% of fibers having a density of 2.2 dtex or more and less than 4.4 dtex and 25 wt% to 80 wt% of fibers having a density of 7.0 dtex or more and 20.0 dtex or less, with the entire nonwoven fabric being taken as 100 wt%. With this configuration, slippage between the base sheet and the slope is suppressed while also maintaining a suction prevention function.

[0018] (Base sheet) The base sheet in the present invention is made of a nonwoven fabric made of a mixture of relatively thin and relatively thick fibers in a specific ratio. By using a base sheet of this composition, it is possible to suppress slippage on the slope while maintaining the properties of a suction prevention material (permeable to water but not to soil and sand on the slope).

[0019] The relatively fine fibers may have a fineness of 2.2 dtex or more and less than 4.4 dtex. The lower limit of the fineness is preferably 2.5 dtex or more, more preferably 2.8 dtex or more, and even more preferably 3.0 dtex or more, and the upper limit of the fineness is preferably 4.3 dtex or less, more preferably 4.0 dtex or less, and even more preferably 3.8 dtex or less.

[0020] The amount of the relatively fine fibers is preferably 20 wt% or more and 75 wt% or less, more preferably 25 wt% or more and 70 wt% or less, even more preferably 30 wt% or more and 65 wt% or less, and particularly preferably 40 wt% or more and 60 wt% or less, based on 100 wt% of the entire nonwoven fabric constituting the base sheet.

[0021] The relatively thick fibers may have a fineness of 7.0 dtex or more and 20.0 dtex or less. The lower limit of the fineness is preferably 10.0 dtex or more, more preferably 12.0 dtex or more, and even more preferably 15.0 dtex or more, and the upper limit of the fineness is preferably 19.0 dtex or less, and more preferably 18.0 dtex or less.

[0022] The amount of the relatively thick fibers is preferably 25 wt% or more and 80 wt% or less, more preferably 28 wt% or more and 70 wt% or less, even more preferably 35 wt% or more and 65 wt% or less, and particularly preferably 40 wt% or more and 60 wt% or less, based on 100 wt% of the entire nonwoven fabric constituting the base sheet.

[0023] As the fibers, for example, short fibers made of synthetic fibers such as polypropylene, polyester, nylon, vinylon, acrylic, polyurethane, etc. can be used. Among them, polypropylene and polyethylene are preferable from the viewpoint of excellent alkali resistance, since the alkaline components of the concrete block 20 and the soil improvement material may contain alkaline substances, and polypropylene is more preferable.

[0024] As described above, the base sheet preferably has an appropriate tensile strength so that it can be handled by lifting it up in the state of the block mat 100. From this viewpoint, the base sheet 10 is preferably configured by inserting reinforcing threads that serve as a core material for reinforcement. The reinforcing threads may be long fibers such as polyester or nylon, or a woven fabric formed by weaving such long fibers. A base sheet 10 having such a structure can be produced, for example, by integrating the nonwoven fabric with the woven fabric or long fibers by wrapping the woven fabric or long fibers when making the nonwoven fabric with a papermaking machine, and then reinforcing the nonwoven fabric with needle punching.

[0025] The thickness of the base sheet 10 is not particularly limited as long as it functions as a base sheet, but is preferably 1 mm or more and 50 mm or less, more preferably 2 mm or more and 30 mm or less, and even more preferably 3 mm or more and 10 mm or less.

[0026] (Concrete Block) As the concrete blocks 20, 20, those used in conventional block mats can be used without any particular limitation. The size of the concrete block 20 is not particularly limited, and typically, in plan view (the surface appearing in FIG. 1), one side is about 15 cm to 50 cm, and the height is about 4 cm to 30 cm. Furthermore, there is no particular limitation on the arrangement pattern of the concrete blocks 20, 20. However, in order to provide flexibility to the block mat 100, it is preferable to provide a gap of 5 mm or more between adjacent concrete blocks 20.

[0027] <Manufacturing method of block mat> Next, a description will be given of a manufacturing method of the block mat 100. The block mat 100 can be manufactured, for example, by manufacturing a base sheet 10 and then integrating the base sheet 10 with the concrete blocks 20, 20.

[0028] The method of integrating the base sheet 10 and the concrete blocks 20, 20 is not particularly limited. For example, the base sheet 10 and the concrete blocks 20, 20 can be integrated as follows. First, concrete is poured into a formwork for molding the concrete blocks 20, 20, and before the concrete hardens, the base sheet 10 is placed on the top (opening side) of the formwork so that the base sheet 10 and the concrete come into contact with each other. At this time, a part of the concrete is impregnated into the base sheet 10, so that the concrete can be hardened (cured) as it is to integrate the concrete blocks 20, 20 and the base sheet 10. In order to more firmly fix the concrete blocks 20, 20 and the base sheet 10, it is preferable to drive a staple from the base sheet 10 side into the area where the concrete blocks 20, 20 are to be molded after the base sheet 10 is placed on the top (opening side) of the formwork as described above.

[0029] <How to install block mats> To lay the block mat 100, the clamping margins 10a, 10b provided at both ends of the base sheet 10 in the longitudinal direction are clamped by a clamping device attached to a heavy machine, and the block mat 100 is lifted and moved while suspended to the specified installation location. The clamping device may be, for example, a device made of a steel frame or the like having a length of the base sheet 10 and suspended horizontally by a crane, and pressure plates attached to both ends of the rod member for gripping the base sheet 10 by a jack mechanism.

[0030] The block mat 100 is laid on the slope with its length direction (vertical direction in FIG. 1) aligned along the gradient line. Then, by overlapping the overlap 10c of the base sheet 10 with the overlap of the adjacent block mat 100, a plurality of block mats 100 can be laid side by side according to the width of the slope. Each block mat 100 is prevented from slipping off due to the frictional resistance of the base sheet 10, so it is easy to lay it on the slope. In addition, in order to fix the block mat 10 to the slope more reliably, it is possible to drive known anchor pins into the gaps between the concrete blocks 20, 20, but when the block mat 100 of the present invention is used, the frictional resistance between the base sheet 10 and the slope is increased, so that the number of anchor pins can be reduced.

[0031] The static friction force (N) of the block mat of the present invention against a slope varies depending on the type of soil forming the slope, but in the case of sandy soil, it is preferably 47.5 N or more per block (58.8 N), more preferably 48.0 N or more, and even more preferably 49.0 N or more. In the case of clayey soil, the pressure is preferably 54.5N or more per block (58.8N), more preferably 55.0N or more, and even more preferably 55.2N or more. It is also preferable that the static friction force is exhibited in at least one of sandy soil and clayey soil, and more preferably that the static friction force is exhibited in both sandy soil and clayey soil.

[0032] Such a block mat 100 can be laid to protect the slopes or bottoms of places where water flows or stagnates, such as rivers, irrigation and drainage channels, dams, regulation ponds, and storage ponds, as well as the slopes of roads or railways built on embankments. EXAMPLES

[0033] The present invention will be specifically described below using examples, but the present invention is not limited to these.

[0034] Substrate sheets were prepared as described below, and the following evaluations were carried out.

[0035] <Evaluation> (Static friction force (N)) Mountain sand (from Edosaki, moisture content 15.2%) was prepared and weighed at 50N / 170cm 2 The soil was then compacted with a weight and the surface was smoothed to create a flat surface (sandy soil) for evaluating frictional force. In addition, Kanto loam (moisture content 76.6%) was prepared and 50N / 170cm 2 The soil was then compacted with a weight and the surface was smoothed to create a flat surface (clay soil) for evaluating frictional force.

[0036] The substrate sheets prepared in the following Examples and Comparative Examples were placed on the two types of flat surfaces prepared as described above, and a plate and a concrete block placed on the plate (total weight of the plate and concrete block is 6 kg = 58.8 N) were further placed on the substrate sheets, and the substrate sheets were pulled horizontally to evaluate the static friction force (N). The evaluation results are shown in Table 1.

[0037] (Opening diameter (O 90 mm) The opening diameter of the base sheet produced in each of the following Examples and Comparative Examples was measured according to the ISO12956 wet method. The opening diameter is preferably 0.2 mm or less, more preferably 0.18 mm or less, even more preferably 0.16 mm or less, still more preferably 0.14 mm or less, and particularly preferably 0.13 mm or less. If the opening diameter exceeds 0.2 mm, it becomes difficult for the material to function as a suction prevention material.

[0038] <Example 1> Polyester reinforcing threads are arranged in parallel, and then a 250g / m2 fabric is applied on top of them. 2 To achieve the above, 70 wt % of 3.3 dtex polypropylene staple fibers and 30 wt % of 17 dtex polypropylene staple fibers were placed, and a nonwoven fabric was formed by a needle punch method. The results of the evaluation according to the above criteria are shown in Table 1.

[0039] <Example 2> A nonwoven fabric was formed in the same manner as in Example 1, except that 50 wt % of 3.3 dtex polypropylene staple fibers and 50 wt % of 17 dtex polypropylene staple fibers were used. The results of the evaluation according to the above criteria are shown in Table 1.

[0040] <Comparative Example 1> A nonwoven fabric was formed in the same manner as in Example 1, except that only polypropylene staple fibers of 4.4 dtex were used. The results of the evaluation according to the above criteria are shown in Table 1.

[0041] <Comparative Example 2> A nonwoven fabric was formed in the same manner as in Example 1, except that only polypropylene staple fibers of 17 dtex were used. The results of the evaluation according to the above criteria are shown in Table 1.

[0042] <Comparative Example 3> A nonwoven fabric was formed in the same manner as in Example 1, except that only polypropylene staple fibers of 4.4 dtex were used. The results of the evaluation according to the above criteria are shown in Table 1.

[0043] <Comparative Example 4> A nonwoven fabric was formed in the same manner as in Example 1, except that only polypropylene staple fibers of 7.8 dtex were used. The results of the evaluation according to the above criteria are shown in Table 1.

[0044] [Table 1]

[0045] The frictional force values ​​in Table 1 are the arithmetic mean values ​​of five measurements.

[0046] As shown in Table 1, the block mat (base sheet) of the present invention exhibited favorable frictional force in both sandy soil and clayey soil. The block mat of Comparative Example 2 exhibited high frictional force, but the opening diameter was more than 0.2 mm, and therefore it could not function as a suction prevention material. In addition, in Comparative Example 4, the frictional force of the clayey soil was high, but the frictional force of the sandy soil was low, and the anti-slip effect was not well-balanced for both types of soil.

Claims

1. A block mat in which a plurality of concrete blocks are fixed to a flexible base sheet, the nonwoven fabric constituting the base sheet is a nonwoven fabric obtained by mixing 20 wt % or more and 75 wt % or less of fibers having a fineness of 2.2 dtex or more and less than 4.4 dtex and 25 wt % or more and 80 wt % or less of fibers having a fineness of 7.0 dtex or more and 20.0 dtex or less, with the entire nonwoven fabric being taken as 100 wt %, The opening diameter of the base sheet is 0.2 mm or less. Block mat.

2. The blocking mat of claim 1 , wherein the base sheet comprises reinforcing threads.

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