Block mat

Abstract

To provide a block mat capable of reducing the number of anchor pins necessary for construction of the block mat and reducing construction costs.SOLUTION: A block mat 100 includes multiple concrete blocks 20 that are fixed to a flexible base sheet 10. In the block mat 100, the nonwoven fabric constituting the base sheet 10 is a nonwoven fabric in which, assuming that the nonwoven fabric as a whole is 100 wt%, fibers of 2.2 dtex or more and less than 4.4 dtex in an amount of 20 wt% or more and 75 wt% or less, and fibers of 7.0dtex or more and 20.0dtex or less in an amount of 25wt% or more and 80wt% or less, are mixed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Block mats, an erosion prevention material, have traditionally been used to protect the slopes of rivers, dams, and retarding basins. Block mats are made by integrating a large number of concrete blocks into a base sheet made of synthetic fiber nonwoven fabric. Block mats are characterized by their ease of construction and excellent durability. Conventional techniques relating to such block mats are disclosed in Patent Document 1 below and elsewhere. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-204918 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 fix it to the slope, but there was a demand to reduce the number of anchor pins, improve workability, and reduce construction costs.

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

[0006] As a result of extensive research conducted by the present inventors to achieve the above object, the present inventors have discovered the following. If the base sheet that makes up the block mat itself has a high frictional force against the slope, the block mat can be prevented from sliding 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 of anti-suction 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 nonwoven fabric that 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 20.0 dtex or less, with the entire nonwoven fabric being 100 wt%.

[0008] [2] The block mat according to [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 comprises reinforcing threads. [Effects of the Invention]

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

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

[0011] The present invention will be described in detail below. In this specification, the term "major 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 as "X to Y" (X and Y are any numbers), unless otherwise specified, it means "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 schematically showing a block mat 100. Fig. 2 is a view schematically showing a cross section of the block mat 100 taken along line II-II shown in Fig. 1.

[0014] As shown in FIGS. 1 and 2, the block mat 100 comprises 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 made of a predetermined 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. As will be described later, when laying the block mat 100, it is preferable that portions (clamping margins) 10a, 10b free from concrete blocks 20, 20, ... be provided at both longitudinal ends of the base sheet 10 in order to attach (clamp) a device for lifting 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 allow the device to be attached, but can be, for example, approximately 400 mm to 600 mm. Furthermore, when laying a plurality of block mats 100 side by side in the width direction (left and right direction in FIG. 1) as will be described later, it is preferable to lay them with a portion of the base sheet 10 overlapping. Therefore, it is preferable that one end of the base sheet 10 in the width direction has a portion (overlap) 10c where no concrete blocks 20, 20, ... are provided. 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 in which a plurality of concrete blocks are fixed to a flexible base sheet, and the nonwoven fabric constituting the base sheet is a mixture of 20 wt% to 75 wt% of fibers of 2.2 dtex to less than 4.4 dtex and 25 wt% to 80 wt% of fibers of 7.0 dtex to 20.0 dtex, with the nonwoven fabric as a whole being 100 wt%. This configuration suppresses slippage between the base sheet and the slope while maintaining a suction prevention function.

[0018] (Base sheet) The base sheet in the present invention is made of a nonwoven fabric that is a mixture of relatively thin and relatively thick fibers in a predetermined ratio. By using a base sheet of this composition, it is possible to suppress slippage on slopes 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, 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. Among them, polypropylene and polyethylene are preferred, and polypropylene is more preferred, from the viewpoint of excellent alkali resistance, since alkaline components in the concrete block 20 and alkaline substances may be contained in soil improvement materials, etc.

[0024] As explained above, the base sheet preferably has an appropriate tensile strength so that it can be lifted and handled in the state of the block mat 100. From this viewpoint, the base sheet 10 is preferably constructed 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 these long fibers. A base sheet 10 having such a structure can be manufactured, for example, by integrating the nonwoven fabric with the woven fabric or long fibers by wrapping the nonwoven fabric or long fibers when making the nonwoven fabric using 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) There are no particular limitations on the size of the concrete blocks 20, 20, and those used in conventional block mats can be used. The size of the concrete blocks 20 is not particularly limited, and typically, the length of one side in plan view (the surface appearing in FIG. 1) is about 15 cm to 50 cm, and the height is about 4 cm to 30 cm. There are no particular limitations 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] <Block Mat Manufacturing Method> Next, a description will be given of a method for manufacturing 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 for 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 over the formwork (opening side) so that the base sheet 10 and the concrete come into contact. At this time, part of the concrete is impregnated into the base sheet 10, and the concrete can be allowed to harden (cure) as is to integrate the concrete blocks 20, 20 and the base sheet 10. Note that in order to more firmly secure the concrete blocks 20, 20 and the base sheet 10, it is preferable to cover the formwork (opening side) with the base sheet 10 as described above, and then drive staples into the areas where the concrete blocks 20, 20 will be molded from the base sheet 10 side.

[0029] <How to install block mats> To lay the block mat 100, the clamping margins 10a, 10b provided at both longitudinal ends of the base sheet 10 are clamped by a clamping device attached to heavy machinery, 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 consisting of a rod member made of steel or the like the length of the base sheet 10 and suspended horizontally by a crane, and pressure plates attached to both ends of the rod member and gripping the base sheet 10 by a jack mechanism.

[0030] The block mat 100 is laid on the slope with its length (vertical direction in FIG. 1 ) aligned with the gradient line. By overlapping the overlap 10c of the base sheet 10 with the overlap of an adjacent block mat 100, multiple block mats 100 can be laid side by side depending on the width of the slope. The frictional resistance of the base sheet 10 makes each block mat 100 less likely to slip off, making it easy to lay on the slope. While it is possible to drive known anchor pins into the gaps between the concrete blocks 20, 20 to more securely secure the block mat 10 to the slope, using the block mat 100 of the present invention increases the frictional resistance between the base sheet 10 and the slope, making it possible to reduce the number of anchor pins required.

[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 per block (58.8 N) is preferably 54.5 N or more, more preferably 55.0 N or more, and even more preferably 55.2 N or more. It is also preferable that the static friction force be exhibited in at least one of sandy soil and clayey soil, and it is even more preferable that the static friction force be 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, drainage channels, dams, regulating ponds, and reservoirs, as well as the slopes of roads or railways built on embankments. [Example]

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

[0034] Substrate sheets were prepared as described below and evaluated as follows.

[0035] <Evaluation> (Static friction force (N)) Mountain sand (produced in Edosaki, moisture content 15.2%) was prepared, and 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 then placed on the substrate sheet, and the substrate sheet was 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 diameters of the substrate sheets produced in the following Examples and Comparative Examples were measured in accordance with 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 yarns are arranged in parallel, and then a weight of 250 g / m is applied on top of them. 2 To achieve this, 70 wt% of 3.3 dtex polypropylene short fibers and 30 wt% of 17 dtex polypropylene short fibers were used, and a nonwoven fabric was formed by needle punching. 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 4.4 dtex polypropylene staple fibers 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 17 dtex polypropylene staple fibers 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 friction 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, so it could not function as a suction prevention material. In addition, in Comparative Example 4, the frictional force on the clayey soil was high, but the frictional force on the sandy soil was low, and the anti-slip effect was not well balanced on 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% to 75 wt% of fibers having a fineness of 2.2 dtex or more and less than 4.4 dtex and 25 wt% to 80 wt% of fibers having a fineness of 7.0 dtex or more and 20.0 dtex or less, with the entire nonwoven fabric being 100 wt%. Block mat.

2. The blocking mat according to claim 1, wherein the base sheet has an opening diameter of 0.2 mm or less.

3. The blocking mat according to claim 1 or 2, wherein the base sheet comprises reinforcing threads.

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