JP-7856261-B2 - Vegetation mat installation method

JP7856261B2JP 7856261 B2JP7856261 B2JP 7856261B2JP-7856261-B2

Inventors

藤原壮一
▲高▼橋遥香
遠山宏一
岡本祐季
湯谷豊

Assignees

日本植生株式会社
プリード湯谷株式会社

Dates

Publication Date: 20260511
Application Date: 20221128

Claims (3)

Multiple vegetation mats, constructed by integrating nonwoven fabric and turf onto a net material, are laid in a row on the back slope of the embankment . The vegetation mat has a main body in which nonwoven fabric and grass are integrated into a net material, and an overhanging part that extends from the periphery of the main body and is thinner than the main body. The two adjacent vegetation mats are installed so that the protruding portion of one mat is laid under the main body of the other mat. For two adjacent vegetation mats along the slope, the mats are installed such that the overhang of the vegetation mat on the slope toe side is laid beneath the main body of the vegetation mat on the slope shoulder side. The net material and the nonwoven fabric constituting the main body extend to the protruding portion. A method for constructing vegetation mats , in which reinforcing nets fixed to the top of the embankment are connected to vegetation mats near the slope shoulder .
The reinforcing net is connected to the vegetation mat near the top of the slope, with the net placed over it from above. The method for constructing a vegetation mat according to claim 1, wherein the length of the reinforcing net inserted into the top of the embankment is greater than the length of the net covering the vegetation mat near the shoulder of the slope .
A method for installing a vegetation mat according to claim 1 or 2 , wherein the grass of adjacent vegetation mats is brought into contact with each other .

Description

This invention relates, for example, to a method for constructing vegetation mats to prevent erosion on the back slope of river embankments. It is known that when river water overflows the crest 91 of a levee during a river flood, the overflowing water 92 erodes the toe 93 of the levee's back slope (Figure 10(A)). Subsequently, as the overflowing water erodes the back slope 94 (Figure 10(B)), the levee will collapse (Figure 10(C)). Effective countermeasures against levee breaches occurring in this manner include reducing and preventing erosion and scouring of the back slope 94 (including the toe of the back slope 93) caused by overflowing water 92. For example, the levee reinforcement device described in Patent Document 1 aims to reduce and prevent the above-mentioned erosion and scouring by covering the inland slope of the levee with a waterproof sheet made of synthetic resin. Japanese Patent Publication No. 2018-168571Japanese Patent Publication No. 2021-38642 This is an explanatory diagram illustrating a schematic method for constructing a vegetation mat according to one embodiment of the present invention.This is a perspective view showing the structure of the vegetation mat used in the aforementioned vegetation mat installation method.This is a perspective view showing a schematic configuration of the vegetation mat and its manufacturing method.(A) to (D) are explanatory diagrams that schematically show the configuration of the method for manufacturing the vegetation mat (standard production method), and (E) to (G) are explanatory diagrams that schematically show the configuration of a modified version of the method for manufacturing the vegetation mat (new production method).(A) and (B) are longitudinal cross-sectional views that schematically show the overall configuration and essential components of the vegetation mat installation method.(A) to (C) are plan views showing the construction procedure of the vegetation mat construction method related to the comparative example, (D) is a longitudinal section view thereof, and (E) is an explanatory diagram showing how overflow water flows in the back slope after construction.(A) to (C) are plan views showing the construction procedure of a vegetation mat construction method according to an example of the present invention, (D) is a longitudinal section view thereof, and (E) is an explanatory diagram showing how overflow water flows in the back slope after construction.(A) is an explanatory diagram showing the overall structure of the test apparatus, (B) is a longitudinal cross-sectional view of the water channel of the test apparatus, (C) is a photograph showing the approximate overall structure of the test apparatus, (D) is a photograph showing the water flow condition of the test specimen, and (E) is a photograph showing the water flow condition upstream of the test specimen in the test apparatus.(A) is an explanatory diagram of the installation method of the comparative example vegetation mat, (B) and (C) are photographs showing the condition of the seams of the vegetation mats in the comparative example before and after the test, (D) is an explanatory diagram of the installation method of the vegetation mat in this example, and (E) and (F) are photographs showing the condition of the seams of the vegetation mats in this example before and after the test.(A) to (C) are explanatory diagrams illustrating the process by which a levee breach occurs.(A) and (B) are explanatory diagrams of the connecting parts of the vegetation mat according to this example and modified examples. Embodiments of the present invention are described below. The method for constructing the vegetation mat according to this embodiment involves laying multiple vegetation mats D, as shown in Figure 2, in a row horizontally and vertically on the back slope N1 of the river embankment (an example of an embankment) shown in Figure 1. The vegetation mat D is, for example, rectangular in shape with a plan view of 1000 mm x 3000 mm, or square in shape with a plan view of 2000 mm x 2000 mm. It is constructed by integrating a grass mat 3 onto a flexible net material 2 with a nonwoven fabric 1 on its lower surface (see Figure 2). Nonwoven fabric 1 is a component formed to have a roughly rectangular shape in plan view and a chemical fiber basis weight of 30 to 80 g/ m² . It is formed by the spunlace method using polyester fibers, coconut mat, and other materials that are highly durable and corrosion-resistant. The net material 2 has approximately the same shape as the nonwoven fabric 1 in plan view, and is formed to have a tensile strength of approximately 30 to 80 kN per meter of width, with a mesh size of approximately 5 to 10 x 5 to 10 mm. The net material 2 is formed in a grid pattern using highly durable fibers, such as nylon, polyester, aramid, carbon, or polyacetal. However, it may also be woven into a mesh-like structure with the same mesh size as described above using the aforementione