History of the Gabion Method andIntroduction to the Gabion Mesh Method

Table of Contents

1. Background and history of the gabion method2. About the gabion3. Characteristics of the gabion method4. Gabion mattress method5. Gabion mesh method6. Merits of the gabion mesh

1. Background and history of the gabion methodWhat is the gabion method?

� In recent years, implications of river construction has significantly changed and the aspect of rivers as an important element forming the regional natural features and culture has been emphasized. There is a growing demand for maintaining the inherent characteristics of the river for providing a relaxing waterfront landscape and facilitating the inhabitation/growth of diverse organisms, as compared to river construction designed only for river improvement or water utilization. With the “Basic Policy for Disaster Restoration Works for Protecting Beautiful Mountains and Rivers" established Restoration Works for Protecting Beautiful Mountains and Rivers" established in June 1998, environmental conservation-oriented construction methods have been selected in river restoration works.

� The gabion method has been highly reevaluated as a nature-oriented embankment method and used for many rivers in recent years. Its major characteristics include the following:● Prevent the lowering of the riverbed● Prevent local scour● Flexibly fit soft ground, etc.

1. Background and history of the gabion methodWhat is a gabion?

� The gabion (jakago in Japanese) was originally a bamboo woven cylindrical basket with tortoise shell-shaped mesh used for river construction with rounded stones, crushed stones, etc. filled inside.

� Gabions were also made of other materials (e.g. tree branches, willow branches, wisteria vines, and grape vines) and called by different names after their materials (e.g. bamboo basket, twig basket (wooden names after their materials (e.g. bamboo basket, twig basket (wooden basket), willow basket (mannen kago), wisteria basket, and grape basket). Jakago became the word commonly used for gabions, including those made of materials other than bamboo.

� The material shifted from bamboo to iron and then to galvanized steel wire, and the fabrication method from hand knitting to machine knitting, in step with technological advancement.

� Jakago literally means “snake basket” and is allegedly named so for its snake-like shape.

1. Background and history of the gabion methodHistory of the gabion in Japan: Before the Meiji Period

Origin・Nara Period: Woven bamboo baskets were the origin of the gabion in Japan.・Edo Period: Bamboo gabions with stones were used for the disaster

restoration works of the Kiso River. ・Meiji Period: The word jakago, after the snake-like shape, became common.

Stones being filled inside a

bamboo gabion

2. About the gabionHistory of the gabion in Japan: From the Meiji Period to the Post-war Period

・Meiji Period: The material changed from bamboo or cane to steel wire.・Pre-WWII: The material changed to a plated wire and machine fabrication was

introduced.

・Post-WWII: The Japanese Industrial Standard (JIS) was established amid the trend of industrial standardization.

� 1953: The River Bureau of the Ministry of Construction issued the � 1953: The River Bureau of the Ministry of Construction issued the “Specifications and Structural Standard for Galvanized Steel Wire for Gabions”.

� 1954: The Agency of Industrial Science and Technology of MITI established the Japanese Industrial Standard (A 5513) for ‘Galvanized Steel Wire Gabions’

� 1984: The standard for the prismatic gabion was added to the JIS Standard� 1993: The standards for thick-plated products (GS-7) were added to the JIS

standard.� 2000: The letter type for jakago changed from katakana to hiragana.

The standard for the panel-type prismatic gabion was added to the JIS standard.

2. About the JakagoTypes of Jakago

� Cylindrical gabion(Jakago)� Prismatic gabion� Prismatic gabion

(Futonkago)� Panel-type prismatic gabion

(Panel-type futonkago)

2. About the gabionPanel-type prismatic gabion

Panel-type prismatic gabion(Panel-type futonkago)� Improved version of the

prismatic gabion� Extremely easy to be � Extremely easy to be

assembled� Panels manufactured at the

plant are assembled with coupling coils on-site

� Heavy equipment can be used for filling the gabions to a certain extent

� Easily removed or repaired

2. About the gabionCylindrical gabion

Cylindrical gabion (Jakago)� The most conventional shape� Called jakago after its shape� Consists of the body mesh, cap mesh, round circles, and

closing wireclosing wire� Easily removed or repaired

3. Characteristics of the gabion methodExample in practice: Afforestation/channel works

3. Characteristics of the gabion methodExample in practice: River/foot protection

4. Gabion mattress and gabion frameDiversification of the gabion method in recent years

In the major revision of the River Act in 1997, a river improvement plan was introduced in line with the demand of local citizens for the improvement and conservation of the river environment (including aspects of water quality, landscape, and the ecosystem), in addition to the purposes of river management, i.e. river improvement and water the purposes of river management, i.e. river improvement and water utilization.Along with this trend, various new forms of gabions have been introduced.

Representative examplesGabion mattress method

・Multi-tier type・Covering type (slope type)Gabion frame method

4. Gabion mattress and gabion frameGabion mattress method (Multi-tier type)

Gabion mattress method - Multi-tier type� Applicable to steep slopes of 1:0.5 to 1:1 slope ratio� Each mattress is 50 cm high� H50 Specifications: Cap mesh and whole area: 5.0 x 65, Body size: 4.0 x 100� All side walls are connected to form an integrated structure.

4. Gabion mattress and gabion frameGabion mattress method (Covering system)

Gabion mattress method - Covering system� Applicable to mild slopes of 1:1.5 to 1:2 slope ratio� Two height types are available: 30 cm high and 50 cm high� H30 Specifications Cap mesh: 4.0 x 65, Body size: 3.2 x 75

H50 Specifications Cap mesh: 5.0 x 65, Body size: 4.0 x 100� All side walls are connected to form an integrated structure.

4. Gabion mattress and gabion frameGabion frame method

Gabion frame method� Applicable to steep slopes of 1:0.3 to 1:1 slope ratio� 50 cm high� Consists entirely of welded steel wire fabrics and has high solidity� Permits easy use of soil as the filler

5. Gabion mesh methodWhat is the gabion mesh method?

The gabion mesh method has two advantages:

Flexibility of the diamond-shaped wire mesh used in the gabion method and the gabion used in the gabion method and the gabion

mattress method+

Solidity of the welded steel wire fabric used in the gabion frame method

6. Merits of the gabion meshDetailed drawing of gabion mesh (Standard product)

Welded steel wire wire fabrics

Diamond-shaped wire mesh

Conventional gabion method:

Although heavy equipment is used, mostly constructed with manual operations; time consuming ↓

Gabion mesh method:

6. Merits of the gabion meshWorkability

Gabion mesh method:

Mostly constructed with heavy equipment; fewer manual operations

↓

Cuts construction lead time!

Filler placement

6. Merits of the gabion meshWorkability

Manual operation for the tops of each basket

Assembled in a similar manner for the second

tier onward

6. Merits of the gabion meshExample of construction

Applicable to ordinary embankment works

6. Merits of the gabion meshExample of construction

Easily combined with planting materials for soil retaining works

6. Merits of the gabion meshSuperiority

1. Equivalent with multi-tier type gabion mattress in costSimple process provides low cost production.

2. Excellent workabilityThe use of welded steel wire fabrics permits shorter filler placement time, thus enabling savings in workload.time, thus enabling savings in workload.

3. Facilitates vegetation growth and thus appropriate for nature-oriented bank protectionThe non-expanding structure of the gabion mesh permits the use of soil —which facilitates vegetation growth— as the filler.

4. Structural characteristics enable easy weedingThe edges of the welded steel wire fabrics are curled to enable the diamond-shaped wire mesh to be connected in a unique manner.

6. Merits of the gabion meshGabion mesh “mini”

The placement of the half-round type or the trapezoid typewill enable the securing of gaps.

Sanritsu is committed to continuing to contribute to society by providing our wire mesh products.

This is the end of my presentation, “History of the Gabion Method and Introduction to the Gabion

Conclusion

Gabion Method and Introduction to the Gabion Mesh Method.”

Thank you very much for your attention.