Example of seawall construction: Maxwall, which requires no skilled labor and can be constructed in a short period of time.

When small and medium-sized rivers are damaged by rising water due to typhoons or torrential rains, conventional methods such as wooden fences, cast-in-place concrete, and cage construction have been the main restoration methods for small-scale restoration work. However, conventional methods are not suitable for small-scale restoration work,

• Cost and construction time will be required due to temporary closing
• Skilled workers are needed for jagokko workers.

For these and other reasons, it has been difficult, especially at the municipal level, to respond to a large number of damaged areas. Riverbank revetment construction using “continuous box-shaped steel frames” solves these problems and enables construction without using temporary barriers, in a short period of time, and without the need for skilled workers. This article introduces the method and examples.

What is Continuous Box Type Steel Frame?

All of the examples shown here employ continuous box-type steel frames. Continuous box-type steel frames consist of multiple cages (steel frames) connected by coiled galvanized iron wire lattice panels, which can be divided, extended, and bent for installation. By lining the inside of the steel frame with non-woven fabric and filling it with locally generated soil, crushed stones, chestnut stones, etc., a continuous embankment can be easily and quickly constructed, and can be used for earth retaining, embankment raising, temporary embankment closure, etc.

Outline and Features of Continuous Box Type Steel Frame "MAXWALL

Maxwall uses lattice-like panels made of galvanized iron wire, which are durable enough to withstand use for about 10 years, making it suitable for temporary construction over a long period of time. Because of its high durability and the fact that it does not require any filling material, Maxwall was introduced in the areas affected by the Great East Japan Earthquake as a temporary earth embankment and earth retaining system for raising embankments and embankments, and has been installed in coastal areas using locally generated soil and concrete rubble recycled from rubble due to the shortage of materials such as crushed stone. The following is a brief introduction of its outstanding features.

Feature 1: High stability

Large sandbags often used for temporary construction are not connected and not integrated, making them vulnerable to external forces and unstable, such as collapsing if the load is concentrated in one place. Maxwall, with its continuous steel frame, can withstand more than four times the external force (approximately 16 kN) of large sandbags, demonstrating its high stability.

Feature 2: Watertightness due to soil continuity

The inner frame (the red frame in the figure below) is not covered with non-woven fabric, and the continuous filling material such as sand and soil ensures high water sealing performance that cannot be achieved with large sandbags.

Feature 3: High durability and can be used as a long-term temporary installation

While large sandbags can be used for only about 6 months to 3 years, Maxwall has a durability of more than 10 years on land and in the soil, and about 5 years in areas where seawater splashes. In the Great East Japan Earthquake, Maxwall was used for a long period of time in coastal areas as a temporary construction material for revetments and earth retaining works.

 

Feature 4: Any filling material can be used, including earth, sand, crushed stone, and locally generated soil.

It can be used not only for earth and sand, but also for crushed stone and chestnut stone, and can also be used as a residual concrete formwork.

 

Feature 5: Can be stacked, split, extended, and bent

The standard size (one unit) consists of a series of ten 1-meter cubic steel frames (cells), which can be freely divided, extended, and bent to suit the scale of construction and site conditions. It can also be stacked, allowing it to be flexibly adapted to the shape of the site.

 

Feature 6: 25% shorter construction period than conventional large sandbags

It does not require skilled labor and can be installed by five people for approximately 40 meters per day. This is an approximate 25% reduction in construction time compared to large sandbags.

Case Studies in Small River Construction

Seawall construction in Takizawa City, Iwate Prefecture

As part of a river maintenance project, restoration work was required to restore riverbanks damaged by torrential rains. However, the following issues made it difficult to implement the work using conventional methods such as wooden fences, cast-in-place concrete, and cage construction.

• Temporary closure of the river is needed
• Lack of special workers (formworkers) and skilled workers * Resulting in longer construction period

Therefore, Maxwall was adopted, which can be constructed in a short period of time and without requiring skilled workers.

 

Urgent small-scale river construction in Himeji City

Emergency work on riverbank revetments damaged by the torrential rains in western Japan required emergency measures until the main restoration work could be completed. Initially, large sandbags and sheet piles were considered for the revetment work, but these were subject to problems such as tipping over and being washed away when the water level rose, noise problems during construction, and a longer construction period due to the need for ground investigation for construction. Therefore, Maxwall was adopted because it does not require a ground survey, has strong integrity and stability, and is easy to install.

 

Ordinary erosion control work on the Oya River, Hiroshima Prefecture

 

Sendai City Yamada River Repair Work (1) (Typhoon No. 19 Disaster in 2019)

 

Sendai City Yamada River Repair Work 2 (Typhoon No. 19 Disaster in 2019)

 

Sendai City Agricultural Waterway Repair Work (1) (Typhoon No. 19 Disaster in 2019)

 

Sendai City Agricultural Waterway Repair Work (2) (Typhoon No. 19 Disaster in 2019)

 

Sendai City Hanawa River Repair Work（Typhoon No. 19 Disaster in 2019)

 

Hokkaido Torinosawa River Repair Work

Inquiry about Continuous Box Type Steel Frame

As a new option for revetment construction that solves the conventional problems, we introduced a method using “Maxwall,” a continuous box-shaped steel frame. Maxwall is a temporary material that can withstand long-term use and shorten the construction period. Moreover, it is an excellent construction method that can reduce overall costs because it does not require special skilled workers or skilled labor. It has been widely used as a countermeasure against flood damage caused by typhoons, which always occur every year, especially by local governments. To learn more about Maxwall or to contact a representative, please access the following link.

> “MAXWALL” continuous box-type steel frame from Taiyo Kogyo Co.