What is the sandbag (soilbag) method?
Through model experiments conducted since around 1990, I came up with the idea that the most effective and reliable way to reinforce loose materials like sand, which breaks down into tiny pieces compared to steel or concrete, is to “completely encase and restrain them.”
I then realized that sandbags have been around for a long time.
I gradually discovered that properly placing sandbags has five effects (strengthening weak ground; reducing liquefaction, vibration, and seismic motion; and preventing frost heave).
- strengthening weak ground
- reducing liquefaction
- reducing vibration
- reducing seismic motion
- preventing frost heave
The essence of the sandbag method is that “when both soil and people are warmly enveloped and united, they exert extraordinary strength.”
*For more information, “A New Earth Reinforcement Method using Soilbags”(Hajime Matsuoka and Sihong Liu, Taylor & Francis Group, London, UK, 2006).
From the Soil Bag Method to the D-Box Method
D-Box is a product developed by Futoshi Nomoto, President of Metry Technical Research Institute, Inc., since 2006, based on the theory, effectiveness, construction track record, and guidance of the soil bag method developed by Matsuoka et al.
This product enhances the diverse benefits of soil bags, such as ground reinforcement and reduction of liquefaction, vibration, and seismic motion, to be applicable to actual public works projects.
Profile of Representative Hajime Matsuoka
When I was young, I, Hajime Matsuoka, devoted myself to thorough fundamental research, such as the movement of individual soil particles.
This was because I wanted to understand the roots—the essence—of things. Looking back on my research career, I believe I have been blessed with two major accomplishments.
❶ Discovery of the SMP (Matsuoka-Nakai) Failure Criterion
In 1974, we were fortunate to discover the SMP (Matsuoka-Nakai) failure criterion (a failure criterion for soil materials based on the spatially mobilized plane (SMP)), which is a three-dimensional version of the Mohr-Coulomb failure criterion (defined by the cohesion force c and the internal friction angle φ) commonly used by soil and geotechnical engineers.
This SMP criterion is clearly positioned alongside the Tresca and Mises criterion for metallic materials.
*For more details, see “The SMP Concept-based 3D Constitutive Models for Geomaterials”(Hajime Matsuoka and De’an Sun, Taylor & Francis Group, London, UK, 2006).
❷ Discovering the Soil Bag Method and Evolving into the D-Box Method
I came up with the idea that the most effective and reliable way to reinforce loose materials like soil is to completely encase and constrain them.
This led me to discover the soil bag method and gradually realized its “five-birds-with-one-stone” effect (strengthening soft ground, reducing liquefaction, vibration, and seismic motion, and preventing frost heave).
Around that time, I met Futoshi Nomoto, president of Metry Technical Research Institute, Inc., and it was a great pleasure to see his brilliant vision lead to the development of the D-Box Method.
Major publications (include a photo of the book cover)
❶ Hajime Matsuoka: “Soil Mechanics,” Basic Civil Engineering Series 15, Morikita Publishing, 1999.
This is a textbook for university and technical college students that carefully explains the basics of soil mechanics, with extensive use of photographs of the author’s experiments, construction examples, and more.
❷ Hajime Matsuoka: “A New Approach to Geotechnical Engineering: Constitutive Equations, Testing Methods, and Reinforcement Methods,” Kyoto University Press, 2003.
This book consists of three research topics conducted by the author and his colleages:
- Lecture 1: “A New Elastic-Plastic Constitutive Equation for Soil”
- Lecture 2: “The Simplest In-Situ Shear Test Method for Ground”
- Lecture 3: “Ground Reinforcement Methods that Turn Enemies into Friends”
❸ Hajime Matsuoka and Sihong Liu: “A New Reinforcement Method using Soilbags,” Taylor & Francis (formerly A. A. Balkema) Group, London, UK, 2006.
This is an English translation of the third lecture of “New Approaches to Geotechnical Engineering: Constitutive Equations, Testing Methods, and Reinforcement Methods,” with additional research findings added.
Co-author Sihong Liu was a Chinese student studying in my lab at the Nagoya Institute of Technology at the time, where he earned his doctorate.
He is now a professor at the School of Hydraulic and Hydroelectric Engineering, Hohai University, Nanjing, China.
❹ Hajime Matsuoka and De’an Sun: “The SMP Concept-based 3D Constitutive Models for Geomaterials,” Taylor & Francis (formerly A. A. Balkema) Group, London, UK, 2006.
This is an English translation of the first lecture of “New Approaches to Geotechnical Engineering: Constitutive Equations, Testing Methods, and Reinforcement Methods,” with additional research findings added.
Co-author De’an Sun was a Chinese student studying in my lab at the Nagoya Institute of Technology, where he earned his doctorate.
He is currently a professor in the Department of Civil Engineering at Shanghai University in Shanghai, China.
❺ Hajime Matsuoka, Haruyuki Yamamoto, Futoshi Nomoto, “Design and Construction Fundamentals of the D-Box Method: Ground Strengthening and Liquefaction, Vibration, and Seismic Motion Reduction,” Morikita Publishing, 2020.
This explains how one construction method provides five benefits:
- countermeasures for soft ground
- countermeasures for liquefaction
- countermeasures for traffic vibration
- countermeasures for earthquakes
- countermeasures for frost heave
It truly is a “five-birds-with-one-stone” construction method.
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