1. Background of the Kankyo Pile Method
Until around 2010, cement and steel pipes were used for ground improvement in housing in japan, and timber was rarely used. Here's why we developed the Kankyo Pile Method.
The Kankyo Pile Method uses preservative and anti-termite treated timber to reinforce the ground. It was developed by Kanematsu Sustech and has been installed in over 45,000 buildings. It has won awards including the Global Environment Award and the Eco Mark Award.
This page introduces the background and history of the development of the Kankyo Pile Method, including why and how wood is used for ground reinforcement.
Until around 2010, cement and steel pipes were used for ground improvement in housing in japan, and timber was rarely used. Here's why we developed the Kankyo Pile Method.
Forests cover much of Japan. If they are not properly thinned, forests will become unhealthy, such that young trees cannot grow, and they cannot absorb as much CO₂ as they should. Thinning and afforestation are essential, but they are expensive. It’s also important to use the thinned wood effectively.
Timber has been widely used as the main material for buildings since ancient times. Timber is also used to reinforce soft ground. Famous examples are the stone walls of Venice and Saga Castle, and the Marunouchi station building of Tokyo Station.
However, Timber has not been used much for ground reinforcement recently. People also worried about the durability of timber, such as corrosion and termites, and the unknown bearing capacity of timber.
The idea that wood rots was deeply rooted and there was not enough evidence to change it.
Kanematsu Sustech (formerly Kanematsu Nissan Norin) had two divisions: the Wood & Housing Materials Division, which handled research and development of wood preservative and anti-termite treatment technology and treated wood, and the Geo-tech Division, which performed foundation reinforcement work.
Against this backdrop, we developed the “Kankyo Pile Method”, which uses our own preservative and anti-termite treatment on domestic thinned wood and casts it into the ground as a improvement material.
Timber deteriorates due to two main causes: corrosion from wood-decay fungi and infestation by termites. Wood-decay fungi and termites can’t live in water, so damage is unlikely below the groundwater level. But areas above the groundwater level can be damaged.
To prevent timber damage from wood-decay fungi and termites, chemicals are injected into the timber in a special kiln, which works whether or not there is groundwater.
Field and indoor tests on timber that has undergone a preservative and anti-termite treatment process have been conducted, and the results confirm the efficacy of the treatment.
In field tests, treated and untreated materials were placed underground in termite-infested areas. The results confirmed that the untreated materials caused damage, while the treated materials remained intact.
In laboratory tests, we have confirmed that the chemical has a long-lasting effect. This was confirmed by repeatedly wetting and drying the material to accelerate deterioration and by exposing test specimens that are equivalent to 60 years to termites and decay fungus.
The bearing capacity of the material was verified through load tests, which involved driving timber pile into the ground and measuring the amount of settlement after applying a load. By conducting these load tests at multiple locations in Japan, we were able to gain valuable insights into the bearing capacity characteristics of the timber pile.
The “Kankyo Pile Method” was developed by aggregating test results of preservative and anti-termite performance and bearing capacity, and obtaining performance certification from a third-party organization.
It has been over 15 years since the Kankyo Pile Method was first developed. In that time, both the construction result and the recognition of the method as an effective approach have significantly improved. Recently, we have been the recipients of an increasing number of awards in recognition of our philosophy and efforts related to the “Kankyo Pile Method”.
The Kankyo Pile Method has resulted in increased demand for domestic timber, a revitalization of the domestic forestry industry, and a reduction in CO₂ by effectively utilizing domestic timber, including thinned timber. In recent years, we have received numerous awards in recognition of our efforts.
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