100 Stories2011 ACCS Pile, Preventing Liquefaction Damage

On March 11, 2011, the Great East Japan Earthquake caused enormous damage to a vast area, mainly in the Tohoku region and extending to the Kanto region. In addition to the earthquake causing buildings to collapse, the tsunami caused secondary damage, leaving behind great damage.

There were various types of secondary damage, including the division of critical infrastructure and landslides. One of the secondary damages that were discussed the most was soil liquefaction. Liquefaction occurred in the Kanto region as well, but Asahi Kasei’s ACCS pile* is what saved the Keiyo Line Shin-Urayasu Station area from this damage.

The business of manufacturing piles as building materials started with the development of the AHS pile in 1968. The AHS pile had excellent quality and was more durable than the PC pile, which was commonly used at the time. In addition, the economy was booming and more public works were carried out, helping the AHS pile achieve rapid growth.

However, another company developed a PC pile that had a higher allowable load, which was the main feature of the AHS pile, causing a temporary setback in the growth of the pile business. The liquefaction-resistant ACCS pile is what got it back on track.

Not only was it highly durable, but was also superior in terms of its production process because it allowed for significant labor and cost-cutting. This gave Asahi Kasei’s pile business, which was the last to join the market, the driving force to reach the top market share.

The ACCS pile was installed at Shin-Urayasu Station in 1978. The ACCS pile passed the comparison test that was carried out to decide whether it will be used in the Joetsu Shinkansen and Tohoku Shinkansen, which were under construction at the time. However, according to the rules of the Japanese National Railways, it had to be tested first at an existing line. The liquefaction zone in the Keiyo Line Urayasu area was selected for this.

The soft soil required 50-meter long piles. It was a large construction project that was covered in the newspaper when multiple pile drivers were deployed.

More than 30 years later, the Great East Japan Earthquake struck. Most of the homes in the Urayasu area suffered liquefaction damage and tilted. In some areas, the damage was so severe that it was even difficult to walk. The residential areas that were developed in a prime location 20 minutes from the Tokyo Station were severely damaged, and their skyrocketing prices suddenly dropped. Despite that, the Keiyo Line’s elevated bridge that used ACCS piles remained completely undamaged.

Japan is an earthquake-prone country, so we never know when earthquakes will strike again. Having experienced the Great East Japan Earthquake (11 March, 2011), we know that just because something has never happened before does not mean that it never will. Technological advancement is indispensable for preparing for disasters.

＊ACCS pile is the abbreviation for Autoclaved Concrete Composite Steel pile. It is a composite pile made by curing concrete that is mixed with a special expansive admixture in an autoclave (a high-temperature, high-pressure steam kiln), completely merging the outer-shell steel pipe with concrete. Just like the AHS pile, the ACCS pile is also Japan’s number one certified highly earthquake-resistant steel-pipe concrete pile.