EXCAVATION SITE INVESTIGATION ON LOGS INSTALLED 8 YEARS EARLIER AS A LIQUEFACTION COUNTERMEASURE

Abstract

 At depths below the groundwater level, wood is not susceptible to biodeterioration such as decay and termite damage, and thus has begun to be used in countermeasures against soil liquefaction that occurs in areas with shallow groundwater conditions. One advantage of using wood is the long-term storage of carbon fixed in the wood. However, this carbon storage effect is not internationally recognized, so there is a need to accumulate scientific knowledge on this carbon storage effect as a carbon dioxide sink. Accordingly, we conducted an excavation site investigation on logs that had been driven into the ground 8 years earlier as a soil liquefaction countermeasure. We present the groundwater level observation records at the site, and the condition of the logs at 2, 4, and 8 years after their installation. The results of this investigation show that the logs were sound after 8 years despite some logs being above the groundwater level.