Proposal of liquefaction countermeasure technique by log piling for residential houses

Abstract

During the 2011 Great East Japan Earthquake in Japan, extreme liquefaction caused extensive damage to residential houses in the Kanto Plain region with the magnitudes of the settlements and tilts larger than that was observed during past earthquakes. This paper deals with a proposal of technique of ground improvement by installing logs into loose sand layer as a countermeasure against soil liquefaction for the residential houses. Small scale shaking table tests in a 1-g gravity field were carried out using some model grounds. It was clarified that the wooden pile could increase the resistance of ground against liquefaction due to the increase of ground density by piling and the dissipation of excess pore water pressure along the surface of piles. As a result, the magnitude of settlements of the house which was set on the improved ground by piling logs became quite small.