Compaction pile method utilizing coal ash as filled material

Clean sand is normally used as the filled material in the sand compaction pile (SCP) method of soft ground improvement, the most widely used method in Japan. But environmental concerns have prompted as an alternative use of coal ash, a by-product of coal-fired thermal power stations, and site tests have been carried out using pile materials composed mostly of coal ash. This paper reports on this experimental ground strengthening work undertaken on a coastal coal ash-filled landfill site liable to liquefaction, to confirm the implementation characteristics and improvement effect of the pile materials. The results showed that the SCP method can be used as a countermeasure (increased density) to liquefaction in coal ash ground, and that coal ash makes a suitable filled material.