ABSTRACT
In the construction projects of seaports, large amounts of mountain soils, river and sea sands have been used for the reclamation or backfilling of quaywalls. However, it is becoming increasingly difficult to obtain these soils especially due to the recent issues of environmental protection. On the other hand, a large volume of soft clayey soils is dredged annually and dumped in waste disposal sites enclosed by seawalls in Japanese seaports. Figure 1.1 shows the change of waste volume dumped during the period of 1980-1995. As shown in the figure, approximately 18 million m3 of the wastes were disposed of every year, of which 45% was dredged soil, 21% was surplus soils from construction sites in land and 8% was industrial waste. Recently, the lack of waste disposal sites in seaports has become a serious problem and about 30 billion yen has been expended annually so far on the construction of seawall structures for new disposal sites. Moreover there have been strong calls due to social and environmental aspects for the reuse of dredged soils in port and harbor construction works.
