ABSTRACT:

To investigate the characteristics of dewatered clay lump ground, a part of revetment backfill was constructed by a trial construction. The dewatered clay lump was the recycle material which was produced from dredged marine clay. In this paper, the construction procedure is outlined, and the density of backfill and compressibility and shear strength behavior of dewatered clay lump ground are described.

INTRODUCTION

Sea bottom sediment has been and will be continuously dredged along the Japanese coastal area. One of the major purposes of the dredging is to widen and deepen existing navigation channels and anchorage areas to accommodate large ship traffics. To maintain the function of these channels and basins, periodic dredging is also needed to remove sediment brought to sea bottom by current or wave actions. The dredged sediment is discharged into a disposal pond in order to protect the marine environment. Due to huge cost and environmental concern associated with the construction of disposal pond, it is becoming difficult to construct new ones. The long use of existing ponds has become important. Katagiri and Terashi (2005) showed the flow of dredging process together with the concept for extending the life of disposal pond, and that emphasized that the extension of the life of disposal pond could be undertaken at various stages in the flow of dredging process under different concept. Here, two ways were selected for the extension of disposal pond. One is the reduction of volume of discharged sediment. The other is the increase of capacity of existing pond by additional embankment as shown in Figure 1. In this case, the strength of the soil behind the revetment should be increased for ensuring the stability of both the embankment and revetment. One of the solutions is adding backfill to the existing revetment by stable materials.

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