The suitable anchor systems of silt curtain were verified by compared dynamic responses of various types of anchor (e.g. suction pile anchor, friction pile anchor with end bearing and gravity anchor) and seabed around them under severe storm condition. Concrete blocks are effectively used in soft seabed as a sinker for mooring silt curtain. Their holding power are estimated by cohesion between soft mud and each faces of bottom and sides of sinker, difference between passive and active earth pressures, the submerged weight and the submerged overburden pressure. Concrete block shows often the higher holding power than the estimated one. Because the estimation does not include suction between faces of concrete block and mud bed. The effects of suction were investigated by simulating the response of sinker in soft bed under the storm wave and current. Usual concrete block and H-beam anchors are reasonable, since they have suction effects. Other types of anchor were also simulated the dynamic responses by in-situ measured tension due to storm wave and current. The results showed the effects of suction increase the holding capacity against the tensile force. It is effective to make use of suction to anchor system in soft seabed.
The demand for developing coastal zone increases not only in the Metropolitan area but also in district capitals. The urban coastal zone has the possibility for those large cities to supply enough space for transportation bases marine recreational sites or business sites for information industry. Those developments are accompanied by reclamation and dredging, which may cause the environmental deterioration. For almost all big project of inner bay in Japan the silt curtain is developed around construction sites to prevent sea pollution. Usually the sea pollution means the diffusion of suspended soil which originates in dredging or casting of soil.