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Tuna fisheries have become the most important contributor to the coastal central provinces of Vietnam since it was introduced in early 1990s. However, developing effective management guidelines for yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tuna, the main target species for longline and handline fisheries, is difficult because there is no information on its growth characteristics. In particular, length-length, length–weight, and weight-weight relationships, the important components of fisheries production models, do not exist for those species. This study first provided those relationship equations and represented an improvement in the knowledge of these species in its distribution range with maximum sizes updated.

It was observed that liquefaction induced by earthquake causes series damages to buildings and threatens the people and their properties. From the past studies, a number of countermeasures were proposed to reduce the build-up of excess pore water pressure and to enhance the stiffness of the soil during earthquake. The vertical drain systems are well known methods and used as remediation against earthquake-induced soil liquefaction for many years. The purpose of the study is to investigate the effect of different vertical drain systems for the liquefiable soil by centrifuge modeling technique. The seismic behavior of liquefiable soil was performed firstly. The free field soil models were then prepared with alternatively arranged drain-belts and gravel-pile drains to investigate the effect of different vertical drain systems on the liquefiable soil. Several arrays of accelerometers, the pore water pressure transducers and displacement transducers were placed to monitor the shear wave propagation, the excitation and dissipation of pore water pressure. Displacement transducers were placed to measure the ground surface settlement. From the test results, it was observed that the vertical drain systems reduce the settlement and excess pore water pressure significantly. In the future, the vertical systems will be applied around the structure and the test results would give engineers suggestions to deal with the arrangements of drain-belts and gravel drains to reduce the damage during and after the earthquake.

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