Identification of design parameter to estimate the long-term subsidence of seabed deposit of Pleistocene clay

本研究的目的是提出更新世粘土存款的地面沉降的合理设计方法。更新统粘土的工程特性是海洋工程开发中的重要课题，但对更新统粘土的工程特性研究还不多见。本研究基于大坂湾海床数据库（SBDB），该数据库是为了处理与大坂湾地区开发有关的许多组织进行的许多岩土数据而建立的。SBDB是由前研究委员会发起的：1984年在JSSMFE关西分支成立的“大坂湾海底沉积物研究委员会”和1990年在JSSMFE关西分支成立的“大坂湾海底沉积物地球技术信息研究委员会”，本项目的调查员负责人为这些委员会做出了贡献。主要研究结果如下：1.提出了利用大量钻孔数据建立的SBDB的应用。提出了SBDB在大范围海底存款存款岩土工程性质评价中的应用。这一结果有助于进行大规模填海工程沉降分析时排水层的选择。3.对大坂湾海底粘土样品进行了粘土矿物的鉴定和定量分析。利用SBDB分析了土的物理性质和工程性质，结合粘土矿物的性质和沉积环境，研究了粘土矿物组成和地基性质的参考值。

The objectives of this research project is to propose the rational design method for ground subsidence of Pleistocene clay deposit. The engineering behavior of Pleistocene clay accompanied with large-scale construction projects is an important issue on the offshore development, however it is not well known. This research is based on the Osaka Bay sea bed database (SBDB), which has been established in order to handle the many geotechnical data conducted by many organizations relating to the development of Osaka Bay area. The SBDB has been launched by the former research committees : "Research Committee on Seabed Deposits in Osaka Bay" established in 1984 and "Research Committee on Geotechnocal Information of Osaka Bay Seabed Deposits" established in 1990 in the JSSMFE Kansai Branch, and the head of investigator of this project has contributed to these committees. The main results obtained are as follows ;1.The application of SBDB which has been established with the many boring data was proposed. The locality of the geotechnical properties of seabed deposit was clarified by using SBDB.2.The application of SBDB to the evaluation of the geotechnical properties of seabed deposit in wide area was proposed. This result contributes to the selection of the drainage layr when the settlement analysis of large-scale reclamation is conducted.3.The identification and quantitative analysis of clay minerals contained in the seabed clay sampled from Osaka bay were conducted. The physical and engineering properties of the soil were also obtained by using the SBDB.The reference of the clay mineral composition and the properties of the ground was investigated with taking the properties of clay mineral and/or sedimentary environment into account well.