Assessment of large and differential settlement of the reclaimed clayey foundations based on the digital surface and underground information

摘要

The geoinformatic database of Oaki Town, Toba City was developed by digitizing the written information of boring logs and 3-dimensional underground model has been developed based on the newly developed geoinformatic database. A serious uneven profile of bed rock overlain by the very soft clayey deposits is expected there. A new surveying procedure, called Mobile Mapping System; MMS, is introduced to monitor the 3-dimensional digital geographical data such as sets of latitude, longitude and elevation of each point of the target area. The monitoring data set provides a detailed distribution of settlement of Oaki Town. Based on this underground model, a series of finite element analyses was conducted to describe the actual differential settlement for the past 40 years. The calculated performance is validated by comparing with the present elevation of the original clay deposits checked by the newly conducted boring as well as the digital information through MMS. The newly developed system is found to be versatile and promising to support local governments to establish a policy for disaster mitigation.