Practical application of mitigation measures for existing underground lifelines subjected to liquefaction

抄録

The 2011 Tohoku Earthquake at the Pacific coast of Japan caused significant liquefaction-induced damage around Tokyo Bay where floated pipelines and manholes were widely observed. To protect existing underground lifelines from future earthquakes in some other regions, mitigation measures are urgently required. The conventional measures require considerable time and economic resources, which hinders the feasibility of these methods. In this regard, the authors previously proposed new mitigation measures: the vertical drain pipe method, connection with pavement by stiff bars (namely, horn structure method) and the chemical grouting method. The proposed measures can be executed with a partial excavation of backfill soil, resulting in less construction period and cost. Satisfactory performances of the proposed measures were demonstrated through 1-g shaking model tests by the authors. The present study aims to develop a framework for practical application with the proposed measures. To evaluate the performance of the proposed measures, challenges of developing a simple analytical method based on simple beam models were discussed. The proposed analytical models qualitatively captured the experimental results.