Thirty Years After Kobe: The Role of Controlled Blasting in Mitigating Liquefaction Hazards

抄録

Following the Kobe earthquake (1995), researchers have conducted several full-scale field tests using controlled blasting in order to determine the performance of critical infrastructure due to liquefaction and lateral spreading. This study summarizes the lessons learned from the field testing conducted to date and the advancement of the geotechnical earthquake engineering practice for the path moving forward. In all of the large field-scale studies discussed herein, controlled blasting methods were used to trigger liquefaction in various deep foundations and ground improvement test programs. Blast charges are installed in a pattern at different depths with various charge weights depending on the project's objective. The detonation of buried explosive charges generates various stress waves, which propagate from the blast source and dynamically load the soil. When multiple blast charges are used with some delay time in between each charge, the soil mass is repeatedly stressed, which leads to the collapse of the soil matrix, and residual excess pore pressure is gradually or rapidly developed (depending on the specifics of the blast program) leading to liquefaction. Soil and structural response were captured during and following the induced liquefaction. Further, opportunities with this testing technique have been discussed for future studies where the understanding of several unexplored earthquake geotechnical engineering issues could be improved.