Traffic Disruptions in Box-Type Embankment-Underpasses Due to Past Earthquakes in Japan

In Japan, road embankments are frequently used for cost-effective highway construction in areas with limited plains, for ensuring that traffic disruptions are minimal, but earthquake activities in the past have caused destruction to them. Despite advancements in the seismic resistance of underpass structures, the practical significance of serviceability in embankment-underpasses has been neglected. The current study investigated the cause of these destructions by carrying out centrifuge test at 50G on a scaled down embankment-underpass model from the actual structure and analyzing the results. From the model outcome, sand boil was formed beneath the underpass and the joint opened. From pressure gauges results, amplification of excess pore water pressure occurred at the joint due to behavior of the underpass as an undrained boundary and embankment as partially drained boundary surface. This unbalanced drainage boundary behavior resulted in the amplification effect, and these residual stresses accumulation at the joint section explained the occurrence of the sand boil, which justified that liquefaction occurred causing the destruction.