Hybrid Type Reinforcement of Highway Embankment Against Earthquake Induced Damage

In this research, a hybrid type pile system is proposed as a countermeasure of embankment failures during earthquakes. In the proposed technique, inclined piles are added in addition to the rows of vertical steel pipe piles. Inclined piles are expected to reduce ground deformation and settlement due to earthquakes, especially when the embankment widths are large. The focus of the research is to evaluate the stability of embankments by the external force of the earthquake and to elucidate the mechanism of the reinforcement effect by the vertical steel pipe piles and inclined piles. Model tests using shaking table and their numerical simulations were performed to evaluate the performance of the hybrid type reinforcement measures. Model tests were conducted by taking into the consideration the pile rigidity and embedment depth. The numerical simulations were also performed in which the effect of the inclination of the inclined piles was also taken into the consideration. Both the test results and numerical simulations have confirmed that in embankment with hybrid reinforcement measures, the increase in excess pore water pressure during an earthquake could be suppressed, and the settlement of the embankment could be significantly reduced.