Seismic behavior of micropile systems

A series of centrifuge tests were conducted on micropile group and network systems in order to investigate the response to earthquake loading and soil-micropile interaction behavior. Model tests on group and network systems embedded in loose to medium dense dry sand are described. Micropile bending moment, deflection, and acceleration were measured during testing. Dynamic p-y curves were derived from the measurements for low and high levels of shaking and were compared with the backbone p-y curves for sand recommended by API and other published data. Group and network effects were investigated for different configurations and at different levels of loading. For the selected frequency of excitation, the results indicate a positive group effect increasing with the number of piles and the batter angle. This paper describes the experimental procedures used to carry out the centrifugal model tests and summarizes the main preliminary results.