Abstract: The shaking table test of buried pipelines under multi-point non-uniform excitation is carried out to investigate the nonlinear seismic response of site soil with the use of a nine sub-table array shaking table system in Beijing University of Technology. Through experiments, the macroscopic phenomena, the dynamic characteristics, and the acceleration response of site soil during vibration were observed. Also, the seismic response characteristics and variation of the soil under different earthquake motions and different seismic intensities were studied. The acceleration amplification factor of the free-field and non-free-field soils and the acceleration time history and Fourier spectrum of the same measuring point were compared. The results show that the seismic response of the soil is not only related to the ground motion record and the loading level, but also has a relationship with the buried structures. The damping ratio and the basic frequency of the non-free field are larger than the parameters of the free field. The seismic response of the pipeline is basically subordinate to the response of the soil under lower loading level, but with the increase of loading level, the restraint effect of soil decreases, and the acceleration of the pipeline is slightly larger than that of the soil. The existence of the buried pipeline has a certain influence on the dynamic characteristics of the soil within a certain range, but if the location is beyond that range, the impact will be rapidly weakened. The conclusions obtained are consistent with the macroscopic phenomena of seismic response obtained by the test, which corroborated each other's rationality. Furthermore, the conclusions support the analysis of seismic damage mechanisms of subsequent buried pipelines.

Key words: non-uniform excitation, shaking table test, seismic response, dynamic characteristics