Seismic response analysis of buried pipelines with varying stiffness by shaking table tests

The relative stiffness between underground structures and surrounding soil may significantly influence the dynamic response of such structures. In this study, two underground pipelines were fabricated using rubber joints with varying stiffness, and the corresponding dynamic response was evaluated. Model soils were prepared based on similarity ratios. Next, reduced-scale shaking table tests were conducted to investigate the impact of circular underground structures with varying stiffness joints on the amplification of ground acceleration, dynamic response, and deformation patterns of the underground pipelines. The comparative analysis showed that structures with lower stiffness exert less constraint on the surrounding soil, resulting in a higher amplification factor of ground acceleration. The seismic response of less stiff structures is generally 1.1 to 1.3 times the response of the stiffer structures. Therefore, the seismic response of the variable stiffness pipeline exhibits pronounced characteristics. Rubber joints effectively reduce the seismic response of underground structures, demonstrating favorable isolation effects. Consequently, relative stiffness plays a crucial role in the seismic design of underground structures, and the use of rubber materials in underground structures is advantageous.