CENTRIFUGAL SEISMIC EXPERIMENTAL STRUDY OF BUIED PIPELINES IN NON-UNIFORM SOIL

The deformation and residual strength of buried pipelines caused by the earthquake in non-uniform sites are crucial for the safety of the pipeline. A centrifugal dynamic experiment is carried out to simulate the seismic response of buried pipelines crossing soft and hard soil and study their residual strength after earthquake. Two simulated seismic waves with 0.6 g and 0.3 g of input peak ground acceleration are exerted in sequence to simulate a series of earthquakes. The deformations of ground and pipelines of polyvinyl chloride (PVC) and aluminum alloy (AL) are obtained during and after the earthquake. Results indicate that the strain amplitude of pipelines caused by transient ground deformation reaches peaks at the interface of two soils as well as in soft soil. The maximum tensile strain of pipelines by seismic excitation in soft soil is larger than that in hard soil, while the maximum compressive strain is on the contrary. The maximum tensile strain of pipelines by seismic excitation in hard soil is larger than the maximum compressive strain in soft soil. The maximum compressive strain of pipelines in hard soil is more affected by seismic intensity than in soft soil. Permanent ground deformation caused by earthquake had great effect on the deformation and residual strength of pipelines. The residual strain of pipelines in hard soil is compressive strain, while in soft soil it is compressive and tensile strain alternatively.