Centrifuge and numerical modeling of brittle damage of buried pipelines subjected to tunneling induced ground settlements

Abstract

Tunnel excavations can seriously threaten the structural integrity of nearby pipelines. In the present study, centrifuge tests and numerical simulations are conducted to systematically investigate the brittle damage of buried pipelines subjected to tunneling induced ground settlements. In the numerical model, the pipeline is characterized as peridynamic (PD) shell structures, and the surrounding soil is modeled as discrete independent Winkler springs, and the modified Gaussian distribution profile is incorporated as displacement-controlled boundary conditions on springs. The effectiveness of the proposed numerical model is demonstrated by comparing against the centrifuge test results. A pipeline is subjected to bending due to tunneling until the initiation of cracks, after which the cracks propagate inwardly quickly and penetrate through the cross-section. Eventually, a ring crack occurs at the cross-section above the tunnel centerline. From parametric analyses, the following factors delay the pipeline damage, i.e., thicker pipe wall, shallower burial depth, loosely soils, smaller soil friction angle, and smaller tunnel-pipeline crossing angle. A pipeline with a thicker wall and a higher critical energy release rate can have a greater initial pipe fracture angle. In any case, the fracture angle always increases steadily if the amount of ground settlement continues to grow.