Active length of a continuous pipe or tunnel subjected to reverse faulting

Numerous researches were conducted to explore the response of a pipe or tunnel to fault-induced deformation, most of which concentrated on strain distribution and failure mechanism. In this study, both centrifuge and numerical modeling are performed to investigate the active lengths of stainless steel pipes and concrete tunnels subjected to reverse faulting. The active length is assumed as the part of a pipe or tunnel with different displacements from the surrounding soil. Two centrifuge tests of pipes are conducted to validate the three-dimensional beam-spring model. Parametric studies are performed to investigate the active length of a structure (continuous pipe or tunnel) in reverse fault and its influence factors. The results showed that the active length depends on fault deformation, size of the structure (diameter and diameter to thickness ratio), material properties of structure (Young's modulus and yielding stress), burial depth, and frictional angle of sand. The active length has a positive correlation with relative structure-soil stiffness. The relationship of active length and relative structure-soil stiffness is obtained by a comprehensive parametric study with 960 finite elements.