A damage-based numerical approach for optimizing the arrangement of articulated sections in an active-fault crossing linear underground structure

The booming development of underground facilities including transportation tunnels, subways stations, buried pipelines, and water convey systems, these linear underground structures (hereafter referred to as LUGS) become an integral part of the infrastructure of modern society. In the last few decades, major earthquakes have induced significant structural damage to numerous LUGS. Articulated design has been widely recognized as an effective strategy for mitigating and shortening the longitudinal damage of LUGS. However, prior research has primarily focused on researching proper material or structure, with limited attention to the optimal arrangement of articulated sections. This study proposes a damage-based numerical approach to optimize articulated configurations using a COMSOL-MATLAB coupled framework. A plasto-elastic model is developed to simulate LUGS crossing a reverse active fault, and a total of 3700 combinations of articulated arrangements are quantitatively assessed with two arrangement types (even and uneven number type) and three controlling factors. The damage length ( L dmg ) is used as a performance index to evaluate the damage response under each configuration. Results demonstrate that arrangement parameters—namely, the number, width, and spacing of articulated sections — significantly influence longitudinal damage and appropriate arrangement could shorten and stabilize the damage response. Specifically, minimizing the width of the articulated sections is effective for mitigating longitudinal damage and more numbers of articulated sections is effective for stabilizing longitudinal damage of LUGS. This study provides a reliable methodology for optimizing fault-resilient designs of underground structures.