Numerical modeling of ground surface settlement due to tunneling in urban areas

The rise in urban traffic challenges has spurred the expansion of subterranean transportation systems within metropolitan areas. In densely populated regions, surface settlement has emerged as a pivotal factor in tunnel design. To ensure effective planning, it is imperative to furnish comprehensive insights into soil profiles, pre-existing structures, and precise modeling. Notably, the ground movements during urban tunnel excavation, sensitive to settlement levels and surface structure vulnerabilities, contrast with those in deeper settings like mine tunnels. The complexities introduced by shifting soil profiles, geotechnical attributes, intricate soil behaviors, surface conditions, and the presence of structures along the tunnel amplify the challenges, necessitating pinpoint accurate modeling to resolve issues. To this end, this study delves into a pertinent segment of a subway project through the lens of a case study. Employing PLAXIS2D software for modeling and monitoring, the research entails a meticulous examination of numerical modeling results. A specific section from the project garners focus, chosen due to its settlement measurement of 9.5 cm, which exceeded allowable limits. The influence of geotechnical parameters on surface settlement is probed, revealing E and k(o) parameters as the most influential. Employing a back-analysis approach, optimal values for these parameters are identified. Furthermore, a comparison ensues between transverse surface settlement curves derived from numerical modeling and actual measurements. Remarkably, this analysis underscores an exceptional alignment between measured and predicted values from numerical simulations.