In densely populated urban zones, seismic performance evaluation of strategic infrastructure during seismic events has become more challenging because the distance between surface and underground structures has been shortened to optimize the urban environment functionality. This is even more important in transit transfer stations, which usually comprise tunnels, bridges, and buildings, in which wave propagation interference is exacerbated. This paper explores the seismic interactions between on-ground and underground structures in soft-soil environments, focusing on a typical urban modal transfer station in Mexico City. The study is conducted through comprehensive parametric analyses using 3D numerical simulations in FLAC3D (v.6.0), considering both intraplate and interplate earthquakes, to assess the effect of differences in their frequency content, duration, and intensity. Multiple scenarios are considered in the numerical study, and the relative distances among the structures are varied to investigate both detrimental and beneficial interaction effects, and to identify the zone of influence where this interaction leads to ground motion variability. The study’s findings established the key variables in the interaction between underground and on-ground structures, providing valuable insights into the seismic design and retrofitting of urban infrastructure in densely populated areas.

Conventional tunnelling, CT, in densely populated urban areas requires ensuring that both serviceability and failure limit states are satisfied throughout construction, to avoid excessive ground deformations and catastrophic failures, while maintaining optimum support and excavation lengths. To achieve both goals, continuous monitoring of the tunnel-ground system behavior and adaptation of the tunneling process through calibrated numerical models becomes critical. This paper documents the field performance and construction optimization of a 4.5 km long tunnel excavated by CT in the stiff soils of the northwestern Mexico City region. A five-step monitoring and back-analyses procedure is introduced for risk reduction and optimization of the tunneling process during CT. The monitoring information, adopted support types, and excavation lengths demonstrate that construction times can be shortened through the proposed approach, enhancing construction processes with the corresponding cost reduction. Both three-dimensional numerical models and geotechnical instrumentation, including convergences, surface topographic references, extensometers, and pressure cells, were implemented throughout construction. The numerical models were continuously calibrated against field measurements to increase their predictive capability, accounting for actual subsoil conditions, tunnel geometries, and construction procedures. From the results gathered here, the benefits of using this integral approach to ensure good tunnel performance during excavation are established, in particular when the tunnel is excavated below densely populated areas in brittle cemented fine-grained soils

Modern performance-based bridge design seeks to control damage in specific failure modes in order to balance safety and economy, particularly in high-seismic regions where inelastic and ductile deformation is expected to occur, both in the structure and soil, allowing potential reduction in seismic demand through fuse elements. In short-span bridges, abutments strongly influence longitudinal response, whereas transverse performance depends largely on seismic components such as shear keys and other energy-dissipation devices. Thus, performance assessment requires explicit representation of their hysteretic behavior. This study presents a numerical evaluation of the damping provided by common elements in typical bridge systems, using as reference damage observations from bridges affected by recent interface earthquakes in Mexico. Three-dimensional finite-difference models were developed, and nonlinear response-history analyses were performed to simulate ductile behavior and energy dissipation. The Sig3 hysteretic model available in FLAC^3D was used for abutments and foundation soils, while shear keys were represented as nonlinear springs. The results established a relationship between plastic deformation and energy dissipation, showing that incorporating the hysteretic behavior of both soil and sacrificial structural components enhanced the seismic bridge performance assessment, and led to more reliable and cost-efficient designs when inelastic deformation capacity was explicitly included in the numerical simulations.

Intense rainfall, and the resulting increase in ground saturation can significantly modify the mechanical performance of rock masses in natural slopes. This is particularly important if material fractured is present. Extended infiltration accelerates material degradation, reduces shear strength along discontinuities, and increases pore-water pressures, reducing effective stresses, and in turn, raises the probability of large-scale landslides. Evaluating these processes requires a thorough understanding of the geotechnical and hydrogeological properties controlling slope response, as well as reliable stability assessments under varying saturation conditions, including factor of safety and deformation estimates. However, in engineering practice most of the time ground exploration is limited, and laboratory testing in rocks only provides an estimation of the rock performance expected in the slope within a reduced zone. This study examines a landslide triggered in a shale–limestone slope after heavy rainfall. A back-analysis was performed within a performance-based design (PBD) framework to reproduce the observed failure and, thus, characterize representative geomechanically parameters for design validation, using three-dimensional finite difference modeling. The performance under monotonic and seismic loading of a tunnel built adjacent to the slope was analyzed as a mitigation measure, thus establishing its technical soundness, from both state limit of failure and service, of the tunnel-slope system.