In complex underground conditions, the excavation of deep foundation pits has a significant impact on the deformation of retaining structures and nearby subway stations. To investigate the influence of deep excavation on the deformation of adjacent structures, a three-dimensional numerical model of the foundation pit, existing subway station, and tunnel structure was established using FLAC 3D software, based on the Shenzhen Bay Super Headquarters C Tower foundation pit project. The study analyzed the deformation characteristics of retaining structures, adjacent subway stations, and tunnels during different stages of deep excavation, and the accuracy of the numerical simulation results was validated through field monitoring data. The results indicate that during the excavation process of the foundation pit, the lateral horizontal displacement of the retaining structure is generally small, with a typical “concave inward” lateral deformation curve; the horizontal displacement value of the contiguous wall section is less than that of the interlocking pile section. The bending moments of the retaining structure show a distribution pattern with larger values in the middle and smaller values at the top and bottom of the pit, with a relatively uniform distribution of internal support forces. The maximum displacement of the nearby subway station is 8.75 mm, and the maximum displacement of the subway tunnel is 2.29 mm. The research findings can provide references for evaluating the impact of newly built foundation pits near subway stations and contribute to the rational design and safe construction of new projects.

Since the mid-20th century, reservoir construction has increased rapidly, and the number of mega-reservoirs has risen. Consequently, the impact of earthquakes on the safety of reservoir dams has attracted growing attention. This study employed the Particle Flow Code (PFC) to conduct a dynamic damage and failure analysis of the Koyna concrete gravity dam under strong seismic loading and to investigate the influence of seismic waves and inertial effects on the dam’s failure characteristics. A damage accumulation and failure index based on PFC, accounting for damage paths and the number of cracks, was proposed. When the dam was subjected to horizontal seismic waves lasting 0.82 s and vertical seismic waves lasting 0.018 s, cracks penetrated the dam. Horizontal and vertical seismic waves caused failure resulting from horizontal and vertical displacement differences, respectively. The horizontal displacement difference exhibited two peaks. The dam was more sensitive to horizontal seismic waves. The greater the inertial force, the faster the rate of damage accumulation and failure, and the greater the number of damage cracks. The inertial force of vertical seismic waves negligibly influenced the damage accumulation rate, crack initiation time, and failure mode.