Geotechnical Assessment, Excavation Support, and Environmental Impact Analysis of the Diyarbakır–Emek Street Pressure Tunnel

Geological observations, excavation performance records, field monitoring data, and support applications obtained during construction were examined in relation to excavation-induced structural behavior. Monitoring systems, including tiltmeters, extensometers, and distomat measurements, were used to evaluate deformation behavior in buildings located near the tunnel alignment. This study additionally discusses the differences between the preliminary FEM-based deformation predictions reported during the design stage and the structural behavior observed during excavation. The results indicate that groundwater-sensitive claystone sections generated significant excavation and stability problems despite controlled excavation and support measures. High groundwater inflow (30–35 L/s) caused base instability, unfavorable excavation conditions, and increased deformation risks. Field observations indicated substantially greater deformation behavior than the preliminary FEM-based predictions reported during the design stage. The findings demonstrate that shallow urban tunneling in weak and groundwater-sensitive formations may generate more complex ground–structure interactions than those represented in preliminary numerical assessments. This study highlights the importance of continuous field monitoring, adaptive support strategies, groundwater control measures, and observational excavation management practices for improving tunnel safety and reducing risks to nearby urban structures.