This study investigates the Gushan Village Tunnel as a case study to systematically analyze the characteristics of karst development and its implications for tunnel construction and operational safety. By integrating ground-penetrating radar (GPR) and borehole drilling techniques, fifteen karst anomaly zones were identified. These zones were further examined through detailed drilling investigations to assess the scale, filling conditions, and spatial distribution of cavities and fissures. The findings reveal that karst predominantly develops around fault zones and fractured rock masses, posing significant threats to tunnel stability, including instability of surrounding rock masses, tunnel floor subsidence, and elevated risks of water inrush. To mitigate these challenges, a series of comprehensive control measures were proposed, including grouting reinforcement, cavity filling, and drainage management. The study highlights the high efficiency and reliability of combining GPR and drilling technologies for karst detection, offering robust theoretical support and practical insights for tunnel construction in similar geological settings.