A tunnel is a subterranean passage excavated through natural geological formations or engineered through artificial means to connect two points. The engineering of tunnels requires detailed analysis of the subsurface materials, including rock mechanics and geotechnical assessment, to determine the optimal construction method. Construction techniques vary widely depending on the surrounding material, ranging from conventional excavation and support systems to advanced methods such as Tunnel Boring Machines (TBMs) which use mechanical cutting and immediate ground stabilization. The structural integrity of a completed tunnel must account for geological stresses, hydrostatic pressure, and long-term ground movement to ensure safety and durability.