Face Stability

Stability of the excavated face of a tunnel or pipe jack.

Factor of Safety

The ratio of the structural capacity of a system to expected or actual loads on the system.

Fairings

Molding features at the ends at the ends of pipes, usually of varying dimensions to the main pipe, to facilitate easy jointing.

Fatigue

The phenomenon leading to fracture under repeated or fluctuating stresses having a maximum value less than the tensile strength of the material.

Fatigue Strength

The stress to which a material can be subjected for a specified number of fatigue cycles.