Geotechnical structures often experience a large number of repetitive loading cycles. This research

examines the quasi-static mechanical response of sands subjected to repetitive loads under

zero-lateral-strain boundary conditions. The experimental study uses an automatic repetitive loading

frame operated with pneumatic pistons. Both vertical deformation and shear wave velocity are

continuously monitored during 10 000 repetitive loading cycles. The void ratio evolves towards the

terminal void ratio eT as the number of load cycles increases. The terminal void ratio eT is a function of

the initial void ratio e0 and the stress amplitude ratio Δσ/σ0. The number of cycles N* required to reach

half of the final volume contraction ranges from N*!1 for densely packed sands (e0!emin) to N!103

for loosely packed sands (e0!emax). As the soil approaches terminal density at a large number of cycles,

peak-to-peak strains are dominated by elastic deformations, and the minute plastic strains that remain

in every cycle reflect local and sequential contact events. The shear wave velocity increases during cyclic

loading with data suggesting a gradual increase in the coefficient of earth pressure K0 during repetitive

loading. Changes in shear wave velocity track the evolution of the constrained modulus M; in fact, the

constrained modulus can be estimated from the shear wave velocity to compute soil deformation in a

given cycle. A simple procedure is suggested to estimate the potential settlement a layer may experience

when subjected to repetitive mechanical loads.