Ground surface vibration generated from construction activities – Rayleigh waves

Moving sources and loads on ground surface can generate Rayleigh waves, such as overground trains, heavy construction vehicles and activities (e.g. pile driving, vibratory compaction), including other heavy vehicles such as moving trucks. Rayleigh waves are surface waves, which quickly diminish in amplitude with depth but can propagate more efficiently along the surface. An interesting fact, the vertical displacement component of Rayleigh waves actually increases just below ground, meaning that, there is in theory a slightly increased level of vertical vibration just below the surface.

Exact plane-strain solution: a stress-free surface, P and S potentials decaying with depth, and the phase speed fixed by the Rayleigh equation. Exact plane-strain solution: a stress-free surface, P and S potentials decaying with depth, and the phase speed fixed by the Rayleigh equation.

Displacements are exaggerated for visibility (linear theory). Dashed ellipses trace one column of particles: retrograde at the surface, prograde below the depth where u_x changes sign. Time is normalised to the wave period.