ACOUSTICS2008/151 Accelerometer measurements of acoustic-to-seismic coupling above buried objects (original) (raw)

Acoustic-to-seismic ground coupling: coupling efficiency and inferring near-surface properties

Geophysical Journal International

Summary A fraction of the acoustic wave energy (from the atmosphere) may couple into the ground, and it can thus be recorded as ground motion using seismometers. We have investigated this coupling, with two questions in mind, a) how strong it is for small explosive sources and offsets up to a few tens of meters, and b) what we can learn about the shallow subsurface from this coupling. 25 firecracker explosions and 5 rocket explosions were analyzed using co-located seismic and infrasound sensors; we find that around 2% of the acoustic energy is admitted into the ground (converted to seismic energy). Transfer coefficients are in the range of 2.85–4.06 nm/Pa for displacement, 1.99–2.74 μm/s/Pa for velocity, and 2.2–2.86 mm/s−2/Pa for acceleration. Recording dynamic air pressure together with ground motion at the same site allows identification of different waves propagating in the shallow underground, notably the seismic expression of the direct airwave, and the later air-coupled Rayle...

Effects of underground structures on amplification of seismic motion for sand with varying density

2011

Kinematic interaction of underground structures can alter the ground input motion parameters. In this paper, the effect of box culverts on ground input motion is investigated with scaled physical modelling in a centrifuge. The centrifuge experimental program was executed to evaluate the ground input motion with different surface cases in dry Nevada Sand at different relative densities at 60g. Three earthquakes with different amplitudes and frequencies were applied. The results show that the presence of structures can cause up to 50% reduction in the free field Peak Ground Acceleration when compared to the structure field. This observation can be helpful when assessing the seismic hazard or evaluating the input ground motion for buildings overlying significant underground structures (e.g. culverts or tunnels). RÉSUMÉ L'interaction de cinématique de structures souterraines peut changer les données de sol font signe des paramètres. Dans ce papier, l'effet de buses de boîte sur ...

Dynamic Response of Underground Structures in Sand: Experimental Data

Earthquake Spectra, 2017

A densely instrumented system of large-scale underground structures consisting of two vertical shafts connected through a cut-and-cover tunnel and two independent shield tunnels was installed in an 8 m-diameter laminar soil box at the E-Defense shake table in Miki, Japan. The system was subjected to step-sine sweeps and scaled ground motion records of the Kobe (1995) earthquake. The underground structures were embedded in Albany Silica Sand with an average relative density of 54%. System instrumentation consisted of over 800 sensors, including strain gauges, accelerometers, displacement transducers, bender elements and pressure sensors. A U.S.-Japanese research collaboration was established to instrument the vertical shaft elements and record seismic soil pressures. Data records are archived at the NHERI DesignSafe Data Depot_and can be used to analyze the structural response, soil-structure interaction and other response parameters of individual subsurface components as well as the...