Effect of soil structure interaction on seismograms

Bycroft, G. N.; Mork, P.N.

doi:10.3133/ofr83328

Cited by 2 publications

(2 citation statements)

References 8 publications

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“…Vol. 166, 2009 Effect of Velocity Inversions on H/V 579 The interaction between soil and structure (i.e., the place where the seismic instrument is set, which partly resembles the effect of taking a recording on a stiff artificial layer) was studied by CROUSE et al (1984), CROUSE and HUSMAND (1989) and BYCROFT (1978). Soil-structure coupling acts in two opposite ways: 1) Tall pedestals have the effect of amplifying the horizontal components of motion while 2) short and large (with respect to horizontal wave length) foundations, as those studied in this work, decrease the horizontal components.…”

Section: Theoretical Modellingmentioning

confidence: 99%

The Effect of Velocity Inversions on H/V

Castellaro

Mulargia

2009

Pure appl. geophys.

126

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We analyzed the phenomenology of microtremor H/V curves under inversions in the shear-wave velocity (V s ) profile in the subsoil. Under no V s inversion the spectral signature of the H/V peaks is found to be 'eye-shaped' with the horizontal components higher than the vertical. Conversely, under negative velocity gradients, numerous of differences emerge. I) A H/V ratio below 1 is observed for a wide range of frequencies, due to the decrease of the horizontal components below the vertical one. II) In the presence of persistent H/V < 1, small bumps in the H/V ratio given by local minima in the vertical spectral component may represent the relics of the peaks indicating resonances and stratigraphic discontinuities. As a consequence, in the presence of velocity inversions the H/V > 2 SESAME (2004) criterion fails but a stratigraphic interpretation may still be possible. III) The H/V curves should always be interpreted together with the single component spectra. IV) Microtremor H/V measurements for stratigraphic/microzonation purposes on stiff artificial soils, (asphalt, concrete, cement, pavements) should always be avoided since the latter often produce velocity inversions. This may have consequences in the intermediate to high frequency domain (> 1 Hz) also in the application of reference site methods, like H site /H bedrock , to microtremor. Theoretical modeling confirms these experimental findings.

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Section: Theoretical Modellingmentioning

confidence: 99%

The Effect of Velocity Inversions on H/V

Castellaro

Mulargia

2009

Pure appl. geophys.

126

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“…In 1941 Washburn found that the geophone-ground coupling system seriously interfered the amplitude and phase of the seismic records. Later many scholars such as Miller and Pursey (1954), Bycroft (1957Bycroft ( , 1978, Lamar (1970), Hoover and O'Brien (1980) have studied the influence of the coupling system when the geophone was well-coupled with the surface soil based on the wave theory. But their theoretical models neglected the impact of the geophone spike [6∼11] .…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Study on the 3‐Degree Freedom Geophone Coupling System for Areas with Limestone Outcrops

Shi¹,

Tian²,

Shen³

et al. 2010

Chinese J of Geophysics

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There is a great potential of extremely abundant oil and gas resources in sedimentary basins of marine carbonate in vast areas of South China. However, it is very difficult to make a good geophone coupling in the field work because of large‐area outcrops of hard limestone, which lead to decline of quality of seismic data and serious limit on hydrocarbon exploration there. Now, geophone coupling test is largely blind due to lack of appropriate theoretical guidance. In this paper, in order to understand the transmission mechanism of the geophone‐limestone coupling system, considering that the coupling media such as gesso, clay and so on involved in field seismic data acquisition, we propose a theory of geophone‐limestone 3‐DOF (degrees of freedom) coupling system based on the vibration dynamic concept. The geophone‐limestone coupling system responses are computed with varying parameters of coupling media, geophone spikes and damping. We find that the geophone‐limestone coupling system is a resonance system which has three resonance frequencies. The results show that the resonance frequency can be increased through increasing the elastic modulus of the coupling medium, reducing the area of the underside and the height of the coupling medium, using spikes with lower material density, reducing the height of the spike and increasing the area of the spike's underside. The results also show that the impact of the narrow frequency bands “band pass filtering” can be decreased by increasing the damping of the coupling system properly. Finally, we preliminarily validate the theoretical model of the geophone‐limestone 3‐DOF coupling system through experiments on a shake table.

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Effect of soil structure interaction on seismograms

Cited by 2 publications

References 8 publications

The Effect of Velocity Inversions on H/V

The Effect of Velocity Inversions on H/V

A Theoretical Study on the 3‐Degree Freedom Geophone Coupling System for Areas with Limestone Outcrops

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