Construed geotechnical characteristics of foundation beds by seismic measurements

Othman, Adel

doi:10.1088/1742-2132/2/2/007

Cited by 48 publications

(24 citation statements)

References 30 publications

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“…), or assess earthquake site response (Jongmans ; Lai and Rix ; Raptakis et al . ; Othman ). More recently, this approach has also been proposed for hydrological applications to characterize shallow aquifers (Grelle and Guadagno ; Mota and Monteiro Santos ; Konstantaki et al .…”

Section: Introductionmentioning

confidence: 99%

2D characterization of near‐surface : surface‐wave dispersion inversion versus refraction tomography

Pasquet

Bodet

Longuevergne

et al. 2015

Near Surface Geophysics

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International audienceThe joint study of pressure (P-) and shear (S-) wave velocities (Vp and Vs ), as well as their ratio (Vp /Vs), has been used for many years at large scales but remains marginal in near-surface applications. For these applications, and are generally retrieved with seismic refraction tomography combining P and SH (shear-horizontal) waves, thus requiring two separate acquisitions. Surface-wave prospecting methods are proposed here as an alternative to SH-wave tomography in order to retrieve pseudo-2D Vs sections from typical P-wave shot gathers and assess the applicability of combined P-wave refraction tomography and surface-wave dispersion analysis to estimate Vp/Vs ratio. We carried out a simultaneous P- and surface-wave survey on a well-characterized granite-micaschists contact at Ploemeur hydrological observatory (France), supplemented with an SH-wave acquisition along the same line in order to compare Vs results obtained from SH-wave refraction tomography and surface-wave profiling. Travel-time tomography was performed with P- and SH- wave first arrivals observed along the line to retrieve Vtomo p and Vtomo s models. Windowing and stacking techniques were then used to extract evenly spaced dispersion data from P-wave shot gathers along the line. Successive 1D Monte Carlo inversions of these dispersion data were performed using fixed Vp values extracted from Vtomo p the model and no lateral constraints between two adjacent 1D inversions. The resulting 1D Vsw s models were then assembled to create a pseudo-2D Vsw s section, which appears to be correctly matching the general features observed on the section. If the pseudo-section is characterized by strong velocity incertainties in the deepest layers, it provides a more detailed description of the lateral variations in the shallow layers. Theoretical dispersion curves were also computed along the line with both and models. While the dispersion curves computed from models provide results consistent with the coherent maxima observed on dispersion images, dispersion curves computed from models are generally not fitting the observed propagation modes at low frequency. Surface-wave analysis could therefore improve models both in terms of reliability and ability to describe lateral variations. Finally, we were able to compute / sections from both and models. The two sections present similar features, but the section obtained from shows a higher lateral resolution and is consistent with the features observed on electrical resistivity tomography, thus validating our approach for retrieving Vp/Vs ratio from combined P-wave tomography and surface-wave profiling

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Section: Introductionmentioning

confidence: 99%

2D characterization of near‐surface : surface‐wave dispersion inversion versus refraction tomography

Pasquet

Bodet

Longuevergne

et al. 2015

Near Surface Geophysics

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“…Hence, we use published data on soft sediments including that obtained on the late Pleistocene lacustrine Samra Formation (Chetrit 2004), which sedimentologically is similar to the Lisan Formation. Soft sediments possess higher Poisson's ratios than hard rocks (Othman 2005). Therefore, we used 0.4 for the Poisson's ratio, which is also in agreement with the suggested 0.3–0.5 values of clay‐rich sediments (e.g.…”

Section: Rock and Fluid Propertiesmentioning

confidence: 99%

Velocities and driving pressures of clay-rich sediments injected into clastic dykes during earthquakes

Levi¹,

Weinberger²,

Eyal³

et al. 2008

Geophysical Journal International

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S U M M A R YWe studied the velocities and driving pressures associated with clastic-dyke formation in the Ami'az plain, where hundreds of clastic dykes cross-cut the soft rock of the late Pleistocene lacustrine Lisan Formation, within the seismically active Dead Sea basin. Flow of clastic material into fractures and opening of the fractures are two mechanisms that occur during earthquake-induced clastic dyke emplacement. Two analytic models were established, based on field observations and experimental viscosity tests, to estimate the velocities and driving pressures that were associated with dyke emplacement: (a) a channel flow for upward injection of a clay-water mixture and (b) a profile of fracture dilation based on the elastic theory analysis. The two models predict that pressures between 1 and 10 MPa are generated in the source layer and dykes in the last stage of the injection process. In addition, the channel flow model predicts that the injection velocity reaches metres to tens of metres per second and the emplacement time of the clastic dykes is on a scale of seconds. It is suggested that the high pressure values represent the static stress drop during earthquake events or represent dynamic stresses resulting from the seismic waves which passed through the soft lacustrine rocks. In both cases, the predicted high pressure values indicate that the clastic dyke was emplaced in close proximity of an active segment of the Dead Sea Fault during the late Pleistocene-Holocene.

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“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17]). Usually their aim is a comparison between results obtained from different methods, soil and site characterization, and recently the use of V s averaged over a defined depth (e.g.…”

Section: Introductionmentioning

confidence: 99%

Pre-loading effect on site response: Site amplification and soil properties mismatch

Raptakis

2013

Soil Dynamics and Earthquake Engineering

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Construed geotechnical characteristics of foundation beds by seismic measurements

Cited by 48 publications

References 30 publications

2D characterization of near‐surface : surface‐wave dispersion inversion versus refraction tomography

2D characterization of near‐surface : surface‐wave dispersion inversion versus refraction tomography

Velocities and driving pressures of clay-rich sediments injected into clastic dykes during earthquakes

Pre-loading effect on site response: Site amplification and soil properties mismatch

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