Inference of Dynamic Shear Modulus from Lotung Downhole Data

Chang, Chi‐Ling; Mok, Chin Man; Tang, Hehan

doi:10.1061/(asce)0733-9410(1996)122:8(657)

Cited by 24 publications

(13 citation statements)

References 2 publications

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“…These results are compatible to our common understanding of soil degradation behavior. Also, this result is consistent with the results of Chang et al [7], Elgamal et al [8], Glaser and Baise [32], and Ching and Glaser [33]. All of these researchers adapted linear methods and obtained similar results about the degradation of the soil.…”

Section: Vertical Seismic Array Data Analysissupporting

confidence: 90%

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Tracking rapidly changing dynamical systems using a non‐parametric statistical method based on wavelets

Ching¹,

Glaser²

2003

Earthq Engng Struct Dyn

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SUMMARYA non-parametric statistical method of tracking rapidly changing dynamical systems is introduced. The method implements the non-linear wavelet thresholding estimator to estimate the evolutionary transfer function of the system. The consistency and optimality of the resulting estimate of our method on rapidly changing systems are stated, while no linear estimator can achieve the same optimality. Two examples of real data are studied using this non-parametric method, including two vertical seismic array case studies and a series of seismic slope experiments. The analysis results are consistent with previous research for the vertical seismic array data. Moreover, our estimate is superior to those from previous research in the sense that our estimate is neither over-smoothed nor under-smoothed. The analysis results are also consistent with the experimental observations for the seismic slope experimental data.

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Section: Vertical Seismic Array Data Analysissupporting

confidence: 90%

“…Methods based on wavelets have been also pursued [5; 6]. Also, geotechnical engineers are concerned with the responses of seismically-excited soils [7][8][9][10][11], whose mechanical properties also vary during an earthquake.…”

Section: Introductionmentioning

confidence: 99%

Tracking rapidly changing dynamical systems using a non‐parametric statistical method based on wavelets

Ching¹,

Glaser²

2003

Earthq Engng Struct Dyn

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“…Lu et al [8] studied the Chiba site and reported that the average natural frequency of the site during a strong earthquake shifted downwards, indicating softening behaviour. Chang et al [9] studied the Lotung site and concluded that the degree of non-linearity increases with earthquake intensity but decreases with depth. The shear modulus degradation curves they estimated were consistent with laboratory results.…”

Section: Introductionmentioning

confidence: 99%

Identification of soil degradation during earthquake excitations by Bayesian inference

Ching

Glaser

2003

Earthq Engng Struct Dyn

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SUMMARYA Bayesian inference approach is introduced to identify soil degradation behaviours at four downhole array sites. The approach of inference is based on a parametric time-varying inÿnite impulse response ÿlter model. The approach is shown to be adaptive to the changes of ÿlter parameters and noise amplitudes. Four sites, including the Lotung (Taiwan), Chiba (Japan), Garner Valley (California), and Treasure Island (California) sites with downhole seismic arrays are analysed. Our results show two major types of soil degradation behaviour: the well-known strain-dependent softening, and reduction in sti ness that is not instantaneously recoverable. It is also found that both types of soil degradation are more pronounced in sandy soils than in clayey soils. The mechanism for the second type of soil degradation is not yet clear to the authors and suggested to be further studied.

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“…For instance, transfer functions may be computed for successive or overlapping time windows which have relatively little variations in acceleration amplitude. Chang et al [17] used such a technique to estimate shear wave velocities of the Lotung (Taiwan) site using acceleration time-histories of the Large Scale Seismic Test (LSST) downhole array [93]. For any two-strata system of soil comprised between a surface and two consecutive downhole accelerometers (Fig.…”

Section: Transfer Function and Spectral Analysesmentioning

confidence: 99%

A survey of geotechnical system identification techniques

Oskay

Zeghal

2011

Soil Dynamics and Earthquake Engineering

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Identification and inverse problem techniques play an important role in the characterization and modeling of geotechnical systems. These techniques have been used in estimation of system parameters, model development and calibration, as well as simulation of earthquake ground motions. The recent availability of high quality seismic records of sites equipped with downhole accelerometer arrays led to a burgeoning of identification and inverse problem studies involving geotechnical systems. This paper presents a survey of system identification techniques and analyses of full-and small-scale soil systems, with an emphasis on geotechnical earthquake engineering problems.

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Inference of Dynamic Shear Modulus from Lotung Downhole Data

Cited by 24 publications

References 2 publications

Tracking rapidly changing dynamical systems using a non‐parametric statistical method based on wavelets

Tracking rapidly changing dynamical systems using a non‐parametric statistical method based on wavelets

Identification of soil degradation during earthquake excitations by Bayesian inference

A survey of geotechnical system identification techniques

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