Seismic inversion of soil damping and stiffness using multichannel analysis of surface wave measurements in the marine environment

2020 ◽  
Vol 221 (2) ◽  
pp. 1439-1449
Author(s):  
M A Armstrong ◽  
M Ravasio ◽  
W G Versteijlen ◽  
D J Verschuur ◽  
A V Metrikine ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Frequency Dependence ◽  
Measurement Errors ◽  
Damping Ratio ◽  
Seismic Inversion ◽  
Material Damping ◽  
Near Surface ◽  
Soil Material ◽  
Wave Measurements ◽  
Degree Of Certainty

SUMMARY Determination of soil material damping is known to be difficult and uncertain, especially in the offshore environment. Using an advanced inversion methodology based on multichannel spectral analysis, Scholte and Love wave measurements are used to characterize subsea soil from a North Sea site. After normalization, a determinant-based objective function is used in a genetic algorithm optimization to estimate the soil shear modulus. The inverted shear-modulus profile is comparable to previously published results for the same data, although a higher degree of certainty is achieved in the near-surface layers. The half-power bandwidth method is used for extracting the attenuation curve from the measurements and efficient reference data points are chosen based on wavelet compression. The material-damping ratio inversion is performed using a modified stochastic optimization algorithm. Accounting for measurement errors, the material-damping ratio profile is retrieved from the fundamental-mode Scholte wave with a high degree of certainty. Furthermore, a method is proposed for identifying the frequency dependence of the material-damping ratio from in situ measurements. No evidence for frequency dependence is found and the small-strain soil material-damping ratio at this site can be said to be frequency independent for the measured conditions.

Tube-wave monitoring as a method to detect shear modulus changes around boreholes: A case study

Geophysics ◽  
2021 ◽  
pp. 1-69
Author(s):  
Daniel Wehner ◽  
Filipe Borges ◽  
Martin Landrø
Keyword(s):  
Shear Modulus ◽  
Body Waves ◽  
Rock Properties ◽  
Step Method ◽  
Monitoring Method ◽  
Near Surface ◽  
Wave Measurements ◽  
Geological Formation ◽  
Tube Wave ◽  
Borehole Seismic

Monitoring the shear modulus of formations around boreholes is of interest for various applications, ranging from near-surface investigation to reservoir monitoring. Downhole logging tools and borehole seismic are common techniques applied to measure and characterize formation properties. These methods rely on transmitted and reflected waves to retrieve the rock properties. Wave modes travelling along the interface between the well and the formation, such as tube waves, are often considered as noise. However, tube waves are less attenuated than body waves, and contain information about the shear modulus of the formation surrounding the well. Hence, a potential use of this interface wave is of interest. As tube-wave properties depend on several parameters, e.g. well geometry, highly accurate measurements should be performed for use in inferring rock properties. We study the feasibility of tube-wave measurements as a monitoring method. Different experiments are conducted using a hydrophone array in two boreholes, with depths of 30 m and 95 m. The experiments are used to investigate how accurate the tube-wave velocity can be measured, and which parameters have most impact on the measurements. Our results suggest that it is hard to estimate the absolute shear modulus of the geological formation using tube-wave velocities only. However, it seems feasible to use them to monitor changes of the shear modulus, depending on the borehole set up and geological formation. The tube-wave monitoring can be used as a first step method to determine the depth along the well where changes occur before more accurate measurements are performed in a second step.

Normalized Shear Modulus and Material Damping Ratio Relationships

2005 ◽  
Vol 131 (4) ◽  
pp. 453-464 ◽  
Author(s):  
Jianfeng Zhang ◽  
Ronald D. Andrus ◽  
C. Hsein Juang
Keyword(s):  
Shear Modulus ◽  
Damping Ratio ◽  
Material Damping

Laboratory Measurements of the Dynamic Properties of Intact and Remolded Offshore Clays From Campeche Bay

2003 ◽  
Author(s):  
Celestino Valle ◽  
Kenneth H. Stokoe
Keyword(s):  
Shear Modulus ◽  
Soil Properties ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Large Strains ◽  
Material Damping ◽  
University Of Texas ◽  
Dynamic Soil Properties ◽  
Intact Condition ◽  
The University

Comparisons of the dynamic properties of intact and remolded offshore clay specimens has been carried out. The clay specimens were obtained from Campeche Bay, offshore Mexico. Combined resonant column and torsional shear (RCTS) equipment at the University of Texas at Austin was used to determine the dynamic soil properties. Each soil specimen was tested twice, first in the intact condition and second as remolded material. Remolding was done by kneading the intact material and then reforming the specimen by compacting in a mold. The effects on the dynamic properties, expressed by shear modulus and material damping ratio, between intact and remolded conditions are discussed. As expected, shear modulus and material damping at small and large strains are affected by remolding. Interestingly, the normalized modulus degradation curves were changed very little by remolding up to strains between 0.06 and 0.1%. The results offer insight into the effects of sampling disturbance on linear and nonlinear dynamic soil properties.

scholarly journals Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2743
Author(s):  
Seongnoh Ahn ◽  
Jae-Eun Ryou ◽  
Kwangkuk Ahn ◽  
Changho Lee ◽  
Jun-Dae Lee ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Sodium Alginate ◽  
Shear Failure ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Reinforced Soil ◽  
Resonant Column ◽  
Column Test ◽  
Alginate Solution ◽  
Resonant Column Test

Ground reinforcement is a method used to reduce the damage caused by earthquakes. Usually, cement-based reinforcement methods are used because they are inexpensive and show excellent performance. Recently, however, reinforcement methods using eco-friendly materials have been proposed due to environmental issues. In this study, the cement reinforcement method and the biopolymer reinforcement method using sodium alginate were compared. The dynamic properties of the reinforced ground, including shear modulus and damping ratio, were measured through a resonant-column test. Also, the viscosity of sodium alginate solution, which is a non-Newtonian fluid, was also explored and found to increase with concentration. The maximum shear modulus and minimum damping ratio increased, and the linear range of the shear modulus curve decreased, when cement and sodium alginate solution were mixed. Addition of biopolymer showed similar reinforcing effect in a lesser amount of additive compared to the cement-reinforced ground, but the effect decreased above a certain viscosity because the biopolymer solution was not homogeneously distributed. This was examined through a shear-failure-mode test.

Shear Modulus and Damping Ratio of Gravel Material

2011 ◽  
Vol 105-107 ◽  
pp. 1426-1432 ◽  
Author(s):  
De Gao Zou ◽  
Tao Gong ◽  
Jing Mao Liu ◽  
Xian Jing Kong
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Strain Amplitude ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Dynamic Shear ◽  
Data Points ◽  
Shear Strain Amplitude

Two of the most important parameters in dynamic analysis involving soils are the dynamic shear modulus and the damping ratio. In this study, a series of tests were performed on gravels. For comparison, some other tests carried out by other researchers were also collected. The test results show that normalized shear modulus and damping ratio vary with the shear strain amplitude, (1) normalized shear modulus decreases with the increase of dynamic shear strain amplitude, and as the confining pressure increases, the test data points move from the low end toward the high end; (2) damping ratio increases with the increase of shear strain amplitude, damping ratio is dependent on confining pressure where an increase in confining pressure decreased damping ratio. According to the test results, a reference formula is proposed to evaluate the maximum dynamic shear modulus, the best-fit curve and standard deviation bounds for the range of data points are also proposed.

scholarly journals Near-surface frequency-dependent nonlinear damping ratio observation of ground motions using SMART1

2021 ◽  
Vol 147 ◽  
pp. 106798
Author(s):  
Chun-Hsiang Kuo ◽  
Jyun-Yan Huang ◽  
Che-Min Lin ◽  
Chun-Te Chen ◽  
Kuo-Liang Wen
Keyword(s):  
Ground Motions ◽  
Damping Ratio ◽  
Nonlinear Damping ◽  
Frequency Dependent ◽  
Near Surface

Experimental Study on Dynamic Characteristics of Ionic Soil Stabilizer Reinforcing Red Clay

2011 ◽  
Vol 374-377 ◽  
pp. 1391-1395
Author(s):  
Xue Song Lu ◽  
Wei Xiang
Keyword(s):  
Shear Modulus ◽  
Shear Strain ◽  
Dynamic Condition ◽  
Damping Ratio ◽  
Confining Pressure ◽  
Natural Soil ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Red Clay ◽  
Soil Stabilizer

Based on the red clay of Wuhan reinforced by Ionic Soil Stabilizer, the red clay soil is treated by different matches of ISS at first, then is tested in the Atterberg limits test and dynamic triaxia test. The results show that the plastic index decreases, and the red clay were greatly improved under the dynamic condition, the maximum dynamic shear modulus ratio acquired an incensement of 27.72% on average after mixing the ISS into the red clay. In addition, It was concluded that the confining pressure influenced the dynamic shear modulus and damping ratio to a certain extent. Given the same strain conditions, with the incensement of confining pressure increases, the dynamic shear modulus increased and the damping ratio decreased. Moreover, when plotting the dynamic shear modulus versus the dynamic shear strain, the similar curve can be formed for both the natural soil and the modified one, the dynamic shear modulus monotonously decreased with the incensement of the dynamic shear strain. However, the value of dynamic shear modulus differed in the same shear strain between the natural soil and the soil modified by ISS.

Shear Modulus and Damping Ratio for Normally Consolidated Peat and Organic Clay in Hokkaido Area

2018 ◽  
Vol 36 (5) ◽  
pp. 3159-3171 ◽  
Author(s):  
Hirochika Hayashi ◽  
Takahiro Yamanashi ◽  
Hijiri Hashimoto ◽  
Masahiko Yamaki
Keyword(s):  
Shear Modulus ◽  
Damping Ratio ◽  
Organic Clay
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