Selection of representative shear modulus reduction and damping curves for rock, gravel and sand sites from the KiK-Net downhole array

2017 ◽  
Vol 88 (3) ◽  
pp. 1741-1768 ◽  
Author(s):  
P. Anbazhagan ◽  
Athul Prabhakaran ◽  
H. Madhura ◽  
Sayed S. R. Moustafa ◽  
Nassir S. N. Al-Arifi
Keyword(s):  
Shear Modulus ◽  
Downhole Array ◽  
Modulus Reduction ◽  
Selection Of

Shear modulus reduction and damping ratio curves for earth core materials of dams

2019 ◽  
Vol 56 (1) ◽  
pp. 14-22 ◽  
Author(s):  
DongSoon Park ◽  
Tadahiro Kishida
Keyword(s):  
Shear Modulus ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Empirical Relationship ◽  
Embankment Dams ◽  
In Situ Data ◽  
Earth Core ◽  
Dynamic Analyses ◽  
Modulus Reduction ◽  
Core Materials

It is essential to obtain shear modulus reduction and damping ratio curves to perform dynamic analyses of earth-cored embankment dams. Many studies have been performed for dynamic properties of clayey soils, but they have been limited for earth core materials of dams. This study conducted resonant column tests to obtain shear modulus reduction (G/Gmax) and damping ratio (D) curves for 31 specimens (17 undisturbed and 14 remolded specimens) from 13 earth-cored embankment dams. Empirical G/Gmax and D curves are proposed for dynamic properties of clayey earth core materials. Fitting curves are provided by using the functional forms of the Ramberg–Osgood and Darendeli models. The observation shows that the undisturbed earth cores yield relatively higher G/Gmax and lower D curves than the remolded cores. G/Gmax curves of compacted earth cores are relatively higher than those of Vucetic and Dobry curves for a similar level of plasticity index. Uncertainty and bias are calculated by performing residual analysis, which shows that there is no clear bias in predicting G/Gmax and the uncertainties between undisturbed earth core materials and natural deposits are at a similar level. A proposed empirical relationship of G/Gmax and D curves for earth core materials can be utilized for dynamic analyses of embankment dams for cases where there is insufficient in situ data.

A Comparative Study of Direct and Iterative Inversion Approaches to Determine the Spatial Shear Modulus Distribution of Elastic Solids

2019 ◽  
Vol 11 (10) ◽  
pp. 1950097 ◽  
Author(s):  
Zhi Liu ◽  
Yanli Sun ◽  
Jianwei Deng ◽  
Dongmei Zhao ◽  
Yue Mei ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Comparative Study ◽  
Inversion Method ◽  
Noise Levels ◽  
Elastic Solids ◽  
Direct Inversion ◽  
Advantages And Disadvantages ◽  
Iterative Inversion ◽  
Very High ◽  
Selection Of

This paper presents a comparative study of two typical inverse algorithms, i.e., direct and iterative inversion methods, to reconstruct the shear modulus distribution of linearly elastic solids. Both approaches are based on the finite element framework and compared utilizing both the simulated and experimental data. The reconstruction results demonstrate that both approaches are capable of identifying the nonhomogeneous shear modulus distribution of solids well. It can also be found that the direct inversion method is much faster than the iterative inversion method, whereas the iterative inversion method is capable of yielding better shear modulus ratio between the stiff inclusion and the soft background even with very high noise levels. Afterwards, a thorough comparison on the advantages and disadvantages of these two approaches has been performed. This comparative study provides useful information on the selection of the proper inverse scheme in estimating nonhomogeneous elastic property distribution of soft solids nondestructively.

scholarly journals Towards more realistic values of elastic moduli for volcano modelling

2020 ◽  
Author(s):  
Michael Heap ◽  
Marlène Villeneuve ◽  
Fabien Albino ◽  
Jamie Farquharson ◽  
Elodie Brothelande ◽  
...  
Keyword(s):  
Rock Mass ◽  
Shear Modulus ◽  
Bulk Modulus ◽  
Volcanic Rock ◽  
Elastic Moduli ◽  
Numerical Models ◽  
Laboratory Data ◽  
Volcanic Rocks ◽  
Published Data ◽  
Selection Of

<p>The accuracy of elastic analytical solutions and numerical models, widely used in volcanology to interpret surface ground deformation, depends heavily on the Young’s modulus chosen to represent the medium. The paucity of laboratory studies that provide Young’s moduli for volcanic rocks, and studies that tackle the topic of upscaling these values to the relevant lengthscale, has left volcano modellers ill-equipped to select appropriate Young’s moduli for their models. Here we present a wealth of laboratory data and suggest tools, widely used in geotechnics but adapted here to better suit volcanic rocks, to upscale these values to the scale of a volcanic rock mass. We provide the means to estimate upscaled values of Young’s modulus, Poisson’s ratio, shear modulus, and bulk modulus for a volcanic rock mass that can be improved with laboratory measurements and/or structural assessments of the studied area, but do not rely on them. In the absence of information, we estimate upscaled values of Young’s modulus, Poisson’s ratio, shear modulus, and bulk modulus for volcanic rock with an average porosity and an average fracture density/quality to be 5.4 GPa, 0.3, 2.1 GPa, and 4.5 GPa, respectively. The proposed Young’s modulus for a typical volcanic rock mass of 5.4 GPa is much lower than the values typically used in volcano modelling. We also offer two methods to estimate depth-dependent rock mass Young’s moduli, and provide two examples, using published data from boreholes within Kīlauea volcano (USA) and Mt. Unzen (Japan), to demonstrate how to apply our approach to real datasets. It is our hope that our data and analysis will assist in the selection of elastic moduli for volcano modelling. To this end, our new publication (Heap et al., 2019), which outlines our approach in detail, also provides a Microsoft Excel© spreadsheet containing the data and necessary equations to calculate rock mass elastic moduli that can be updated when new data become available. The selection of the most appropriate elastic moduli will provide the most accurate model predictions and therefore the most reliable information regarding the unrest of a particular volcano or volcanic terrain.</p><p>Heap, M.J., Villeneuve, M., Albino, F., Farquharson, J.I., Brothelande, E., Amelung, F., Got, J.L. and Baud, P., 2019. Towards more realistic values of elastic moduli for volcano modelling. Journal of Volcanology and Geothermal Research, https://doi.org/10.1016/j.jvolgeores.2019.106684.</p>

Predicting Vp and constrained modulus reduction curve based on Vs and shear modulus reduction curve in accordance with poroelastic theory

Géotechnique ◽  
2021 ◽  
pp. 1-39
Author(s):  
Chi-Chin Tsai ◽  
Hsing-Wen Liu ◽  
Domniki Asimaki
Keyword(s):  
Shear Modulus ◽  
Wave Velocity ◽  
Poisson’S Ratio ◽  
Site Response ◽  
Vertical Motion ◽  
Poisson's Ratio ◽  
Reduction Curve ◽  
Constrained Modulus ◽  
Poroelastic Theory ◽  
Modulus Reduction

The compression wave velocity (Vp) of sediments plays a key role in seismic wave amplification of vertical motion and is required in site response analysis. However, such information is usually lacking during field exploration (e.g., surface wave method) because only shear wave velocity (Vs) is obtained. This study aims to predict Vp based on Vs empirically and theoretically, especially focusing on saturated conditions. The empirical approach is to establish the Vp correlation dependency on Poisson's ratio and Vs, and the theoretical approach is based on poroelastic theory that accounts for the interaction between fluid and soil skeleton. The Engineering Geological Database for the Taiwan Strong Motion Instrumentation Program and the Kiban Kyoshin Network database in Japan are adopted to establish an empirical model and validate poroelastic theory. The validated poroelastic approach is used to develop a constrained modulus reduction curve dependency on the porosity, Vs, Poisson's ratio, and degree of saturation with a shear modulus reduction curve. The proposed approach can be used to develop generic Vp profiles and constrained modulus reduction curves for the site response to vertical motion given a site specific Vs profile.

Spreading plastic failure as a mechanism for the shear modulus reduction in amorphous solids

2015 ◽  
Vol 110 (4) ◽  
pp. 48001 ◽  
Author(s):  
Vijayakumar Chikkadi ◽  
Oleg Gendelman ◽  
Valery Ilyin ◽  
J. Ashwin ◽  
Itamar Procaccia ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Amorphous Solids ◽  
Plastic Failure ◽  
Modulus Reduction

Extended model of shear modulus reduction for cohesive soils

2021 ◽  
Author(s):  
John Kok Hee Wong ◽  
Soon Yee Wong ◽  
Kim Yuen Wong
Keyword(s):  
Shear Modulus ◽  
Cohesive Soils ◽  
Extended Model ◽  
Modulus Reduction

Effects of current suction ratio and recent suction history on small-strain behaviour of an unsaturated soil

2012 ◽  
Vol 49 (2) ◽  
pp. 226-243 ◽  
Author(s):  
C.W.W. Ng ◽  
J. Xu
Keyword(s):  
Shear Modulus ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Small Strain ◽  
Triaxial Tests ◽  
Stress History ◽  
Reduction Curve ◽  
Small Strain Shear Modulus ◽  
Suction History ◽  
Modulus Reduction

Although the small-strain shear modulus of saturated soils is known to be significantly affected by stress history, consisting of the overconsolidation ratio (OCR) and recent stress history, the effects of suction history on the small-strain shear modulus of unsaturated soils have rarely been reported. In this study, the effects of suction history, which refers to current suction ratio (CSR) and recent suction history, on both the very-small-strain shear modulus (G0) and shear modulus reduction curve of an unsaturated soil, are investigated by carrying out constant net mean stress compression triaxial tests with bender elements and local strain measurements. In addition, the effect of suction magnitude on G0 and the shear modulus reduction curve is also investigated. At a given suction, G0, elastic threshold strain (εe), and the rate of shear modulus reduction all increase with CSR. On the other hand, the effect of recent suction history on G0 is not significant. The effect of direction of recent suction path (θ) on the shear modulus reduction curve is not distinct. However, the magnitude of recent suction path (l) affects the shear modulus reduction curve significantly when θ = –90°.

MODULUS REDUCTION AND DAMPING CURVES FOR SAND OF SOUTH-EAST COAST OF INDIA

2012 ◽  
Vol 06 (04) ◽  
pp. 1250016
Author(s):  
V. JAYA ◽  
G. R. DODAGOUDAR ◽  
A. BOOMINATHAN
Keyword(s):  
Shear Modulus ◽  
Triaxial Test ◽  
Damping Ratio ◽  
Triaxial Tests ◽  
Hyperbolic Model ◽  
Cyclic Triaxial Test ◽  
Cyclic Triaxial ◽  
Wide Range ◽  
Predictive Relationships ◽  
Modulus Reduction

Adequate information on dynamic soil properties, especially strain dependent shear modulus (G) and damping ratio (ξ) for each soil layer are the essential input data for seismic ground response analysis and soil-structure interaction studies. In the present study, the shear modulus and damping ratio of sand are estimated for a wide range of strains based on undrained strain-controlled cyclic triaxial tests. The bender elements are also utilized in the cyclic triaxial test to estimate the low strain shear modulus. For this purpose, the soil samples are taken from a nuclear power plant site located at the south-east coastal region of India. Based on the experimental results, an empirical expression is developed to calculate the maximum shear modulus, G max as function of void ratio and effective confining stress. Predictive relationships are also developed for estimating normalized shear modulus and damping ratio curves for the sand. The predictive relationships are based on the hyperbolic model and cyclic triaxial test results. The developed modulus reduction and damping ratio curves from the predictive relationships are compared with the previously available curves in the literature.

Sign in / Sign up

Export Citation Format

Share Document