Damping ratio evolution of saturated Ningbo clays under cyclic confining pressure

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.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.374-377.1391 ◽

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.

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A Study on Dynamic Properties of Cement-Stabilized Soils

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.2050 ◽

2011 ◽

Vol 243-249 ◽

pp. 2050-2054 ◽

Cited By ~ 2

Author(s):

Pei Hsun Tsai ◽

Sheng Huoo Ni

Keyword(s):

Shear Modulus ◽

Dynamic Properties ◽

Damping Ratio ◽

Confining Pressure ◽

Test Results ◽

Resonant Column Test ◽

Stabilized Soil ◽

Shearing Strain ◽

Relationship Of ◽

The Relationship

In this paper the dynamic property (shear modulus and damping ratio) of cement-stabilized soil is studied with using the resonant column test. The amount of cement admixed, the magnitude of confining pressure, and shearing strain amplitude are the parameters considered. Test results show that the maximum shear modulus of cement-stabilized soil increases with increasing confining pressure, the minimum damping ratio decreases with increasing confining pressure. The shear modulus of cement-stabilized soil decreases with increasing shearing strain while the damping ratio increases with increasing shearing strain. In the paper the relationship of shear modulus versus shearing strain is fitted into the Ramberg-Osgood equations using regression analysis.

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Characterization of the Dynamic Properties of Clay–Gravel Mixtures at Low Strain Level

Sustainability ◽

10.3390/su12041616 ◽

2020 ◽

Vol 12 (4) ◽

pp. 1616 ◽

Cited By ~ 3

Author(s):

Xianwen Huang ◽

Aizhao Zhou ◽

Wei Wang ◽

Pengming Jiang

Keyword(s):

Shear Modulus ◽

Shear Strain ◽

Mechanical Performance ◽

Dynamic Properties ◽

Damping Ratio ◽

Confining Pressure ◽

Strain Level ◽

Dynamic Shear Modulus ◽

Dynamic Shear ◽

Gravel Content

In order to support the dynamic design of subgrade filling engineering, an experiment on the dynamic shear modulus (G) and damping ratio (D) of clay–gravel mixtures (CGMs) was carried out. Forty-two groups of resonant column tests were conducted to explore the effects of gravel content (0%, 10%, 20%, 30%, 40%, 50%, and 60%, which was the mass ratio of gravel to clay), gravel shape (round and angular gravels), and confining pressure (100, 200, and 300 kPa) on the dynamic shear modulus, and damping ratio of CGMs under the same compacting power. The test results showed that, with the increase of gravel content, the maximum dynamic shear modulus of CGMs increases, the referent shear strain increases linearly, and the minimum and maximum damping ratios decrease gradually. In CGMs with round gravels, the maximum dynamic shear modulus and the maximum damping ratio are greater, and the referent shear strain and the minimum damping ratio are smaller, compared to those with angular gravels. With the increase of confining pressure, the maximum dynamic shear modulus and the referent shear strain increase nonlinearly, while the minimum and maximum damping ratios decrease nonlinearly. The predicting equation for the dynamic shear modulus and the damping ratio of CGMs when considering confining pressure, gravel content, and shape was established. The results of this research may put forward a solid foundation for engineering design considering low-strain-level mechanical performance.

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Study on Dynamic Characteristics of Rubber-Red Clay Mixtures

Advances in Materials Science and Engineering ◽

10.1155/2020/2343242 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Kaisheng Chen ◽

Qinqin Wang ◽

Dipu Luo ◽

Bo Zhou ◽

Kun Zhang

Keyword(s):

Particle Size ◽

Shear Modulus ◽

Vibration Frequency ◽

Damping Ratio ◽

Rubber Particle ◽

Confining Pressure ◽

Dynamic Strain ◽

Dynamic Shear Modulus ◽

Dynamic Shear ◽

Red Clay

Rubber powder formed from discarded tire rubber is mixed with red clay to form a rubber-red clay mixture. The dynamic triaxial test was carried out on the mixtures under different conditions. The effects of rubber content, rubber particle size, moisture content of mixed soil, compactness, confining pressure, and vibration frequency on shear strain relation, dynamic shear modulus, and damping ratio of the mixture were investigated. The results show that under the same dynamic strain, the dynamic shear stress-strain curve of rubber mixed soil decreases with the increase in rubber particle content and moisture content and decrease in rubber particle size. On the other hand, it increases with the increase in compactness, confining pressure, and vibration frequency, and as the dynamic strain increases, the τd-γd curve becomes more nonlinear. In addition, with the increase in the rubber particle content, the dynamic shear modulus decreased while the damping ratio increased. When the content was 2%, the change was fastest. After continued addition, it gradually became stable, and when the decrease in rubber particle size also shows the same pattern, 2.00 mm rubber-red clay mixture shows better structure. The water content has great influence on dynamic shear modulus and damping ratio of rubber-red clay mixtures. With the increase in compactness, confining pressure, and vibration frequency, the interaction between mixed soil particles was enhanced, the dynamic shear modulus increased, and the damping ratio decreased.

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DEGRADATION EFFECT OF SEAWATER ON THE LONG-TERM DYNAMIC BEHAVIOR OF ARTIFICIALLY CEMENTED SAND

Journal of Earthquake and Tsunami ◽

10.1142/s1793431113500310 ◽

2013 ◽

Vol 07 (04) ◽

pp. 1350031 ◽

Cited By ~ 1

Author(s):

BO LI ◽

YUANQIANG CAI ◽

XIANGWU ZENG ◽

LINYOU PAN

Keyword(s):

Shear Modulus ◽

Dynamic Behavior ◽

Tap Water ◽

Damping Ratio ◽

Confining Pressure ◽

Triaxial Tests ◽

Resonant Column ◽

Cyclic Triaxial Tests ◽

Cemented Sand

The dynamic behavior of lightly cemented sand under long-term seawater attack was evaluated in this study. Resonant column and cyclic triaxial tests were employed to investigate the evolution of the shear modulus and damping ratio of cemented sand with respect to soaking period (SP), confining pressure, and cement content (CC). The results of this study show that the cementation of the sand is affected by soaking in seawater to a greater extent than by soaking in tap water. The shear modulus of the cemented sand soaked in seawater was smaller than that of the cemented sand soaked in tap water. The damping ratio increased significantly, as the SP increased and was greater for the cemented sand soaked in seawater than for the cemented sand soaked in tap water. The dynamic behavior of nonhomogenous specimens was examined. Crystallization of salts could be clearly observed and probably explains the evolution of the dynamic behavior of the cemented sand. Finally, the shear modulus was fitted using Rollins' Law [Rollins et al., 1998], which demonstrates that the parameters used in the equation can be reasonably fitted linearly over a range of SPs.

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Experimental Investigation of Dynamic Characteristics of Subsea Sand-Silt Mixtures

Advances in Civil Engineering ◽

10.1155/2019/5619039 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Tugen Feng ◽

Yu Tang ◽

Qiyenan Wang ◽

Jian Zhang ◽

Jian Song

Keyword(s):

Cement Content ◽

Damping Ratio ◽

Shear Stiffness ◽

Confining Pressure ◽

Dynamic Responses ◽

Resonant Column ◽

Dynamic Shear ◽

Column Tests ◽

Mixture Ratio ◽

Curing Age

In this paper, extensive resonant column tests were conducted to investigate dynamic responses of subsea sand-silt mixtures. The effects of confining pressure, mixture ratio, curing age, and cement content were evaluated. For the test condition considered in this study, the measured damping ratio is the smallest when the ratio of subsea sand to silt is in a range of 1.5 to 2.0. Moreover, unsolidified subsea sand-silt mixed at a ratio of 1.5 has almost the same maximum shear stiffness as the pure sand. For solidified subsea sand-silt mixture, cement can significantly increase the dynamic shear stiffness when the curing age is less than 14 days. However, the increase of the maximum dynamic shear stiffness is negligible when the curing age is longer than 14 days. When the cement content is 2%, the damping ratio of the solidified mixtures is very close to that of the unsolidified mixture. When the cement content is higher than 4%, the damping ratio of the solidified mixtures reduces significantly. This is mainly due to hydration reactions occurring in the solidified mixtures.

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Test Study on the Dynamic Parameters of Compound Composite Foundation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.1548 ◽

2012 ◽

Vol 450-451 ◽

pp. 1548-1552

Author(s):

Na Wang ◽

Zhen Feng ◽

Yong Da ◽

Wei Lin

Keyword(s):

Regression Analysis ◽

Seismic Design ◽

Dynamic Properties ◽

Damping Ratio ◽

Confining Pressure ◽

Composite Foundation ◽

Dynamic Parameters ◽

Simple Method ◽

Test Study ◽

Wide Range

Influence of factors such as displacement ratio and confining pressure on the dynamic properties of composite specimen with GC pile and CFG pile was studied under a wide range of strains by regression analysis，a simple method for calculating the dynamic elastic modulus and damping ratio is Proposed and an empirical formula considering the mentioned factors above is also presented to provide a elementary reference for anti-seismic design of composite foundations with GC piles and CFG piles.

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Laboratory Characterization of a Compacted–Unsaturated Silty Sand with Special Attention to Dynamic Behavior

Applied Sciences ◽

10.3390/app10072559 ◽

2020 ◽

Vol 10 (7) ◽

pp. 2559

Author(s):

Andrzej Głuchowski ◽

Zdzisław Skutnik ◽

Marcin Biliniak ◽

Wojciech Sas ◽

Diego Lo Presti

Keyword(s):

Shear Modulus ◽

Dynamic Properties ◽

Damping Ratio ◽

Confining Pressure ◽

Silty Sand ◽

Triaxial Tests ◽

Bender Element ◽

State Dependent ◽

Laboratory Characterization ◽

Dynamic Excitations

The dynamic properties of compacted non-cohesive soils are desired not only because of the risk of natural sources of dynamic excitations such as earthquakes, but mostly because of the anthropogenic impact of machines that are working on such soils. These soils are often unsaturated, which positively affects the soil’s mechanical properties. The information about the values of these parameters is highly desirable for engineers. In this article, we performed a series of tests, including oedometric tests, resonant column tests, bender element tests, and unsaturated triaxial tests, to evaluate those characteristic parameters. The results showed that sandy silt soil has a typical reaction to dynamic loading in terms of shear modulus degradation and the damping ratio curves’ characteristics, which can be modeled by using empirical equations. We found that the compaction procedure caused an over-consolidation state dependent on the moisture content during compaction effort. The article analyzed the soil properties that impact the maximum shear modulus G0 value. Those properties were suction s, confining pressure σ3, and compaction degree represented by the void ratio function f(e).

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Effect of Sand Fouling on the Dynamic Properties and Volume Change of Gravel During Cyclic Loadings

Periodica Polytechnica Civil Engineering ◽

10.3311/ppci.15857 ◽

2020 ◽

Author(s):

Meysam Bayat

Keyword(s):

Shear Modulus ◽

Shear Strain ◽

Dynamic Behavior ◽

Volume Change ◽

Dynamic Properties ◽

Damping Ratio ◽

Confining Pressure ◽

Triaxial Tests ◽

Practical Applications ◽

Large Shear Strain

Understanding the factors that influence the dynamic behavior of granular soils during cyclic loading is critical to infrastructure design. Previous research has lacked quantitative study of the effects of fouling index (FI), mean effective confining pressure, relative density, shear strain level and anisotropic consolidation, especially when the effective vertical stress is lower than the effective horizontal stress on the dynamic behavior of gravelly soils. The objective of the present study was to evaluate the dynamic behavior and volume change of both clean and fouled specimens for practical applications. To this end, cyclic triaxial tests with local strain measurements under both isotropic and anisotropic confining conditions were conducted. It is found that the fouled specimen with 50 % sand (i.e. the specimen which contains 50 % gravel and 50 % sand) has the highest shear modulus at low shear strain levels and the largest volume reduction and damping ratio at large shear strain levels. The results of tests indicate that the effect of fouling index on the shear modulus is reduced at large shear strain levels. Volumetric contraction due to the increase in mean effective confining pressure is more significant at large shear strain levels. The results also indicate that the stiffness of the specimens under anisotropic compression mode are larger than those in extension or isotropic mode.

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