Moduli and Damping Factors of Soft Marine Clays

Kagawa, Takaaki

doi:10.1061/(asce)0733-9410(1992)118:9(1360)

Cited by 56 publications

(20 citation statements)

References 15 publications

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“…According to this figure, G/G max increases with increasing σ' 0 and decreasing γ. This finding is in qualitatively good agreement with the results of laboratory studies carried out by some researchers (e.g., Kagawa, 1992;Lanzo et al, 1997).…”

Section: Comparison With the Previous Studiessupporting

confidence: 92%

Predictive model for normalized shear modulus of cohesive soils

Jafarian¹

2013

Acta Geodynamica Et Geomaterialia

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called maximum shear modulus, G max . It can be determined by in-situ methods from the measurements of the shear wave velocity, V s , by means of crosshole, down-hole, up-hole, or surface wave testing. The relationship between maximum shear modulus and shear wave velocity is rigorous:ABSTRACT Evaluating dynamic properties of geomaterials is an essential step for solving geotechnical earthquake engineering problems. The shear stiffness-reduction curves of soils are commonly presented in normalized form and have many applications in equivalent-linear and nonlinear dynamic analyses. In this study, a radial basis function (RBF) neural network model was developed to predict normalized shear modulus of cohesive soils. The most important factors that affect this parameter include effective confining pressure, shear strain, and plasticity index. The comprehensive database used for the development of the model was obtained from previously published experimental results. Validation of the model performance was carried out by using centrifuge tests results. A parametric analysis was then performed to evaluate sensitivity of the proposed model to variations of the influencing parameters. The results indicate that the neural network model could provide predictions more accurate than those obtained by the previous models.

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Section: Comparison With the Previous Studiessupporting

confidence: 92%

Predictive model for normalized shear modulus of cohesive soils

Jafarian¹

2013

Acta Geodynamica Et Geomaterialia

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“…The shear modulus becomes very small compared to G max when the shear strain exceeds 1%. This finding is consistent with the findings of Thiers and Seed (1968), Park and Silver (1975), Anderson et al (1983), Seed et al (1986), Kagawa (1992), Viggiani and Atkinson (1995), Macari and Hoyos (1996), Guha et al (1997), Rollins et al (1998), Ng and Wang (2001), Wehling et al (2003) and Yasuhara et al (2003). As discussed earlier (Section 7.2), shear modulus is affected by effective confining pressure.…”

Section: Stiffness-strain Relationshipssupporting

confidence: 91%

“…It is observed that shear modulus decreases as the shear strain level increase, a trend which is similar to Figure 2.1. It is' consistent with the trend reported in the literature (Thiers and Seed 1968, Silver and Seed 1971, Hardin and Dmevich 1972, Dobry et al 1981, Ray and Woods 1988, Vucetic and Dobry 1991, Kagawa 1992, Macari and Hoyos 1996, Lanzo et al 1997, Rollins et al 1998, Hsu 2002, D'Elia et al 2003, Matesic and Vucetic 2003, Wehling et al 2003and Yashuhara et al 2003.…”

Section: Loading Conditionsupporting

confidence: 90%

“…A similar trend is obtained by Thiers and Seed (1968), Park and Silver (1975), Anderson et al (1983), Seed et al (1986), Kagawa (1992)…”

Section: Loading Conditionsupporting

confidence: 85%

“…The variation of the damping ratio of Singapore residual soil with shear strain in Figure 7.2 shows that the damping ratio increases as the shear strain increases. A similar trend is obtained by Thiers and Seed (1968), Park and Silver (1975), Anderson et al (1983), Seed et al (1986), Kagawa (1992), Macari and Hoyos (1996), Guha et al (1997), Rollins et al (1998), Wehling et al (2003) andYasuhara et al (2003). The damping ratio of Singapore residual soils ranges from 7% to 9% at very small shear strain.…”

Section: Damping Ratio-strain Relationshipssupporting

confidence: 80%

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Relationship of stiffness and damping ratio with strain for residual soils

Yeo¹

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There is very little work done on characterization of soil stiffness and damping ratio with strain for residual soils in Singapore. This is because routine geotechnical design does not usually incorporate the non-linearity of soil stiffness and damping ratio is only needed for dynamic problems. However, the use of large strain (>1%) soil stiffness to compute ground movement is over conservative as the mobilized strain due to construction loads and working loads is usually in the range of 0.01 % to 1%. Furthermore, the demand for seismic analysis is increasing due to ground tremors felt in Singapore arising from earthquakes in Indonesia. Thus, the characterization of soil stiffness and damping ratio with respect to strain is important. To characterize the Singapore residual soils' stiffness-strain and damping ratio-strain relationships, pulse• transmission tests (bender element tests and ultrasonic tests), cyclic simple• shear and triaxial compression tests for shear strain ranging from 0.0005% to 5% were performed. Inaddition,theeffects of soil parameters such as void ratio, confining pressure, degree of saturation and loading conditions such as frequency and number of loading cycles on soil stiffness and damping ratio are investigated. Both compacted and undisturbed residual soils were tested. However, most of the work concentrated on compacted residual soils because Singapore residual soils are highly heterogeneous and soil characteristics such as void ratio, density and degree,of saturation cannot be systematically studied. Anisotropy of soil was not considered in the study. A few tests on undisturbed. residual soils were performed for comparison with the compacted residual soils. The pulse transmission tests (bender element tests and ultrasonic tests) were evaluated with different materials to gain a• better understanding of the teclmique. The study shows that the waveform, magnitude and frequency of the applied voltage affect the receiver signal for bender element tests. The travel time should be based on first arrival time. Acoustic coupling is essential to obtain reliable wave velocities for ultrasonic test. The L/D and L/λ w ratios affect the measurement of compression and shear wave velocities in bender element tests and ultrasonic tests.

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