A Parallel Comparison of Small-Strain Shear Modulus in Bender Element and Resonant Column Tests

2018 ◽  
pp. 564-568
Author(s):  
Xin Liu ◽  
Jun Yang
Keyword(s):  
Shear Modulus ◽  
Small Strain ◽  
Resonant Column ◽  
Bender Element ◽  
Column Tests ◽  
Small Strain Shear Modulus

Measurement of small-strain shear modulus Gmax of dry and saturated sands by bender element, resonant column, and torsional shear tests

2008 ◽  
Vol 45 (10) ◽  
pp. 1426-1438 ◽  
Author(s):  
Jun-Ung Youn ◽  
Yun-Wook Choo ◽  
Dong-Soo Kim
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Shear Wave Velocity ◽  
Small Strain ◽  
Resonant Column ◽  
Test Results ◽  
Bender Element ◽  
Small Strain Shear Modulus ◽  
Torsional Shear ◽  
Saturated Sands

The bender element method is an experimental technique used to determine the small-strain shear modulus (Gmax) of a soil by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure the Gmax of wet and dry soils in various laboratory apparatuses. However, certain aspects of the bender element method have yet to be clearly specified because of uncertainties in determining travel time. In this paper, the bender element (BE), resonant column (RC), and torsional shear (TS) tests were performed on the same specimens using the modified Stokoe-type RC and TS testing equipment. Two clean sands, Toyoura and silica sands, were tested at various densities and mean effective stresses under dry and saturated conditions. Based on the test results, methods of determining travel time in BE tests were evaluated by comparing the results of RC, TS, and BE tests. Also, methods to evaluate Gmax of saturated sands from the shear-wave velocity (Vs) obtained by RC and BE tests were investigated by comparing the three sets of test results. Biot’s theory on frequency dependence of shear-wave velocity was adopted to consider dispersion of a shear wave in saturated conditions. The results of this study suggest that the total mass density, which is commonly used to convert Gmax from the measured Vs in saturated soils, should not be used to convert Vs to Gmax when the frequency of excitation is 10% greater than the characteristic frequency (fc) of the soil.

Small strain shear modulus and damping ratio of two unsaturated lateritic sandy clays

2020 ◽  
Author(s):  
C.W.W. Ng ◽  
Obed Takyi Bentil ◽  
Chao Zhou
Keyword(s):  
Shear Modulus ◽  
Damping Ratio ◽  
Small Strain ◽  
Resonant Column ◽  
Column Tests ◽  
Small Strain Shear Modulus ◽  
Confining Pressures ◽  
The Difference ◽  
Elastic Threshold ◽  
Scanning Electron

In this study, resonant column tests carried out to investigate the influence of suction on the shear modulus and damping ratio of two compacted lateritic sandy clays from Ghana (GL) and Nigeria (NL) are reported. Each type of soils was tested under two confining pressures and at three suctions. The microstructure of the soils was also studied through a scanning electron microscope. It is found that the effects of suction on maximum shear modulus (G<u><sub></u>0<u></sub></u>) are about 10% larger for GL than NL, mainly due to the existence of smaller aggregates in GL. Moreover, an increase in suction from 0 to 300 kPa for both soils resulted in a lower elastic threshold shear strain, different from the behaviour of other soils reported in the literature. The uniqueness of lateritic soils is likely attributed to their high sesquioxide content and much larger aggregates, which shrink upon an increase in suction. Drying of specimens from 0 to 300 kPa resulted in an increase of about 22% and 100% in initial damping ratio (D<sub>0</sub>) for GL and NL, respectively. The difference in D<sub>0</sub> for GL and NL and is attributed to larger aggregation of NL because of its higher iron sesquioxide content, leading to more cladding

Bender Element Measurement for Small-Strain Shear Modulus of Compacted Loess

2021 ◽  
Vol 21 (5) ◽  
pp. 04021063
Author(s):  
Fangtong Wang ◽  
Dianqing Li ◽  
Wenqi Du ◽  
Chia Zarei ◽  
Yong Liu
Keyword(s):  
Shear Modulus ◽  
Small Strain ◽  
Bender Element ◽  
Small Strain Shear Modulus ◽  
Compacted Loess

scholarly journals A semi-empirical relationship for the small-strain shear modulus of soft clays

2019 ◽  
Vol 92 ◽  
pp. 04005
Author(s):  
Vashish Taukoor ◽  
Cassandra J. Rutherford ◽  
Scott M. Olson
Keyword(s):  
Shear Modulus ◽  
Effective Stress ◽  
Void Ratio ◽  
Empirical Relationship ◽  
Small Strain ◽  
High Plasticity ◽  
Bender Element ◽  
Stress History ◽  
Small Strain Shear Modulus ◽  
Semi Empirical

The small-strain shear modulus (Gmax) is a soil property that has many practical applications. The authors compiled a database of Gmax measurements for 40 normally consolidated to slightly overconsolidated low to high plasticity clays. Using these data, the authors propose a semi-empirical relationship between Gmax, effective stress (σ'v or σ'c), preconsolidation stress (σ'p) and in-situ void ratio (e0) for four ranges of plasticity index (Ip): Ip < 30%, 30% ≤ Ip < 50%, 50% ≤ Ip < 80% and 80% ≤ Ip < 120%. With results from bender element tests on a Gulf of Mexico clay subjected to multiple load-unload consolidation loops, the authors were able to validate the proposed relationships for 30% ≤ Ip < 50% and 50% ≤ Ip < 80%. The proposed relationship for 30% ≤ Ip < 50% and 50% ≤ Ip < 80% captures changes in laboratory Gmax resulting from variations in effective stress (σ'c), maximum past stress (σ'v,max), and void ratio. The proposed relationships are a simple and efficient tool that can provide independent insight on Gmax if the stress history of a clay is known, or on stress history if Gmax is known.

Comparison of small-strain shear modulus and Young’s modulus of dry sand measured by resonant column and bender–extender element

2020 ◽  
Vol 57 (11) ◽  
pp. 1745-1753
Author(s):  
Kai Xu ◽  
Xiaoqiang Gu ◽  
Chao Hu ◽  
Lutong Lu
Keyword(s):  
Shear Modulus ◽  
Resonant Frequency ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Small Strain ◽  
Calibration Method ◽  
Resonant Column ◽  
Small Strain Shear Modulus ◽  
Torsional Excitation ◽  
Dry Sand

The small-strain shear modulus and Young’s modulus of dry sand are simultaneously measured by resonant column and bender–extender element tests. Two different methods are adopted to calibrate the resonant column and the results indicate that the conventional calibration method may significantly underestimate the Young’s modulus obtained in flexural excitation, while it only slightly underestimates the shear modulus obtained in torsional excitation. A new calibration method that establishes a calibration curve based on the resonant frequency is used to overcome the error. With this new calibration method, the shear modulus and Young’s modulus from the resonant column agree well with those from the bender–extender element. It convincingly explains the reason why a very small Poisson’s ratio was observed in previous resonant column tests and suggests that the effect of resonant frequency on the calibration results must be considered in flexural excitation.

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