Effects of gravel content on liquefaction resistance and its assessment considering deformation characteristics in gravel – mixed sand

2019 ◽  
Vol 56 (12) ◽  
pp. 1743-1755
Author(s):  
Hirofumi Toyota ◽  
Susumu Takada
Keyword(s):  
Shear Modulus ◽  
Small Strain ◽  
Bender Element ◽  
Liquefaction Resistance ◽  
Liquefaction Potential ◽  
Shear Moduli ◽  
Linear Elastic ◽  
Undisturbed Samples ◽  
Strong Relation ◽  
Secant Shear Modulus

Many reports describe overestimation of liquefaction resistance based on sounding data related to ground materials containing coarse particles such as gravel and cobbles. Better methods of liquefaction potential estimation must be developed using investigation data other than those from sounding. Gathering perfect and undisturbed samples is difficult, but using seismic methods such as PS logging might be effective for assessing liquefaction potential. For this study, bender element (BE) tests and local small strain (LSS) tests were conducted, respectively, to measure the dynamic and static shear moduli of gravel – mixed sand specimens. Subsequently, relations between liquefaction strength and secant shear moduli were examined to provide reliable estimation of liquefaction in gravel – mixed sand. Although the liquefaction resistance increased considerably with overconsolidation, the initial shear modulus exhibited only a slight change with the same overconsolidation. The experimentally obtained results elucidated that the important shear strain level, for which secant shear modulus has a strong relation with liquefaction strength, was not a linear elastic region of 0.001%: it was about 0.01%.

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

Bender Element Test and Numerical Simulation of Sliding Zone Soil with Gravels of Huangtupo Landslide

2021 ◽  
Author(s):  
Yu Chen
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Small Strain ◽  
Testing System ◽  
Bender Element ◽  
Gravel Content ◽  
Consolidation Pressure ◽  
Bender Element Test ◽  
Sliding Zone

<p>In order to study the effect of the different consolidation pressure, loading-unloading path and gravel content on the shear modulus of the small strain of sliding zone soil, a set of consolidation bender element test device was developed. The device consists of three parts: a consolidation system, a deformation measuring system, and a shear wave testing system. The consolidation system is composed of a traditional consolidation instrument and the plexiglass cylinder box. The sample is cylindrical in shape and has a size of 50 mm×50 mm. The consolidation displacement is measured by a digital display micrometer. Shear wave testing system is a wave velocity measurement system made of piezoelectric ceramic. The experimental results show that the device can control the consolidation pressure and measure the vertical deformation, measure the shear wave velocity of the sliding zone soil in real-time, and then study the variation rule of the small strain shear modulus of the sliding zone soil with gravels. The shear modulus of the sliding zone soil increases with an increase in the consolidation pressure. The shear modulus of the unloading of sliding zone soil is larger than that of loading. Under the loading pressure of 200 kPa and 400 kPa, the shear modulus of the sliding zone soil first decreases and then increases with an increase in the gravel content. In the process of unloading, the shear modulus of the sliding zone soil increases with an increase in the gravel content. </p>

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.

Moving Morphable Inclusion Approach: An Explicit Framework to Solve Inverse Problem in Elasticity

2020 ◽  
Vol 88 (4) ◽  
Author(s):  
Yue Mei ◽  
Zongliang Du ◽  
Dongmei Zhao ◽  
Weisheng Zhang ◽  
Chang Liu ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Shear Modulus ◽  
New Paradigm ◽  
Elastic Solids ◽  
Shear Moduli ◽  
Numerical Examples ◽  
Linear Elastic ◽  
Inverse Approach ◽  
Optimization Parameters ◽  
Very High

Abstract In this work, we present a novel inverse approach to characterize the nonhomogeneous mechanical behavior of linear elastic solids. In this approach, we optimize the geometric parameters and shear modulus values of the predefined moving morphable inclusions (MMIs) to solve the inverse problem. Thereby, the total number of the optimization parameters is remarkably reduced compared with the conventional iterative inverse algorithms to identify the nonhomogeneous shear modulus distribution of solids. The proposed inverse approach is tested by multiple numerical examples, and we observe that this approach is capable of preserving the shape and the shear moduli of the inclusions well. In particular, this inverse approach performs well even without any regularization when the noise level is not very high. Overall, the proposed approach provides a new paradigm to solve the inverse problem in elasticity and has potential of addressing the issue of computational inefficacy existing in the conventional inverse approaches.

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.

A new theory about single-walled carbon nanotubes

2014 ◽  
Vol 28 (26) ◽  
pp. 1450186
Author(s):  
Yao Yang Tsai ◽  
Shih Chung Fang
Keyword(s):  
Carbon Nanotubes ◽  
Shear Modulus ◽  
Small Diameter ◽  
Small Strain ◽  
Closed Form Expression ◽  
Angle Variation ◽  
Shear Moduli ◽  
Total Potential ◽  
Definition Of ◽  
Walled Carbon Nanotubes

Since carbon nanotubes were discovered, till now no definitive formulation for computing the shear modulus of them was presented. To develop a theoretically rigorous and mathematically elegant expression for the shear modulus, thus, we initially propound a new small-strain theory in which merely small strain will arise when small-diameter carbon nanotubes are formed and thereby conclude the total potential energy including bond elongation and bond angle variation will suffice and the utilization of Quantum Mechanics and certain far complicated potential functions is unnecessary. Then based on it, a closed-form expression derived entirely from the "definition" of shear modulus, which was never published in all other literature, will be evolved. It should be noted that previously there was only one formula by which the shear moduli for all carbon nanotubes with diverse diameters and configurations could be predicted. By comparing the values calculated by the expression in this paper with those reckoned from the article mentioned above, it is obvious that both classes of quantities are similar to each other. It should also be noted that because the expression in this paper is the first (really having no precedent in related study fields) to be derived entirely according to the definition of shear modulus, perhaps this paper can be used as a useful theoretical tool for further study.

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