Anisotropy of lacustrine soils in a large oedometer equipped with bender elements

Chamorro-Zurita, Claudia; Ovando-Shelley, Efraín

doi:10.1016/j.sandf.2020.02.009

Cited by 8 publications

(7 citation statements)

References 19 publications

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“…They constructed a large-size odometer apparatus (sample size: diameter—96 mm, height—120 mm) made of thin-walled aluminum tubes with drilled mini two holes to accommodate the lateral bender elements in the sample ( Figure 18 ). Thanks to this research, Chamorro-Zurita and Ovando-Shelley [ 72 ] confirmed the correlation between the yield stress (or overconsolidation ratio, OCR), the anisotropy ratio, the type of anisotropy (inherent or induced anisotropy) and the liquidity index (I L ).…”

Section: Interesting Solutionssupporting

confidence: 57%

“…The fact is that the bender elements can be mounted in any geotechnical device capable of controlling stresses while measuring deformations, or vice versa, as mentioned by Ferreira [ 42 ]. Such equipment includes: odometer [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 ], direct shear apparatus [ 65 , 73 ], resonant-column [ 74 , 75 , 76 , 77 ], centrifuge [ 78 , 79 ], hollow cylinder [ 80 , 81 , 82 ], calibration chambers [ 83 , 84 ], true triaxial and cubical cel apparatus [ 85 , 86 ]. Some examples are presented in Section 6 .…”

Section: Modern Measuring Systemsmentioning

confidence: 99%

“…In turn, Chamorro-Zurita and Ovando-Shelley [ 72 ] from the National Autonomous University of Mexico (UNAM) were investigating the lacustrine soils and an anisotropy of their shear stiffness modulus at very small strain levels under static and dynamic conditions. They constructed a large-size odometer apparatus (sample size: diameter—96 mm, height—120 mm) made of thin-walled aluminum tubes with drilled mini two holes to accommodate the lateral bender elements in the sample ( Figure 18 ).…”

Section: Interesting Solutionsmentioning

confidence: 99%

“… Schematic peripheral equipment and arrangement of bender elements [ 72 ] (available via 2020 license CC BY-NC-ND 4.0). …”

Section: Figurementioning

confidence: 99%

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Modern Displacement Measuring Systems Used in Geotechnical Laboratories: Advantages and Disadvantages

Jastrzębska

2021

Sensors

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The paper presents the contemporary displacement measurement systems used in geotechnical laboratories during the determination of soil precise mechanical parameters, e.g., the shear modules G: initial and in the range of small and very small strains. In the laboratory, researchers use standard sensors for measuring deformation, pressure, and force as well as modern measuring systems such as linear variable differential transformers (LVDT), proximity transducers (PT), magnetic encoder sensors with fiber Bragg grating (FBG), or methods based on laser or X-ray measurement. None of the measurements are universal and their use depends on the type of soil (cohesive, non-cohesive), its condition (loose or dense, stiff or very soft), and its characteristic properties (e.g., organic soil, swelling soil). This study points out the interesting equipment solutions and presents the guidelines for selecting appropriate methods of deformation measurement.

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Section: Interesting Solutionssupporting

confidence: 57%

Section: Modern Measuring Systemsmentioning

confidence: 99%

Section: Interesting Solutionsmentioning

confidence: 99%

“… Schematic peripheral equipment and arrangement of bender elements [ 72 ] (available via 2020 license CC BY-NC-ND 4.0). …”

Section: Figurementioning

confidence: 99%

See 2 more Smart Citations

Modern Displacement Measuring Systems Used in Geotechnical Laboratories: Advantages and Disadvantages

Jastrzębska

2021

Sensors

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“…Although many standards (e.g., ASTM D2435, BS 1377-part5, and DS/CEN ISO/TS 17892-5) suggest that the minimum ratio of the specimen diameter to height (D/H) should be 2.5 to minimize the side friction effect, specially designed large oedometers are often used for research purposes or for testing materials including large-sized granular materials, organic soils, municipal solid waste, mine tailings, and a mixture of soil and other materials [2][3][4][5][6][7][8]. When the elastic wave velocities are measured under one-dimensional conditions, relatively low ratio of D/H oedometric cells are applied to ensure the wave propagation length [9][10][11][12][13] because it is difficult to define the first arrival owing to the near field effect [14]. A low ratio of D/H increases the side friction, and the friction causes a lower change in the mean stress throughout the entire specimen than the change in stress at the top of the specimen.…”

Section: Introductionmentioning

confidence: 99%

Modified Fixed Wall Oedometer When Considering Stress Dependence of Elastic Wave Velocities

Lee

Park

Byun

et al. 2020

Sensors

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A modified oedometer cell for measuring the applied stresses and elastic waves at the top and bottom of the specimen is developed to evaluate the effect of the side friction on the stress dependence of the elastic wave velocities. In the modified cell, two load cells are installed at the top and bottom plates, respectively. To generate and detect the compressional and shear waves, a pair of piezo disk elements and a pair of bender elements are mounted at both the top and bottom plates. Experimental results show that the stresses measured at the bottom are smaller than those measured at the top during the loading and vice versa during unloading, regardless of the densities and heights of the specimens. Under nearly saturated conditions, the compressional wave velocities remain almost constant for the entire stress state. With plotting stresses measured at top, the shear wave velocities during unloading are greater than those during loading, whereas with plotting stresses measured at bottom, the shear wave velocities during unloading are smaller than those during loading owing to the side friction. The vertical effective stress may be simply determined from the average values of the stresses measured at the top and bottom of the specimens.

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An Alternative Method to Analyze Waveforms from Bender Element Tests in Soft Clays

2023

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Bender element (BE) testing has become a widely used technique to evaluate S-wave velocities and to derive shear moduli from them in laboratory tests. Results of BE tests depend heavily on the proper identification of the S-wave travel time from waveforms often affected detrimentally by factors such as the near-field effect, crosstalk, noise, or drift. The authors have performed BE tests on soil specimens of Texcoco Clay over the last few years in triaxial cells and oedometers and have sometimes dealt with waveforms influenced by those undesirable factors thus, it was observed that the using of different available techniques to evaluate the S-wave travel time are often prone to errors. This paper shows that the S-wave travel time can be assessed unambiguously from the distance between the inflection points present in both the source and the received signals when waveforms generated with different input frequencies are superimposed, even in signals affected by the near-field effect, crosstalk, noise, or drift. This approach, named here the Wave Inflection Method (WI method), yields good results, at least when applied to data obtained from BE tests on soft Texcoco Clays. The method was validated by applying it to synthetic signals and experimental waveforms obtained from triaxial and oedometer tests equipped with BE. When applied to previously published waveforms on a wide range of soil types, our results suggest that the WI method significantly reduces subjectivity and produces improved reliability in evaluating the S-wave travel time.

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Anisotropy of lacustrine soils in a large oedometer equipped with bender elements

Cited by 8 publications

References 19 publications

Modern Displacement Measuring Systems Used in Geotechnical Laboratories: Advantages and Disadvantages

Modern Displacement Measuring Systems Used in Geotechnical Laboratories: Advantages and Disadvantages

Modified Fixed Wall Oedometer When Considering Stress Dependence of Elastic Wave Velocities

An Alternative Method to Analyze Waveforms from Bender Element Tests in Soft Clays

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