scholarly journals EFFECTS OF INITIAL CYCLIC LOADING ON ANISOTROPY OF SMALL STRAIN SHEAR MODULI AND LIQUEFACTION CHARACTERISTICS OF TOYOURA SAND

2017 ◽  
Vol 73 (4) ◽  
pp. I_761-I_768
Author(s):  
Chiehyu WU ◽  
Takashi KIYOTA ◽  
Toshihiko KATAGIRI
Keyword(s):  
Cyclic Loading ◽  
Small Strain ◽  
Shear Moduli ◽  
Toyoura Sand

An Experimental Study of Inhomogeneous Cyclic Plastic Deformation

2001 ◽  
Vol 123 (3) ◽  
pp. 274-280 ◽  
Author(s):  
Yanyao Jiang
Keyword(s):  
Plastic Deformation ◽  
Cyclic Loading ◽  
Small Strain ◽  
Local Deformation ◽  
Gage Section ◽  
Strain Gages ◽  
Cyclic Plastic ◽  
Symmetrical Loading ◽  
Increasing Cyclic Loading ◽  
Cyclic Plastic Deformation

A localized inhomogeneous cyclic plastic deformation phenomenon was experimentally investigated in a mild steel. Small strain gages were utilized to characterize the local deformation within the gage section and the gross deformation was measured with an extensometer. Both fully reversed symmetrical loading and asymmetrical loading with a mean stress were used in the cyclic experiments. Plastic deformation was initiated in local areas of the specimen and it propagated into the whole gage section in the specimen with increasing cyclic loading. The local inhomogeneous cyclic deformation was dependent on the loading magnitude and evolved with continued cyclic loading.

scholarly journals Effect of Fiber and Cement Additives on the Small-Strain Stiffness Behavior of Toyoura Sand

2020 ◽  
Vol 12 (24) ◽  
pp. 10468
Author(s):  
Muhammad Safdar ◽  
Tim Newson ◽  
Colin Schmidt ◽  
Kenichi Sato ◽  
Takuro Fujikawa ◽  
...  
Keyword(s):  
Model Comparison ◽  
Local Strain ◽  
Small Strain ◽  
Experimental Results ◽  
Compression Tests ◽  
Cemented Sand ◽  
Strain Measurements ◽  
Good Comparison ◽  
Toyoura Sand ◽  
Comparison Of The Results

The disposal of 2011 Japan earthquake waste has become an important issue in Japan and it is not realistic or economical to send all of these wastes to landfill sites, due to limited space, high costs, and related environmental issues. In sustainable geotechnical applications, mixing of the separated soils from disaster wastes with additives (e.g., cement and fiber) is required to improve their strength and stiffness characteristics. In this study, monotonic triaxial drained compression tests are performed on medium dense specimens of Toyoura sand-cement-fiber mixtures with different percentages of fiber and cement (e.g., 0–3%) additives. The experimental results indicate that behavior of the mixtures is significantly affected by the concentration of fiber and cement additives. Based on a comprehensive set of test results, modifications to the series of equations were developed that can be used to evaluate the shear modulus and mobilized stress curves at small-strain levels. The experimental results and model comparison show that the elastic threshold strain (γe), reference strain (γr), increases with fiber and cement additives. In addition, the range of curvature parameter, from 0.88 to 1.0, provides a good comparison with the results of small-strain measurements. Overall, the comparison of the results and model shows that the small-strain measurements obtained using local strain transducers fall within the range of model upper and lower bound curves. The results of the unreinforced, fiber, and cemented sand shows a close agreement with the model mean curve, but fiber-reinforced cemented sand shows a good comparison with model upper bound.

scholarly journals Small-strain behaviour and crushability of Ballyconnelly carbonate sand under monotonic and cyclic loading

2018 ◽  
Vol 55 (7) ◽  
pp. 979-987 ◽  
Author(s):  
S. Nanda ◽  
V. Sivakumar ◽  
S. Donohue ◽  
S. Graham
Keyword(s):  
Cyclic Loading ◽  
Large Scale ◽  
Sea Water ◽  
High Stress ◽  
Small Strain ◽  
Offshore Structures ◽  
Particle Breakage ◽  
Triaxial Tests ◽  
Bender Element ◽  
Carbonate Sand

In various parts of the globe, carbonate sands are found at shallow sea water depth. These types of sands are very susceptible to large-scale particle breakage. Offshore structures like wind turbines and sea defences are constructed on these types of soils. From a design perspective, it is essential to assess the extent of particle breakage and the subsequent change in soil properties that occur under working load conditions. This paper presents the data obtained from a number of drained monotonic and cyclic triaxial tests on crushable carbonate sand (“Ballyconnelly sand”) in conjunction with small-strain shear stiffness (Gmax) measurements using the bender element technique. The soils were allowed to shear under three different loading patterns to understand the factors influencing the breakage of particles. The degree of crushing was quantified and analysed based on the total energy input. It was observed that, apart from applied stress, the total strain accumulation governs the amount of particle breakage. It was observed that Gmax increased significantly under high stress ratio. Gmax also increased noticeably during resting periods without any change in loading conditions as a result of creep, and subsequently during cyclic loading although at a reduced rate.

scholarly journals Development of vertical and horizontal disk transducers for wave velocity measurements in a large rectangular specimen

2019 ◽  
Vol 92 ◽  
pp. 02001
Author(s):  
Troyee Tanu Dutta ◽  
Masahide Otsubo ◽  
Reiko Kuwano ◽  
Takeshi Sato
Keyword(s):  
Wave Velocity ◽  
Small Strain ◽  
Elastic Wave Velocity ◽  
Coarse Grained ◽  
Velocity Measurements ◽  
Compression Waves ◽  
Wave Velocities ◽  
Triaxial Apparatus ◽  
Horizontal Wave ◽  
Toyoura Sand

For the accurate design of structures subjected to both static and dynamic loadings, elastic wave velocity and small strain stiffness are essential parameters. Numerous techniques have been developed to estimate wave velocities of geomaterials. Bender elements which are widely adopted for wave velocity measurements are invasive in nature and are not suitable for coarse-grained materials. In the present study, new design configuration of disk transducer has been introduced to measure both vertical and horizontal wave velocities for coarse granular soils considering multidirectional oscillation of propagating waves. An innovative arrangement of both compression and shear type elements has been installed in a large-sized triaxial apparatus having rectangular specimens of size 236×236×500 mm to assess the wave velocities. The materials described are Toyoura sand (D50 = 0.24 mm) and Oiso gravel (D50 = 11.8 mm). This arrangement enables measurements of nine types of wave velocities, and thus the stiffness anisotropy to be quantified. For Oiso gravel, horizontal wave velocities are greater than vertical wave velocities for both shear and compression waves. For Toyoura sand, shear wave velocities are higher in horizontal direction of propagation, whereas similar compression wave velocities are observed from both horizontal and vertical directions.

Measurement of Small-Strain Shear Moduli of Partially Saturated Sand During Infiltration in a Geotechnical Centrifuge

2011 ◽  
Vol 34 (5) ◽  
pp. 103608 ◽  
Author(s):  
L. D. Suits ◽  
T. C. Sheahan ◽  
Majid Ghayoomi ◽  
John S. McCartney
Keyword(s):  
Small Strain ◽  
Saturated Sand ◽  
Shear Moduli ◽  
Geotechnical Centrifuge ◽  
Partially Saturated ◽  
Partially Saturated Sand

scholarly journals Small strain shear moduli of unsaturated natural and compacted loess

Géotechnique ◽  
2017 ◽  
Vol 67 (7) ◽  
pp. 646-651 ◽  
Author(s):  
C. W. W. Ng ◽  
R. Kaewsong ◽  
C. Zhou ◽  
E. E. Alonso
Keyword(s):  
Small Strain ◽  
Shear Moduli ◽  
Compacted Loess

Effects of wetting–drying and stress ratio on anisotropic stiffness of an unsaturated soil at very small strains

2009 ◽  
Vol 46 (9) ◽  
pp. 1062-1076 ◽  
Author(s):  
C. W.W. Ng ◽  
J. Xu ◽  
S. Y. Yung
Keyword(s):  
Unsaturated Soils ◽  
Stress Ratio ◽  
Shear Stiffness ◽  
Small Strain ◽  
Matric Suction ◽  
Bender Elements ◽  
Shear Moduli ◽  
Small Strains ◽  
Stiffness Anisotropy ◽  
Stress Dependent

The very small strain shear modulus of soil, G0, is affected by many factors including soil properties, current stress state, stress history, and matric suction. Very little research has been conducted on anisotropic shear moduli of unsaturated soils. In this study, the effects of wetting–drying and stress ratio on anisotropic shear stiffness of an unsaturated completely decomposed tuff (CDT) at very small strains have been investigated using a modified triaxial testing system equipped with three pairs of bender elements. During drying and wetting tests, the measured very small strain shear moduli increased in a nonlinear fashion, but at a reduced rate as the matric suction increased. Similar to the stress-dependent soil-water characteristic curves (SDSWCCs), there was hysteresis between the drying and wetting curves showing the variations in shear moduli with matric suction. Variation in suction on the specimens under isotropic conditions produced changes in stiffness anisotropy (expressed as G0(hh)/G0(hv)) together with anisotropic strains. In shearing tests at constant suctions, significant stress-induced stiffness anisotropy was observed due to a change in the stress ratio. While shearing at a constant stress ratio, G0(hh)/G0(hv) appeared to be constant.

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