ON THE SHEAR STIFFNESS DECREASE OF SANDY SOILS DUE TO PARTICLE CRUSHING PROGRESS

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
haruyuki yamamoto
Keyword(s):  
High Pressure ◽  
Sandy Soil ◽  
Shear Failure ◽  
Sandy Soils ◽  
Shear Stiffness ◽  
Deviatoric Stress ◽  
Mean Stress ◽  
Particle Crushing ◽  
Soil Particles ◽  
The Mean

Many previous studies have focused on theoretical and experimental evaluations of the crushing of sandy soil particles under high pressure conditions. From the perspective of practical scenarios, the decreased bearing capacity caused by volume shrinkage and the reduced shear strength and stiffness caused by the crushing of sandy soil particles are important aspects. Therefore, this study aims to confirm the decrease in the shear stiffness of sandy soils subjected to various stress levels combined with high principal stresses. Author conducted crushing tests using the high-pressure true tri-axial compression apparatus under the planned stress paths. Tests on isotropic compression without deviatoric stress q and those involving combinations of the mean stress p and deviatoric stress q up to the shear failure line (SFL) on the p-q plane are employed to characterize the particle crushing of sandy soils. The results indicate that the shear stiffness of sandy soils starts to decrease due to particle crushing under a combination of low mean stress p and high deviatoric stress q. Furthermore, experimental formulas regarding the decrease in shear stiffness due to particle crushing were estimated based on the relationships among the mean stress p, deviatoric stress q and deviatoric strain εd.

ON THE PARTICLE CRUSHING FEATURES OF SANDY SOILS

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Haruyuki Yamamoto
Keyword(s):  
High Pressure ◽  
Volumetric Strain ◽  
Sandy Soils ◽  
Deviatoric Stress ◽  
Volume Shrinkage ◽  
Silica Sand ◽  
Mean Stress ◽  
Stress Tests ◽  
Particle Crushing ◽  
Weathered Granite

Previous studies have investigated particle crushing of sandy soils in high-pressure conditions. In practice, the volume shrinkage and decreasing shear strength due to particle crushing around the pile-foundation tip in crushable sandy soils may be more important. Therefore, this study aims to confirm the volume shrinkage of sandy soils, e.g., silica sand, weathered granite, and volcanic sand, under various stress paths with a combination of high principal stresses. High-pressure crushing tests were carried out using a true tri-axial compression apparatus under the planned stress paths. Isotropic compression tests and combined stress tests (mean stress p and deviatoric stress q) were employed for three types of sandy soil. The particle-crushing progress became active in combination with mean stress p and deviatoric stress q. In addition, the relationships between the plastic volumetric strain and relative breakage were found to be approximately linear. As expected, the silica sand was less crushable than the weathered granite sand and volcanic sand under the same stress conditions.

CRUSHING CHARACTERISTICS OF SOIL PARTICLE ON THE EFFECT OF STRESS PATH

2018 ◽  
Vol 5 (2) ◽  
Author(s):  
Keigo Fukuda ◽  
Haruyuki Yamamoto
Keyword(s):  
Axial Compression ◽  
Mechanical Characteristics ◽  
Shear Failure ◽  
Stress Path ◽  
Deviatoric Stress ◽  
Particle Crushing ◽  
Principal Stresses ◽  
The Mean ◽  
Lode Angle ◽  
Failure Line

In previous studies, we have conducted tests under various conditions of stress for the particle crushing. Anyway, it is necessary to perform the crushing test that assumed stress conditions in ground under controlled each principal stresses individually, to find the mechanical characteristics of the soil with particle crushing. Therefore, the purpose of this study is to confirm the effect for particle crushing under various stress paths in the combination of principal stresses. We planned four combinations of principal stresses when operate the mean stress p and deviatoric stress q up to the Shear Failure Line (SFL) on the 𝜋-plane. First, we set tri-axial extension test as Lode angle 𝛳=60° and tri-axial compression test as 𝛳=0°, and set two of the remainder as 𝛳=40°, 20°. The crushing tests are carried out using the high pressure true tri-axial compression apparatus under the planned stress paths. As a result, the progress of the particle crushing becomes active in order of 𝛳=40°, 20°, 60°, 0°, and found out that deviatoric stress q has essential effect on the particle crushing.

scholarly journals Effect of grain shape to potential liquefaction

2020 ◽  
Vol 156 ◽  
pp. 02014
Author(s):  
Arif Rahman
Keyword(s):  
Sandy Soil ◽  
Laboratory Tests ◽  
Grain Shape ◽  
Sandy Soils ◽  
Soil Liquefaction ◽  
Liquefaction Potential ◽  
Soil Particles ◽  
Different Shapes

Earthqueke is one of the most frequent disaster in Indonesia, Earthqueke have caused losses both in terms of life and material. An earthquake also can trigger to soil liquefaction. Attention to liquefaction in Indonesia has raised after the Palu Earthquake in 2018. Liquefaction may happen in sandy soil in certain condition. Here, a series laboratory tests to study potentially liquefied in sandy soils is conducted. The liquefaction potential of sand are analyzed with the effect of the shape of the soil particles. The sandy sample is made up by special selected in three different shapes that are sharp, angular and round. Finally, it can be seen the effect of the shape of the soil grain on the liquefaction potential. The results of this study can be used to further investigation in order to mitigate the liquefaction.

scholarly journals Role of Biochar in Improving Sandy Soil Water Retention and Resilience to Drought

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 407
Author(s):  
Ling Li ◽  
Yong-Jiang Zhang ◽  
Abigayl Novak ◽  
Yingchao Yang ◽  
Jinwu Wang
Keyword(s):  
Climate Variability ◽  
Sandy Soil ◽  
Water Retention ◽  
Sandy Soils ◽  
Crop Productivity ◽  
Future Research ◽  
Soil Water Retention ◽  
The World ◽  
Water Holding

In recent years, plants in sandy soils have been impacted by increased climate variability due to weak water holding and temperature buffering capacities of the parent material. The projected impact spreads all over the world, including New England, USA. Many regions of the world may experience an increase in frequency and severity of drought, which can be attributed to an increased variability in precipitation and enhanced water loss due to warming. The overall benefits of biochar in environmental management have been extensively investigated. This review aims to discuss the water holding capacity of biochar from the points of view of fluid mechanics and propose several prioritized future research topics. To understand the impacts of biochar on sandy soils in-depth, sandy soil properties (surface area, pore size, water properties, and characteristics) and how biochar could improve the soil quality as well as plant growth, development, and yield are reviewed. Incorporating biochar into sandy soils could result in a net increase in the surface area, a stronger hydrophobicity at a lower temperature, and an increase in the micropores to maximize gap spaces. The capability of biochar in reducing fertilizer drainage through increasing water retention can improve crop productivity and reduce the nutrient leaching rate in agricultural practices. To advance research in biochar products and address the impacts of increasing climate variability, future research may focus on the role of biochar in enhancing soil water retention, plant water use efficiency, crop resistance to drought, and crop productivity.

Two New Universal Relations in Nonlinear Elasticity and Some Related Matters

1994 ◽  
Vol 61 (4) ◽  
pp. 784-787 ◽  
Author(s):  
M. Aron ◽  
S. Aizicovici
Keyword(s):  
Nonlinear Elasticity ◽  
Ground State ◽  
Mean Stress ◽  
The Mean

Two inequalities which for certain deformation classes may be viewed as universal relations are shown to hold for two distinct subclasses of unconstrained rubberlike solids. The inequalities express the fact that the mean stress corresponding to any purely distortional deformation originating from a given ground state is dominated by (and, respectively, dominates) the mean stress in that ground state. Also discussed is a case in which the deformations involved are necessarily homogeneous.

Fracture of Sifcon Under Combined Tensile and Shearlike Loading

1990 ◽  
Vol 211 ◽  
Author(s):  
J. G. M. Van Mier
Keyword(s):  
Shear Failure ◽  
Crack Opening ◽  
Shear Stiffness ◽  
Fiber Direction ◽  
Axial Tension ◽  
Crack Band ◽  
Fiber Concrete ◽  
Axial Crack ◽  
Fiber Action ◽  
Inclined Cracks

AbstractIn a series of preliminary experiments, the shear stiffness degradation and ’shear’ failure mechanisms of pre-cracked Slurry Infiltrated Fiber CONcrete (SIFCON) were studied. The specimens were first subjected to axial tension (in displacement control), whereafter a lateral shear was applied over the crack band. Variables in the investigation were the direction of loading with regard to the main fiber direction, and the axial crack opening before shearing. The degradation of shear stiffness resembles that of normal concrete at low crack openings, but seems governed by fiber action at larger crack openings. At low crack openings, shear failure was observed in the sense of an array of inclined tensile microcracks. At larger crack openings, inclined cracks developed through coalescence of preexisting tensile cracks.

scholarly journals THE EFFECT GRAIN-SIZE COMPOSITION ON THERMAL CONDUCTIVITY OF SANDY SOILS

2020 ◽  
Vol 11 (2) ◽  
pp. 19-27
Author(s):  
A. V Zakharov ◽  
S. E Makhover
Keyword(s):  
Thermal Conductivity ◽  
Grain Size ◽  
Sandy Soil ◽  
Alternative Energy ◽  
Radiant Energy ◽  
Sandy Soils ◽  
Size Composition ◽  
Experiment Planning ◽  
Pore Filling ◽  
Grain Size Composition

Today the issue of energy saving is acute. The main sources of energy are radiant energy of the Sun, wind energy, energy of moving water. Therefore, the issue of solving alternative energy sources is relevant. The article aims to solve the problem by using low-potential heat of the soil mass by means of energy-efficient building constructions - foundations. It is necessary to know the thermal characteristics of soils for this. At the moment, methods for determining the thermophysical properties of inert materials with subsequent practical application in the field of construction have been widely studied, but no one of these methods takes into account the grain-size composition. Thus, the study of the connection between the thermal conductivity and the grain-size composition of the soil is important. The aim of the work is to Estimation of thermal conductivity of sandy soils based on grain-size composition. This article presents an analysis of the dependence of the thermal conductivity of the sandy soil of its grain-size composition. The matrix of experiment planning is made; the methodology and technological sequence of the experiment were tested. Statistical processing of the obtained experimental data was carried out. Based on a series of test experiments, it was concluded that there are two factors competing in its thermal conductivity: an increase in λ due to an increase in the degree of pore filling and a decrease in total heat conductivity due to a decrease in the degree of pore filling. These results suggest that grain-size composition has an impact on the thermal conductivity of the sandy soil. During the experiment, the dependence of the thermal conductivity of sandy soils on their grain-size composition was experimentally established.

scholarly journals Vibrational anisotropy of <i>δ</i>-(Al,Fe)OOH single crystals as probed by nuclear resonant inelastic X-ray scattering

2021 ◽  
Vol 33 (4) ◽  
pp. 485-502
Author(s):  
Johannes Buchen ◽  
Wolfgang Sturhahn ◽  
Takayuki Ishii ◽  
Jennifer M. Jackson
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystals ◽  
Vibrational Properties ◽  
Phonon Density ◽  
Phonon Density Of States ◽  
X Ray ◽  
X Ray Scattering ◽  
The Mean ◽  
Vibrational Anisotropy

Abstract. The formation of high-pressure oxyhydroxide phases spanned by the components AlOOH–FeOOH–MgSiO2(OH)2 in experiments suggests their capability to retain hydrogen in Earth's lower mantle. Understanding the vibrational properties of high-pressure phases provides the basis for assessing their thermal properties, which are required to compute phase diagrams and physical properties. Vibrational properties can be highly anisotropic, in particular for materials with crystal structures of low symmetry that contain directed structural groups or components. We used nuclear resonant inelastic X-ray scattering (NRIXS) to probe lattice vibrations that involve motions of 57Fe atoms in δ-(Al0.87Fe0.13)OOH single crystals. From the recorded single-crystal NRIXS spectra, we calculated projections of the partial phonon density of states along different crystallographic directions. To describe the anisotropy of central vibrational properties, we define and derive tensors for the partial phonon density of states, the Lamb–Mössbauer factor, the mean kinetic energy per vibrational mode, and the mean force constant of 57Fe atoms. We further show how the anisotropy of the Lamb–Mössbauer factor can be translated into anisotropic displacement parameters for 57Fe atoms and relate our findings on vibrational anisotropy to the crystal structure of δ-(Al,Fe)OOH. As a potential application of single-crystal NRIXS at high pressures, we discuss the evaluation of anisotropic thermal stresses in the context of elastic geobarometry for mineral inclusions. Our results on single crystals of δ-(Al,Fe)OOH demonstrate the sensitivity of NRIXS to vibrational anisotropy and provide an in-depth description of the vibrational behavior of Fe3+ cations in a crystal structure that may motivate future applications of NRIXS to study anisotropic vibrational properties of minerals.

scholarly journals Effects of repeated phosphorus fertilisation on field crops in Finland 2.Sufficient phosphorus application rates on silty and sandy soils

2008 ◽  
Vol 15 (4) ◽  
pp. 423 ◽  
Author(s):  
I. SAARELA ◽  
H. HUHTA ◽  
P. VIRKAJÄRVI
Keyword(s):  
Relative Yield ◽  
Sandy Soils ◽  
Application Rate ◽  
Application Rates ◽  
P Application ◽  
The Mean ◽  
Yield Responses ◽  
Phosphorus Application ◽  
Phosphorus Fertilisation ◽  
Annual Application

In order to update fertilisation recommendations for Finnish silty and sandy soils, the effects of repeated phosphorus (P) fertilisation on the yields of cereals, grasses and other crops were measured at ten sites for 9 to 18 years. Results of some earlier studies were also used in examining the relationships of the yield responses to applied P and to the soil test values measured by the Finnish ammonium acetate method (PAc). Significant effects of P fertilisation were observed at all sites that had low or medium PAc values; in the case of potatoes, even at sites with fairly high values. The mean relative yield without applied P divided by yield with 60 or 45 kg P ha-1 of the ten sites was 81% (mean PAc 11.6 mg dm-3) varying from 55% at the PAc value of 4.7 mg dm-3 to 100% at the highest PAc values. In order to achieve a relative yield of 97%, which is considered the optimum for cereals and leys, the required mean annual application of P in the later parts of the experiments was 25 kg ha-1 (variation 0-42 kg ha-1). On the six soils that had low or medium PAc values (4.5-9.1 mg dm-3, mean 8.0 mg dm-3), relative yield was 97% at the P application rate of 35 kg ha-1 (variation 22-42 kg ha-1), while 11 kg P ha-1 (variation 0-25 kg ha-1) sufficed on the four soils that had higher PAc values (mean 20.8 mg dm-3, variation 11.7-35.2 mg dm-3). Reasons for the poor availability of P in silty and sandy soils were discussed.;

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