scholarly journals Changes in the Strength Characteristics of Glinistx Soils under the Influence of Dynamic Forces

2020 ◽  
Vol 9 (5) ◽  
pp. 639-643
Keyword(s):  
Internal Friction ◽  
Experimental Studies ◽  
Sharp Decrease ◽  
Friction Angle ◽  
Strength Characteristics ◽  
Clay Soils ◽  
Angle Of Internal Friction ◽  
Dynamic Forces ◽  
The Impact ◽  
Soil Indicators

In order to study in depth the impact of vibration on the strength characteristics of clay soils, as well as to develop methods that increase the strength characteristics and contribute to the elimination of seismic shrinkage deformations of clay soils, we conducted research in the field. In field experimental studies, the svaw-12 trailed, smooth vibration roller, manufactured in Germany, was used. We paid special attention to the further behavior of the soil after the vibration and made observations and measurements of soil indicators for two months. The experiments in the field with vibration column showed an increase of soil deformation with increasing duration of the fluctuations, i.e. there is a linear relationship between the increases in soil density on the duration of oscillations. In the process of vibration, there is a sharp decrease in the force of adhesion and the angle of internal friction, which is apparently associated with a violation of the structure of the soil and its compaction. And then at the end of the vibration process, over time, there is an increase in the adhesion (1.5-2 times) and the internal friction angle (1.2 times) of the soil, obviously as a result of the soil acquiring new strength and compaction under the influence of its own weight. This circumstance is also associated with the humidity state of the soil.

THE INFLUENCE OF THE REPOSE ANGLE AND POROSITY OF GRANULAR PLANT MATERIALS ON THE ANGLE OF INTERNAL FRICTION AND COHESION

Tribologia ◽  
2017 ◽  
pp. 117-123 ◽  
Author(s):  
Artur WÓJCIK ◽  
Jarosław FRĄCZEK
Keyword(s):  
Internal Friction ◽  
Goodness Of Fit ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Complex Phenomenon ◽  
Plant Materials ◽  
Vast Number ◽  
Angle Of Internal Friction ◽  
Number Of Factors ◽  
The Impact

Internal friction in granular plant materials is a very complex phenomenon. This is due to a vast number of factors that determine the behaviour of these materials. This article looks at exploring the impact of porosity, the repose angle, and moisture on the value of the internal friction angle and cohesion. Statistical analysis showed that the influence of the examined factors on the parameters of friction is statistically significant. Nonlinear estimation was performed, which allowed developing functions describing the mentioned relationship, for which the goodness-of-fit (depending on the material type) ranged from 0.813 to 0.915 for the internal friction angle and from 0.748 to 0.963 in the case of cohesion. It has been found that internal friction and cohesion need further research that will take into account additional factors defining the examined material in a more accurate manner.

scholarly journals Numerical Modelling of Soil Arching in a Shallow Backfill Layer

2015 ◽  
Vol 15 (4) ◽  
pp. 127-137 ◽  
Author(s):  
Waldemar St. Szajna
Keyword(s):  
Internal Friction ◽  
Flexible Structures ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Plasticity Condition ◽  
Flow Rule ◽  
The Finite Element Method ◽  
Soil Arching ◽  
Plain Strain ◽  
The Impact

Abstract The paper presents the application of the finite element method into the modelling of soil arching. The phenomenon plays fundamental role in soil-shell flexible structures behaviour. To evaluate the influence of arching on a pressure reduction, a plain strain trapdoor under a shallow layer of backfill was simulated. The Coulomb-Mohr plasticity condition and the nonassociated flow rule were used for the soil model. The research examines the impact of the internal friction angle and the influence of the backfill layer thickness on the value of soil arching. The carried out analyses indicate that the reduction of pressures acting on a structure depends on the value of the internal friction angle, which confirms the earlier research. For a shallow backfill layer however, the reduction is only a local phenomenon and can influence only a part of the structure.

scholarly journals The Influence of Compaction and Water Conditions on Shear Strength and Friction Resistance between Geotextiles and Ash-Slag Mixture

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1086
Author(s):  
Andrzej Gruchot ◽  
Tymoteusz Zydroń ◽  
Agata Michalska
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Saturation ◽  
Friction Angle ◽  
Interaction Coefficient ◽  
Interfacial Friction ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Friction Resistance

The paper presents the results of tests of the shear strength of the ash–slag mixture taken from the landfill located in Kraków (Poland) and the interfacial friction resistance at the contact between the ash–slag mixture and woven or nonwoven geotextiles. The tests were carried out in a direct shear apparatus on samples with and without water saturation. The samples for testing were formed in the apparatus box at the optimum moisture by compacting them to IS = 0.90 and 1.00. The test results reveal that the shear strength parameters of the ash-slag mixture were large. It was stated the significant influence of the compaction, the growth of which has resulted in an increase in the angle of internal friction (from 7% to 9%) and cohesion (from 60% to 97%). Whereas the saturation of the samples reduced the shear strength parameters (from 4% to 6%, of the internal friction angle and 30% to 43% of cohesion). The values of the interfacial friction resistance at the contact between the ash–slag mixture and the geotextiles were large as well, but slightly smaller than the values of the shear strength parameters of the mixture itself. The compaction caused an increase in the angle of interfacial friction (from 1% to 5%) and adhesion (from 31% to 127%). The water-saturation of the samples caused a change in the angle of interfacial friction (from −6% to 3%) and decline in the adhesion (from 22% to 69%). Values of the interaction coefficient were about 0.8–1.0 and they tended to rise with increasing the normal stress. Higher values of this parameter were obtained in tests with water saturation and for non-woven geotextiles.

Characterisation of Titanium Powder Flow, Shear and Bulk Properties Using the FT4 Powder Rheometer

2014 ◽  
Vol 1019 ◽  
pp. 218-224 ◽  
Author(s):  
Silethelwe Chikosha ◽  
Linda M. Mahlatji ◽  
Hilda K. Chikwanda
Keyword(s):  
Particle Size ◽  
Internal Friction ◽  
Fine Powder ◽  
Friction Angle ◽  
Wall Friction ◽  
Flow Shear ◽  
Coarse Powder ◽  
Bulk Properties ◽  
Angle Of Internal Friction ◽  
Powder Rheometer

In order to reliably design and operate different powder processes, an understanding of the dynamic flow, shear and bulk properties of powders is required. Generally, powders are evaluated by several techniques that determine their flow, shear and bulk properties. The techniques can include compression tests, shear tests, angle of repose, flow of powder in a funnel, tapped density and many others. In order to minimize the number of instruments required to characterise the powder and eliminate operator error, automated powder rheometers that can do most of the required tests have been developed. The FT4 powder rheometer is one of these and has found widespread use in the pharmaceutical industry. In this study, the FT4 powder rheometer was used to characterise two metallic titanium powders with different particle sizes, namely CSIR Ti-45μm (Fine Powder) and CSIR Ti +45-180μm (Coarse Powder). Their particle size, particle size distribution, bulk densities, compressibility, cohesion, flowability index, effective angle of internal friction and wall friction angle were determined. Preliminary results of the study indicated that fine powder had a lower bulk density, was more compressible and more cohesive than the coarse powder. The fine powder had a lower flowability index compared to the coarse powder for both the Jenike and Peschl classification. The varying degrees of cohesion of these powders were confirmed by the cohesion values that were higher for the fine powder. The fine powder had a lower angle of internal friction but higher wall friction angle compared to the coarse powder.

An Experimental Study on the Mechanical Characteristics of Sandstone-Like Material with Preset Filling Joints

2013 ◽  
Vol 353-356 ◽  
pp. 644-649
Author(s):  
Xin Yu Liu ◽  
Ai Hua Liu ◽  
Bang Biao Wu
Keyword(s):  
Internal Friction ◽  
Uniaxial Compression ◽  
Shear Failure ◽  
Experimental Studies ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Filling Material ◽  
Shear Tests ◽  
Intact Specimen

This paper investigates the strength and deformation characteristics of the sandstone-like material containing the preset filling joints. The test specimens are designed with different height-diameter ratio. The uniaxial compression and shear tests were performed during the experimental studies. The results show that: (1) the failure models of the 3 kinds specimens including ones without joints, ones with "cruciform" joints and ones with "intersecting parallels" joints are similar to the general trend, e.g. X-shaped conjugated single-slope shear failure and single-slope shear failure under compression and shear tests ; (2) under uniaxial compression, the performance of intact specimen is clearly affected by its size, and the strength of jointed one is significantly affected by the weakening of the structure. This impact depends on the joints conditions, e.g. joint density, with filling material or without filling material; (3) Deformation modulus E and Cohesion c have no significant change for the 2 kinds jointed specimens, but the internal friction angle is obviously affected by joints and their fillings. The internal friction angle decreases rapidly with the increase of joints number.

scholarly journals Direct Shear Strength on the São Francisco River Bank, Northeastern Brazil, With or Without Roots of Different Native Species

2020 ◽  
Vol 9 (1) ◽  
pp. 146
Author(s):  
Igor Pinheiro da Rocha ◽  
Francisco Sandro Rodrigues Holanda ◽  
Mario Monteiro Rolim ◽  
Alceu Pedrotti ◽  
Marks Melo Moura ◽  
...  
Keyword(s):  
Internal Friction ◽  
Native Species ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Northeastern Brazil ◽  
Degree Of Saturation ◽  
Void Content ◽  
Direct Shear ◽  
River Bank ◽  
Angle Of Internal Friction

Several plant species have been studied as reinforcement elements against landslides at slopes, either to protect against the splash effect offered by shoots or anchoring the soil by the root system. The objective of this work was to investigate the influence of roots from shrub species over the soil mechanical attributes such as cohesion and angle of internal friction at the São Francisco riverbank, northeastern Brazil. A trench was excavated under the treetop of every shrubby individual, sampling blocks at 0-0.25, 0.25-0.50, 0.50-0.75, and 0.75-1.00 m depths. The moisture contents, particle size, liquidity limits, plasticity and actual specific mass of the samples were determined. The soil physical and mechanical attributes such as initial and final specific weight, initial and final void content, initial and final degree of saturation, shear resistance peaks, cohesion, and internal friction angle were identified through direct, elementary, consolidated, and undrained tests. In the samples with Solanum paniculatum, Mimosa pigra species, the highest values for cohesion were registered for the samples with roots. Sesbania virgata presented the greatest variation in cohesion and internal friction angle among samples with and without roots. The position and root status influenced the results of the direct shear tests.

scholarly journals Evaluation of the Impact of Hydrostatic Pressure and Lode Angle on the Strength of the Rock Mass Based on the Hoek–Brown Criterion

2015 ◽  
Vol 37 (2) ◽  
pp. 85-91
Author(s):  
Halina Marczak
Keyword(s):  
Rock Mass ◽  
Hydrostatic Pressure ◽  
Friction Angle ◽  
Stress Path ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Minimum Principal Stress ◽  
Lode Angle ◽  
The Impact

Abstract Determination of the global uniaxial compressive strength of rock mass on the basis of the Hoek-Brown failure criterion requires knowledge of the strength parameters: cohesion and the angle of internal friction. In the conventional method for the determination of these parameters given by Balmer, they are expressed by the minimum principal stress. Thus, this method does not allow for the assessment of an impact of hydrostatic pressure and stress path on the value of cohesion, friction angle and global uniaxial compression of rock mass. This problem can be eliminated by using the Hoek-Brown criterion expressed by the invariants of the stress state. The influence of hydrostatic pressure and the Lode angle on the strength parameters of the rock mass was analysed.

scholarly journals Cost Optimization of Cantilever Retaining Wall Using Flower Pollination Algorithm

2021 ◽  
pp. 915-930
Author(s):  
Arpit Mevada ◽  
Vishal Patel ◽  
Dr. Vishal Arekar
Keyword(s):  
Internal Friction ◽  
Structural Stability ◽  
Fitness Function ◽  
Retaining Wall ◽  
Cost Optimization ◽  
Friction Angle ◽  
Flower Pollination Algorithm ◽  
Angle Of Internal Friction ◽  
Flower Pollination ◽  
The Cost

The flower pollination algorithm is nature-inspired in which it mimics the pollination process of the flowers. In this study, the cost of the cantilever retaining wall is optimized, which includes the cost of concrete and the cost of reinforcement steel. The eight design variables define the geometry of the RC wall. The external stability and structural stability are considered as constraints. Overturning, sliding, eccentricity, and bearing are considered external constraints. The structural stability constraints are shear and moment failure of toe slab, heel slab, and stem. The fitness function is developed using a static exterior penalty. The study found that the FPA outperforms the non-dominated sorting genetic algorithm (NSGA-Ⅱ) in this design problem without violating any constraints. An analysis of sensitivity is carried out for the angle of internal friction of backfill soil and the angle of backfill slope. Results show that the total cost rapidly increases after 5 m height of backfill but significantly decreases with the internal friction angle of backfill increases. For backfill heights from 6 to 10 m, the change in cost is significant after the value of the inclination angle of 15°.

Influence of temperature on the hydrothermal clay soils' shear strength of the Nizhne-Koshelevsky and Verkhne-Pauzhetsky thermal fields.

2021 ◽  
Author(s):  
Ruslan Kuznetsov ◽  
Mikhail Chernov ◽  
Victoria Krupskaya ◽  
Ruslan Khamidov
Keyword(s):  
Internal Friction ◽  
Double Layer ◽  
Electric Double Layer ◽  
Geothermal Field ◽  
The Other ◽  
Clay Soils ◽  
Clayey Soils ◽  
Clay Particles ◽  
Angle Of Internal Friction ◽  
Thermal Fields

<p>Nizhne-Koshelevskoe and Verkhne-Pauzhetskoe thermal fields are located in the south of Kamchatka, the first - within the Koshelevsky volcanic massif, the second - on the territory of the Pauzhetsky geothermal field. The first horizon from the surface in these fields is formed by clayey soils, that have been formed as a result of hydrothermal alteration of volcanic rocks. And in the natural conditions clayey soils are at temperatures reaching 100 °C.</p><p>Samples of undisturbed clay soils were taken within the thermal fields. The samples are characterized by a density of 1.29 - 1.42 g/cm<sup>3</sup>, rather high values of the weight moisture (90-110%), and temperatures of 50 - 70 °C.</p><p>The samples are dominated by clay minerals: kaolinite and mixed-layer - kaolinite-smectite, their content is about 75%. The other 25% are microcline, cristobalite, anatase, gypsum, pyrite, marcasite, quartz and alunite.</p><p>For samples of undisturbed clay soils, direct shear tests were carried out at a temperature of 20 °C and at a temperatures of the samples close to their natural temperatures (50–70 °C). Thus, the values of cohesion and the angle of internal friction of the samples were determined.</p><p>The obtained results can be interfered as follows: as a result of an increase in the temperature of clayey soils, the thickness of electric double layer on the surface of clay particles decreases. On the one hand, it leads to a decrease of cohesion value between the clay particles and the beginning of shear deformations at lower vertical loads. On the other hand, a smaller thickness of electric double layer brings particles closer to each other, which is the reason for an increasing angle of internal friction and shear resistance at higher vertical loads.</p>

scholarly journals The impact of particle shape on the angle of internal friction and the implications for sediment dynamics at a steep, mixed sand–gravel beach

2014 ◽  
Vol 2 (2) ◽  
pp. 469-480 ◽  
Author(s):  
N. Stark ◽  
A. E. Hay ◽  
R. Cheel ◽  
C. B. Lake
Keyword(s):  
Internal Friction ◽  
Particle Motion ◽  
Particle Shape ◽  
Sediment Dynamics ◽  
Tidal Range ◽  
Strong Increase ◽  
Angle Of Internal Friction ◽  
Elliptic Plate ◽  
The Impact ◽  
Gravel Beach

Abstract. The impact of particle shape on the angle of internal friction, and the resulting impact on beach sediment dynamics, is still poorly understood. In areas characterized by sediments of specific shape, particularly non-rounded particles, this can lead to large departures from the expected sediment dynamics. The steep slope (1 : 10) of the mixed sand–gravel beach at Advocate Harbour is stable in large-scale morphology over decades, despite a high tidal range of 10 m or more, and intense shore-break action during storms. The Advocate sand (d < 2 mm) was found to have an elliptic, plate-like shape (Corey Shape Index, CSI ≈ 0.2–0.6). High angles of internal friction of this material were determined using direct shear, ranging from φ ≈ 41 to 49°, while the round to angular gravel was characterized as φ = 33°. The addition of 25% of the elliptic plate-like sand-sized material to the gravel led to an immediate increase in friction angle to φ = 38°. Furthermore, re-organization of the particles occurred during shearing, characterized by a short phase of settling and compaction, followed by a pronounced strong dilatory behavior and an accompanying strong increase of resistance to shear and, thus, shear stress. Long-term shearing (24 h) using a ring shear apparatus led to destruction of the particles without re-compaction. Finally, submerged particle mobilization was simulated using a tilted tray submerged in a water-filled tank. Despite a smooth tray surface, particle motion was not initiated until reaching tray tilt angles of 31° and more, being &amp;geq;7° steeper than for motion initiation of the gravel mixtures. In conclusion, geotechnical laboratory experiments quantified the important impact of the elliptic, plate-like shape of Advocate Beach sand on the angles of internal friction of both pure sand and sand–gravel mixtures. The resulting effect on initiation of particle motion was confirmed in tilting tray experiments. This makes it a vivid example of how particle shape can contribute to the stabilization of the beach face.

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