The strength and dilatancy of sand

1992 ◽  
Vol 29 (3) ◽  
pp. 522-526 ◽  
Author(s):  
Y. P. Vaid ◽  
S. Sasitharan
Keyword(s):  
Relative Density ◽  
Triaxial Test ◽  
Friction Angle ◽  
Stress Path ◽  
Triaxial Tests ◽  
Confining Stress ◽  
Peak Friction Angle ◽  
Loading Direction ◽  
Dilation Rate ◽  
Unique Relationship

The effects of stress path and loading direction in the triaxial test on strength and dilatancy of sand are investigated. It is shown that the unique relationship observed between peak friction angle and dilation rate at peak in conventional triaxial tests is followed regardless of stress path, confining stress at failure, relative density, and the mode of loading (compression or extension). Key words : sand, peak friction angle, dilatancy, stress path, triaxial test.

scholarly journals VOLUME CHANGE BEHAVIOUR OF BANTING CLAY BY THE CONCEPT OF EFFECTIVE STRESS AND SHEAR STRENGTH INTERACTION

2020 ◽  
Vol 80 (2) ◽  
Author(s):  
Syahmizzi Ifwat Bin Azharnim ◽  
Mohd Jamaludin Md. Noor
Keyword(s):  
Shear Strength ◽  
Laboratory Test ◽  
Effective Stress ◽  
Volume Change ◽  
Triaxial Test ◽  
Axial Strain ◽  
Friction Angle ◽  
Stress Strain ◽  
Actual Volume ◽  
Unique Relationship

Effective stress and shear strength interaction which the stress – strain curves and mobilised shear strength envelope explained the actual volume change behaviour of the soils. The interaction that useful in prediction of stress – strain curves and unique relationship between Effective Mobilised Minimum Friction Angle and Axial Strain is important to predict the settlement at any effective stresses include the effective stress that not conducted in laboratory test. Consolidated drained triaxial test is conducted for saturated Banting CLAY and the volume change behaviour of Banting CLAY is presented from the concept of effective stress and shear strength interaction with the establishment of unique relationship between effective mobilised minimum friction angle with respect to axial strain and prediction of stress – strain curves for the saturated Banting CLAY.

scholarly journals Evaluation of Sand-Shell Mixture Behaviour for Breakwater Foundation

2016 ◽  
Author(s):  
Abbass Tavallali ◽  
Justine Mollaert
Keyword(s):  
Internal Friction ◽  
Relative Density ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Triaxial Tests ◽  
Direct Shear Tests ◽  
Different Depths ◽  
Sand Material

The available sand material for a breakwater foundation is mixed with shells. The shell percentage of the sand material is variable and percentages up to even 50% are observed. It is essential to evaluate the properties and the behaviour of the sand-shell mixture as this will form the improved breakwater foundation. In reality the backfilled sand of the breakwater foundation has different relative densities in different depths. In this study the mechanical properties of the sand-shell mixture for different relative densities are evaluated. For different relative densities of sand-shell mixture the direct shear tests and the consolidated undrained triaxial tests are carried out on some samples. The results of the experiments showed that the samples with higher relative density show a higher internal friction angle. However, for the samples with even low relative density, an internal friction angle of less than 32° is not observed. The volume variation of the samples with different relative densities are monitored. Samples with low relative density showed a contraction behaviour; resulting in an increase of the pore water pressure, a reduction of the effective strength and finally the samples become susceptible to liquefaction. While the samples with high relative density showed a dilatancy behaviour.

scholarly journals The Shear Strength and Dilatancy Behavior of Wheat Stored in Silos

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Changnv Zeng ◽  
Yuke Wang
Keyword(s):  
Relative Density ◽  
Quantitative Relationship ◽  
Friction Angle ◽  
Practical Method ◽  
Density Peak ◽  
Dilatancy Angle ◽  
Stored Wheat ◽  
Direct Shear Tests ◽  
Peak Friction Angle ◽  
Advanced Model

This paper focuses on the shear and dilatancy behavior of wheat stored in silos with various densities and normal stresses. The goal is to find a quantitative relationship modeling the peak friction angle and maximum dilatancy angle of wheat stored in silos. A total of 48 direct shear tests were carried out to research the evolution of shear and dilatancy of stored wheat in silos. It is revealed that strength of wheat in bulk attributes to the combination of frictional and dilatant during shearing, in particular attributing to its elliptic shape. An increase in relative density enhances the peak friction angle as well as the dilation. The relationships between relative density, peak friction angle, and dilatancy angle were presented based on the tests data and Bolton’s theory. Then an advanced model is developed to evaluate the peak shear behavior of wheat stored in silos considering the dilatancy of the stored wheat. It is a practical method to predict the strength and dilatancy behavior of wheat stored in silos.

Estimating in situ relative density and friction angle of nearshore sand from portable free-fall penetrometer tests

2020 ◽  
Vol 57 (1) ◽  
pp. 17-31
Author(s):  
Ali Albatal ◽  
Nina Stark ◽  
Bernardo Castellanos
Keyword(s):  
Strain Rate ◽  
Bearing Capacity ◽  
Relative Density ◽  
Free Fall ◽  
Friction Angle ◽  
Rate Coefficients ◽  
Triaxial Tests ◽  
Site Assessment ◽  
K Value

The friction angle of sand in the nearshore zone of Cannon Beach, Yakutat, Alaska, was estimated from the deceleration measured by a portable free-fall penetrometer (PFFP) at 72 test locations. A correlation between the relative density and PFFP’s maximum deceleration was developed from controlled PFFP deployments into sand of different relative densities. Two approaches were tested: (i) a correlation between relative density and friction angle and (ii) bearing capacity theory. For the former, laboratory vacuum triaxial tests were performed to adjust an existing correlation between relative density and friction angle for the tested nearshore sediments. In situ peak friction angles were then determined using this adjusted correlation and estimates of relative densities. The resulting in situ relative density and friction angle varied between 32%–88% and 44°–56°, respectively. Two bearing capacity–based methods suitable for shallow penetrations were tested. For this approach, equivalents of static cone resistance were determined from the measured decelerations considering the strain rate effect. A range of empirical strain rate coefficients K = 0.1–1.5 were tested. A K value between 0.2 and 0.4 yielded matching results between the two approaches. The estimated friction angles agreed well with expected values and may be applied to problems of sediment transport or early site assessment.

scholarly journals Behaviour of Uniform Drava River Sand in Drained Condition—A Critical State Approach

2020 ◽  
Vol 10 (17) ◽  
pp. 5733
Author(s):  
Vedran Jagodnik ◽  
Ivan Kraus ◽  
Sandi Ivanda ◽  
Željko Arbanas
Keyword(s):  
Relative Density ◽  
Critical State ◽  
Constitutive Models ◽  
Friction Angle ◽  
State Theory ◽  
Shear Behaviour ◽  
Triaxial Tests ◽  
River Sand ◽  
Drava River ◽  
The Difference

Numerous triaxial tests on sand and sand-like materials have been performed worldwide during the past several decades. Their results provided a development of the advanced soil constitutive models and laboratory testing devices, as well as the establishment of a worldwide database of different types of uniform sandy materials. From such research, the critical state and steady state theory has emerged as one of the most useful tool for the modelling of a soil behaviour. This paper presents the results of static drained tests performed on the uniform Drava River sand from the Osijek region in Croatia. The main aim was to determine the shear behaviour and critical state, given that these characteristics are mostly unknown for the tested sand material. A series of detail triaxial tests were performed in drained conditions for three different initial relative densities, DR, and two different loading directions; e.g., axial compression and axial extension. In total, 18 drained tests were performed. The study indicated that the value of 33.75∘ is the critical friction angle for the tested sand. The relative density of 57% is determined as the critical relative density. Additionally, the study confirmed the difference in critical state for compression and extension loading. In addition, the results indicate that the sample preparation procedure has an important impact on the critical state of loosely prepared sandy samples. These results give the first insights into the behaviour of the Drava River sand, which can generally contribute to the worldwide sand behaviour knowledge base.

scholarly journals Determination of Passive Failure Surface Geometry for Cohesionless Backfills

2020 ◽  
Author(s):  
Behzad Soltanbeigi ◽  
Adlen Altunbas ◽  
Ahmet Talha Gezgin ◽  
Ozer Cinicioglu
Keyword(s):  
Relative Density ◽  
Failure Surface ◽  
Friction Angle ◽  
Model Tests ◽  
Small Scale ◽  
Geometrical Parameters ◽  
Surface Geometry ◽  
Peak Friction Angle ◽  
Non Linear

Correct determination of the passive failure surface geometry is necessary for the design of retaining structures. The conventional theories assume linear passive failure surfaces even though it is known that the actual failure surfaces are non-linear. Many researchers claimed the appropriateness of a hybrid curved-linear method. This approach estimates the curved section by a log-spiral function, which then connects to the backfill surface with the conventional linear assumption. The main drawback here is that the geometric properties of the hybrid mathematical function is not directly related to the mechanical properties of soils. Thus, this study attempts to provide a mechanical description for the assumed geometrical parameters. For this purpose, a series of 1 g small scale retaining wall model tests, simulating passive failure, are conducted on two different backfill soils. The relative density is varied in the model tests and the resultant peak friction angles of the backfills are calculated as functions of failure stress state and relative density using a well-known empirical equation. Transparent sidewalls allow for visualization of the failure surface evolution, which is obtained by capturing images and analysing then through Particle Image Velocimetry (PIV) technique. Subsequently, the quantified slip zones are fitted with the hybrid curved-linear approach. The relationships between the peak friction angle and the geometrical characteristics of the best-fit log-spiral and linear functions are investigated. Obtained results are used to propose a set of equations that allow the estimation of non-linear passive failure surfaces as function of peak friction angle.

Static liquefaction of sands under multiaxial loading

1998 ◽  
Vol 35 (2) ◽  
pp. 273-283 ◽  
Author(s):  
M Uthayakumar ◽  
Y P Vaid
Keyword(s):  
Steady State ◽  
Hollow Cylinder ◽  
Void Ratio ◽  
Friction Angle ◽  
Stress Path ◽  
Shear Loading ◽  
Multiaxial Loading ◽  
Fundamental Study ◽  
Torsional Shear ◽  
Loading Direction

A fundamental study of the undrained behaviour of sands under multiaxial loading is presented. The investigation was carried out using Fraser River and Syncrude sands in a hollow cylinder torsional shear device. Shear loading was carried out under strain control to capture the postpeak strain-softening characteristics of loose sands. It is shown that the undrained response of loose sands is highly dependent on the loading direction. The friction angle mobilized at phase transformation and steady state is a unique material property, independent of the mode of loading, direction of principal stress and initial consolidation stress, and void ratio state. There is no unique relationship between steady state strength and void ratio which is independent of stress path and the level of initial confining stress.Key words: anisotropy, hollow cylinder torsional shear, liquefaction, sand, simple shear, triaxial.

Transversely isotropic stiffness parameters and their measurement in Colorado shale

2006 ◽  
Vol 43 (12) ◽  
pp. 1290-1305 ◽  
Author(s):  
Rajeeb Gautam ◽  
Ron CK Wong
Keyword(s):  
Triaxial Test ◽  
Transverse Isotropy ◽  
Transversely Isotropic ◽  
Torsion Test ◽  
Stress Path ◽  
Small Strain ◽  
Loading Path ◽  
Triaxial Tests ◽  
Isotropic Elasticity ◽  
Colorado Shale

Drained stress path triaxial tests and confined torsion tests were conducted on Colorado shale core samples to investigate transversely isotropic stiffness parameters at small strain deformation. Nonlinear plastic behaviour occurred along the primary loading path even at strains less than 0.01%. Nonlinear, hysteric behaviour was only observed during the loading–unloading path. However, the shale material displayed transverse isotropy in deformation, and very small or nondetectable Poisson's ratios in vertical and horizontal directions. This special response alludes to the postulate that the Colorado shale could be approximated by a transversely isotropic elasticity model at small strain levels with negligible yielding.Key words: anisotropy, elasticity, stiffness, triaxial test, torsion test, shale.

An experimental examination of the critical state and other similar concepts for granular soils

1995 ◽  
Vol 32 (6) ◽  
pp. 1065-1075 ◽  
Author(s):  
J. Chu
Keyword(s):  
Critical State ◽  
Friction Angle ◽  
Stress Path ◽  
Dense Medium ◽  
Triaxial Tests ◽  
Granular Soils ◽  
Test Results ◽  
Dense Sand ◽  
Strain Behaviour ◽  
Series Of Experiments

Measuring the critical state parameters of dense granular soil by drained triaxial tests is problematic, as significant nonhomogeneous deformations can develop prior to approaching a critical state. This leads to further questions on the verification of the critical state concept for granular soils. In this study a new testing method, which enables the critical state of dense sand to be measured in the homogeneous deformation region, was adopted to measure the critical state of dense sand and to examine the critical state concept. A series of experiments was carried out to measure the critical state for dense, medium dense, and loose sand. The test results show that although a unique critical state curve may exist, the critical state friction angle is not constant but stress level dependent. The other similar concepts, namely, the phase transformation state, the characteristic state, and the steady state, were also examined, and the relationships among these states were established. Key words : critical state, granular soils, stress path, stress–strain behaviour, triaxial test.

Effects of Stress Path and Stress History on the Stiffness of Reconstituted London Clay

1986 ◽  
Vol 2 (1) ◽  
pp. 139-144 ◽  
Author(s):  
J. H. Atkinson ◽  
J. S. Evans ◽  
D. Richardson
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Parameters ◽  
Stress History ◽  
Strain Behaviour ◽  
Reconstituted Soil ◽  
Path Dependent ◽  
London Clay ◽  
Soil Behaviour

AbstractSoil behaviour is stress history dependent and stress path dependent and soil parameters, particularly those for stress-strain behaviour, measured in conventional triaxial tests may not represent the behaviour of soil in many civil engineering works.To obtain more realistic parameters it may be necessary to conduct laboratory tests which more closely represent in situ conditions before and during construction.The paper describes equipment developed at The City University to carry out stress path tests simply and economically. A series of CU triaxial tests and stress path tests on reconstituted soil illustrate the dependence of measured soil parameters on stress history and stress path.

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