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 Recommended Procedures to Assess Critical State Locus from Triaxial Tests in Cohesionless Remoulded Samples

Geotechnics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 95-127
Author(s):  
António Viana da Fonseca ◽  
Diana Cordeiro ◽  
Fausto Molina-Gómez
Keyword(s):  
Critical State ◽  
Review Paper ◽  
State Theory ◽  
Soil Freezing ◽  
Triaxial Tests ◽  
Cohesionless Soils ◽  
Saturation Condition ◽  
Testing Procedures ◽  
Laboratory Procedures ◽  
Soil Behaviour

The critical state theory is a robust conceptual framework for the characterisation of soil behaviour. In the laboratory, triaxial tests are used to assess the critical state locus. In the last decades, the equipment and testing procedures for soil characterisation, within the critical state framework, have advanced to obtain accurate and reliable results. This review paper summarises and describes a series of recommended laboratory procedures to assess the critical state locus in cohesionless soils. For this purpose, results obtained in the laboratory from different cohesionless soils and triaxial equipment configurations are compiled, analysed and discussed in detail. The procedures presented in this paper reinforce the use of triaxial cells with lubricated end platens and an embedded connection piston into the top-cap, together with the verification of the full saturation condition and the measurement end-of-test water content—preferable using the soil freezing technique. The experimental evidence and comparison between equipment configurations provide relevant insights about the laboratory procedures for obtaining a reliable characterisation of the critical state locus of cohesionless geomaterials. All the procedures recommended herein can be easily implemented in academic and commercial geotechnical laboratories.

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 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.

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 A Laboratory Study on the Shear Strength Behavior of Two Till Deposits from Northern Germany

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1692
Author(s):  
Henok Hailemariam ◽  
Frank Wuttke
Keyword(s):  
Shear Strength ◽  
Laboratory Study ◽  
Elevated Temperatures ◽  
Constitutive Models ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Experimental Program ◽  
Soil Behavior ◽  
Northern Germany ◽  
Triaxial Cell

This paper presents the findings of a laboratory study of the shear strength and yielding behavior of two glacial till soil deposits from the area of Heiligenhafen, northern Germany. The tests were conducted on reconstituted forms of the soils using a triaxial cell capable of controlling the temperature of the specimens. The experimental program included a series of multi-stage consolidated drained (CD) compression triaxial tests at temperature ranges between 20 and 60 °C. For the temperature range considered in this study, a mild reduction in the effective friction angle of the two till soils of less than 1° was observed due to an increase in temperature from 20 to 60 °C. All the results were carefully assessed in view of the intrinsic soil behavior and fabric, and existing trends are highlighted. The findings of this study provide valuable insights into the shearing properties of till deposits, and can contribute to the enhancement of existing soil constitutive models as well as the development of new models that are particularly suited to the behavior of glacial tills under elevated temperatures.

scholarly journals Critical State Model of Sand-Tire Derived Aggregate Mixtures Based on Triaxial Tests

2021 ◽  
pp. 036119812199783
Author(s):  
Adolfo Foriero ◽  
Nima Ghafari
Keyword(s):  
Critical State ◽  
Axial Strain ◽  
Friction Angle ◽  
Critical State Model ◽  
State Model ◽  
Triaxial Tests ◽  
Experimental Program ◽  
Modified Cam Clay ◽  
Tire Derived Aggregate ◽  
Confining Pressures

This study is part of an environmental experimental program on the use of scrap automobile tires for geotechnical applications. Different types of laboratory tests were conducted to determine the elastic, plastic, and creep parameters of tire derived aggregate (TDA)-sand granulated mixtures. However, this paper emphasizes the plasticity parameters via the development of a critical state model based on the results of triaxial tests. This was attained by considering loose sand specimens, at a predetermined TDA volumetric content, subject to three different confining pressures under a constant axial displacement rate. The calculated deviatoric stress versus axial strain curves, obtained via the modified Cam Clay model, captured the non-linear elastoplastic response obtained in the tests. Results indicated that the level of the shear strength is highly dependent on critical state friction angle which in turn depends on the TDA content. For the loose TDA-sand mixtures used in the present study, the effect of the TDA content demonstrates a reinforcement of the sand matrix. However this reinforcement diminishes as the TDA content increases.

scholarly journals A Generalised Plastic Model for Gravelly Soils Considering Evolution of Void Ratio and Particle Breakage

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiuchang Zhang ◽  
Yue Li ◽  
Rubin Wang
Keyword(s):  
Relative Density ◽  
Critical State ◽  
Void Ratio ◽  
Volumetric Strain ◽  
Particle Breakage ◽  
Triaxial Tests ◽  
Plastic Model ◽  
Density State ◽  
Gravelly Soils ◽  
Stress Dependent

Gravelly soils exhibit complicated mechanical behaviours closely related to particle breakage and relative density state. To better capture the mechanical responses of gravelly soils, a generalised plastic model considering evolution of void ratio and particle breakage was developed within the framework of critical state soil mechanics. In the model, particle breakage effect was described by incorporating breakage index to deviate the critical state line off the ideal position. A differential equation relating increment of void ratio to variation of volumetric strain was used to depict the evolution of current void ratio. It indirectly reflected the relative density state of gravelly soils. The model was applied to conducting numerical simulations for a series of triaxial tests on four types of gravelly soils. Comparisons between the test data and the modelling results indicated that considerations of void ratio evolution and particle breakage could better simulate the stress-dependent dilatation/contraction behaviours of gravelly soils.

Effect of particle fabric on the coefficient of lateral earth pressure observed during one-dimensional compression of sand

2013 ◽  
Vol 50 (5) ◽  
pp. 457-466 ◽  
Author(s):  
Sheri Northcutt ◽  
Dharma Wijewickreme
Keyword(s):  
Relative Density ◽  
Stress Measurement ◽  
Earth Pressure ◽  
Friction Angle ◽  
Fraser River ◽  
Initial Particle ◽  
River Sand ◽  
One Dimensional ◽  
Lateral Earth Pressure ◽  
The One

The effect of initial particle fabric on the one-dimensional compression response of Fraser River sand was investigated. One-dimensional compression with lateral stress measurement was carried out on reconstituted Fraser River sand specimens using an instrumented oedometer. Laboratory specimens were reconstituted by air pluviation, tamping, and vibration and were prepared with an initial relative density ranging from medium loose to very dense. For Fraser River sand in one-dimensional compression, air-pluviated specimens yielded the highest values for the coefficient of lateral earth pressure at rest (Ko), tamped specimens produced the lowest Ko values, and vibrated specimens produced intermediate Ko values. The results from the present study demonstrate that specimens resulting from different laboratory reconstitution methods (i.e., different initial particle fabrics) exhibit different one-dimensional compression responses and produce different Ko values. A “fabric factor” was introduced to account for the effect of the initial particle fabric on the measured coefficient of lateral earth pressure at rest. Using the fabric factor, the constant volume friction angle, and the specimen relative density, a new empirical equation defining the coefficient of lateral earth pressure at rest during normally consolidated loading is proposed.

scholarly journals Observed and predicted behaviour of rail ballast under monotonic loading capturing particle breakage

2015 ◽  
Vol 52 (1) ◽  
pp. 73-86 ◽  
Author(s):  
Buddhima Indraratna ◽  
Qi Deng Sun ◽  
Sanjay Nimbalkar
Keyword(s):  
Critical State ◽  
Large Scale ◽  
Soil Mechanics ◽  
Confining Pressure ◽  
Particle Breakage ◽  
Shear Behaviour ◽  
Triaxial Tests ◽  
Triaxial Apparatus ◽  
Elastoplastic Constitutive Model ◽  
Constitutive Parameters

A substantial amount of experimental evidence suggests that the critical state envelope for ballast is nonlinear, especially at low confining pressure. To study the implications of this nonlinearity and the associated role of particle breakage, monotonically loaded drained triaxial tests were conducted using a large-scale cylindrical triaxial apparatus. A nonlinear critical state envelope is determined in the q–p′ and υ–lnp′ planes. Mathematical expressions for critical state stress ratio and specific volume are proposed to incorporate the evolution of particle breakage during monotonic shearing. In this paper, an elastoplastic constitutive model based on the critical state soil mechanics framework is presented to capture the salient aspects of stress–strain behaviour and degradation of ballast. Constitutive parameters were conveniently determined from large-scale laboratory tests. The model is able to predict the monotonic shear behaviour of ballast corroborating with the laboratory measurements. The proposed model is further validated using experimental results available from past independent studies.

scholarly journals Implication of end restraint in triaxial tests on the derivation of stress–dilatancy rule for soils having high compressibility

2019 ◽  
Vol 56 (6) ◽  
pp. 840-851 ◽  
Author(s):  
S. Muraro ◽  
C. Jommi
Keyword(s):  
Laboratory Tests ◽  
Constitutive Models ◽  
Deformation Mode ◽  
Friction Angle ◽  
Numerical Approach ◽  
Triaxial Tests ◽  
Material Behaviour ◽  
Definition Of ◽  
Experimental Findings ◽  
End Restraint

Constitutive models for soils are developed and validated against laboratory tests assuming these give representative information on the true material behaviour. However, data from standard laboratory tests reflect the sample response rather than the true material behaviour, due to nonuniformities in stresses and strains generated over the experimental test. The work examines the implications of end restraint on the definition of the stress–dilatancy rule of highly compressible soils with a finite element numerical approach. The numerical model replicates a reconstituted peat, typically characterized by a combination of high compressibility and high friction angle, which increases the severity of end restraint effects. Simulated results show that the global measurements from standard triaxial tests with rough end platens would not give the proper stress–dilatancy rule, if they were interpreted as the response of a single soil element at the constitutive level. Both overestimation and underestimation of the true dilatancy compared to the material response can be observed, depending on the deformation mode. To support the validity of the numerical results, experimental findings from drained triaxial tests on reconstituted peat are presented. Practical indications are given on how the standard interpretation of drained triaxial tests data on peats can be improved.

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