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.

Stress Path Tests on 100 mm Diameter Samples

1986 ◽  
Vol 2 (1) ◽  
pp. 133-137
Author(s):  
J. H. Atkinson ◽  
D. B. Clinton
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Test Results ◽  
Design Problems ◽  
Strain Behaviour ◽  
Engineering Design Problems ◽  
Geotechnical Design ◽  
Pore Pressure Response ◽  
The City ◽  
Test Stress

AbstractThe use of stress path tests is discussed in relation to geotechnical design, and a description is given of the triaxial test stress path apparatus developed at The City University.Test results are presented from a series of triaxial tests following stress paths commonly encountered in engineering design problems. These are compared with the results of conventional triaxial tests.The stress-strain behaviour and pore pressure response of soil are shown to be very much dependent on the stress path followed, and the advantages of using stress-controlled loading in triaxial tests is demonstrated.

Effect of consolidation history and stress path on hyperbolic stress–strain relations

1985 ◽  
Vol 22 (2) ◽  
pp. 172-176 ◽  
Author(s):  
Y. P. Vaid
Keyword(s):  
Stress Path ◽  
Triaxial Tests ◽  
Soil Deformation ◽  
Test Results ◽  
Stress Strain ◽  
Deviator Stress ◽  
Strain Behaviour ◽  
Stress Variable ◽  
Anisotropic Consolidation ◽  
Soil Behaviour

The hyperbolic approximation of the stress–strain behaviour of soil based on the results of conventional triaxial tests, which is used in incremental elastic analysis of soil deformation problems, is shown to be inapplicable for representing soil behaviour under anisotropic consolidation and different stress paths. Test results on a normally consolidated clay are presented to show that a separate hyperbolic representation of stress–strain behaviour is possible for each consolidation history and stress path if increment in deviator stress after consolidation, rather than deviator stress, is used as the stress variable. Hyperbolic parameters are thus shown to depend on test type.

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.

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 The influence of rubber crumbs on the critical state behavior of waste mixtures

2019 ◽  
Vol 92 ◽  
pp. 06004
Author(s):  
Buddhima Indraratna ◽  
Yujie Qi ◽  
Ana Heitor ◽  
Jayan S. Vinod
Keyword(s):  
Critical State ◽  
Geotechnical Properties ◽  
Triaxial Tests ◽  
Test Results ◽  
State Behavior ◽  
Steel Furnace ◽  
Waste Tyres ◽  
State Behaviour ◽  
Absorbing Property ◽  
Energy Absorbing

The practical application of waste materials such as steel furnace slag (SFS) and coal wash (CW) is becoming more prevalent in many geotechnical projects. It was found that the inclusion of rubber crumbs (RCs) from recycled tyres into mixtures of SFS and CW not only solves the problem of large stockpiles of waste tyres, it also can provide an energy-absorbing medium that will reduce track degradation. In order to investigate the influence of RC on the geotechnical properties of the granular waste matrix (SFS+CW+RC), a series of monotonic consolidated drained triaxial tests were conducted on waste mixtures. The test results reveal that the inclusion of RC significantly affects the geotechnical properties of the waste mixtures, especially their critical state behaviour. Specifically, the waste matrix can achieve a critical state with a low RC content (<20%), whereas those mixtures with higher RC contents (20-40%) cannot attain a critical state within the ultimate strain capacity that can be applied to specimens using the traditional triaxial equipment. Therefore, for the waste matrix with higher RC contents extrapolation of the measured volumetric strains had to be adopted to obtain the appropriate critical state parameters. Moreover, the influence of energy absorbing property by adding RC on the critical state behaviour has also been captured through an empirical equation.

UNDRAINED SHEAR STRENGTH OF K0 CONSOLIDATED SOFT CLAYS UNDER TRIAXIAL AND PLANE STRAIN CONDITIONS

2014 ◽  
Vol 06 (03) ◽  
pp. 1450032 ◽  
Author(s):  
QIUSHENG WANG ◽  
XIULI DU ◽  
QIUMING GONG
Keyword(s):  
Shear Strength ◽  
Plane Strain ◽  
Yield Surface ◽  
Critical State ◽  
Volumetric Strain ◽  
Stress Path ◽  
Undrained Shear Strength ◽  
Triaxial Tests ◽  
Soft Clays ◽  
Undrained Shear

Theoretical formulas for predicting the undrained shear strength of K0 consolidated soft clays under the stress path related to triaxial and plane strain tests are presented within the framework of critical state soil mechanics. An inclined elliptical yield surface is adopted to take account of the initial anisotropic stress state. The undrained strength is determined by combining the undrained stress path in the volumetric stress–strain space and the initial yield surface in the deviator-mean stress space. The derived mathematical expressions are functions of the critical state frictional angle, the plastic volumetric strain ratio and the overconsolidation ratio, which can be simplified into the solutions for isotropically consolidated clays under triaxial tests or under plane strain tests. The results calculated by using the theoretical formulas obtained in this paper are in good agreement with the available collected test results. It indicates that these new formulas are applicable to triaxial and plane strain tests on normally and lightly to moderately overconsolidated soft clays.

scholarly journals The Bearing Capacity of Circular Footings in Sand: Comparison between Model Tests and Numerical Simulations Based on a Nonlinear Mohr Failure Envelope

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Sven Krabbenhoft ◽  
Johan Clausen ◽  
Lars Damkilde
Keyword(s):  
Bearing Capacity ◽  
Yield Criterion ◽  
Friction Angle ◽  
Triaxial Tests ◽  
Test Results ◽  
Finite Element Program ◽  
Model Foundation ◽  
Element Program ◽  
Confining Pressures ◽  
Good Agreement

This paper presents the results of a series of triaxial tests with dry sand at confining pressures varying from 1.5 kPa to 100 kPa at relative densities of 0.20, 0.59, and 0.84. The results, which are in reasonable accordance with an equation given by Bolton, show that the friction angle is strongly dependent on the stress level and on the basis of the test results, a nonlinear Mohr failure criterion has been proposed. This yield criterion has been implemented in a finite element program and an analysis of the bearing capacity of a circular shaped model foundation, diameter 100 mm, has been conducted. Comparisons have been made with results from 1g model scale tests with a foundation of similar size and a good agreement between numerical results and test results has been found.

The Strength and Stress-Strain Behavior of the Cemented Rockfill

2012 ◽  
Vol 598 ◽  
pp. 565-568 ◽  
Author(s):  
Qi Wen Zheng ◽  
Chen Wang ◽  
Jian Wei Zhang
Keyword(s):  
Friction Angle ◽  
The Other ◽  
Triaxial Tests ◽  
Elastoplastic Material ◽  
Test Results ◽  
Maximum Volume ◽  
Volume Strain ◽  
Stress Strain ◽  
Strain Behavior ◽  
Mixing Proportion

The cemented rockfill is mixed with cement, water and the siltstone rockfill with a certain mixing proportion. To study the strength and stress-strain behavior of the cemented rockfill, two groups of triaxial tests are carried out under the saturated and consolidated-drained conditions. One group specimens don’t include cement while the other group specimens include. The test results show that the cemented rockfill is a kind of elastoplastic material and the structure of the cemented rockfill is forced due to the effect of cementation. Compared with rockfill, the initial tangent elastic modulus, strength and cohesion of the cemented rockfill increase apparently, the residual strength and internal friction angle of the cemented rockfill increase a little, the maximum volume strain of the cemented rockfill decreases apparently.

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 sphere packing model for shear bands in dense soils

2021 ◽  
Vol 249 ◽  
pp. 11003
Author(s):  
Calixtro Yanqui
Keyword(s):  
Shear Bands ◽  
Sphere Packing ◽  
Friction Angle ◽  
Plastic State ◽  
Granular Soils ◽  
Biaxial Test ◽  
Strain Behaviour ◽  
Coefficient Of Lateral Pressure ◽  
Soil Stress ◽  
Line Of Discontinuity

The rhombic sphere packing can be used to model the biaxial test on granular soils in a very simple way. According to the angle of assemblage, the packing is dilatant or contractive. Correspondingly, overall stresses are transmitted as chains of forces or oblique forces of contact. The connection of the soil stress-strain behaviour and the packing void ratio is achieved by mapping both of the plots. The mapping shows that dense soils are dilatant and loose soils are contractive, separated by the critical state. It also shows that the bifurcation point and the peak strength are features only of dense soils. The band of strain localization is analysed in the elastic regime, and its inclination is found maximizing the intensity of the mobilized stress ratio. The stresses within the shear band are obtained by assuming a partially coaxial packing rotated to reach the full plastic state. The equilibrium of the overall stress at the line of discontinuity reveals a relationship between the peak friction angle and the coefficient of lateral pressure at rest. As long as these parameters are obtained independently of each other, they allow the validation of the theory.

Sign in / Sign up

Export Citation Format

Share Document