A New Elasto-Plastic Critical State Model RU+MCC for Overconsolidated Soil

2016 ◽  
Vol 837 ◽  
pp. 68-74
Author(s):  
Rafal Uliniarz
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Small Strain ◽  
Computer Code ◽  
Constitutive Law ◽  
Isotropic Hardening ◽  
Loading Test ◽  
Modified Cam Clay ◽  
Soil Behaviour ◽  
Cam Clay

The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

Effects of fines on liquefaction behaviour in well-graded materials

2017 ◽  
Vol 54 (10) ◽  
pp. 1460-1471 ◽  
Author(s):  
Katherine A. Kwa ◽  
David W. Airey
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
State Parameter ◽  
Triaxial Tests ◽  
Particle Sizes ◽  
Graded Materials ◽  
Fines Content ◽  
Cyclic Resistance ◽  
Wide Range ◽  
Soil Behaviour

This study uses a critical state soil mechanics perspective to understand the mechanics behind the liquefaction of metallic ores during transport by ship. These metallic ores are transported at relatively low densities and have variable gradings containing a wide range of particle sizes and fines contents. The effect of the fines content on the location of the critical state line (CSL) and the cyclic liquefaction behaviour of well-graded materials was investigated by performing saturated, standard drained and undrained monotonic and compression-only cyclic triaxial tests. Samples were prepared at four different gradings containing particle sizes from 9.5 mm to 2 μm with fines (<75 μm) contents of 18%, 28%, 40%, and 60%. In the e versus log[Formula: see text] plane, where e is void ratio and [Formula: see text] is mean effective stress, the CSLs shifted upwards approximately parallel to one another as the fines content was increased. Transitional soil behaviour was observed in samples containing 28%, 40%, and 60% fines. A sample’s cyclic resistance to liquefaction depended on a combination of its density and state parameter, which were both related to the fines content. Samples with the same densities were more resistant to cyclic failure if they contained higher fines contents. The state parameter provided a useful prediction for general behavioural trends of all fines contents studied.

scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

scholarly journals Experimental Study of Silty Clay Plane Strain Tri-axial Test under RTC Path and Modified Cam-clay Model

2018 ◽  
Vol 4 (3) ◽  
pp. 518
Author(s):  
Tao Cheng ◽  
Yi Zhang ◽  
Keqin Yan
Keyword(s):  
Plane Strain ◽  
Stress Path ◽  
Physical Parameters ◽  
Silty Clay ◽  
Model Framework ◽  
Loading Test ◽  
Clay Model ◽  
Modified Cam Clay ◽  
Institute Of Technology ◽  
Cam Clay

The character of geomaterials is affected by stress path remarkably. Under different stress paths, the stress-strain characteristics of geomaterials are difference. For the unloading path in existing engineering situation, the physical parameters and constitutive model is usually determined by loading test. The path to uninstall the actual project conditions which may be a larger error. Therefore, this work proceeding from the actual project, deep excavation of the lateral unloading condition is analysed. The tests of CTC path and RTC path on silty clay in Huangshi city of china by multi-path tri-axial plane strain are carried on in the geotechnical Engineering Laboratory of Huangshi Institute of Technology. Then, the phenomenon under the two stress paths are compared with each other and describing the differences between them. The mechanical properties in the RTC stress path is analyzed mainly. Based on the Cam-Clay model framework, then derived this material yield equation based on Cam-clay model, Laiding the foundation for the numerical analysis.

Description of compression behaviour of structured soils and its application

2014 ◽  
Vol 51 (8) ◽  
pp. 921-933 ◽  
Author(s):  
Chao Yang ◽  
John P. Carter ◽  
Daichao Sheng
Keyword(s):  
Soil Mechanics ◽  
Sensitivity Coefficient ◽  
Stress Sensitivity ◽  
Compression Behaviour ◽  
Structure Degradation ◽  
Modified Cam Clay ◽  
Structured Soils ◽  
Series Of Experiments ◽  
Normal Compression ◽  
Cam Clay

One of the most distinct characteristics of structured soils is the nonlinearity in the normal compression lines in a plot of specific volume or voids ratio against logarithmic mean or vertical effective stresses, when compared with reconstituted soils. The change in the compressibility (or compression index) with loading is attributed to structure degradation and is expressed as a function of the plastic straining. A direct description of the compression behaviour of structured soil is then established. The validity of this approach is examined via merely incorporating the newly defined normal compression line into the modified Cam-Clay constitutive model. Comparisons against a series of experiments on different types of soils illustrate the feasibility and advantage of the adopted methodology. The dependence of shear strength on the compression behaviour considered initially in critical-state soil mechanics is reemphasized here for structured soils. Analysis also indicates that the stiffness sensitivity coefficient, Sλ, should be considered together with the traditional strength (or stress) sensitivity coefficient, St (or Sσ), to better characterize the sensitivity of structured soils.

Soil mechanics: breaking ground

2007 ◽  
Vol 365 (1861) ◽  
pp. 2985-3002 ◽  
Author(s):  
Itai Einav
Keyword(s):  
Grain Size ◽  
Critical State ◽  
Void Ratio ◽  
Soil Mechanics ◽  
Constitutive Models ◽  
Energy Balance Equation ◽  
Constitutive Modelling ◽  
Alternative Theory ◽  
Fitting Parameters ◽  
Cam Clay

In soil mechanics, student's models are classified as simple models that teach us unexplained elements of behaviour; an example is the Cam clay constitutive models of critical state soil mechanics (CSSM). ‘Engineer's models’ are models that elaborate the theory to fit more behavioural trends; this is usually done by adding fitting parameters to the student's models. Can currently unexplained behavioural trends of soil be explained without adding fitting parameters to CSSM models, by developing alternative student's models based on modern theories? Here I apply an alternative theory to CSSM, called ‘breakage mechanics’, and develop a simple student's model for sand. Its unique and distinctive feature is the use of an energy balance equation that connects grain size reduction to consumption of energy, which enables us to predict how grain size distribution (gsd) evolves—an unprecedented capability in constitutive modelling. With only four parameters, the model is physically clarifying what CSSM cannot for sand: the dependency of yielding and critical state on the initial gsd and void ratio.

Undrained triaxial strength and stress–strain characteristics of a glacial till soil

1988 ◽  
Vol 25 (3) ◽  
pp. 428-439 ◽  
Author(s):  
J. H. Atkinson ◽  
J. A. Little
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Triaxial Compression ◽  
Practical Importance ◽  
Small Strain ◽  
Compression Tests ◽  
Triaxial Strength ◽  
Current State ◽  
Boulder Clay ◽  
Triaxial Compression Tests

Undrained triaxial compression tests were carried out on reconstituted and nominally undisturbed tubed samples of a lodgement till from the Vale of St. Albans in Hertfordshire, England. The soil is a matrix-dominant, chalky boulder clay of Anglian age with little discernable engineering fabric. Electron microscope observations showed the presence of crystalline calcite in tube samples.The test results were examined within the general framework of critical state soil mechanics using normalizing procedures to take account of the different states and stress histories of the samples. These analyses demonstrate the practical importance of accounting for the current state and stress history in the interpretation of soil test data.The present results form a self-consistent pattern of behaviour. Differences between reconstituted and tubed samples were found only at small strain and may be attributed to cementing in tubed samples, which is broken down during reconstitution and during relatively large straining in recompression and shearing. Key words: boulder clay, cemented soil, critical state, shear strength, soil mechanics, stiffness, till, triaxial test.

Development of Time Dependent Stress-Strain Simulation of Clay

2009 ◽  
Vol 25 (1) ◽  
pp. 27-40 ◽  
Author(s):  
C.-Y. Ou ◽  
C.-C. Liu ◽  
C.-K. Chin
Keyword(s):  
Constitutive Law ◽  
Time Dependent ◽  
Soil Behavior ◽  
Creep Tests ◽  
Clay Model ◽  
Model Sets ◽  
Dependent Behavior ◽  
Modified Cam Clay ◽  
Parametric Studies ◽  
Cam Clay

AbstractThe objective of this study is to derive a time dependent effective based constitutive law on the basis of framework of the Modified Cam-Clay model. This model takes into account the anisotropic characteristics and creep behavior, based on the theory of viscoplasticity. The model sets the initial yield surface symmetric to the Ko line for modeling the initial Ko condition. A method is then developed to compute the gyration and expansion of the loading surface to simulate the anisotropic behavior due to the principal stress gyration after shear. The creep or time dependent behavior is considered in the model by adopting Kutter and Sathialingam's model, which was derived from Taylor's secondary consolidation theory and Bjerrum's delayed compression model. Compared with the Modified Cam-Clay model, the model requires five additional parameters to describe the soil behavior. All of the additional parameters can be obtained through conventional soil tests or parametric studies. The model is evaluated through a series of simulation of undrained shear tests and undrained creep tests.

scholarly journals Description of Limit States in the Subsurface Layer of Loosened Subsoil in View of Critical State Soil Mechanics

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7288
Author(s):  
Jan Fedorowicz ◽  
Lidia Fedorowicz ◽  
Marta Kadela
Keyword(s):  
Safety Assessment ◽  
Soil Mechanics ◽  
Limit State ◽  
Subsurface Layer ◽  
Limit States ◽  
Modified Cam Clay ◽  
In Situ Observations ◽  
Model C ◽  
Cam Clay

The article aims to present an effective numerical method for the behaviour analysis and safety assessment of a subsurface layer of subsoil in the existing or predicted states of mining and post-mining deformations. Based on our own analytical record, using the equations of the Modified Cam-Clay model, the description of limit states in the subsurface layer of subsoil was validated, making it consistent with in situ observations. The said effect was demonstrated by comparing numerical analyses of the subsoil layer subjected to the limit state, using the Modified Cam-Clay (MCC) model and the Coulomb-Mohr model (C-M). The article also presents the applicability potential of the numerical analysis of the loosened subsoil layer for the assessment of protection elements (e.g., geo-matresses) used under linear structures in the areas subjected to mining and post-mining impacts.

Sign in / Sign up

Export Citation Format

Share Document