scholarly journals An Elastic-Viscoplastic Model for Time-Dependent Behavior of Soft Clay and Its Application on Rheological Consolidation

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Jinzhu Li ◽  
Wenjun Wang ◽  
Yijun Zhu ◽  
Haofeng Xu ◽  
Xinyu Xie

To describe the time-dependent behavior of soft clay, this paper extended one-dimensional Nishihara model to three-dimensional stress state based on the framework of Perzyna’s overstress theory and modified cam-clay model. The yield criterion of modified cam-clay model was used to describe the plastic properties of soft clay, and the overstress theory was used to describe the strain rate effect. Triaxial rheological tests were carried out on Ningbo soft clay and the rheological characteristics were studied. Based on laboratory results, the parameters of proposed model were determined by curve fitting, which show that this model is suitable for the rheological characteristics of Ningbo soft clay. The analysis of parameters shows that, the value of parameters changes slightly with different deviatoric stress when the confining pressure was constant, but changes notably with the increase of confining pressure. A user material subroutine of the proposed constitutive mode was coded on the platform of the FEM software ABAQUS and verified by triaxial compression of soil column. A plain strain problem was computed to analyze the rheological consolidation properties of soft clay, in which the rheological effect and the finite strain effect were considered.

2009 ◽  
Vol 25 (1) ◽  
pp. 27-40 ◽  
Author(s):  
C.-Y. Ou ◽  
C.-C. Liu ◽  
C.-K. Chin

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.


Author(s):  
Aleksandar D. Spasojević ◽  
Dejan M. Divac ◽  
Nenad M. Šušić

2018 ◽  
Vol 4 (3) ◽  
pp. 518
Author(s):  
Tao Cheng ◽  
Yi Zhang ◽  
Keqin Yan

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.


Author(s):  
Yuki YAMAKURI ◽  
Shun-ichi KOBAYASHI ◽  
Jun SAITO ◽  
Tatsunori MATSUMOTO

2013 ◽  
Vol 671-674 ◽  
pp. 357-362
Author(s):  
Hai Ming Liu ◽  
Jing Cao ◽  
Wei Feng Zhang

With the continuous development of urban underground space, the environmental effects of foundation pit excavation have been paid extensive close attention. Unfortunately, there are few researches in mucky soil and peaty soil. Adopted the software of FLAC-3D, the ground deformation due to the foundation pit excavation is simulated. Considering the characteristic of the soil, the Modified Cam-clay model and Mohr-coulomb model are used during the simulation. Meanwhile, the structure units are used to simulate foundation pit structure. The results of the field measurement and numerical simulation suggest that the influenced range soil is about 2.7 times of the excavation depth. Furthermore, the Modified Cam-clay model can obtain a better result to simulate the mucky soil and peaty soil in Kunming. The results can be referred to design and construct of foundation pits.


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