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Implementing a soil stress-strain model with hysteretic damping in FLAC
Published in Christine Detournay, Roger Hart, FLAC and Numerical Modeling in Geomechanics, 2020
A model for the undrained stress-strain behaviour of cohesive soil has been explained and the application to the cyclic behaviour of soil illustrated. The model is formulated within the framework of critical state soil mechanics. Unlike the classical critical state models, Cam clay and modified Cam clay, this model has inelastic behaviour for overconsolidated clay. With the addition of small-strain elastic shear behaviour the model is shown to represent well the degradation, with shear strain amplitude, in the apparent shear modulus and equivalent viscous damping ratio. Also, as the number of soil parameters needed are few and well understood, the model is useful for investigation of the general features of the solutions to boundary value problems in soil dynamics. The particular version of the model implemented herein is for a lightly overconsolidated soil, which deforms in an undrained manner at constant mean principal effective stress.
Offshore site investigation
Published in White David, Cassidy Mark, Offshore Geotechnical Engineering, 2017
Critical state soil mechanics provides a framework that links the shear strength, and the dilatational or contractive response of soils when sheared, to the water content and effective stress level. Interpreting the plasticity index as the change in water content for a given ratio of shear strength (∼100) allows the compressibility to be expressed in terms of the plasticity index (Wroth and Wood 1978).
Taking groundwater into account in a drought plan
Published in Jan van ‘t Hoff, Art Nooy van der Kolff, Hydraulic Fill Manual, 2012
Jan van ‘t Hoff, Art Nooy van der Kolff
In critical state soil mechanics, the state parameter ψ is used to express the difference between void ratio and void ratio at critical state, for the same effective stress. This concept is used, among others, in liquefaction analysis and reference can be made to Section 8.6.2 for a basic explanation of this parameter.
The use of Eulerian finite element method in face stability analysis of shield tunnels in undrained clay
Published in European Journal of Environmental and Civil Engineering, 2021
Gang Zheng, Jibin Sun, Tianqi Zhang, Qi Fan, Jingbo Tong, Haizuo Zhou, Yu Diao
One of the most important development in geotechnical analysis may be the establishment of critical state soil mechanics, which impart further insights into the mechanical behaviour of the soils. To make use of the classical theory framework, the Eulerian FE method was extended to effective stress analysis. In this way, many advanced critical state soil models (Hong et al., 2017; Mašín, 2014; Stallebrass, 1990) can be adopted in the analysis. In this article, three-surface kinematic hardening (3-SKH) model (Stallebrass, 1990) was coded and incorporated into the analysis. This model was an extension of the Modified Cam Clay (MCC) model, which introduced two additional surfaces, i.e. the yield surface (YS) and the history surface (HS) inside a MCC critical state bounding surface (BS), as shown in Figure 6. The stiffness of the soil at a stress point within BS was defined according to the relative positions of current stress point and the three surfaces (more details about the model were shown in the Appendix). This extension makes it possible to accurately simulate the behaviours of the soil within the small strain range, so that the whole process of face collapse (from small deformation stage to large deformation stage) may be more realistically reproduced.
An extended modified cam clay model for improved accuracy at low and high-end stress levels
Published in Marine Georesources & Geotechnology, 2020
M. D. Liu, D.W. Airey, B. Indraratna, Z. Zhuang, S. Horpibulsuk
The Cam Clay model proposed by Roscoe et al. (Roscoe, Schofield, and Wroth 1958; Roscoe, Schofield, and Thurairajah 1963) has played an important role in the development of modern soil mechanics. The model elegantly combined various topics in soil mechanics into a coherent science, critical state soil mechanics. Not only was it the first proper constitutive model for soil, but also it remains the corner-stone for most geotechnical engineering computations. Since the 1960s constitutive modeling has been an active area of research in geomechanics. For the first three decades, the work was mainly concentrated on modeling the behavior of laboratory reconstituted soil, whereas more recent developments have focused on soils with “structure,” either found in nature or formed artificially (e.g., Lade 1977; Nova and Wood 1979; Gens and Nova 1993; Whittle and Kavvadas 1994; Baudet and Stallebrass 2001; Wheeler et al. 2003; Masin 2005; Horpibulsuk et al. 2010; Yan and Li 2011; Ouria 2017; Mohamadi, Wan, and Shen 2018).
Explicit stress–strain equations for modeling frictional materials
Published in Marine Georesources & Geotechnology, 2018
Kenneth J. Xu, Martin D. Liu, Buddhima Indraratna, Suksun Horpibulsuk
In Section 4, model parameters for 27 types of frictional materials are identified. Based on these data, a study on the model parameters is made here. The correlation between parameter Mf and Mv is shown in Figure 16. The range of final failure stress ratio is in a band of 0.5 to 2.5. This strength corresponds to critical state strength in critical state soil mechanics. The average value of strength is 1.5. The value of initial volumetric slope Mv is between 0 and 2.2. On average, the following relationship is obtained