Abstract
SummaryThis paper presents a simple hypoplastic model capturing mostly all salient features of clays: rate dependency, time dependency and inherent and induced anisotropy without being restricted to only viscoplastic clays. Therefore, due to the strain rate decomposition into three parts, nonviscous clays, that is, rate‐independent clays, can also be simulated. The incorporation of a loading surface allows to capture the behaviour of normal and overconsolidated clays. The model requires eight material parameters, which are simple to calibrate from standard laboratory tests. In total, 77 simulations of five different clayey‐like soils are compared with experimental data. The simulations contain one oedometer test with loading–unloading–reloading cycles, creep and relaxation stages, both undrained and drained triaxial tests in compression and extension, as well as eight incremental response envelopes capturing also the directional response of Beaucaire Marl clay. Some limitations of the model such as the description of temperature effects on the behaviour of clays are also pointed out.
Highlights
There are a number of important geotechnical engineering problems—notably the analysis of soil–structure interaction in deep excavations, shallow foundations and tunneling—where large differences typically exist between stress paths experienced in different regions of the surrounding soil, both in terms of magnitude and direction[1,2,3,4] and in terms of time for most fine-grained soils.[5,6]
In hypoplastic constitutive equations, as well as for the proposed model, the Jaumann rate is used. To overcome these shortcomings and in order to obtain a conservative constitutive model for clays under purely elastic conditions, a hyperelastic stress–strain relation derived from an elastic potential is being developed by the authors
With the y-axis as the vertical direction representing the direction of anisotropy and the x z-plane as the plan of isotropy, the stress–strain increment equation for a transversal isotropic material considering the simplifications provided by Graham and Houlsby[42] can be expressed through the relation given in Equation (24), whereby Etrans is the transversal isotropic stiffness
Summary
There are a number of important geotechnical engineering problems—notably the analysis of soil–structure interaction in deep excavations, shallow foundations and tunneling—where large differences typically exist between stress paths experienced in different regions of the surrounding soil, both in terms of magnitude and direction[1,2,3,4] and in terms of time for most fine-grained soils.[5,6] the question arises if the fine-grained soil is normally consolidated or overconsolidated In these cases, the quality of the engineering prediction crucially depends on the ability of the adopted constitutive model to correctly describe the behaviour of the soil along a wide range of loading paths and rates. Components of the effective stress tensor σ or strain tensor ε in compression are negative
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: International Journal for Numerical and Analytical Methods in Geomechanics
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
