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Summary: In this paper, we describe a soil‐fluid‐structure interaction model that combines soil mechanics (saturated sediments), fluid mechanics (seawater or air), and solid mechanics (structures). The formulation combines the Material Point Method, which models large deformation of the porous media and the structure, with the Implicit Continuous‐fluid Eulerian, which models complex fluid flows. We validate the model and simulate the whole process of earthquake‐induced submarine landslides. We show that this model captures complex interactions between saturated sediment, seawater, and structure, so we can use the model to estimate the impact of potential submarine landslides on offshore structures. [ABSTRACT FROM AUTHOR]

The thermodynamically based hyperplasticity framework is employed to develop a hyper-viscoplastic constitutive model describing clay's creep and rate-dependent behaviour. The proposed model complies with the concept of the isotache viscosity and the paradigm of the critical state soil mechanics that is the uniqueness of the critical state friction envelope. A versatile force potential or dissipation rate function is presented that provides adjustability of the location of the critical state while securing a unique critical state friction envelope. A non-associated flow rule as an essential property of frictional material is adopted by further development of the force potential. Adequacy of the proposed constitutive model is evaluated through the simulation of the triaxial tests conducted on Hong Kong marine deposits. [ABSTRACT FROM AUTHOR]

The Skempton pore pressure coefficient, B, is defined as the variation in pore pressure with the unit change in confining pressure under undrained conditions. The B parameter is an essential parameter to consider the coupled effects of solid–fluid compressibility and skeleton compressibility in a porous system. It is a key factor in exploring a possible definition of effective stress in frozen soil. However, limited experimental and theoretical research is available in the literature to give insight to the problem. Therefore, a series of B tests on frozen clay was conducted in this study. Results from these tests, along with tests on Ottawa sand, as available in the literature, are analysed considering the effect of the ice crystallisation mode on the skeleton stiffness. The measured B values were lower than expected compared with B values using models that consider single grain bulk stiffness. However, when the difference in bulk stiffness of ice and that of soil grains is considered, even an increase in pore volume, for an increase in fluid pressure, at constant Terzaghi effective stress is possible. The 'pore stiffness', which is different from the solid phase stiffness, can take a negative value and can be used to explain the low measured B values. [ABSTRACT FROM AUTHOR]

This paper presents a fully coupled thermo‐hydro‐mechanical (THM) model which simulates frost heave in fully saturated soils. The model is able to simulate the formation and growth of multiple distinct ice lenses. The basic equations of the system were derived using the continuum theory of mixtures, nonequilibrium thermodynamics, and fracture mechanics, considering skeleton deformation, water flow and heat transport. Central to this model is the coupled transport of mass due to the temperature gradient across the frozen fringe, which acts as the main driving force of the phenomenon. The model is formulated in terms of measurable physical properties and thus no ad hoc parametrization is required. In an ice‐lens‐free state, the system is solved as a continuum using the finite element method (FEM). It is then locally treated as a discontinuous system upon the formation of ice lens, by enriching the elements carrying the embedded ice lens(es) using the extended finite element method (X‐FEM). The accuracy and efficiency of the proposed model has been verified using several laboratory tests on Devon silt samples at different overburden pressures and thermal boundary conditions. Shut‐off pressures have been also estimated and compared with the experimental results. [ABSTRACT FROM AUTHOR]

Despite the prevalence of peat in northern areas of Europe and elsewhere, there are comparatively few case histories of carefully monitored embankments constructed directly on peat. In addition the use of relatively advanced and commercially available numerical models for prediction of the settlement in peat has only infrequently been documented. Practising geotechnical engineers lack advice on the use of such models and in particular on the selection of the input parameters. This paper demonstrates that a combination of routine oedometer tests, careful use of published correlations and simulations of independent data can provide reliable input parameters. The work demonstrates a good match between field measurements and simulations, but shows that it is difficult to model all stages of loading accurately with one set of input parameters. The user may need to focus on what specific output is critical and a number of analyses may be needed to obtain accurate prediction for all cases. Although the focus of the model used was on creep prediction, the work demonstrates that other benefits of using a finite-element analysis over hand calculations – such as modelling layers, buoyancy, variation in parameters such as permeability with strain and time – are perhaps more important than creep. [ABSTRACT FROM AUTHOR]

This paper gives a summary of some of the main findings of the EU founded project "Creep of geomaterials", CREEP. CREEP was an Industry-Academia Partnerships and Pathways (IAPP) project funded from the 7th Framework Programme (FP7/2007–2013) of the EC under grant agreement PIAG-GA-2011-286397. The project aimed at establishing a consensus in creep modelling within geotechnical engineering. The materials studied were clay, peat and frozen soils (permafrost). Throughout the project, research on material behaviour in laboratory and field studies was combined with numerical studies using existing and newly developed mathematical frameworks. This paper summarises some of the findings in the project, although the focus is on the developments in the field of soft soils and soft clay in particular. The paper presents a unified enhanced soft clay creep model, which takes into account anisotropy, structure and rate dependency of the material. The performance of the model is demonstrated through analysis of the Murro test embankment. In addition, the paper gives an overview of some characteristics for frozen soil and peat. Some of the considerations regarding, e.g. over consolidation ratio for clay with respect to strain rate are very much valid for peat and frozen soil as well. [ABSTRACT FROM AUTHOR]