Stabilized‐coupled modelling of creep phenomena for saturated porous media

Abstract

The proposal of two models for simulating the behaviour of soils subjected to secondary consolidation (creep) is here described. In normal circumstances, settlements due to secondary consolidation account for only a small fraction of the total settlements, having a magnitude of a small percentage of the primary consolidation settlements due to compression. However, in a situation where very soft organic clays are under compression, secondary consolidation may be a much more important factor. The models are implemented in a fully coupled finite element code where the governing equations are discretized in time in accordance to what proposed by the characteristic-based split method, well known in Fluid Mechanics, obtaining a stabilizing split-type method. In this way, pressure oscillations (wiggles)-usually present in consolidation problems-have been eliminated. The first model assumes that the soil skeleton consists of a linear spring in series with a Kelvin body: the spring is representative of an elastic model, whereas the Kelvin body keeps count of a time-progressing strain, once the primary consolidation has stopped. The second model considers some Maxwell chains in parallel. Their efficiency is proved studying the long-term behaviour of soft soils; the results, compared with in situ measurements, show a good accuracy in predicting creep phenomena for soils

Time scales in the primary and secondary compression of soils

“…The layer is assumed to deform elasto–viscoplastically and modeled by the simple frictional‐link and dashpot system shown in Figure 2, where $$D$$ is the constrained elastic modulus of the spring and $$\cal H$$ is the constrained plastic modulus of the link. The setup readily reduces to a Maxwell viscoelastic model when the initial yield stress $$\sigma _0$$ and plastic modulus $$\cal H$$ are both zero 72,73 ; however, it does not reduce to the Kelvin arrangement 72,74,75 . The plastic modulus $$\cal H$$ can be made to be a nonlinear function of deformation to closely match real soil behavior, 76 but for now we shall assume it to be constant.…”

Coupling Biot and Navier–Stokes equations for modelling fluid–poroelastic media interaction

“…There is much less work for the stabilization of the Biot problem in mixed form. The work of Salomoni and Schrefler [71] is one effort in this direction: the authors have used the non-consistent characteristic-based splitting (CBS) algorithm to analyze creep phenomena in consolidation processes.…”

“…where a f is defined by (71) and f is a suitable function. Combining (74) to the fixed point iterations associated to (69) u kþ1…”

A two‐step Taylor‐characteristic‐based Galerkin method for incompressible flows and its application to flow over triangular cylinder with different incidence angles

“…Simultaneously, the CBS scheme and its extension have been applied widely for the solution of fluid and solid dynamic problems encountered in engineering, including general compressible and incompressible flows [22,[26][27][28][29][30], turbulent flows [18,31], shallow-water flows [14,32], thermal flows [33,34], porous medium flows [35][36][37][38], viscoelastic flows [39], solid dynamics [40] and bulk metal forming [41]. However, the application of the CBS algorithm to the flow over triangular cylinder with different incidences, which has fundamental fluid mechanics interest with respect to many technical applications, is not yet found 1183 in the existing literature, and that motivates us to numerically simulate this problem by using the characteristic-based method.…”