On the Stability of Underground Caves in Calcareous Rocks Due to Long-Term Weathering

Numerical simulation of underground excavations in an indurated clay using non-local regularisation. Part 1: formulation and base case

“…However, in the presence of localised plastic deformations, a fine discretisation of the domain is generally required and, consequently, 3D simulations tend to exceed conventional computational capacities. In those situations, two-dimensional (2D) plane strain analyses are, at present, the main alternative to incorporate localisation in the simulation of geotechnical problems such as the stability of slopes (Summersgill et al, 2017b) or underground excavations (Pardoen et al, 2015;Mánica et al, 2020a). Furthermore, in the case of flexible supports with completion close to the face (as in the GCS drift), the difference between 2D (plane strain) and 3D analyses tend to be small (Cantieni and Anagnostou, 2009).…”

“…As shown in Mánica et al (2018), the softening rate is closely related to the length scale parameter of the nonlocal regularisation l s . In fact, the selection of a softening rate for regularised simulations of boundary value problems involving quasi-brittle materials and localised deformations is not a trivial issue, as discussed in Mánica et al (2020a). In the model described in section 2, an explicit distinction is made between post-rupture and residual strengths (Eqs.…”

A finite deformation multiplicative plasticity model with non–local hardening for bonded geomaterials

“…However, given the high deformability typically observed in bonded soils when affected by mechanical and/or chemical bond degradation, geometric non-linearity may play an important role in some practical applications. These applications include: the evaluation of pile bearing capacity of offshore platforms (McLelland, 1988;King and Lodge, 1988); the modeling of subsidence phenomena associated to hydrocarbon extraction (Potts et al, 1988) and sinkhole formation (Mánica et al, 2020); the study of the effects of pile driving (Jardine et al, 2018); the interpretation of cone penetration tests under undrained or partially drained conditions (Ceccato and Simonini, 2017;Monforte et al, 2018;Martinelli and Galavi, 2021); the modeling of slow slope deformations in presence of significant modifications of the slope geometry (Conte et al, 2019). Notable exceptions are the recent works of Monforte et al (2019) who have extended to finite deformations the Gens-Nova model (Gens and Nova, 1993), and of Oliynyk and Tamagnini (2020), who presented a finite deformation version of the theory of hyperplasticity (Houlsby and Puzrin, 2007) and applied it to the micromechanically inspired plasticity model for bonded, crushable granular materials of Tengattini et al (2014).…”