Analysis and modelling of longitudinal deformation profiles of tunnels excavated in strain-softening time-dependent rock masses

Song, Fei; Rodríguez-Dono, Alfonso; Olivella, S.; Zhong, Zhen

doi:10.1016/j.compgeo.2020.103643

Cited by 42 publications

(65 citation statements)

References 66 publications

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“…The magnitude of the viscoplastic deformation is determined using the flow rule, which writes as where and are viscoplastic strain and viscosity, respectively. In contrast to purely plastic theories, the viscoplastic model allows the stress to exceed the yield surface and reside in a range determined by the overstress function 60 .…”

Section: Methodsmentioning

confidence: 99%

Cooling-induced reactivation of distant faults during long-term geothermal energy production in hot sedimentary aquifers

Kivi

Pujades

Rutqvist

et al. 2022

Sci Rep

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Deep geothermal energy (DGE) represents an opportunity for a sustainable and carbon-free energy supply. One of the main concerns of DGE is induced seismicity that may produce damaging earthquakes, challenging its widespread exploitation. It is widely believed that the seismicity risk can be controlled by using doublet systems circulating water to minimize the injection-induced pressure changes. However, cold water reinjection may also give rise to thermal stresses within and beyond the cooled region, whose potential impacts on fault reactivation are less well understood. Here, we investigate by coupled thermo-hydro-mechanical modeling the processes that may lead to fault reactivation in a hot sedimentary aquifer (HSA) in which water is circulated through a doublet. We show that thermal stresses are transmitted much ahead of the cooled region and are likely to destabilize faults located far away from the doublet. Meanwhile, the fault permeability mainly controls the fault reactivation timing, which entails the importance of employing appropriate characterization methods. This investigation is crucial for understanding the mechanisms controlling induced seismicity associated with DGE in a HSA and allows the success of future DGE projects.

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Section: Methodsmentioning

confidence: 99%

Cooling-induced reactivation of distant faults during long-term geothermal energy production in hot sedimentary aquifers

Kivi

Pujades

Rutqvist

et al. 2022

Sci Rep

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“…The time-dependent behaviour has been widely observed in laboratory tests for different types of rocks, such as rock salt (Sulem et al 1987;Wang et al 2013;Paraskevopoulou 2016;Chu et al 2019;Song et al 2020;Song 2021). Figure 1(a) shows a typical creep curve of rock samples, which can be usually characterised by four stages (Sterpi and Gioda 2009;Paraskevopoulou 2016): the instantaneous elastic response, the primary, the secondary and the accelerated creep stages.…”

Section: The Time-dependent Behaviour Of Geomaterialsmentioning

confidence: 99%

“…Based on the viscoelastic models, including Maxwell, Kelvin, Generalized Kelvin and Burgers models, some researchers developed theoretical solutions to analyse underground structures, such as circular openings (Brady and Brown 1986;Wang and Nie 2010;Wang et al 2020b), or supported tunnels (Lo and Yuen 1981;Sulem et al 1987;Pan and Dong 1991;El Naggar et al 2008;Mason and Abelman 2009;Fahimifar et al 2010;Nomikos et al 2011;Song et al 2018a, b;Chu et al 2021) excavated in time-dependent rocks. On the other hand, some researchers developed numerical approaches for modelling the excavation of tunnels in time-dependent geomaterials (Paraskevopoulou 2016;Paraskevopoulou and Diederichs 2018;Song et al 2020;Song 2021). However, none of these researches considered the anisotropy of geomaterials.…”

Section: Introductionmentioning

confidence: 99%

Modelling underground excavations in rock masses with anisotropic time-dependent behaviour

Song

Rodríguez-Dono

Farfan

2022

Geomech. Geophys. Geo-energ. Geo-resour.

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When modelling rock masses that behave anisotropically and in addition present a time dependent behaviour, it is relevant to select a constitutive model able to represent their actual behaviour realistically. This article presents an alternative anisotropic time-dependent constitutive model able to predict the coupling between anisotropic behaviour and time-dependent (or viscous) behaviour. The viscous behaviour is simulated with the Burgers model and all elastic springs and viscous dashpots are considered to exhibit transversely isotropic properties. The proposed constitutive model has been implemented in the finite element method software CODE_BRIGHT. To verify the basic anisotropic elastic solution, it has been compared with that of PLAXIS results. And to verify the isotropic viscoelastic solution, it has been compared with analytical solutions. Furthermore, the proposed constitutive model has been used to predict the behaviour of samples from laboratory tests. Finally, parametric analyses have been carried out to investigate the influence of different factors on tunnelling responses, including the selection of different constitutive models, anisotropy of initial stresses and anisotropy of material properties. The proposed model provides an alternative method for the preliminary design of geotechnical engineering works involving geomaterials that exhibit anisotropic time-dependent behaviour.Article highlights • An anisotropic time-dependent model has been implemented in CODE_BRIGHT and validated. • The model can predict the coupled anisotropic time-dependent behaviour of geomaterials. • Parametric analyses have been performed to study the influence of different factors in ground response.

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“…As known to all, the macromechanical properties of rock materials are very important for the design and construction of rock engineering, such as macroelastic modulus and macrofracture toughness [1][2][3][4]. The former is commonly obtained from unconfined compressive tests [5][6][7] and the latter from specific fracture tests, such as the short rod test [8] and notched semicircular bending (NSCB) test [9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Estimating Macrofracture Toughness of Sandstone Based on Nanoindentation

et al. 2021

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An upscaling method for estimating macrofracture toughness by nanoindentation results was proposed in this study. Grid nanoindentation tests were conducted on sandstone samples to obtain micromechanical properties of indents, including elastic modulus, hardness, and stiffness. Multifactor cluster analysis was then carried out to categorize the sandstone into five mechanical phases. Finally, the macrofracture toughness was predicted by using the macroelastic modulus of the sample and the critical energy release rate of the weakest phase. To verify this method, the upscaling result was compared with the macrofracture toughness measured by the notched semicircular bending (NSCB) test. The discrepancy in the macrofracture toughness from our method and the NSCB test was 8.8%, which was acceptable. Also, it is proved that our method can provide more accurate upscaling results compared to other methods.

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Analysis and modelling of longitudinal deformation profiles of tunnels excavated in strain-softening time-dependent rock masses

Cited by 42 publications

References 66 publications

Cooling-induced reactivation of distant faults during long-term geothermal energy production in hot sedimentary aquifers

Cooling-induced reactivation of distant faults during long-term geothermal energy production in hot sedimentary aquifers

Modelling underground excavations in rock masses with anisotropic time-dependent behaviour

Estimating Macrofracture Toughness of Sandstone Based on Nanoindentation

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