Supported Axisymmetric Tunnels Within Linear Viscoelastic Burgers Rocks

Nomikos, Pavlos; Rahmannejad, Reza; Sofianos, A.I.

doi:10.1007/s00603-011-0159-0

Cited by 120 publications

(34 citation statements)

References 27 publications

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“…Burgers model is one of the most successful constitutive laws that have been used to model creep behaviour of rocks 1,25,[31][32][33][34][35][36][37] . Burgers model possesses instantaneous deformation Fig.…”

Section: Analysis Of Creep Modelmentioning

confidence: 99%

Creep properties of intact and fractured muddy siltstone

Omar

Stace

2018

International Journal of Rock Mechanics and Mining Sciences

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Time-dependent characterisation of rocks for the entire strain range (i.e. up to and beyond the yield point, where rocks are expected to be fractured) have received considerable attention for improving the long-term stability of deep underground openings. Although extensive experimental studies have been carried out on creep of different types of rocks, very limited studies exist, which investigate intact as well as fractured rock samples taken from the same type of rock. In this paper, the time-dependent behaviour of muddy siltstone was investigated to determine and compare creep properties of intact and fractured rock samples. A series of multistage uniaxial and triaxial creep tests were conducted on the rock samples at room temperature. In addition, multistage triaxial testing was conducted on the rock (intact and fractured) to determine the instantaneous (short-term) stiffness and explore its correlation with creep properties. All stain curves showed an initial instantaneous strain followed by two phases of timedependent strain including transient creep phase (particularly for the first loading stage) and a steady state creep phase. The results indicate that both the instantaneous and creep strain are proportional to the deviatoric stress and confining pressure. This is clearly evident in the fractured rock samples, where larger deviatoric stress resulted in an increased creep strain and strain rate. The relationship between axial strain and time was successfully fitted to Burgers creep model. In comparison with the intact rock, creep parameters (of the Burgers model) for the fractured rock were found to be significantly smaller, corresponding to the larger creep deformation and steady-state creep rate experienced by the fractured rock samples. Despite this difference between the intact and fractured rock samples, the study showed a considerable correlation between the creep parameters of both types of rock samples and their instantaneous elastic modulus (obtained at typical confining pressures). Regression analysis revealed that creep parameters could be reasonably estimated from instantaneous elastic modulus using an exponential function. Furthermore, based on the experimental findings, an improved characterisation of timedependent properties was proposed. We believe this approach provides a good basis for future research to enhance geotechnical modelling of long-term stability of abandoned mines as well as for the application of underground disposal of radioactive waste and oil and gas storage.

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Section: Analysis Of Creep Modelmentioning

confidence: 99%

Creep properties of intact and fractured muddy siltstone

Omar

Stace

2018

International Journal of Rock Mechanics and Mining Sciences

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“…The most well‐known constitutive laws used for creep behavior can be divided into two groups: Viscoelastic models (e.g. Maxwell, Kelvin & Burger models) , the power low model, and the Waste Isolation Pilot Plant (WIPP) empirical model . Visco‐elastoplastic models. The most well known models in this group are the Burger model (Cvisc), the power law viscoplastic model (Cpower) , and the visco‐plastic WIPP model (Pwipp) . …”

Section: Parameters Affecting Oil Storage In Salt Cavernsmentioning

confidence: 99%

Analysis of the behavior of large underground oil storage caverns in salt rock

Mortazavi

Nasab

2016

Int. J. Numer. Anal. Meth. Geomech.

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The storage of petroleum products above ground surface has many constraints and limitations. A viable alternative is to excavate large underground spaces in rock to provide a safer way for oil storage. Soft rock formations such as salt domes provide suitable conditions from environmental and operational aspects. The potential for high volume storage and low permeability are among advantages of oil storage in caverns excavated in salt rocks. The complicated shape of oil storage caverns, complex behavior of salt rock, and boundary conditions associated with large underground openings are major challenges in the design of salt caverns excavated for oil storage purposes. In this study, the deformation mechanism and stability of salt caverns were investigated. A comprehensive 3D numerical study was carried out to investigate the effects of cavern size and depth, salt rock deformation modulus, and ground in-situ stress regime on the behavior of large salt caverns. The stress field and deformation mechanisms were studied numerically aiming at shedding lights into the design aspects of salt caverns for oil storage. The analysis results show that the cavern safety factor is reduced as a function of cavern depth and storage volume. Also, with decrease in k (ratio of horizontal to vertical in-situ stress), the stability of salt caverns will increase; however, with increase in salt rock young modulus, the sensitivity of cavern stability to k ratio is reduced. The Pwipp constitutive model was used in the numerical analysis. This model gives a good description of salt rock creep behavior under varying stress levels. This model also is calibrated based on laboratory and field testing [25]. A set of parameters given for the Pwipp model by [11] was used in the presented study (see Table I). Figure 16. Run no.16 stability analysis results (volume 1, E = 18 GPa, k = 0.75): a) Cavern wall displacement history, b) contours of minimum principal stress distribution, c) safety factor along measuring lines, d) contours of wall safety factor, e) SFR change along measuring lines, f) contours of SFR change. [Colour figurecan be viewed at wileyonlinelibrary.com]

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“…Sulem et al 1987, Pan & Dong 1991, Nomikos et al 2011), numerical (e.g. Ghaboussi & Gioda 1977, Boidy et al 2002, Debernardi 2008, Fortsakis 2012), statistical (e.g.…”

Section: Introductionmentioning

confidence: 98%

Influence of rock mass creep on tunnel loading

Fortsakis

Kalos

Despotaki

et al. 2013

Rock Mechanics for Resources, Energy and Environment

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Rock mass creep in tunnelling through weak rock masses under high overburden may lead to the potential development of significant convergence. Should this convergence be restrained by a rigid support shell, tunnel loading tends to increase. Although, such increase could be significant, it is often not taken into account in design, due to uncertainties in the calculation procedure. This paper proposes a simplified approach for estimating the additional creep loads on the lining of circular tunnels excavated in one phase. This is achieved by performing a parametric set of 2D numerical analyses with the finite element code ABAQUS. The rock mass is modeled as an elasto-plastic material yielding according to the Drucker-Prager criterion, with time-dependent characteristics described by the Singh-Mitchell creep model. The time-dependent behaviour is initially formulated upon the assumption of a new set of parameters. Typical ranges of these parameters are estimated using creep experiments from the literature.

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Supported Axisymmetric Tunnels Within Linear Viscoelastic Burgers Rocks

Cited by 120 publications

References 27 publications

Creep properties of intact and fractured muddy siltstone

Creep properties of intact and fractured muddy siltstone

Analysis of the behavior of large underground oil storage caverns in salt rock

Influence of rock mass creep on tunnel loading

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