Permeability evolution and water transfer in the excavation damaged zone of a ventilated gallery

Pardoen, Benoît; Talandier, Jean; Collin, Frèdèric

doi:10.1016/j.ijrmms.2016.03.007

Cited by 45 publications

(14 citation statements)

References 76 publications

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“…The results for β = 1 × 10 10 and YI thr = 0.95 illustrated in Fig. 4 show a permeability increase in a quite good agreement with the experimental measurements for all the directions.…”

Section: Excavation Phasesupporting

confidence: 81%

“…The first numerical phase is the gallery excavation modelling during which the development of the fractures that compose the EDZ is reproduced by shear banding [8]. Considering the fractured rock as a continuous medium at the macroscale, the intrinsic hydraulic permeability evolution is reproduced through a straindependent relation [10]. Succeeding to the excavation, the air ventilation experiment is reproduced in the underground gallery.…”

Section: Introductionmentioning

confidence: 99%

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Modelling an in-situ ventilation test in the Andra Underground Research Facilities

2016

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Abstract. Wastes resulting from the nuclear electricity production have to be isolated from the biosphere for a very long period of time. For this purpose, deep underground repository in weak permeable geological layers is considered as a reliable solution for the nuclear waste storage. It is however well established that during excavation, the underground drilling process engenders cracks and eventually fractures [1] that deteriorate the hydro-mechanical properties of the surrounding host material in the so-called Excavation Damaged Zone (EDZ). The EDZ behaviour is a major issue because it may constitute a preferential flow path for radionuclide migration. Consequently, the characterisation of the material transport properties and of the transfer kinetics that occur around galleries still need to be investigated. The EDZ properties may be also affected by host rock-gallery air interactions. Ventilation induced drying may also provoke additional cracking, which potentially alters the transport properties of the damaged zone. Large-scale air ventilation experiments are performed in Underground Research Laboratories (URL) that have been constructed to check the feasibility of the repository. A numerical modelling of the SDZ air ventilation test (Andra URL) performed in a low permeability rock is proposed in order to both predict the development of the EDZ during excavation and study the air interaction with the host formation during maintenance phases.

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“…The results for β = 1 × 10 10 and YI thr = 0.95 illustrated in Fig. 4 show a permeability increase in a quite good agreement with the experimental measurements for all the directions.…”

Section: Excavation Phasesupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Modelling an in-situ ventilation test in the Andra Underground Research Facilities

2016

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“…As a porous material, rock has cracks and pores, which are the main seepage channels for fluid flow [7]. In nature, water inevitably exists in the small pores and cracks of rock [8][9][10]. For instance, rock in underground oil and gas reservoirs is often subjected to artificial water injection to improve the tightness of underground oil and gas reservoirs, and for the host rock for hydropower stations, water is forced into the pores and cracks of rock under a hydrostatic load [11,12].…”

Section: Introductionmentioning

confidence: 99%

A Support Vector Machine Model with Hyperparameters Optimised by Mind Evolutionary Algorithm for Assessing Permeability of Rock

Zhu

Chao

2020

Advances in Civil Engineering

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In this paper, a database developed from the existing literature about permeability of rock was established. Based on the constructed database, a Support Vector Machine (SVM) model with hyperparameters optimised by Mind Evolutionary Algorithm (MEA) was proposed to predict the permeability of rock. Meanwhile, the Genetic Algorithm- (GA-) and Particle Swarm Algorithm- (PSO-) SVM models were constructed to compare the improving effects of MEA on the foretelling accuracy of machine learning models with those of GA and PSO, respectively. The following conclusions were drawn. MEA can increase the predictive accuracy of the constructed machine learning models remarkably in a few iteration times, which has better optimisation performance than that of GA and PSO. MEA-SVM has the best forecasting performance, followed by PSO-SVM, while the estimating precision of GA-SVM is lower than them. The proposed MEA-SVM model can accurately predict the permeability of rock indicating the model having a satisfactory generalization and extrapolation capacity.

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“…However a visco-plastic framework is necessary to capture the long-term effects. In addition permeability changes are linked to the shear plastic deformation, significantly high inside strain localisation zones, in order to reproduce damage of the host rock [45].…”

Section: Introductionmentioning

confidence: 99%

Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

et al. 2018

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Highlights1. Excavation process of a gallery is modelled through a fully coupled model including concrete hydration, rock hardening/softening, water flow, desaturation and permeability evolution with deformation 2. A good compromise between convergence of the gallery and limited stress development in support concrete can be achieved by optimising the application moment of sprayed concrete and the use of deformable wedges 3. The strain localisation pattern around the gallery strongly depends on the concrete support solution usedAbstract Production of energy from nuclear power plants generates high-level radioactive nuclear waste, harmful during dozens of thousand years. Deep geological disposal of nuclear waste represents a reliable solutions for its safe isolation. Confinement of radioactive wastes relies on the multi-barrier concept in which isolation is provided by a series of engineered (canister, backfill) and natural (host rock) barriers. Few underground research laboratories have been built all over the world to test and validate storage solutions. The drilling of disposal drifts may generate cracks, fractures/strain localisation in shear bands within the rock surrounding the gallery especially in argillaceous rocks. These degradations affect the hydro-mechanical properties of the material, such as permeability, e.g. creating a preferential flow path for radionuclide migration. Hydraulic conductivity increase within this zone must remain limited to preserve the natural barrier. In addition galleries are currently reinforced by different types of concrete supports such as shotcrete and/or prefab elements. TheirAddress(es) of author(s) should be given purpose is twofold: avoiding partial collapse of the tunnel during drilling operations and limiting convergence of the surrounding rock. Properties of both concrete and rock mass are time dependent, due to shotcrete hydration and hydromechanical couplings within the host rock. By the use of a hydro-mechanical coupled Finite Element Code with a Second Gradient regularization, this paper aims at investigating and predicting support and rock interactions (convergence, stress field). The effect of shotcrete hydration evolution, spraying time and use of compressible wedges is studied in order to determine their relative influence.

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Permeability evolution and water transfer in the excavation damaged zone of a ventilated gallery

Cited by 45 publications

References 76 publications

Modelling an in-situ ventilation test in the Andra Underground Research Facilities

Modelling an in-situ ventilation test in the Andra Underground Research Facilities

A Support Vector Machine Model with Hyperparameters Optimised by Mind Evolutionary Algorithm for Assessing Permeability of Rock

Modelling of Short-Term Interactions Between Concrete Support and the Excavated Damage Zone Around Galleries Drilled in Callovo–Oxfordian Claystone

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