Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
Tome Architecture and management of a geological repository - Andra
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5 – B waste <strong>repository</strong> zonegeometric dimensions <strong>of</strong> the st<strong>and</strong>ardised packages. This scenario also enables those packages thatproduce gases to be separately managed.Thus allocation to distinct cells has been made for:- packages that do not contain organic matter or release hydrogen;- packages that do not contain organic matter but release hydrogen;- packages that contain organic matter (<strong>and</strong> release hydrogen);- reference packages B2 (bituminised waste).Furthermore disposal packages <strong>of</strong> identical dimensions or those that provide stacks <strong>of</strong> very similarwidths <strong>and</strong> heights to be built up, are emplaced in each cell.Accordingly ten different types <strong>of</strong> cell have been identified.5.4.2.2 Dimensioning <strong>and</strong> description <strong>of</strong> non-exothermic waste tunnelsFrom a mechanical point <strong>of</strong> view, preliminary dimensioning calculations [39] at the plannedconstruction depths have been made both to check the stability <strong>of</strong> the large diameter tunnels <strong>and</strong> makesure that the fissured zone 31 around the structures remains limited.These calculations have been based on the selection <strong>of</strong> mechanical properties considered as the median<strong>of</strong> a comparison <strong>of</strong> six granite sites in France <strong>and</strong> abroad, in the absence <strong>of</strong> specific site.The results <strong>of</strong> these calculations show that tunnels about ten metres high by about 25 m wide with an"inverted U" section are "self-stable" in the event <strong>of</strong> stress isotropy along the horizontal plane. Thecalculations indicate that there is little likelihood <strong>of</strong> a fissured zone appearing. In the event <strong>of</strong>anisotropy (with a hypothesis <strong>of</strong> the horizontal stress being twice the vertical stress), even if themechanical stability is confirmed, a fissured zone extending several tens <strong>of</strong> metres may appear.From a technological point <strong>of</strong> view, the design <strong>of</strong> mechanical h<strong>and</strong>ling equipment for the B waste,which is the same as for the studies for the clay medium, enables piles <strong>of</strong> waste packages to be stackedto a height <strong>of</strong> some ten metres.The sections envisaged for the non-exothermic disposal cells are about 200-260 m 2 .Figure 5.4.4Cross section <strong>of</strong> a disposal tunnel <strong>of</strong> non-exothermic B waste31The fissured zone, in this case, refers to the damaged zone in the geo-technical sense. It is the zone where irreversible displacements arelikely to take place along existing fractures (natural or generated by the excavation works).In the rest <strong>of</strong> this report the term "damaged zone" is used exclusively to refer to the zone impacted by the excavation technique used, toavoid ambiguity.Dossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY132/228
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