Tome Architecture and management of a geological repository - Andra

4 - General architecture of the repository in a granite mediumThe exploratory drifts, 4-6 m wide, form a network with a 400-500 m mesh.These drifts are developed in a "comb pattern" with dead-ends on either side. The aim of thisarrangement is to limit any disturbance to the hydro-geology of the medium that could be caused by alarge system of interconnected drifts.The exploration programme of the upper level in the context of dual-level repository architecture alsoincludes downward cored boreholes. The exploration programme of the lower level, the layout andnumber of exploration drifts are adjusted to the validation elements remaining to be acquired.At both repository levels, the access and connecting structures needed to construct the repositoryprovide support to the exploration drifts construction.4.2.2.5 Connecting driftsAn organised network of connecting drifts at each repository level links the modules (and theirassociated disposal cells) to the shared infrastructures of the shaft zone. This network has a treestructure from the shaft zone to give access to more or less dispersed blocks on a horizontal plan of thegranite massif.It may be a simple tree structure with a main cluster of connecting drifts, giving access to blocks oneither side, or a more ramified tree structure with secondary clusters.Figure 4.2.5Tree structure adjusted to the distribution of blocks in the graniteDossier 2005 Granite - ARCHITECTURE AND MANAGEMENT OF A GEOLOGICAL REPOSITORY68/228