159 conventional fleet requirements (see Fig. 3). One approach is the creation of a so-called horseshoe profile by selectively trimming the lower side wedges in competent rock. Alternatively, a flat invert can be established through the installation of prefabricated concrete floor segments or by placing engineered backfill material. Each option involves trade-offs between excavation diameter, advance performance, material demand, and long-term operational flexibility. Profile Horse Shoe Floor installation in circular profile Method Cutting out wedges Concrete floor segments Backfill Pros • Closest to conventional profile • Smaller excavation diameter • Higher advance rates reachable • Lateral space can be used for ducts, conveyors and cable trays • Floor segment design can include drainage channel Cons • Only for very competent rock • Slows down overall advance rate • Increased excavation diameter required Figure 3 – Floor preparation Beyond geometric adaptation, the circular profile offers additional functional potential. A backfilled floor can accommodate integrated drainage pipelines or service channels within the invert. The sidewall zones above the flat floor level provide protected corridors for the installation of power, water, and data lines. Conveyor systems and electrical infrastructure installed during the development phase may, where compatible with mine planning, remain in place for later operational stages, potentially reducing reinstallation effort and associated costs. These interface solutions demonstrate that circular TBM profiles can be aligned with established mining operational standards while simultaneously offering opportunities for integrated infrastructure planning. In this context, profile adaptation becomes part of the broader system-level shift from sequential excavation toward infrastructure-integrated underground development.
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