Segmented TBM Cutterheads for Semicircular Tunnels With Flat Floors
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Solution Overview
Problem
Conventional tunnel boring machines (TBMs) produce circular tunnel cross sections that require additional construction processes to facilitate transportation by standard vehicles, disrupting mining and civil construction operations.
Innovation Solution
A tunnel boring machine (TBM) configured to excavate a semicircular-arched tunnel with a main cutterhead assembly and secondary cutterhead assemblies, allowing efficient excavation of 88% and 12% of the tunnel respectively, creating a semicircular-arched crown and flat bottom suitable for standard vehicle transportation without additional construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional TBM with a single circular cutterhead is used, then rock stability is improved due to the curved tunnel crown, but additional construction processes are required to create a flat invert for standard vehicle transportation
Solution Approach 1:
The cutterhead is divided into multiple functional zones with different cutter configurations: the upper portion features rock-breaking cutters arranged in a circular pattern for stability, while the lower portion incorporates flat-bottoming cutters to create a level invert. This segmentation allows simultaneous achievement of both rock stability and vehicle accessibility in a single excavation pass.
Solution Approach 2:
The invention merges two previously separate operations (circular tunnel excavation and flat invert construction) into a single integrated cutterhead design. The cutterhead combines both the curved crown-forming elements and the flat-bottoming elements, allowing the TBM to produce a tunnel profile that is both stable and ready for standard vehicle transportation without requiring additional construction processes.
2Ease of operation
If additional construction processes are performed to create a flat invert, then vehicle transportation is enabled, but operational disruptions increase and decommissioning is delayed
Solution Approach 1:
The flat invert is created during the primary tunnel excavation process itself, rather than as a subsequent operation. The cutterhead's lower portion is designed to simultaneously excavate the tunnel floor and level it, performing the flat-bottoming action in advance before the tunnel is fully completed and before any vehicle transportation is needed. This eliminates the need for separate invert construction operations and reduces overall project timeline.
3Stability of the object's composition
If a circular tunnel cross section is excavated, then rock stability is maximized, but the tunnel floor cannot be traversed by standard vehicles without additional construction
Solution Approach 1:
The cutterhead applies different cutting geometries to different local zones of the tunnel cross-section. The upper three-quarters of the cutterhead features curved, rock-stabilizing cutters that maintain the拱形 crown, while the lower quarter incorporates flat-bottoming cutters that create a level surface. This local differentiation of cutter quality allows the tunnel to simultaneously exhibit rock-stabilizing curvature where needed and vehicle-compatible flatness where required.
Data Source
AI summary
A Tunnel Boring Machine (TBM) with a circular cutting profile includes secondary cutterhead components that produce a semicircular-arched tunnel profile for use in underground mining and/or civil construction operations, e.g., for boring in material containing rocks with Unconfined Compressive Strength (UCS) of up to 200 MPA or stronger. The machine is particularly suited to excavate long access tunnels, mine development drifts, road tunnels, and other types of tunnels that require flat bottom, semicircular-arched profiles. The substantially flat tunnel floor allows immediate and effective use of standard vehicles for material and crew transport as well as other construction and mining activities.