Semicircular-Arched TBM Cutterhead Assemblies for Flat-Floor Tunnels
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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 for efficient excavation of approximately 88% and 12% of the tunnel respectively, creating a semicircular-arched crown, vertical sidewalls, and a 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 through a curved tunnel crown, but additional construction processes are required to create a flat invert for vehicle transportation
Solution Approach 1:
The cutterhead is divided into multiple independent cutterhead assemblies (first, second, and third cutterhead assemblies) that can be selectively positioned and operated. The first and second cutterhead assemblies excavate the curved crown portion while the third cutterhead assembly excavates the flat invert portion, allowing simultaneous creation of both stable arch and vehicle-accessible floor in a single tunneling operation
Solution Approach 2:
The cutterhead assemblies are configured with adjustable positioning mechanisms that allow dynamic repositioning during operation. The third cutterhead assembly can be positioned below the first and second assemblies to excavate the flat invert, and the cutterhead assemblies can be independently rotated and controlled to adapt to different excavation stages and requirements
2Ease of operation
If auxiliary cutterheads are added to excavate non-circular cross sections, then vehicle accessibility is improved, but device complexity increases
Solution Approach 1:
Multiple cutterhead assemblies are integrated onto a single TBM platform, each capable of independent rotation and excavation operations. The first and second cutterhead assemblies handle the curved crown excavation while the third cutterhead assembly handles the flat invert excavation, allowing one machine to perform multiple excavation functions that would otherwise require separate operations or equipment
Solution Approach 2:
The third cutterhead assembly is positioned below and integrated with the first and second cutterhead assemblies in a nested configuration. The cutterhead assemblies share common support structures, drive systems, and control mechanisms, allowing compact integration of multiple cutting functions within the constrained space of the TBM while maintaining independent operational capability
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.