Tunnel Boring Machine Cutterhead Assembly for Composite Section Excavation
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Solution Overview
Problem
Current tunnel boring machines face challenges with low utility rates of internal space, high construction costs, complex designs, and high pressures on segments, making them unsuitable for large-scale use.
Innovation Solution
A tunnel boring machine design featuring a main cutterhead with a large diameter and auxiliary cutterheads with smaller diameters, arranged in a semicircular and rectangular configuration, which allows for high utility rates of internal space, low segment pressures, and simplified structure, reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If circular section tunnels are used, then construction cost is reduced and structure is simplified, but internal space utility rate decreases
Solution Approach 1:
The cutterhead is segmented into a main cutterhead and multiple auxiliary cutterheads that work together to excavate different portions of the tunnel section. The main cutterhead excavates the upper semicircular portion while auxiliary cutterheads excavate the lower rectangular portion, enabling the machine to create composite sections that optimize both space utility and construction simplicity.
2Volume of moving object
If rectangular section tunnels are used, then internal space utility rate is improved, but segment pressure increases and design complexity increases
Solution Approach 1:
Different portions of the tunnel section are excavated by different cutterheads with specialized functions. The main cutterhead creates the upper semicircular arc with optimal stress distribution, while auxiliary cutterheads form the lower rectangular portion. This local differentiation allows each section to have optimized properties for its specific structural requirements.
3Volume of moving object
If multi-circle-spliced section tunnels are used, then internal space utility rate is improved, but design complexity and manufacturing cost increase
Solution Approach 1:
Multiple cutterheads (main cutterhead and auxiliary cutterheads) are merged into a single integrated cutterhead assembly that operates as one coordinated unit. This assembly excavates the composite semicircular-rectangular section in a single pass, eliminating the need for multiple separate tunneling operations and reducing overall system complexity despite achieving complex section geometry.
4Volume of moving object
If horseshoe-like tunnel boring machines are used, then internal space utility rate is improved, but structure complexity and maintenance cost increase
Solution Approach 1:
The main cutterhead serves multiple functions: it rotates to excavate the upper semicircular portion and simultaneously moves up and down to create the composite section shape. The auxiliary cutterheads are rotatably arranged to excavate the lower portions. This multi-functionality reduces the number of separate mechanisms needed compared to traditional horseshoe-like machines with multiple independent cutterheads and drive mechanisms.
Data Source
AI summary
A tunnel boring machine includes: a shield body; a cutterhead assembly, a first drive mechanism; a second drive mechanism; and a third dive mechanism. The cutterhead assembly includes a main cutterhead and a plurality of auxiliary cutterheads. The main cutterhead is rotatably arranged at a front side of the shield body and defines a soil chamber between the main cutterhead and the shield body, and is movable along an up-down direction. The plurality of auxiliary cutterheads are rotatably arranged in the soil chamber, and adjacent to a bottom of the shield body and arranged at left and right sides of a vertical central line of the main cutterhead. A rotation diameter of the main cutterhead is greater than a rotation diameter of the auxiliary cutterhead, and the rotation diameter of the main cutterhead is the same as a maximum width of the shield body.