Tunnel Boring Machine Core Removal and Annular Cutting
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Solution Overview
Problem
Tunnel boring machines for rock face excavation face limitations in boring speed and rock removal efficiency due to uneven cutting head speeds and high energy consumption, particularly in large diameter tunnels.
Innovation Solution
A tunnel boring machine design featuring a core removal assembly with a rupturing mechanism and multiple cutting assemblies with radially spaced cutting blades, allowing for efficient annular face boring and core exposure, with drive mechanisms to facilitate larger rock fragment removal and reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional cutting heads are used for large diameter tunnels, then the tunnel can be bored, but the linear speed at the periphery becomes significantly higher than at the centre, limiting boring speeds
Solution Approach 1:
The tunnel boring process is segmented into two distinct operations: an outer annular boring assembly that removes the peripheral rock and an inner core removal assembly that extracts the central core. This segmentation allows each assembly to operate at optimized speeds independent of the other, eliminating the speed differential problem between peripheral and central cutting heads in traditional single-head designs
Solution Approach 2:
The invention extracts the core removal function from the traditional single cutting head system and creates a separate core removal assembly. This extracted core assembly operates independently behind the annular boring assembly, allowing the peripheral cutting heads to maintain consistent linear speed without being constrained by the need to also handle core removal at varying speeds
2Productivity
If traditional cutting heads remove all rock, then the tunnel can be bored, but more pulverisation is required which consumes more energy
Solution Approach 1:
Rock removal is segmented into two stages: the annular boring assembly performs initial rock removal with minimal pulverisation, and the core removal assembly handles the remaining core material. This segmentation reduces the total pulverisation requirement compared to traditional single-head systems where all rock must be pulverised by rotating cutting heads, thereby reducing energy consumption
Solution Approach 2:
The invention applies different quality approaches to different regions: the annular boring assembly uses cutting heads for clean peripheral removal, while the core removal assembly uses a different mechanism (such as a splintering or breaking mechanism) suited for core material. This local quality differentiation optimizes rock removal efficiency while minimizing overall pulverisation and energy consumption
3Area of stationary object
If large diameter tunnels are bored with traditional machines, then the tunnel size is achieved, but the linear speed difference between periphery and centre limits the boring speed
Solution Approach 1:
The tunnel boring system is segmented into an outer annular assembly for peripheral rock removal and an inner core assembly for central core extraction. This segmentation enables the large diameter tunnel to be bored while maintaining high and uniform boring speeds, as each segmented assembly operates independently at optimized speeds without the speed differential constraint that plagues traditional single-head large-diameter borers
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances boring speed and efficiency by allowing larger diameter tunnel excavation with reduced energy consumption and enabling smoother tunnel walls for lining installation, while converting rock fragments into usable aggregate.
Implementation Method 1
a core removal assembly operatively associated with said frame and disposed axially with respect to said first boring assembly away from the annular face, said core removal assembly being operable for removing the core exposed by the first boring assembly transverse to the tunnel axis
Implementation Method 2
a first boring assembly operatively associated with said frame for boring into an annular face surrounding a core substantially coaxial with the tunnel axis, the annular face being a portion of the boring face
Data Source
AI summary
A tunnel boring machine for boring a tunnel in rock including: locating means mounted to a frame for supporting and locating the frame in a disposition with respect to a tunnel axis and a boring face of the tunnel being bored; a first boring assembly operatively associated with said frame for boring into an annular face surrounding a core substantially coaxial with the tunnel axis, the annular face being a portion of the boring face; a core removal assembly operatively associated with said frame and disposed axially with respect to said first boring assembly away from the annular face, said core removal assembly being operable for removing at the core exposed by the first boring assembly transverse to the tunnel axis to expose the remainder of the boring face; and drive means operatively associated with said first boring assembly for driving said boring assembly into the annular face.