Prism-Shaped Bore Layout for Tunnel Construction Through Variable Geology
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Solution Overview
Problem
Long tunnels face significant challenges due to varying geologies, which conventional methods fail to address effectively, leading to potential catastrophic issues and inefficiencies in construction.
Innovation Solution
A method involving drilling a first bore and multiple parallel second bores to define a prism-shaped region, allowing for detailed geological data collection and subsequent excavation using a tunnelling shield with probes and directional boring technology to form a tunnel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sampling and extrapolation methods are used to assess geology, then the construction process is simpler and faster to initiate, but the reliability and accuracy of geological understanding deteriorates, leading to potential catastrophic problems
Solution Approach 1:
The tunnel construction process is segmented into multiple drilling phases: first bores are drilled to establish primary geological data points, then second bores are drilled between adjacent first bores to fill gaps. This segmentation allows comprehensive geological mapping without requiring a single complex deep bore, improving reliability while managing system complexity through modular data collection
Solution Approach 2:
The invention transitions from conventional single-point or single-line sampling to a multi-dimensional grid of bores. By drilling first bores at spaced intervals and then second bores between them, the system creates a two-dimensional array of data points that fully characterizes the geological prism, dramatically improving geological understanding accuracy
2Productivity
If TBMs are used for tunnel construction, then large scale excavation is achieved, but the stop-start nature and inability to transition between different rock/soil types reduces productivity and increases time
Solution Approach 1:
The system performs preliminary drilling of multiple bores through different geological zones before actual tunnel excavation begins. This advance geological mapping allows the excavation team to know ahead of time what rock or soil types they will encounter and plan appropriate excavation strategies, eliminating the stop-start nature of TBMs and improving continuous productivity
Solution Approach 2:
Data from the drilled bores provides continuous feedback about subsurface geology along the proposed tunnel path. This feedback loop allows real-time adjustment of excavation plans and methods as different geological conditions are encountered, enabling smooth transitions between rock and soil types without the adaptability limitations of conventional TBMs
3Length of moving object
If directional boring is used for long distance holes, then the ability to bore through geology is improved, but the diameter is limited to 100-1200 mm which is insufficient for tunnel construction
Solution Approach 1:
The invention merges multiple small-diameter directional bores (first bores and second bores) to collectively define and characterize a much larger prism-shaped region. By combining the data from numerous small bores, the system achieves comprehensive understanding of a large volume of geology without requiring any single bore to have large diameter, enabling subsequent large-scale tunnel excavation
Data Source
AI summary
Long tunnels of many kilometres are likely to pass through a range of geologies which may cause problems. The present invention seeks to overcome the disadvantages of the prior art by: drilling a first bore 10 along a first predetermined path, the first bore having a length of at least 25 m; drilling a plurality of second bores 20 along respective second predetermined paths, each substantially parallel to the first predetermined path in order to define a substantially prism-shape region therebetween; and excavating material within the substantially prism-shape region to form a tunnel. In this way, data from drilling the first bore 10 and the plurality of second bores 20 can be recorded and used to inform operators as to the types of material through which they will be excavating. Thus, a more complete view of the underlying geology can be achieved before beginning excavations.