Tubular Shell Structure for Tunnel Ground Consolidation
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Solution Overview
Problem
Existing methods for consolidating and impermeabilizing ground around tunnels excavated beneath a water table are ineffective in creating a stable and leakproof structure due to inhomogeneities in the ground and deviations from vertical columnar formations formed by jet grouting techniques.
Innovation Solution
A method involving the formation of a tubular shell structure using jet grouting to create primary and infill blocks of artificial conglomerate, with infill blocks having a larger diameter to cover adjacent primary blocks and provide a sealing action, ensuring a continuous and stable annular structure that can withstand lithostatic and hydrostatic pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If jet grouting techniques are used to form columnar structures around the tunnel, then ground consolidation is achieved, but deviations from vertical and inhomogeneities in the ground create leaks and structural instability
Solution Approach 1:
The tubular shell is divided into multiple separate columnar structures (first plurality and second plurality of columnar structures) positioned at different locations around the tunnel. Each column acts as an independent element that can tolerate some deviation, while collectively forming a stable arch-shaped structure. This segmentation allows the system to maintain overall stability even when individual columns deviate from perfect vertical alignment.
Solution Approach 2:
The method forms the arch-shaped structures of columnar structures preliminarily before tunnel excavation begins. This preliminary consolidation creates a stable framework that can withstand the subsequent excavation process and the inhomogeneities of the ground, preventing structural instability that would occur if consolidation attempted to correct deviations during or after excavation.
2Reliability
If conventional jet grouting forms separate columnar structures, then ground consolidation is achieved, but the structure is not leakproof due to gaps and inhomogeneities
Solution Approach 1:
Multiple separate columnar structures are merged to form continuous arch-shaped structures that encircle the tunnel. The first plurality and second plurality of columnar structures are positioned and connected to create a closed-loop tubular shell. This merging eliminates gaps between individual columns, creating a leakproof barrier while the modular arch design keeps the overall structure manageable and not excessively complex.
Solution Approach 2:
The columnar structures are formed by mixing particles of the soil with binders (cementitious mixtures) injected at high pressure, creating artificial conglomerate. This composite material combines the existing ground particles with binding agents to form a unified, impermeable structure that seals potential water passages while maintaining structural integrity.
3Object-affected harmful factors
If multiple separate columnar structures are formed around the tunnel, then ground consolidation is achieved, but ensuring continuous coverage and sealing against water pressure requires additional sealing measures
Solution Approach 1:
The columnar structures are arranged to form arch-shaped structures with curved geometries that naturally distribute water pressure and lithostatic loads more effectively than straight vertical columns. The arch shape provides structural efficiency in resisting the radial water pressure from all directions, reducing the need for additional reinforcement while maintaining manufacturing simplicity through standardized jet grouting procedures.
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
The method achieves a stable and impermeable tubular shell structure around the tunnel, effectively sealing potential water passages and improving the structural integrity and leakproofness, allowing safe excavation beneath a water table.
Implementation Method 1
mixing particles of the soil with binders, usually cementitious mixtures, which are injected at high pressure through radial nozzles of small size formed close to the lower extremity of a tubular shaft which is caused to rotate and rise towards the surface. The jets of binder disaggregate and mix with the surrounding soil, generating a column of conglomerate
Implementation Method 2
a stable and leakproof structure regardless of any inhomogeneities in the ground and the inevitable deviations from the vertical occurring in the columnar formations formed by jet grouting techniques
Implementation Method 3
withstand lithostatic and hydrostatic pressures
Implementation Method 4
infill blocks having a larger diameter to cover adjacent primary blocks and provide a sealing action, ensuring a continuous and stable annular structure
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A set of primary blocks of artificial conglomerate (10, 11) spaced apart from each other around the portion of ground (T) which has to be excavated is formed using jet grouting techniques in a vertical plane transverse to the axis of the tunnel which has to be excavated. A set of infill blocks of artificial conglomerate (20, 21) each located between two consecutive primary blocks in order to firmly connect them together is then formed. Each infill block has an outer portion (22) which extends over the outer surfaces (13-16) of two consecutive primary blocks (10, 11). A continuous closed ring structure is thus obtained. By repeating these operations alongside the structure already formed, a continuous tubular structure of artificial conglomerate is obtained.