Tunnel Pre-supporting Beam Consolidation Grouting
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Solution Overview
Problem
Existing methods for constructing buried structures, such as tunnels, do not adequately prevent soil decompression and surface settlement issues during excavation, which can lead to damage and instability in the surrounding ground.
Innovation Solution
A method involving the use of pre-retaining vaults with sealing grouts, followed by the injection of consolidation grouts through the same tubes to enhance the mechanical properties of the soil, thereby prestressing the ground and reducing the likelihood of settlement and decompression during tunnel excavation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If pre-retaining systems with sealing grout are used to reinforce ground, then tensile and shear strength of soil is improved, but soil decompression and surface settlement problems are not sufficiently avoided
Solution Approach 1:
The invention applies preliminary action by injecting consolidation grout into the ground before excavation occurs. The grout is injected through the pre-retaining vault tubes to pre-consolidate the soil mass, anticipating and preventing future settlement issues before they can manifest during tunneling operations.
Solution Approach 2:
The invention changes the physical and mechanical parameters of the soil by injecting consolidation grout that modifies the soil structure. This transforms the soil from a loose, compressible state to a consolidated, rigid state with improved load-bearing capacity and reduced compressibility, directly addressing the settlement problem.
2Reliability
If additional drilling is performed for consolidation injection, then ground consolidation is achieved, but construction time and complexity increase
Solution Approach 1:
The invention applies universality by making the pre-retaining vault tubes serve multiple functions: they act as both the pre-retaining reinforcement structure and as the injection conduits for consolidating the ground. This eliminates the need for separate drilling operations, as the same tubes are reused for both retention and consolidation purposes.
Solution Approach 2:
The invention merges two separate operations (pre-retaining installation and consolidation injection) into a single integrated system. The pre-retaining vault tubes are simultaneously used for both structural reinforcement and as injection pathways, combining functions that would traditionally require separate equipment and operations.
3Reliability
If injection is performed in already excavated zones, then ground is treated, but settlements have already occurred
Solution Approach 1:
The invention applies preliminary action by strategically injecting consolidation grout into zones of ground that have not yet been excavated. This proactive treatment consolidates the soil before the excavation disturbance can occur, preventing settlement from happening in the first place rather than attempting to correct it afterward.
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
This method effectively improves the soil's mechanical characteristics, reducing the risk of settlement and decompression by prestressing the ground before excavation, thus ensuring the stability of the tunnel structure and minimizing damage to surrounding areas.
Implementation Method 1
bonded to the surrounding ground by a sealing grout
Implementation Method 2
bonded to the surrounding ground by a sealing grout
Implementation Method 3
The ground treated by injection is hardened. The structure of the injected soil is modified to increase its apparent rigidity
Implementation Method 4
The consolidation process thus makes it possible to anticipate future settlements, by modifying the characteristics of the ground in line with a future tunnel section, before said section is excavated. In other words, the injection of the consolidation grout is intended, at least to a certain extent, to prestress the soil
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a method for consolidating the ground (S) encasing a tunnel (10) excavated in sections (R1,...RN), a pre-supporting beam (V1,..., VN) being mounted over each section (R1,...RN) of the tunnel (10), said beam consisting of a plurality of tubes (12) arrangement substantially parallel to each other and to the axial direction of the tunnel (10) and sealed to the ground (S) by means of a sealing grout. Once the sealing grout has hardened, the method comprises a novel step of injecting a consolidation grout into the ground (S) via at least one tube (12) of the pre-supporting beam (V1,..., VN).