Tunnel Sealing System with Bentonite Swelling Layer
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Solution Overview
Problem
Existing tunnel structures constructed using the cut-and-cover method face challenges with sealing systems that lead to backward leakage and damage propagation, affecting larger areas due to defects in the primary sealing layer, and the quality of concrete is compromised by manual installation methods.
Innovation Solution
A multi-layer sealing system using a water-permeable textile material filled with swellable bentonite is applied as a secondary sealing layer on the concrete body, which swells to form a water-blocking layer when the primary sealing layer is compromised, preventing water from reaching the concrete and utilizing a drainage layer and protective plates to manage seepage and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary sealing layer is applied directly on the concrete structure, then sealing coverage is achieved, but local defects cause backflow and damage propagation to larger areas
Solution Approach 1:
The patent divides the sealing system into multiple independent layers: a primary sealing layer and a secondary sealing layer with drainage capability. Each layer performs a specific function, and the segmentation prevents damage propagation because water cannot penetrate through both layers simultaneously, isolating defects to localized areas rather than allowing widespread contamination.
Solution Approach 2:
The patent incorporates a secondary sealing layer with drainage functionality before water can penetrate the concrete structure. This pre-positioned protective layer acts as a cushion against water infiltration, capturing and draining water that penetrates the primary layer, thereby preventing backflow and protecting the concrete from damage before significant harm occurs.
2Ease of manufacture
If sealing joint strips are pressed into fresh concrete manually, then sealing sections are created, but air pockets form and concrete cover quality is compromised
Solution Approach 1:
The patent removes the sealing joint strips from the concrete structure entirely. Instead of pressing strips into fresh concrete, the sealing system is applied as surface layers on the hardened concrete, eliminating the manual insertion process that creates air pockets and compromising concrete cover quality.
Solution Approach 2:
The patent introduces a protective fleece as an intermediary layer between the sealing membrane and the concrete structure. This fleece facilitates water drainage and prevents direct adhesion issues, allowing the sealing system to function effectively without requiring manual insertion of joint strips into the concrete.
3Ease of manufacture
If sealing membranes are welded manually to joint strips, then sealing sections are formed, but verification of welding quality is impossible
Solution Approach 1:
The patent designs the sealing system to be self-verifying through the drainage layer. The drainage layer provides visible and measurable indicators of water flow and pressure, allowing automatic verification of sealing effectiveness without requiring manual welding inspection. Water behavior itself becomes the verification mechanism.
Solution Approach 2:
The patent replaces manual welding operations with a system based on mechanical drainage and pressure equalization. Instead of relying on welded joints that are difficult to verify, the system uses a drainage layer that mechanically indicates sealing performance through water flow patterns and pressure distribution, substituting unverifiable mechanical welding with verifiable hydraulic behavior.
4Device complexity
If a single-layer sealing system is used, then construction is simple, but water penetration affects large areas due to gradient-driven backflow
Solution Approach 1:
The patent segments the sealing system into functionally distinct layers: a primary sealing layer for initial water barrier protection and a secondary sealing layer with integrated drainage. This segmentation increases reliability by ensuring that water must penetrate through multiple independent barriers and drainage paths, preventing large-area contamination even if one layer is compromised.
Solution Approach 2:
The patent employs hydraulic principles through the drainage layer, which uses water pressure and flow dynamics to actively manage water that penetrates the primary sealing layer. The drainage layer creates hydraulic gradients that redirect water flow away from the concrete structure, using fluid mechanics to enhance protection rather than relying solely on physical barriers.
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 solution effectively prevents water from penetrating the concrete body by creating a self-sealing effect, maintaining the structural integrity and service life of the tunnel structure, while ensuring better concrete quality and preventing damage propagation.
Implementation Method 1
filled with a swelling bentonite, which swells to form a water-blocking layer when the primary sealing layer is compromised
Data Source
Figure 1
Figure 2~3
AI summary
A tunnel structure (100) constructed using the cut-and-cover method, comprising at least one concrete body (10') whose outer surface is covered with a non-backflow sealing system (20), includes at least: - a lower, secondary sealing layer (22) formed from overlapping sealing sheets, each consisting of at least one textile layer filled with a swelling bentonite, and - a primary sealing layer (21) formed by a plastic sealing sheet laid on the secondary sealing layer (22).