Sealing Gasket for Shield Tunnel Segments

The core function of tunnel sealing strips is to solve the waterproofing and
seepage prevention problems of tunnel structures (such as shield tunnel
segments and lining joints). They must also adapt to complex tunnel conditions
(such as structural settlement, vibration, and corrosive environments). Their
performance characteristics revolve around "sealing reliability, environmental
adaptability, and structural compatibility."
High seepage resistance and waterproofing:
They must withstand the pressure of groundwater in the tunnel (typically 0.3-
1.0 MPa, reaching over 1.5 MPa in special geological conditions). After the
strip adheres to the segment/lining joints, it forms a "continuous sealing
barrier," preventing groundwater and sediment from seeping into the tunnel
interior.
Most use either "water-swellable" or "elastic compression" designs: water-
swellable strips can absorb water and expand (expansion ratio 150%-300%) to
fill tiny gaps, while elastic strips achieve long-term sealing through
structural compression. In some scenarios, both types are used in combination.
In tunnel environments that are chronically humid and lack sunlight (or have
weak lighting), the strips must be resistant to... "Damp heat aging" and "ozone
aging" (vehicle exhaust contains ozone) are required, with a standard service
life of ≥20 years (matching the tunnel structure's design life). After aging,
tensile strength retention should be ≥70%, and elastic recovery rate ≥80%.
UV resistance does not need to be excessively high (UV radiation is weak inside
tunnels), but it must withstand temperature fluctuations (-30℃~60℃, down to
-40℃ in frigid northern regions), without becoming brittle at low temperatures
or softening and deforming at high temperatures.

Click to Enlarge