Module Spec 2.0

Precast Segment Assembly

The structural lining of a bored tunnel relies entirely on the precise placement of precast concrete segments. These segments form rings that immediately support the surrounding rock or soil mass once the TBM shield advances. Tolerance at the segment joints is strictly regulated to ±1.5mm to ensure hydrostatic sealing via elastomeric gaskets.

Erector mechanics operate in a continuous cycle, utilizing a vacuum lifting pad or mechanical clamp to position the segments (weighing upwards of 12 tons each) into place.

Annular Gap Grouting

Between the excavated geological profile and the extrados of the concrete ring lies the annular gap. Mechanical stabilization requires the immediate, synchronized injection of a bi-component grout (Component A: cement/bentonite/water; Component B: sodium silicate accelerator).

This paste solidifies in under 12 seconds, preventing settlement of the surface structures above and locking the concrete ring tightly into the earth profile, providing uniform load distribution.