U-shaped Tunnel Steel Formwork

Shaanxi Flourish Industrial Co., Ltd.'s U-shaped Tunnel Steel Formwork leads U-section tunnel construction with its "U-specific precision + multi-scene load resistance" system-solving "section deformation" and "environment vulnerability" of generic formworks. Crafted from tunnel-optimized Q355ND steel, it delivers ±2mm linear precision for 2-6m wide U-tunnels, 90kN/m² lateral pressure resistance, and 35% faster assembly-trusted by municipal utility corridors, water diversion, and underground drainage projects globally.

1. U-Section Integral Precision Forming

Patented "bottom-side integrated module" design: Eliminates seams between U-tunnel bottom (thickness 150-300mm) and side walls (height 1-3m), avoiding "step-shaped" defects common in split formworks (seam error ≥5mm). Linear precision ±2mm ensures smooth water flow (for diversion tunnels) and easy utility pipe installation (for corridors). Surface finish ≤Ra 6.3μm reduces post-construction grinding by 70%.

2. Dual Load Resistance (Lateral + Water Pressure)

"Side wall vertical rib + bottom cross rib" structure (vertical rib 14mm thick, cross rib 12mm thick): Withstands 90kN/m² soil lateral pressure (equivalent to 8m-deep soil) and 40kN/m² water pressure (for diversion tunnels). 5-point load test shows no deformation under 110% rated load-outperforming circular tunnel formworks (not designed for U-section vertical side load).

3. Corrosion & Humidity Resistant Coating

85μm hot-dip galvanizing (full surface) + 15μm epoxy-polyurethane composite coating: Resists 95% humidity (underground dampness) and 2000h salt-spray (coastal drainage tunnels). Prevents rust in water-immersed areas (e.g., diversion tunnel bottoms)-service life ≥8 years (250+ reuses), 50% longer than bridge capping formworks (not anti-water corrosion).

4. Modular Assembly for Narrow Spaces

Lightweight modules (single side wall panel ≤45kg, bottom panel ≤60kg) + stainless steel snap-locks (12s/piece): 3 workers assemble 15m U-tunnel formwork daily-35% faster than bolt-connected types. Detachable side walls fit narrow construction entrances (≥2.5m width), no large crane needed (saves $1800/day rental).

5. Waterproof Seam Design

Rubber waterproof strips (embedded in bottom-side joints) + tongue-and-groove panel connection: Reduce concrete leakage to ≤0.2% (vs. 3% for ordinary formworks). Avoids water seepage in U-tunnel joints-critical for water diversion projects (saves $20,000 waterproof repair cost per km).

1. Material & Performance

 Steel Grade: Q355ND (yield strength 355MPa, tensile strength 470-630MPa, -40℃ impact resistance ≥34J)

 Coating: 85μm hot-dip galvanizing + 15μm epoxy-polyurethane coating, salt-spray resistance ≥2000h, humidity resistance ≥95%

 Precision: Linear error ±2mm, surface finish ≤Ra 6.3μm, U-section angle error ≤0.5°

 Load-Bearing: Lateral soil pressure 90kN/m², water pressure 40kN/m², deflection ≤1.5mm (6m wide tunnel)

 Reusability: ≥250 times, service life ≥8 years (inland) / ≥6 years (coastal)

2. Modular Components

 U-Bottom Panel: Thickness 8/10mm, width 2-6m, length 2-3m (customizable)

 U-Side Wall Panel: Thickness 8mm, height 1-3m, length 2-3m

 Snap-Lock: Stainless steel, M18×70mm, service life ≥500 uses

 Waterproof Strip: Nitrile rubber, 15×25mm, water resistance ≥0.3MPa

3. Adaptation Parameters

 U-Tunnel Width: 2-6m (telescopic bottom panel for 6-8m custom width)

 U-Tunnel Height: 1-3m (modular side wall extension)

 Application Scenarios: Municipal utility corridors, water diversion tunnels, underground drainage, subway access tunnels

 Concrete Grade: C30-C50 (common for U-tunnel linings)

1. Municipal Utility Corridor

A 8km utility corridor (4m wide U-tunnel) used 300 sets of formwork. Integral precision (±2mm) enabled smooth installation of water/gas pipes; snap-lock assembly cut 25 days off the 80-day schedule. Composite coating withstood underground humidity-3 years no rust.

2. Water Diversion Tunnel 

A 12km diversion tunnel (5m wide, water pressure 35kN/m²) adopted waterproof seams. Leakage rate ≤0.1%, avoiding $240,000 waterproof repair cost. Dual load resistance prevented deformation under soil and water pressure.

3. Coastal Drainage Tunnel (Region C)

A 5km coastal drainage tunnel (3m wide, high salt fog) used our corrosion-resistant formwork. After 4 years, formworks remained rust-free; detachable modules fit narrow coastal construction entrances (2.5m width), saving $12,000 crane rental.

1. Installation Steps

Step 1: Level tunnel base → mark U-section center line (error ≤1mm)

Step 2: Lay U-bottom panel → lock with side wall panels via snap-locks (laser level verification)

Step 3: Install waterproof strips at bottom-side joints → seal with waterproof mortar

Step 4: Apply water-based release agent → pour C30-C50 concrete (layer height ≤500mm)

2. Maintenance Tips

After demolding: Rinse with high-pressure water (remove concrete residue) → dry with air blower

Weekly: Inspect waterproof strips for wear (replace if cracks appear)

Monthly: Lubricate snap-locks with anti-rust oil → check panel flatness

Annually: Touch up coating scratches (use composite epoxy-polyurethane paint)

1. Can it fit U-tunnels wider than 6m?

Yes-we provide "telescopic bottom panels" (6-8m width) with reinforced cross ribs, maintaining ±3mm linear precision.

2. How is it different from circular tunnel formwork?

Circular formwork is for round sections (no vertical side load design), while ours is U-specific: integrated bottom-side structure, vertical rib for side pressure, and waterproof seams-critical for U-tunnel water/utility scenarios.

3. Warranty & after-sales?

2-year warranty for panels/strips; free on-site guidance for first use (within 500km). 

Choose Shaanxi Flourish's U-shaped Tunnel Steel Formwork-U-tunnel exclusive, not repurposed circular or bridge formwork-for precise, durable, and efficient U-section tunnel construction!