Construction Specifications for Composite Drainage Net Installation in Reservoir Projects

I. Pre-Construction Preparation

Material Inspection

• Verify composite drainage net specifications (mass per unit area, tensile strength, puncture resistance, permeability coefficient) against design requirements.

• Inspect for physical damage (tears, deformations) and certify material test reports.

Site Preparation

• Clear debris, rocks, and vegetation; level the ground to achieve ≤50 mm surface undulation.

• Remove sharp objects to prevent net damage during installation.

II. Composite Drainage Net Installation

Positioning & Laying

• Mark net placement areas (e.g., dam body, reservoir floor) per design drawings.

• Install upstream-to-downstream or low-to-high to minimize wrinkles/sags.

• Unroll nets without stretching; ensure full contact with substrate.

Connection Methods

• Overlap joints: Minimum 300 mm overlap; secure with U-pins (spacing ≤500 mm).

• Sewn joints: Use heavy-duty stitching machines (thread strength ≥ net strength) at ≤10 mm stitch intervals.

Special Area Treatment

• Cut and tailor nets for corners, pipe penetrations, or irregular shapes.

• Seal pipe penetrations with waterproof membranes/bands to maintain integrity.

III. Backfilling & Protection

Backfill Material Selection

• Use permeable materials (sand, gravel) with ≤5% fines content.

• Prohibit angular/sharp-edged aggregates (>5 mm particle size).

Backfilling Procedure

• Layer thickness: 200–300 mm per lift.

• Compaction: Lightweight equipment (≤1.5-ton vibratory rollers) within 1 m of nets; manual tamping near nets.

Protective Layer

• Options: Geotextile (≥200 g/m²), 50 mm mortar, or 100 mm concrete.

• Install immediately after backfilling to prevent UV degradation.

IV. Quality Control & Acceptance

Visual Inspection

• Check for:

• Wrinkles (>50 mm height) or voids (>100 mm diameter).

• Loose joints (overlaps <300 mm; missing fasteners).

Performance Testing

• Flow capacity test: Measure discharge rate (e.g., ≥10 L/min per m² under 0.1 MPa hydraulic head).

• Permeability verification: Confirm coefficient ≥1×10⁻³ cm/s.

Documentation

• Compile: Material certs, installation logs, inspection reports, and test results for final handover.

Key Technical Parameters

Best Practices

• Sequential workflow: Install nets within 48 hours of site prep to minimize weather risks.

• Safety: Use non-slip footwear during slope installations.

Composite Drainage Net Systems for Reservoirs: Engineering Precision for Reliable Water Management.