Key Role and Construction Techniques of Geomembranes in Tailings Dam Seepage Control

Pre-Construction Preparation

1. Material Selection & Inspection

• Type Selection: High-Density Polyethylene (HDPE) geomembranes are commonly used due to their chemical resistance, low permeability, and high strength, making them ideal for harsh tailings environments.

• Specifications: Thickness typically ranges from 1.0–2.0mm, with widths of 4–8m for ease of installation.

• Quality Checks: Inspect for defects (scratches, holes, bubbles) and test mechanical properties (tensile strength, puncture resistance, permeability) to ensure compliance with standards.

2. Site Preparation & Foundation Treatment

• Debris Removal: Clear vegetation, roots, rocks, and sharp objects to prevent geomembrane damage.

• Surface Leveling: Compact and level the foundation (surface irregularities ≤±5cm). Soft soil requires reinforcement (e.g., compaction, drainage).

• Drainage Slope: Ensure a minimum 2–3% slope for proper leachate drainage and avoid water pooling.

Geomembrane Installation

1. Laying Sequence & Direction

• Sequence: Progress from the dam base to the crest, starting downstream to upstream, minimizing wrinkles and stress.

• Orientation: Align the geomembrane’s longitudinal direction perpendicular to slope contours to reduce shear forces.

2. Installation Methods

• Manual Laying: Used for small/complex areas; workers unroll and adjust geomembranes to ensure tight contact with the foundation.

• Mechanical Laying: Large-scale projects use specialized laying machines (speed: 5–8m/min) for uniform tension and alignment.

3. Seaming & Anchoring

• Hot Wedge/Extrusion Welding: Adjust temperature, speed, and pressure for consistent, defect-free seams.

• Quality Tests: Post-weld checks via air pressure/vacuum tests or spark testing to detect leaks.

• Overlap Width: Minimum 100mm, with clean, debris-free surfaces for welding.

• Welding Techniques:

• Anchoring: Secure edges using trench anchoring (buried in backfilled soil/concrete) or bolt fixation (anchored to concrete beams).

Quality Control & Testing

1. In-Process Checks

• Monitor平整度, seam integrity, and environmental conditions (halt work during rain/wind > 4–5级).

• High-temperature precautions to prevent deformation.

2. Post-Installation Tests

• Visual Inspection: Identify and mark defects (scratches, poor seams) for repair.

• Seam Strength: Sample welds must achieve 80–90% of the geomembrane’s tensile strength.

• Leak Detection: Spark testing (for holes) or vacuum testing (pressure drop analysis).

Why Geomembranes?
✔ Pollution Prevention – Blocks tailings seepage into soil/water.
✔ Structural Integrity – Resists chemical corrosion and mechanical stress.
✔ Efficiency – Mechanized installation speeds up large-scale projects.
✔ Longevity – Proper QC ensures decades of reliable performance.