Composite Geomembrane Applications in Channel Anti-Seepage Projects

Composite geomembranes are widely used in channel anti-seepage engineering, gaining attention for their efficiency and reliability. With extensive applications of geosynthetics in civil engineering, especially in flood control and emergency projects, these materials have become indispensable. Comprehensive technical requirements for functions like anti-seepage, filtration, drainage, reinforcement, and protection have accelerated their adoption in various projects. This article explores the application techniques of composite geomembranes, especially in irrigation channel anti-seepage projects.

Key Considerations for Installation

1. Embedded Installation:
   Composite geomembranes must be installed using an embedded method, with a covering layer not less than 30 cm in thickness.

2. Seepage Control System:
   The system should consist of a base layer, anti-seepage layer, transition layer, and protective layer to ensure overall stability.

3. Ground Preparation:
   The ground should be compact and free from uneven settlements, cracks, grass, or tree roots. Protective layers of fine sand or clay should be laid on surfaces in contact with the geomembrane.

4. Avoiding Over-Tension:
   The geomembrane should not be stretched too tightly during installation. The edges embedded in the soil should remain slightly wavy, allowing for thermal expansion and contraction, especially when anchored to rigid materials.

5. Protective Measures:
   Heavy objects or sharp stones should not be dropped directly onto the geomembrane. During construction, the membrane should be laid while simultaneously adding a protective layer to prevent damage.

Performance Characteristics of Composite Geomembranes

Composite geomembranes, also known as composite anti-seepage membranes, are available in configurations such as one fabric and one membrane, or two fabrics and one membrane. They are typically 4-6 meters wide, weighing 200–1500 g/m². Their physical and mechanical properties include:

• High Strength: Excellent tensile, tear, and puncture resistance.
• Durability: Resistant to acid, alkali, corrosion, and aging, making them suitable for harsh environments.
• Adaptability: Designed for unconventional temperature ranges due to the use of polymer materials and anti-aging additives.

These geomembranes meet the demands of water conservancy, municipal projects, construction, transportation, subways, tunnels, and other engineering applications for anti-seepage, isolation, reinforcement, and crack prevention. They are also widely used in dams, drainage ditches, and waste disposal sites for anti-seepage and anti-pollution purposes.

Installation Process of Composite Geomembranes

Composite geomembranes consist of a thin membrane laminated on one or both sides with geotextiles. Common configurations include:

• One fabric and one membrane.
• Two fabrics and one membrane.
• Two membranes and one fabric.

Steps for Installation:

1. Preparation of the Base Layer:
   Level the foundation using fine sand or clay to create a smooth surface.

2. Membrane Placement:
   Avoid excessive tension; ensure that the membrane edges embedded in the soil have a slight wave to accommodate movement.

3. Transition Layer:
   Place a 10 cm layer of fine sand or clay over the geomembrane to protect it from external damage.

4. Protective Layer:
   Cover the transition layer with 20-30 cm of stones or pre-cast concrete blocks for erosion protection.

5. Connection to Structures:
   Use expansion bolts and steel pressing strips to anchor the geomembrane to surrounding structures. Apply 2 mm of emulsified asphalt to connection points to prevent seepage.

6. Damage Prevention:
   Avoid direct impacts on the geomembrane from stones or heavy objects. As construction progresses, ensure the protective layer is applied immediately after the membrane is laid.