The majority of slope failures within the geosynthetics industry can often be avoided with proper engineering and material selection. However, the factors that affect slope stability can be difficult to discern and measure. Soil thickness, seepage forces, seismic forces, gas uplift, geomembrane texturing, engineering and provision of reinforcing elements are only a few of the factors affecting slope stability. Many failures occur at interfaces with geosynethics and most notably at the geomembrane/geotextile interface or geotextile/soil interface.
The history of slope failures on final cover systems for solid-waste landfills has been well documented. Manufacturers were prompted to develop an alternative geomembrane that increased factors of safety and frictional characteristics. The result was a “textured” geomembrane surface.
The need for consistently high-quality textured geomembranes is met by the flat die extrusion calendaring process, patented and utilized by Agru America in the United States. Using this process, the geomembrane tensile, elongation and other properties are closer to the values of smooth sheet, thus providing more strength. Moreover, other imperfections and thickness variations are not introduced during manufacturing.
Today, Agru America’s MicroSpike Liner is the material of choice in containment applications where slope stability is critical. Consistent surface structuring gives the textured geomembrane reproducible friction angle values with the industry’s highest surface friction values. Manufactured using the flat die extrusion calendaring process, MicroSpike remains the only textured liner with a consistent core thickness, resulting in greater puncture, tear performance and greater than 3 times tensile elongation at break performance of blown-film materials.
MicroSpike Liner has smooth edges to allow for the thermal fusion welding between adjacent panels and the material provides excellent friction characteristics with sand, clay, geotextile and geocomposite. MicroSpike Liner meets or exceeds GRI GM liner test values, frequency of testing and functional requirements established by the environmental waste containment and civil engineering community; and it is rolled on plastic cores to ensure ease of installation without damage due to collapsed cores. For example, the Agru 60 mil MicroSpike product is manufactured with an asperity height of 20 mils, whereas GRI GM 13 only requires 16 mils.
Another textured product produced using the flat die extrusion calendaring process is Agru America’s Super Gripnet Liner. Designed for applications where drainage and stability are critical, such as landfill caps, landfill slopes and mining reclamation projects, Super Gripnet features underside spikes for adherence to steep slopes. With this product, no geonets and geocomposites are required, which lead to considerable cost savings. Super Gripnet Liners have smooth edges, allowing wedge welds between adjacent panels. The geomembrane is installed as a single layer without geocomposite sections, reducing installation time and cost. A non-woven geotextile is then installed directly over the Super Gripnet as a filter layer.
Increased Strength and Factors of Safety
Products manufactured by Agru America provide higher shear strengths and greater factors of safety for the engineering community. Their consistency and strength, from uniform core thickness, allows landfill owners to utilize 3:1 or 2:1 slopes. The increased slope steepness provides additional air space for storing waste, increasing efficiency and cost-savings. Download the Microspike and Super Gripnet Liner Brochures below and discover how Agru America is helping prevent slope failure.
