What is a geocell, its working principle and why is it necessary in geotechnical engineering?
A geocell is a three dimensional hollow cellular confinement system, which is used to confine soil in honeycomb structure. It is comprised of a matrix of several honeycomb-like structures which are interconnected [either by bonding or extrusion] with each other to form a layer that can retain or hold soil in its hollow structure. Geocells can be made from geosynthetic materials such polyester, or HDPE among others. These geocells are then filled with in-fill material such as aggregate, sand, clay, or soil to stabilize the soil underneath it. The main application of a geocell is to provide structural stability to the soil it’s laid on top by integrating with the terrain to reduce soil erosion, provide slope retention and offer soil reinforcement. The geocell layer is placed on the subgrade, or within the base layer, depending on the application. The principle behind its function is that when the cells of the geocell are filled with soil, or infill material, any vertical pressure applied on this structure, it reduces the horizontal, or lateral movement of the soil particles. Due to this unique confinement phenomenon, it improves the shear strength of the soil surface it’s holding. In turn, it creates a mattress which has improved load bearing capacity, and decreases deformation of the soil, or infill material. The pressure from adjoining cells and high hoop strength further enhances resistance. This is a turn that maintains compaction for long-term reinforcement. This feature makes it a necessary addition to subgrade improvement, soil reinforcement, slope reinforcement, or projects in need of soil erosion prevention. Due to its ability to create an extra stable layer, it finds application in railbed tracks, pavement load support, steep soil slopes, earth retention walls, and all other applications where weak soils are in need of reinforcement or load bearing support.
What are some common applications of geocells?
The most common application of geocells is to provide structural stability to soil either when its on a horizontal or planar surface or angular surface such as slopes, or earth retention projects. With its unique ability to confine in-fill material, plus also create a vegetative cover on the surface, geocells are unique materials since they can be used for stabilization of soil, and to prevent erosion, both. When used for load bearing support, such as a pavement, or a railway track, it reduces the volume of aggregate material needed since its lateral pressure contains infill well and creates a thinner surface or subgrade. Using a polymer material, it further spreads the vertical load from traffic and distributes it while keeping the soil from moving laterally. Since geocells are used in layers from rolls, for these types of applications, they also make it easy to transport and lead to quick installation times. With a reduced need for excavation, subgrade reinforcement, and reduced in-fill material, geocells can provide upto 30% savings often on construction projects. In the case of slopes, or embankments, the use of geocells allows for much sharper inclines that are stable to load from vehicular movement, pressure from trains, or other lateral loads that affect the slope. If a project can use local infill material, it further minimizes the cost of installation and reinforcement. With vegetative fascia, geocells also work to offset the carbon footprint of reinforcement and load bearing improvements over the life of a given project. StrataWeb® cover has advantages over conventional slow-paced stone pitching, requiring skilled masons or vegetated mats that require post-construction fostering. It is relatively difficult to adopt these conventional systems on steep slopes. The most common industries that use geocells include railways, highways, paved roads, mining, logistics yards, and freight and container loading ports.
Examples of geocells being used:
At Strata Geosystems, our geocells are found using the product name StrataWeb®. As the first manufacturer of geocells in India, our expertise in ground improvement has enabled product design that works for all types of subgrades. Our projects include construction of a geocell wall of 32 metres in height over a 111km stretch in Manipur, Reinforced Soil (RS) wall along the NH-363 highway, spanning a 42-kilometer stretch from Mancherial to Repallewada in Telangana, ground improvement of subgrade for the container freight station with a low bearing limit in Kolar, Karnataka. From mountains, plains, and plateaus, geocells work across a variety of terrains to reinforce soil, improve the load bearing capacity and California Bearing Value where needed, all the while optimising construction costs and overall ecological footprint.
