Written By: Samantha Justice, P.E., Bryan Wedin, P.E. Geocells provide one of the most powerful solutions available to engineers and contractors when designing and constructing roadways over soft and weak subgrades. With a successful track record of over 40 years, geocells have proven effective in load support applications over challenging conditions. If you’ve ever wondered how geocells work in load support applications – and the relationship between lateral confinement, hoop stress and wall tension – you’ve come to the right place. Geocells are used to alter vertical stresses beneath an applied cyclical load. When a vertical, cyclical load is applied over geocells, active earth pressures develop in the loaded cell. These pressures arise due to the friction between the infill material and the cell wall. This friction pushes back against the passive earth pressure in the adjacent cells, helping to support the load. Refer to Figure 1. The balance of active and passive earth pressures activates the hoop stress in the cell walls, which increases the stiffness and bearing capacity of infill material. The infill material is confined within the individual cells with no chance of displacement, or lateral or vertical spreading and the result is increased stiffness. In effect,… Read more »
Posts Tagged: geocells
Advancing Rail Resilience: How Geosynthetics Help Achieve CRISI Objectives for Robust and Stable Infrastructure
Discover the Latest CRISI Rail Infrastructure Funding Opportunities: Apply Before the May 2024 Deadline The U.S. Department of Transportation is bolstering rail infrastructure advancements through the Consolidated Rail Infrastructure and Safety Improvements (CRISI) program. With a recent allocation of $2.47 billion, the CRISI program is set to significantly impact rail safety, efficiency, sustainability, and reliability across the United States. This funding initiative is designed to support a variety of projects that are pivotal to enhancing the nation’s passenger and freight rail systems. It represents a call to action for rail industry professionals, including engineers, planners, and project managers, to leverage this opportunity to advance their rail infrastructure projects. The deadline for application submissions is 11:59 p.m. ET, May 28, 2024. Professionals in the rail sector are urged to prepare their proposals that align with CRISI’s mission to improve the rail infrastructure’s overall landscape. For a comprehensive overview of the application process and to assess project eligibility, stakeholders are encouraged to review the Fiscal Years 2023-2024 Notice of Funding Opportunity (NOFO) available through the CRISI program. This funding presents a pivotal chance for those involved in rail infrastructure to gain the support and resources needed to propel their projects forward…. Read more »
Geocell Technology Proves Effective in Solving Soil Stabilization Challenges for Solar Farms on Underutilized Lands
With the increasing demand for clean energy, there is a growing interest in repurposing underutilized lands for solar farm developments, particularly abandoned mines, capped landfills, brownfields, and other unused areas. These locations offer a unique opportunity to transform unused spaces into sources of renewable energy, and can be particularly enticing because they are often situated near established transmission infrastructure. This makes the interconnection process simpler and more cost-effective than connecting to remote greenfield sites. In addition to contributing to the shift toward sustainable energy sources, the development of solar farms on underutilized lands can create jobs, generate revenue, and bring new life to areas that have been neglected or forgotten. However, poor soil conditions can pose significant challenges for solar farm developers. To ensure the long-term success of solar projects, factors such as erosion control, stormwater management, and site access must be carefully considered during the design and construction phases, especially when repurposing underutilized lands for solar farm developments where the site conditions may be less than ideal. GEOWEB® Geocells: A Versatile Site Development Solution for Solar Projects Geosynthetics, specifically geocells, can be highly effective in mitigating the challenges posed by poor soil conditions during the development of solar farms…. Read more »
Why Geocells Outperform Geogrids for Road Construction
Geocells (cellular confinement system CCS) offer a more effective and practical 3D design solution to load support challenges than multilayered 2D geogrid efforts. Geocells transfer applied loads instantaneously, delivering practical soil stabilization in a product that is fast and easy to install. How do geogrids work? Geogrids rely on rutting, displacement and lateral movement of the road material to activate the load support reaction of the product. As shown below, failure of the driving surface must occur before the geogrid reacts. As a result, rutting and soil displacement is a prerequisite reality to the system. Since the geogrid is two-dimensional, material not located directly within the plane occupied by the geogrid is free to move, shift and displace. It is essential that geogrids are placed in a flat or a pre-tensioned manner—but that is not practical in a construction environment. It is common to see geogrids unrolled over a prepared grade with an undulating surface. As aggregate is placed over the top of the geogrid, the material kinks and waves, further warping the 2D plane. The geogrid is rarely pulled tight during installation which does not allow full tension under load. Geogrids are difficult to… Read more »
Are material shortages delaying your road construction projects? Here is how to stay on schedule and within budget.
Written by: Bryan Wedin, P.E., Chief Design Engineer Road construction is booming, and this trend is expected to remain strong due to high demand and the Infrastructure Investment and Jobs Act (IIJA), which includes investments across many sectors, including public infrastructure. Along with this boom, the road construction industry has been dealing with inflation-related cost increases and limited availability of construction materials. The industry has been impacted by supply-chain interruptions and shortages for many roadway materials including lime, cement, and even aggregate. These materials are typically used for roadway base construction, which means road construction projects that use these materials may be subject to delays. Due to these shortages and delays, on-site material or sand-filled GEOWEB® geocells can provide a cost-effective, readily available substitute for base materials–especially where native subgrade conditions consist of weak or soft soils. GEOWEB® Geocells for Roadway Base Stabilization The GEOWEB geocells have been used for load support and foundation applications worldwide for more than 40 years. Developed in collaboration with the U.S. Army Corps of Engineers (USACE) in the late 1970s, Presto co-invented the technology now known as geocells or a cellular confinement system (CCS). The early applications of geocells consisted primarily of stabilized, expedient… Read more »
How Geosynthetics Are Uniquely Poised to Help Alleviate Congestion at U.S. Ports
Written by: Michael J. Dickey, PE, Director and Bryan Wedin, PE, Chief Design Engineer On May 6, 2022, the Maritime Administration (MARAD) released an amended Notice of Funding Opportunity (NOFO), allocating over $234 million for port infrastructure development in 2022. Adding to the previously appropriated amount of $450 million from the Infrastructure Investment and Jobs Act (IIJA, or Bipartisan Infrastructure Law), this will bring the total amount available for port improvement projects to $684 million for FY2022. The significance of this investment comes at a crucial time. According to the American Association of Port Authorities, the pandemic has laid bare the need for a transport system that is able to surge and stretch across all links—from sea, to land, to rail, to warehouse, to consumer. The question is, how can this funding be used to meet this need quickly and cost-effectively? The answer may lie in a strategy implemented in 2021 in the state of Georgia to alleviate congestion at the Port of Savannah. The Georgia Port Authority, in partnership with Norfolk Southern, implemented a solution that has caught the attention of other U.S. port authorities and Class I railroads using what is being referred to as “pop-up container yards”…. Read more »
Protecting Environmental Geomembrane Covers With Suspended GEOWEB Geocells
Economic pressure, the desire for green solutions, and the intensification of climate extremes have converged to create a need for better methods to effect soil stabilization. Fortunately, a proven technology exists that addresses issues associated with these conditions and provides a more stable cover solution for landfill covers, lagoons, stormwater containment basins, and other geomembrane-covered systems. Soil, aggregate, and concrete protective covers over geomembranes can be secured against known gravitational, hydrodynamic, and seismic forces using the GEOWEB® Soil Confinement System. Soil and aggregate are commonly used as a protective cover over liners on slopes of 3H:1V or less. However, when slope gradients are greater, unconfined soil and aggregate covers are typically unstable and not used. In arid areas, cover depth may range from 75 mm (3 in) to 150 mm (6 in). Where conditions support vegetation, cover depth may range from 100 (4) to 600 mm (24 in) or greater where the final depth is a function of the characteristics of the desired vegetation. Regardless of cover depth, if an extreme rainfall event occurs that is 10%, or greater than what would typically be expected, soil mass increases, assumed friction angles decrease, and factors of safety for soil stability drop to… Read more »
GEOWEB Geocells Combined with a Turf Reinforcement Mat (TRM)
GEOWEB® System – Research Synopsis Research Objective Measure the performance of the GEOWEB (GW) material combined with a turf reinforcement mat (TRM) (integrated system) with topsoil infill and vegetation under varying shear stresses and flow rates to quantify both hydraulic forces and corresponding soil loss. The test consisted of a series of continuous one-hour flows over the GW-TRM system at incrementally increasing discharges. The performance threshold was defined as the point at which 0.5 inches (13 mm) of soil loss occurred. Research Scenario The Research Facility Steep-Gradient Overtopping Facility (SGOF) at the Hydraulics Laboratory of the Engineering Research Center (ERCD) at Colorado State University (CSU), Ft. Collins, Colorado Test Timeframe April 2005-August 2006 Test Materials GEOWEB Soil Stabilization System North American Green C350 Turf Reinforcement Mat Scope of Test Hydraulic performance testing was conducted on an integrated system comprising the GW30V textured/perforated GEOWEB System and the North American Green C350 composite turf reinforcement mat. The C350 TRM was chosen for its known performance in the test apparatus. Six tests were conducted under the research program to measure the performance of the integrated system, identify stability threshold conditions, and quantify both hydraulic forces and soil loss. Assembling the Test Components The… Read more »
The History of Geocells
Geocell technology has come a long way over the past four decades. In its early days of development, the geocellular soil confinement system consisted of wax-coated craft paper; a plastic drainage pipe matrix fastened with staples; paper-thin, hexagon-shaped, glued aluminum; low- and medium-density recycled materials; pure polyethylene without UV stabilization; and square cells similar to old-fashioned egg carton separators. The Invention of Modern Geocell Technology In the late 1970s, the U.S. Army Corps of Engineers (USACE) contacted Presto Products Company—a private-label consumer packaging manufacturer—to develop a more robust honeycomb-shaped confinement system that would maintain load-bearing strength under heavy vehicle loads. Working with Steve Webster at the Waterways Experiment Station (WES), Presto’s Gary Bach devised a method to weld polyethylene strips to form a cellular structure. This innovative system became known as Sandgrid and was used by the military primarily for road applications. After the development of Sandgrid, Presto Products created a new business unit to focus solely on the geosynthetics business. With this expansion, Presto Geosystems® was established. Presto Geosystems and the USACE tested various resin blends and concluded that virgin high-density polyethylene (HDPE) provided superior weld consistency and structural strength. Presto Geosystems introduced the GEOWEB® Cellular Confinement System (CCS)… Read more »
Designing Sustainable Ports & Yards with 3D Geocells
Stabilization for Higher-Performing Pavements Ports and intermodal yards in coastal areas are more prone to pavement problems due to inherent soft, unsupportive soils and high water levels. Heavy traffic patterns and the constant weight of loaded parked trailers and stacked containers at these facilities can accelerate the degradation of the paved or unpaved surfaces and subbase materials. The repeated pressure over poor soil conditions results in settlement, ruts, potholes, and even pavement failure. These surface problems require continual, costly maintenance and interruptions to facility operations. But the problem isn’t at the surface—it’s a base stabilization problem. Transforming Base Materials through 3D Confinement Creating and ensuring a stable surface supportive of the long-term, heavy traffic needs starts with better stabilization of the base materials. The GEOWEB® 3D Confinement System is built for this function. The system’s deep, cellular network controls both the horizontal and vertical movement of unstable base soils. When vertical loads are applied, active earth pressures in the loaded GEOWEB® cells push against passive earth pressures in adjacent cells to form a stable system. The benefits of confining fill are applied to both base reinforcement and unpaved surface applications. Permeable Unpaved Pavements Utilizing the GEOWEB® 3D system at the… Read more »
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