Cellular confinement

Cellular confinement systems (CCS)—also known as geocells—are widely used in construction for erosion control, soil stabilization on flat ground and steep slopes, channel protection, and structural reinforcement for load support and earth retention.[1] Typical cellular confinement systems are geosynthetics made with ultrasonically welded high-density polyethylene (HDPE) strips or novel polymeric alloy (NPA)—and expanded on-site to form a honeycomb-like structure—and filled with sand, soil, rock, gravel or concrete.[2][3]

CellularConfinementSystem-Hex
A cellular confinement system being installed on an experimental trail in south-central Alaska
CellularConfinementSystem-Wood
Wood matrix after installation in Wrangell–St. Elias Park in Alaska
Geocells
Geocell materials
USMC-17299
Filling a geocell envelope with earth to make a temporary barrier wall

History of cellular confinement

Research and development of cellular confinement systems (CCS) began with the U.S. Army Corps of Engineers in 1975 to devise a method for building tactical roads over soft ground.[4] Engineers found that sand-confinement systems performed better than conventional crushed stone sections and they could provide an expedient construction technique for access roads over soft ground, without being adversely affected by wet weather conditions. [5][6] The US Army Corps of Engineers in Vicksburg, Mississippi (1981) experimented with a number of confining systems, from plastic pipe mats, to slotted aluminum sheets to prefabricated polymeric systems called sand grids and then, cellular confinement systems. Today cellular confinement systems are typically made from strips 50–200 mm wide, ultrasonically welded at intervals along their width. The CCS is folded and shipped to the job site in a collapsed configuration (see picture above).

Efforts for civilian commercialization of the cellular confinement system by the Presto Products Company, led to the Geoweb®.[7] This cellular confinement system was made from high density polyethylene (HDPE), relatively strong, lightweight[8] and suitable for geosynthetic extruding manufacturing. The cellular confinement system was used for load support, slope erosion control and channel lining and earth retention applications in the United States and Canada in the early 1980s.[9][10][11][12]

Research

Early research (Bathurst and Jarrett, 1988)[13] found that cellular confinement reinforced gravel bases are "equivalent to about twice the thickness of unreinforced gravel bases" and that geocells performed better than single sheet reinforcement schemes (geotextiles and geogrids) and were more effective in reducing lateral spreading of infill under loading than conventional reinforced bases. However, Richardson (2004) (who was onsite at the US Corps of Engineers CCS Vicksburg facility) laments 25 years later on the "near absence of research papers on geocells in all of the geosynthetic national and international conferences."[14]

A comprehensive review of available research literature by Yuu, et al (2008) concluded that the use of CCS technology in base reinforcement of paved roads and railways in particular was limited, due to the lack of design methods, lack of advanced research in the last two decades and limited understanding of the reinforcement mechanisms.[15] Fortunately in the last decade research and development in geocell systems expanded significantly. Extensive research has been conducted in recent years on CCS reinforcement for roadway applications at many leading research institutes around the world, to understand the mechanisms and influencing factors of confinement reinforcement, evaluate its effectiveness in improving roadway performance, and develop design methods for roadway applications (Han, et al. 2011).[16]

Han (2013) summarizes comprehensive research conducted at the University of Kansas including static and cyclic plate loading tests, full-scale moving wheel tests, and numerical modeling on geocell-reinforced base courses with different infill materials and discusses the main research findings from these studies regarding permanent, elastic, and creep deformations, stiffness, bearing capacity, and stress distribution, and the development of design methods for geocell-reinforced bases. These studies showed that base courses reinforced with Novel Polymeric Alloy geocells reduced the vertical stresses at the interface between subgrade and base course, reduced permanent and creep deformations, increased elastic deformation, stiffness, and bearing capacity of base courses.[17] Additional literature reviews can be found in Kief et al (2013).[16] and Marto (2013) [18]

Recent innovations in cellular confinement technology

The strength and stiffness of pavement layers determines the performance of highway pavements while aggregate use impacts the cost of duration of installation; therefore alternatives are needed to improve pavement quality using new materials with less aggregate usage (Rajagopal et al 2012).[19] Geocells are recognized as a suitable geosynthetic reinforcement of granular soils to support static and moving wheel loads on roadways, railways and similar applications. But stiffness of the geocells was identified as a key influencing factor for geocell reinforcement, and hence the rigidity of the entire pavement structure.[19][20]

Laboratory plate loading tests, full-scale moving wheel tests, and field demonstrations showed that the performance of geocell-reinforced bases depends on the elastic modulus of the geocell. Geocells with a higher elastic modulus had a higher bearing capacity and stiffness of the reinforced base. NPA Geocells showed higher results in ultimate bearing capacity, stiffness, and reinforcement relative to geocells made from HDPE.[21] NPA geocells showed better creep resistance and better retention of stiffness and creep resistance particularly at elevated temperatures, verified by plate load testing, numerical modeling and full scale trafficking tests.[22][23]

Application vs. long-term performance

CCS have been successfully installed in thousands of projects worldwide. However, it is incumbent to differentiate between low load applications, such as slope and channel applications, and new heavy-duty applications, such as in the base layer of asphalt pavement structures of heavily trafficked motorways and highways. While all polymeric materials used in CCS creep over time and under loading, the question is; what is the rate of degradation, under which conditions, how will this impact performance, and when will it fail?

The lifespan of CCS in slope protection applications, for example, is less critical as vegetative growth and root interlock stabilize the soil. This in effect compensates for any long-term loss of confinement in the CCS. Similarly, load support applications for low volume roads that are not subject to heavy loading usually have a short design life; therefore minor loss of performance is tolerable. However, in critical applications such as reinforcement of the structural layer of asphalt highway pavements, long-term dimensional stability is critical. The required design life for such roads under heavy traffic loads is typically 20–25 years, requiring verifiable long-term durability.

Development of standards for CCS

There were few test standards for geocells and fewer for their use in design. Test standards for CCS were developed more than 40 years ago, while other test methods evolved from 2D planar geosynthetics. These do not reflect the composite behavior of 3D geometry of CCS, nor do they test long-term parameters such as: dynamic elastic stiffness, permanent plastic deformation and oxidation resistance. However, ISO/ASTM procedures have been developed for testing polymers in the space and automobile industries, as well as for other geosynthetic products. These new standards for CCS were proposed and under discussion by leading experts in geosynthetics in ASTM technical committee D-35. The stated goal is to set new industry standards that more accurately reflect 3D cellular confinement system geometry and material performance in the field rather than lab tests of individual strips and virgin materials that are typically used today.

A recent development in standards for the use of reinforcement geosynthetics in roadways was recently published by in the Netherlands.[24] This standard covers geocell (as well as geogrid) applications, support mechanisms, and design principles. It also emphasizes the importance of the geocell material attributes (stiffness and creep resistance) and how they influence long-term reinforcement factors. Additional guidelines for the use of geocells in roadway applications are currently under development by the ISO and ASTM organizations, but have not yet been published.[25]

How it works

A Cellular Confinement System when infilled with compacted soil creates a new composite entity that possesses enhanced mechanical and geotechnical properties. When the soil contained within a CCS is subjected to pressure, as in the case of a load support application, it causes lateral stresses on perimeter cell walls. The 3D zone of confinement reduces the lateral movement of soil particles while vertical loading on the contained infill results in high lateral stress and resistance on the cell-soil interface. These increase the shear strength of the confined soil, which:

  • Creates a stiff mattress or slab to distribute the load over a wider area
  • Reduces punching of soft soil
  • Increases shear resistance and bearing capacity
  • Decreases deformation

Confinement from adjacent cells provides additional resistance against the loaded cell through passive resistance, while lateral expansion of the infill is restricted by high hoop strength. Compaction is maintained by the confinement, resulting in long-term reinforcement.

On site, the geocell sections are fastened together and placed directly on the subsoil's surface or on a geotextile filter placed on the subgrade surface and propped open in an accordion-like fashion with an external stretcher assembly. The sections expand to an area of several tens of meters and consist of hundreds of individual cells, depending on the section and cell size. They are then filled with various infill materials, such as soil, sand, aggregate or recycled materials and then compacted using vibratory compactors. Surface layers many be of asphalt or unbound gravel materials.

Applications

Roadway load support

Cellular Confinement Systems (CCS) have been used to improve the performance of both paved and unpaved roads by reinforcing the soil in the subgrade-base interface or within the base course. The effective load distribution of CCS creates a strong, stiff cellular mattress. This 3D mattress reduces vertical differential settlement into soft subgrades, improves shear strength, and enhances load-bearing capacity, while reducing the amount of aggregate material required to extend the service life of roads. As a composite system, cellular confinement strengthens the aggregate infill, thereby simultaneously enabling the use of poorly graded inferior material (e.g. local native soils, quarry waste or recycled materials) for infill as well as reducing the structural support layer thickness. Typical load support applications include reinforcement of base and subbase layers in flexible pavements, including: asphalt pavements; unpaved access, service and haul roads; military roads, railway substructure and ballast confinement; working platforms in intermodal ports; airport runways and aprons, permeable pavements; pipeline road support; green parking facilities and emergency access areas.

Steep soil slope and channel protection

The three-dimensional lateral confinement of CCS along with anchoring techniques ensures the long-term stability of slopes using vegetated topsoil, aggregate or concrete surfacing (if exposed to severe mechanical and hydraulic pressures). The enhanced drainage, frictional forces and cell-soil-plant interaction of CCS prevents downslope movement and limits the impact of raindrops, channeling and hydraulic shear stresses. The perforations in the 3D cells allow the passage of water, nutrients and soil organisms. This encourages plant growth and root interlock, which further stabilizes the slope and soil mass, and facilitates landscape rehabilitation. Typical applications include: construction cut and fill slopes and stabilization; road and rail embankments; pipeline stabilization and storage facility berms; quarry and mine site restoration; channel and coastline structures. They can be built as an underlying mass or as a facing.

Earth retention

CCS provide steep vertical mechanically stabilized earth structures (either gravity or reinforced walls) for steep faces, walls and irregular topography. Construction of CCS earth retention is simiplified as each layer is structurally sound thereby providing access for equipment and workers, while eliminating the need for concrete formwork and curing. Local soil can be used for infill when suitable and granular, while the outer faces enable a green or tan fascia of the horizontal terraces/rows utilizing topsoil. Walls also can be used for lining channels and in cases of high flow, it is required that the outer cells contain concrete or cementious slurry infill. CCS have been used to reinforce soft or uneven soil foundations for large area footings, for retaining wall strip footings, for load sharing of covers over pipelines and other geotechnical applications.

Reservoirs and landfills

CCS provides membrane liner protection, while creating stable soil, berms and slopes, for non-slip protection and durable impoundment of liquids and waste. Infill treatment depends on the contained materials: concrete for ponds and reservoirs; gravel for landfill drainage and leachates, vegetated infill for landscape rehabilitation. Concrete work is efficient and controlled as CCS functions as ready-made forms; CCS with concrete forms a flexible slab that accommodates minor subgrade movement and prevents cracking. In medium and low flow-velocities, CCS with geomembranes and gravel cover can be used to create impermeable channels, thereby eliminating the need for concrete.

Sustainable construction

CCS is a green solution that makes civil infrastructure projects more sustainable. In load support applications, by reducing the amount and type of infill needed to reinforce soil, the usage of haul and earthmoving equipment is reduced. This in turn decreases fuel use, pollution and the carbon footprint, and at the same time minimizes on-site disruption from dust, erosion and runoff. When used for slope applications, perforated CCS provides excellent soil protection, water drainage and growth stratum for plants. The long-term design life of advanced CCS technology means that maintenance and the associated environmental costs are significantly reduced, as are long-term economic costs.

Additional details

  • CCS strip widths, hence the on-site height, come in various sizes from 50 to 300 mm.
  • CCS walls are usually made from textured or structured polymer sheet so as to increase frictional resistance against the infill soil from displacement.
  • CCS are made of HDPE, NPA, low-density polyethylene and nonwoven heat-bonded geotextiles.
  • CCS walls are typically perforated so as to allow for drainage from one cell to another.
  • On steep slopes CCS may have a tendon or cable extending through the central region up the slope and anchored to, or within, a concrete plinth so as to resist downgradient sliding of the system.
  • The backfilling of CCS on long and wide slopes is quite labor-intensive. Construction equipment called phneumatic sand-slingers or stone-slingers have been used advantageously.

See also

References

  1. ^ Geosynthetics in landscape architecture and design Archived 2015-02-14 at the Wayback Machine
  2. ^ State of California Department of Transportation, Division of Environmental Analysis, Stormwater Program. Sacramento, CA."Cellular Confinement System Research." 2006.
  3. ^ Managing Degraded Off-Highway Vehicle Trails in Wet, Unstable, and Sensitive Environments Archived October 15, 2008, at the Wayback Machine, US Department of Agriculture in conjunction with USDOT, Federal Highway Administration. Page 28. October 2002.
  4. ^ Webster, S.L. & Watkins J.E. 1977, Investigation of Construction Techniques for Tactical Bridge Approach Roads Across Soft Ground. Soils and Pavements Laboratory, US Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS, Technical Report S771, September 1977.
  5. ^ Webster, S.L. 1979, Investigation of Beach Sand Trafficability Enhancement Using Sand-Grid Confinement and Membrane Reinforcement Concepts – Report 1, Geotechnical Laboratory, U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS, Technical Report GL7920, November 1979.
  6. ^ Webster, S.L. 1981, Investigation of Beach Sand Trafficability Enhancement Using Sand-Grid Confinement and Membrane Reinforcement Concepts – Report 2, Geotechnical Laboratory, U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS, Technical Report GL7920(2), February 1981
  7. ^ Prestogeo.com
  8. ^ Webster, S.L. 1986, Sand-Grid Demonstration Roads Constructed for JLOTS II Tests at Fort Story, Virginia, Geotechnical Laboratory, U.S. Army Corps of Engineers Waterways Experiment Station, Vicksburg, MS, Technical Report GL8619, November 1986.
  9. ^ Richardson, Gregory N. "Geocells: a 25-year Perspective Part ‘l: Roadway Applications." Geotechnical Fabrics Report (2004).Richardson, Gegory N. "Geocells, a 25-year Perspective Part 2: Channel Erosion Control and Retaining Walls." Geotechnical Fabrics Report 22.8 (2004): 22-27.
  10. ^ Engel, P. & Flato, G. 1987, Flow Resistance and Critical Flow Velocities for Geoweb Erosion Control System, Research and Applications Branch – National Water Research Institute Canada Centre for Inland Waters, Burlington, Ontario, Canada, March 1987
  11. ^ Bathurst, R.J, Crowe, R.E. & Zehaluk, A.C. 1993, Geosynthetic Cellular Confinement Cells for Gravity Retaining Wall – Richmond Hill, Ontario, Canada, Geosynthetic Case Histories, International Society for Soil Mechanics and Foundation Engineering, March 1993, pp. 266-267
  12. ^ Crowe, R.E., Bathurst, R.J. & Alston, C. 1989, Design and Construction of a Road Embankment Using Geosynthetics, Proceedings of the 42’nd Canadian Geotechnical Conference, Canadian Geotechnical Society, Winnipeg, Manitoba, October 1989, pp. 266–271
  13. ^ Bathurst, R. J. & Jarrett, P. M. 1988, Large-Scale Model Tests of Geocomposite Mattresses Over Peat Subgrades, Transportation Research Record 1188 – Effects of Geosynthetics on Soil Properties and of Environment on Pavement Systems, Transportation Research Board, 1988, pp. 2836
  14. ^ Richardson, Gregory N. "Geocells: a 25-year perspective Part ‘l: roadway applications." (2004)
  15. ^ Yuu, J., Han, J., Rosen, A., Parsons, R. L., Leshchinsky, D. (2008) “Technical Review of Geocell-Reinforced Base Courses over Weak Subgrade,” The First Pan American Geosynthetics Conference & Exhibition proceedings (GeoAmericas), Appendix VII, Cancun, Mexico
  16. ^ a b Kief, O., Schary, Y., Pokharel, S.K. (2014). “High-Modulus Geocells for Sustainable Highway Infrastructure.” Indian Geotechnical Journal, Springer. September
  17. ^ Han, J., Thakur, J.K., Parsons, R.L., Pokharel, S.K., Leshchinsky, D., and Yang, X. (2013)
  18. ^ Marto, A., Oghabi, M., Eisazadeh, A., (2013), Electronic Journal of Geotechnical Engineering. vol 18, Bund. Q., 3501-3516
  19. ^ a b Rajagopal, K., Veeraragavan, A., Chandramouli, S. (2012). “Studies on Geocell Reinforced Road Pavement Structures,” Geosynthetics Asia 2012, Thailand
  20. ^ Emersleben, A. (2013). “Analysis of Geocell Load Transfer Mechanism Using a New Radial Load Test. Sound Geotechnical Research to Practice 2013. GeoCongress, San Diego, 345-357
  21. ^ Pokharel, S. K. , Han J., Leshchinsky, D., Parsons, R. L., Halahmi, I. (2009). “Experimental Evaluation of Influence Factors for Single Geocell-Reinforced Sand,” Transportation Research Board (TRB) Annual Meeting, Washington, D.C., January 11–15
  22. ^ Han, J., Pokharel, S. K., Yang, X. and Thakur, J. (2011). Unpaved Roads: Tough Cell - Geosynthetic Reinforcement Shows Promise, Roads and Bridges, 40-43
  23. ^ 3. Pokharel, S .K., Han, J., Manandhar, C., Yang, X. M., Leshchinsky, D., Halahmi, I., and Parsons, R. L. (2011). “Accelerated Pavement Testing of Geocell-Reinforced Unpaved Roads over Weak Subgrade.” Journal of Transportation Research Board, 10th Int’l Conference on Low-Volume Roads, Florida, USA, July 24–27
  24. ^ Vega, E., van Gurp, C., Kwast, E. (2018). Geokunststoffen als Funderingswapening in Ongebonden Funderingslagen (Geosynthetics for Reinforcement of Unbound Base and Subbase Pavement Layers), SBRCURnet (CROW), Netherlands
  25. ^ ASTM technical committee D-35 on geosynthetics, www.astm.org
  • "WES Developing Sand-Grid Confinement System," (1981), Army Res. Ver. Acquisition Magazine, July–August, pp. 7–11.

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Borehole

A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water, other liquids (such as petroleum) or gases (such as natural gas), as part of a geotechnical investigation, environmental site assessment, mineral exploration, temperature measurement, as a pilot hole for installing piers or underground utilities, for geothermal installations, or for underground storage of unwanted substances, e.g. in carbon capture and storage.

Clay

Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO2), metal oxides (Al2O3 , MgO etc.) and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red.

Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger.

Mixtures of sand, silt and less than 40% clay are called loam. Loam makes good soil and is used as a building material.

Erosion control

Erosion control is the practice of preventing or controlling wind or water erosion in agriculture, land development, coastal areas, river banks and construction. Effective erosion controls handle surface runoff and are important techniques in preventing water pollution, soil loss, wildlife habitat loss and human property loss.

Gabion

A gabion (from Italian gabbione meaning "big cage"; from Italian gabbia and Latin cavea meaning "cage") is a cage, cylinder, or box filled with rocks, concrete, or sometimes sand and soil for use in civil engineering, road building, military applications and landscaping.

For erosion control, caged riprap is used. For dams or in foundation construction, cylindrical metal structures are used. In a military context, earth- or sand-filled gabions are used to protect sappers, infantry, and artillerymen from enemy fire.

Leonardo da Vinci designed a type of gabion called a Corbeille Leonard ("Leonard[o] basket") for the foundations of the San Marco Castle in Milan.

Geosynthetics

Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products used to solve civil engineering problems. This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites. The polymeric nature of the products makes them suitable for use in the ground where high levels of durability are required. They can also be used in exposed applications. Geosynthetics are available in a wide range of forms and materials. These products have a wide range of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture.

Gravel

Gravel is a loose aggregation of rock fragments. Gravel is classified by particle size range and includes size classes from granule- to boulder-sized fragments. In the Udden-Wentworth scale gravel is categorized into granular gravel (2 to 4 mm or 0.079 to 0.157 in) and pebble gravel (4 to 64 mm or 0.2 to 2.5 in). ISO 14688 grades gravels as fine, medium, and coarse with ranges 2 mm to 6.3 mm to 20 mm to 63 mm. One cubic metre of gravel typically weighs about 1,800 kg (or a cubic yard weighs about 3,000 pounds).

Gravel is an important commercial product, with a number of applications. Many roadways are surfaced with gravel, especially in rural areas where there is little traffic. Globally, far more roads are surfaced with gravel than with concrete or asphalt; Russia alone has over 400,000 km (250,000 mi) of gravel roads. Both sand and small gravel are also important for the manufacture of concrete.

Gravel road

A gravel road is a type of unpaved road surfaced with gravel that has been brought to the site from a quarry or stream bed. They are common in less-developed nations, and also in the rural areas of developed nations such as Canada and the United States. In New Zealand, and other Commonwealth countries, they may be known as 'metal roads'. They may be referred to as 'dirt roads' in common speech, but that term is used more for unimproved roads with no surface material added. If well constructed and maintained, a gravel road is an all-weather road.

Index of soil-related articles

This is an index of articles relating to soil.

Natchez silt loam

In 1988, the Professional Soil Classifiers Association of Mississippi selected Natchez silt loam soil to represent the soil resources of the State. These soils exist on 171,559 acres (0.56% of state) of landscape in Mississippi.

Neoloy Geocell

The Neoloy Geocell (previously under the Neoweb trademark) is a Cellular Confinement System (geocell) developed and manufactured by PRS Geo-Technologies Ltd. Composed of ultrasonically welded strips, Geocells are opened up on-site to form a 3D honeycomb-like matrix, which is then filled with granular soil material to create a soil stabilization / road reinforcement system. In addition to reinforcement of the subgrade, subbase or base layer of roads and railways, cellular confinement is also used for soil stabilization and erosion control in slopes, channels, retention walls, reservoirs and landfills.

Neoloy Geocells are manufactured from Neoloy, a novel polymeric alloy (NPA). This material provides high dynamic stiffness (elastic modulus), resistance to permanent deformation (creep) and tensile strength. Research has shown a stiff geocell material better retains the cell geometry (dimensional stability) confinement and reinforcement. These geocell performance parameters are critical for the requirements of base-layer reinforcement of heavy-duty pavements and infrastructure. Neoloy Geocells are a sustainable solution for road construction as they reduce the use of virgin aggregate. This is achieved by the use of locally available but marginal-quality soils for structural infill and a reduction in the thickness of the pavement layers. Reinforcement with high modulus geocells also optimizes pavement design by enabling a longer design life and lower maintenance cycles/costs.

Novel polymeric alloy

Novel polymeric alloy, also known as Neoloy, is a polymeric alloy composed of polyolefin and thermoplastic engineering polymer. It was developed specifically for use in high-strength geosynthetics. The first commercial application was in the manufacturer of polymeric strips used to form cellular confinement systems (geocells).

Novel polymeric alloy was developed to replace high-density polyethylene (HDPE) in geosynthetics. Although HDPE is widely used due to its low cost, ease of manufacturing and flexibility, its relatively high creep, low tensile strength and sensitivity to elevated temperatures limit its use, for example, in long-term, critical geocell applications.Used in the manufacture of geosynthetics, such as the Neoloy Geocell cellular confinement system, novel polymeric alloy provides geocells with a higher tensile strength and stiffness, and are more durable over dynamic loading and under elevated temperatures than those made from HDPE (Han, 2011). The lifespan of novel polymeric alloy geosynthetics, such as geocells, makes them suitable for long-term design in infrastructure, such as highways, railways, container yards and high retaining walls.

Paradox Access Solutions

Paradox Access Solutions is a construction company specializing in customized access solutions for companies who need temporary or permanent roadways built on unstable terrain, such as muskeg, permafrost or mud. The company is located in Acheson, Alberta with distribution nodes across Alberta and Saskatchewan.

Retaining wall

Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides.

Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to (typically a steep, near-vertical or vertical slope). They are used to bound soils between two different elevations often in areas of terrain possessing undesirable slopes or in areas where the landscape needs to be shaped severely and engineered for more specific purposes like hillside farming or roadway overpasses. A retaining wall that retains soil on the backside and water on the frontside is called a seawall or a bulkhead.

Route Trident

Route Trident (known locally as the New or Big Road) was built by the British Army's Royal Engineers in Helmand Province, Afghanistan. The construction of the road was codenamed Operation Lar Jarowel by the Ministry of Defence. Route Trident (named after the Regimental emblem of 28 Engineer Regiment—the Amphibious Engineers who have the Trident as their emblem) replaced an older road that was vulnerable to attack by insurgents on convoys supplying three patrol bases established in the Gholam Dastagir Kalay area as part of Operation Panther's Claw. In the immediate aftermath of operation the Light Dragoons Battlegroup were suffering casualties as they tried to secure the area and resupply their patrol bases. The attacks resulted in the deaths of two British servicemen and led to the cancellation of the convoys, forcing the bases to be resupplied by air.

Following a meeting between the Commanding Officer of the Light Dragoons (Lt Col Fair) and Commanding Officer of 28 Engineer Regiment (Lt Col MTG Bazeley) it was decided that a new and easier to protect road would be constructed by the Royal Engineers. 28 Engineer Regiment had used a new geosynthetic cellular confinement system for road construction on an exercise in the UK prior to deployment and this was considered to be a practical option to reduce aggregate cost and provide a barrier to the planting of IEDs. Construction began in December 2009 and was completed in March 2010, during which time the construction teams and security forces came under frequent attack. This was the first road to be built under fire since British operations in the Dhofar Rebellion in the early 1970s, the completed road allowed resupply convoys to travel its length in about 30 minutes, compared to 36 hours along the old road. The success of the project led to the approval of plans for an extension to connect the provincial capital Lashkar Gah with the economic capital of Gereshk. Construction of the extension began in July 2010 and was completed in April 2011.

Silt

Silt is granular material of a size between sand and clay, whose mineral origin is quartz and feldspar. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water (also known as a suspended load) and soil in a body of water such as a river. It may also exist as soil deposited at the bottom of a water body, like mudflows from landslides. Silt has a moderate specific area with a typically non-sticky, plastic feel. Silt usually has a floury feel when dry, and a slippery feel when wet. Silt can be visually observed with a hand lens, exhibiting a sparkly appearance. It also can be felt by the tongue as granular when placed on the front teeth (even when mixed with clay particles).

Soil stabilizer

soil stabilizer may refer to:

Soil cement, a mix of pulverized natural soil with small amount of Portland cement and water

Cellular confinement, a honeycomb-like plastic soil stabilizer

Soil stabilization, a way of improving the weight bearing capabilities of sub-soils, sands, and other waste materials

Soil stabilizer (vehicle), a machine used to make soil cement

Thixotropy

Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick or viscous under static conditions will flow (become thin, less viscous) over time when shaken, agitated, sheared or otherwise stressed (time dependent viscosity). They then take a fixed time to return to a more viscous state.

Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others such as yogurt take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated. Thixotropy arises because particles or structured solutes require time to organize. An excellent overview of thixotropy has been provided by Mewis and Wagner.Some fluids are anti-thixotropic: constant shear stress for a time causes an increase in viscosity or even solidification. Fluids which exhibit this property are sometimes called rheopectic. Anti-thixotropic fluids are less well documented than thixotropic fluids.

Trench

A trench is a type of excavation or depression in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole).In geology, trenches are created as a result of erosion by rivers or by geological movement of tectonic plates. In the civil engineering field, trenches are often created to install underground infrastructure or utilities (such as gas mains, water mains or telephone lines), or later to access these installations. Trenches have also often been dug for military defensive purposes. In archaeology, the "trench method" is used for searching and excavating ancient ruins or to dig into strata of sedimented material.

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