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| HOW TERRACELL WORKS |
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The TERRACELL cellular confinement systems provides confinement throughout the depth of the aggregate layer, not just at the interface between the aggregate and the subgrade. The ability of the aggregate layer to spread surface forces and reduce pressures on the |
subgrade is no longer dependent solely upon the properties of the aggregate itself. TERRACELL provides the necessary confinement and preservation of compaction. This action allows the use of lower quality and/or quantity of more readily available aggregates | thus saving time and money. Studies and actual installations have shown that rounded aggregates, such as sand, confined within the cells, perform better than thicker layers of higher quality aggregates used without a cellular confinement system. |
| ECONOMICS |
| During construction of roads, parking lots, sewer lines, etc., pocket of soft, poor soils are sometimes encountered. Typically, soil is removed to a significant | depth and replace with expensive fill materials. This procedure can be costly and time consuming. An effective alternative is to use a stabilization fabric with | TERRACELL placed directly on the prepared subgrade. Cells are then filled with readily available granular materials and compacted. |
| INSTALLATION | ||||
| TERRACELL
is installed quickly and easily by semi-skilled labor and without any
special equipment. Section are shipped to the job site in collapsed form,
measuring 11 x 5 x the height of the cells.
1. A geotextile should be
used to separate fill materials from the subgrade. Simply unroll
the fabric directly onto the prepared subgrade, overlapping adjacent
panels 12 to 24 inches.
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3. Stretch out the section of TERRACELL
as much as possible (beyond its 8 x 20 size) several times and then
place the four corners over the embedded stakes. Additional stakes may be needed
along the perimeter in order to get full expansion of each section. In
situations where it is difficult or impractical to use stakes to hold a
section open, such as over an impervious liner, a stretcher frame may be
needed. Adjacent sections are
installed in a similar fashion and butted together to achieve continuous
coverage. |
all
cells are filled. Never allow equipment to drive over unfilled cells. It is best to
overfill slightly to allow for reduction in volume of the granular
materials as it is compacted.
Compact the fill materials. Depending on the nature of the
aggregate, a vibratory roller and/or water may be required to achieve a
desired compaction level. The most common method of compacting the
aggregate is through multiple passes by tracked
equipment
Once the cell are filled and the aggregate compacted, the TERRACELL constructed base is ready to withstand heavy traffic loads. |
Slope Protection
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The function of TERRACELL cellular confinement system is: (A) EROSION CONTROL to minimize and/or eliminate the erosion actions of wind and water on exposed soils. (B) SLOPE STABILITY to prevent sliding or sloughing off by providing sufficient weight at the foot and/or along the face of the slope Benefits include cost savings in materials and or labor during both installation and subsequent periodic maintenance. TERRACELL can be used in a variety of erosion control or slope protection project, including:
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| MECHANICS |
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EROSION
CONTROL: Most
unprotected soil surfaces are prone to erosion. It takes place when the
forces of the wind or flowing water dislodge and transport soil particles.
Although silty soils are most susceptible to erosion, clays and sand are
at risk when strong erosion forces exist. Erosion occurs when flowing
water or heavy winds form rills in the soil. Over time, these forces are
concentrated within the rills. This accelerates the erosion process and
makes the rills deeper, For a storm of a given duration and intensity,
three principal site parameters determine the amount of erosion likely to
take place:
On short and gentle slopes, seeding that is protected by excelsior/straw blankets or an erosion control fabric is usually the most cost-effective method of erosion protection. In more severe erosion situations, a geotextile and a layer of stone 12 to 24 inches deep might be required on the face of the slope. Although this arrangement can be effective in preventing erosion, in comparison to the TERRACELL system, it tends to be very costly and highly unattractive. Drawbacks include creating an environment for rodents and insects by allowing vegetation to grow where it is difficult to cut and control. This creates a potential hazard for children and animals. |
(B) SLOPE STABILITY: For any given soil at a certain moisture content, there is an angle beyond which the soil will not stand without external support. Whenever the steepness of the slope exceeds this failure angle, gravitational forces act on the soil mass to create shear stresses causing the slope to fail through sliding or sloughing off. The process ends when a new equilibrium is achieved at an angle less steep than the initial one. In many situations, it is desirable to have a slope steeper than the shear strength of the soil will allow. One method employed to achieve this objective is to provide external weight at the foot and/or along the face of the slope. The resulting counterweight increases the effective failure angle, preserving the stability of the slope. Riprap is commonly used because of its weight and the fact that it also acts as an erosion control material. As discussed previously, riprap has serious drawbacks. |
| HOW TERRACELL WORKS |
| For difficult erosion control situations, the TERRACELL cellular Confinement system can be substituted for a more conventional hard system of expensive, heavy materials such as riprap, armor stone, revetment mats, gabions, etc., depending upon the severity of the erosive forces encountered. TERRACELL can be filled with soil or sand, small rock, concrete, etc. The cells confine the fill material and protect it from being moved by wind or water. Each cell in the system acts as a small dam that allows water or wind to pass over the top while holding the fill in place. The cell walls inhibit formation of rills, thus preventing the erosion process from developing. Lastly, a soil-filled TERRACELL slope can be seeded without worry that the system will interfere with mowing operations. | In areas
subjected to substantial erosive forces such as shorelines, bends along
river banks, outflow pipes, etc., concrete might be the most effective
material selected to prevent erosion. When filled with concrete, TERRACELL
becomes an articulated concrete mat that conforms to possible differential
settlement while protecting the underlying soil from either wind or water
erosion. In slope stability situations, where external weight on the slope
is needed to achieve stability, TERRACELL keeps the fill material in place
so that its function as a counterweight is preserved. TERRACELL (8)
filled with sand provides an evenly distributed weight of approximately 80
pounds per square foot.
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| ECONOMICS |
| Slope protection using heavy armor stone tends to be very costly in terms of materials and the time consumed in installation, especially if the rock must be transported from | off site. Slope protection using TERRACELL filled with locally available soils, small rocks, or concrete can be more effective than expensive alternatives and | is usually less costly to maintain. The TERRACELL system provides one solution for both erosion control and slope stability problems. |
| INSTALLATION |
| TerraCell used in erosion control and slope protection applications is installed in the same manner as in ground stabilization projects. (Additionally, stakes should be left in place to insure | that TERRACELL will remain permanently anchored to subgrade). When using concrete, place the concrete as in any other form, exercising care not to cause the TERRACELL to be displaced | during the
pouring operation. Whether using fill materials or concrete, it is
recommended that the cells be filled from the base of the slope
upward. |
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The TERRACELL cellular confinement system acts as a form for containing the granular materials used to build the structure and provides tensile reinforcement. TERRACELL accomplishes the following:
In many situations, TERRACELL makes it possible to build a retaining wall using locally available soils and/or aggregates. In some cases, a combination of the two types of materials is both practical and cost effective. The locally available soil, including material not of the quality normally specified for use in constructing retaining walls, is placed in the cells. A free-draining material would be placed behind and below the TERRACELL to alleviate any potential hydrostatic problems developing at the back of the wall. TERRACELL can also be used in a variety of other vertical or near vertical, structures, including:
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| Retaining Walls |
| MECHANICS |
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Retaining walls are structures built for the purpose of stabilizing very steep slopes using minimal land area. A common example is a cut into the side of a hill to build or widen a road. The slope created is so steep as to be unstable and requires a retaining wall to prevent slope failure. There are two basic types of retaining walls: A CANTILEVER retaining wall is usually made of reinforced concrete and acts as a structural member. A GRAVITY retaining wall has a vertical or near vertical face and its ability to retain the soil behind it depends on gravity (its own weight). This type of wall is usually composed of unreinforced concrete or soil. If made of soil, the wall generally consists of a facia and one or more layers of reinforcing member (geotextile, grid, metal strips, etc.) extending from the facia back into the soil mass. The
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functions of
the facia are to prevent soil from sloughing off the surface of the wall
and to prevent erosion of the face of the wall. The function of the reinforcing
member is to increase the effective thickness of the wall which increases
its stability.
The wall itself must be built to withstand pressures applied by the retained soil. This force, lateral earth pressure, is dependent upon several parameters, including the geometry of the wall and the characteristics of the retained soil such as its unit weight and angle of internal friction. In designing a retaining wall, it is necessary to consider potential forces that could cause wall failure and compare them to the stability calculations of the proposed wall, taking into account generally accepted safety factors. |
| HOW TERRACELL WORKS |
| When the TERRACELL cellular confinement system is used to construct a retaining wall it functions as both the facia and the reinforcing element. A section of standard dimensions (8 x 20) filled with soil or rock acts as a large, heavy mattress. These mattresses are the building blocks for a gravity retaining wall. The mattresses can be placed with either the 8 x 20 dimension along the face of the wall creating a structure with inherent stable characteristics. TERRACELL keeps the soil or rock from falling or being eroded off the face of the wall. Its confining action prevents dislodging of the fill at or near the face during compaction. Lastly, the size of expanded TERRACELL panels |
significantly increases the effective thickness of a wall. This allows walls of considerable height to be built without the need for additional reinforcing elements, such as grids or metal tie-backs. Although TERRACELL can make the building of retaining walls simple and straightforward, the design of these structures is crucial to their successful performance. Considerations, such as internal and external drainage in critical portions of the wall, must be addressed. Plans for any vertical structure should always be prepared by an experienced designer.
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| ECONOMICS |
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A poured-in-place concrete wall or a wall composed of costly materials such as select fills, timbers, steel, concrete block, or gabion baskets, can be very expensive and time consuming to construct. A gravity retaining wall made of TERRACELL and locally available soils and/or aggregates offers an economic alternative to these other systems. |
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| INSTALLATION |
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Install the bottom section of TERRACELL in much the same manner as described in the stabilization section. In most applications, place the second and subsequent sections such that the front of each panel is slightly offset back from the front of the panel below. Also, stagger the sections in brick laying fashion so that the panels are not directly on top of each other. As the wall increases in height, keep heavy compaction equipment off the face and sides. As always, observe all safety precautions. Insure that any internal or external drainage materials or procedures required are properly installed. |
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| TerraCell SPECIFICATIIONS |
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