Tarmaxx Geocell Cellular Confinement Systems provide a wide variety of flexible erosion control, slope stabilization treatments for open channels and hydraulic structures.
The structural performance and durability of conventional protection materials such as concrete, gravel, riprap and vegetation can be significantly improved by confining the materials within the cells of Tarmaxx Geocell systems. The design of protective linings requires a clear definition of the maximum anticipated flow conditions and the associated hydraulic stresses to which the channel protection will be subjected.
Consideration must be given to subgrade drainage requirements and the potential for longterm or seasonal deformations of the structure as a whole. Other factors include the surface roughness, i.e. the hydraulic efficiency of the lining system, and the ease with which future maintenance and sediment cleaning operations could be carried out.
Channel protection design must also have compatibility with local environmental, ecological and aesthetic requirements. A technical overview of the design and construction of a range of open channel and energy dissipation structures that incorporate Geocell Channel Protection systems is presented herein.
The protection of channels and open-channel structures takes many forms and can include a range of natural and man-made materials. Broad categories of protection include:
- Natural or vegetated linings (e.g. grass or reinforced grass)
- Hard flexible armoring (e.g. rip-rap, gabions, pre-cast blocks, Geocell protection system)
- Rigid armoring (e.g. poured in-place reinforced concrete)
Combinations of protection materials are commonly applied within a channel system to account for variations in hydraulic conditions, aesthetic requirements, environmental factors, and cost constraints.
Selection of appropriate lining systems can be greatly influenced by the type and function of a particular channel structure in that the potential for extreme discharge events and associated hydraulic stresses may preclude the use of certain protective systems.
The main classes of channel structure can be summarized as follows..
Natural Drainage Channels : Natural drainage channels are formed by the erosive effects of concentrated storm-water runoff, as the flow gravitates to lower elevations. The horizontal alignment and bed slopes of natural channels are often irregular, due to variations in topography and the erosion resistance of surface soils.
Major storm runoff events can impose extremely damaging hydraulic stresses throughout the channel. Urban development within the channels’ catchment area may significantly increase the severity of storm discharges in comparison to historical levels. Special measures and restrictions may be imposed to protect existing plant and aquatic animal habitats.
Man-Made Channels :
Man-made channels, whether for drainage, irrigation, power generation or navigation, are generally more consistent in terms of alignment and cross-section. Predictions of maximum design flows can often be made with greater confidence thereby reducing the risk of underdesign of protective works.
Hydraulic Structures :
Hydraulic structures are incorporated into many open-channel systems at inlets, outlets, constrictions, and severe changes in grade. In most situations, the primary function of these structures is related to the controlled dissipation of hydraulic energy.
This is generally achieved by the transformation of potential energy (hydraulic head) to kinetic energy (velocity head), and the ultimate dissipation of the kinetic energy through frictional losses, turbulence and the generation of heat.
Consequently, hydraulic structures, such as spillways and drop-structures, are especially prone to severe erosion and hydrodynamic stresses and generally require more substantial forms of surface protection than those associated with channel linings.
Channel Protection
Using geocell cellular confinement system gives deformed cover of a precisely defined roughness and stability.
It creates single- and multi-layer protection systems complying to a wide range of structural and hydraulic requirements.
A vegetated embankment is ideal for areas with intermittent flow, muddy valleys and steep walled stream channels. Concrete is recommended for areas with continuous or high flow.
Vegetated Protection
Geocell Cellular Confinement System increases the natural resistance to erosive forces, protecting the root zone of vegetated layer. Reinforces vegetation during high flow, directing the flow rather over the layer than through its inside.
Concrete Protection / Geocell Cellular Concrete
After filling with concrete the geocells act like a flexible slab and stable expansion joints. The Geocells bend and adapt to the minor subgrade movements, reducing cracking of the concrete.
The Cellular Confinement System is ideal for protection of channel slopes, exposed to severe erosive conditions, as well as channels with continuous flows.
