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When construction occurs in areas close to existing trees, the roots can be particularly vul-nerable and it’s necessary to use systems that do not inhibit construction and, at the same time, protect the trees and their root system. According to the British Standard BS5837:2012 the design in Tree Root pro-tection areas should not require excavation into the soil and avoid localized compaction, preserving the zone completely undisturbed. The majority of tree roots will grow in the top 600mm of soil and when the soil is compacted, it will adversely affect drainage, gas exchange, nutrient uptake and organic content, and will seriously impede or restrict root growth. A Cellweb confinement system was specifically de-signed for root protection area (RPA). The system creates a stable no-dig solution, load bearing structure for traffic and reduces the stress in the subgrade soils. This system confines aggregate materials and en-sures that the load placed upon it is laterally dissipated rather than transferring to the soil and roots below.
The system is comprised of three key elements: Cellweb TRP to support and distribute the applied load on the surface, Geotextile Treetex(Nonwoven geotextile) used as a separator and pollution control and a selected clean angular stone 4-20 mm used as infill material which is self-compacted.
The design using this system is based on the reinforcement of unpaved roads proposed by Webster (1981) and adapted to the system using the bearing capacity analysis.