Geosynthetics are typically included beneath or within a granular platform in order to improve its structural stability and minimise deformations during trafficking and loading.
The range of geosynthetics typically used to construct working platform designs are geotextiles and a range of geogrids. Geotextiles are primarily used as a protective separation layer to prevent the loss of fines and contamination of the platform material and to provide a secondary degree of reinforcement/stabilisation. Geogrids are specifically required to provide reinforcement and stabilisation of the granular fill, providing a lateral restraint via friction and interlock/confinement. As a rule of thumb, a layer of geogrid is equivalent in cost to 100mm of granular fill and it is generally safe and economically justifiable to incorporate a grid when the platform depth can be reduced by 100mm or more.
For stabilising haul roads, site access routes and working platform areas with soft subgrades, we can provide design assistance to strengthen the in-situ soils in accordance with the relevant foundation classes.
Geosynthetic cellular confining systems such as Abweb TRP may also be used to provide additional stabilisation of working platforms and to protect tree roots that are to be preserved alongside the installation of temporary work areas.
Geogrids
We provide a range of punched and drawn polypropylene geogrids with a typical design life in excess of 100 years and with aperture sizes to maximise stone interlock within the grids. They provide reinforcement of loading platforms in areas of weak compressible or variable sub-soils. In addition, by improving interlock/confinement, the geosynthetic acts to increase the load spread angle via increased shear resistance within the platform. Where a reclaimed on site fill is to be used, the geogrid can be selected to suit the specified maximum particle size.
Geotextiles
The geotextile layer primarily acts as a separation layer to prevent contamination and loss of fines content and to allow efficient drainage of the platform. Since it also acts in tension under loading, especially in soft soil conditions and often in combination with a geogrid, it provides additional restraint against the outward movement of the fill material and to confine the lowest layers of fill when they are compacted. Geotextiles used for working platforms must have sufficient puncture resistance to minimise damage from the gravel platform and in order to maintain exclusion of contaminants and retain tensile capacity. Geotesan NT is available where high resistance to puncture is required.
Design approach
Working platform design is carried out by our experienced geotechnical engineers using our in-house empirical load spread method and following the HSE guidance for tracked plant. The layer configuration specified will depend on the subgrade strength, the platform materials and the construction traffic loads. Our designs seek to achieve a balance between platform safety with adequate bearing capacity whilst still being economic and straightforward to construct. In our design proposal we consider the site plan and the possibilities to re-use existing materials as a carbon saving alternative.
Drainage of the platform is also key, and a poorly drained platform will deteriorate more rapidly. A geotextile may also be specified to treat platforms that are close to, or below the ground water table. Our technical service includes initial budget cost estimates and indicative thickness calculations, through to full PI backed designs available on request.
Input parameters required for design
The design approach promotes health and safety first. A properly designed and installed working platform enhances the efficient working of a site, as well as ensuring a safe environment. The design brief should be developed as required for any other temporary works design, but ideally the following information is required:
- What is the subgrade formation like:
- Ground investigation report
- Cohesive or granular soil
- Undrained shear strength
- Angle of friction
- Ground water table
- What is the platform to be made of:
- Specific source of gravel from site, or gravel to be specified and delivered
- Site layout:
- Plan of the working platform area and access roads
- Existing services survey (above and below ground)
- Existing structures survey (below ground chambers, retaining walls etc)
- What equipment will be operating on the working platform:
- FPS certificate / plant data sheets (dimensions, configurations, weights etc)
- Crane track ground bearing pressures, outrigger or mast foot loads
Working Platform Design Service
Submit your working platform design request via our Design Solutions form.
Temporary Works
Geosynthetics are used in temporary works applications to provide significant cost and time savings throughout the construction process; from stabilising temporary access roads, haul roads, site compounds, embankments and slopes.
Our range of geotextiles and geogrids are quick to install compared to traditional methods, reducing the volume of natural materials required and saving material and transport costs. Our geosynthetic products provide permanent and temporary solutions for ground reinforcement, slope reinforcement, erosion control, pavement reinforcement and structural drainage. Haul Roads / Temporary Access Roads
Biaxial and triaxial geogrids and woven and nonwoven geotextile options can all be used to reduce the construction time and materials required for haul roads and temporary access routes across construction sites. Our technical team are able to offer cost-benefit advice on which is best suited to your project.
Road Foundation Design Service
Submit your road foundation design request via our Design Solutions form.
Tree Root Protection
Abweb TRP is a geocellular system for protecting tree roots where a temporary access route is required without damaging nearby trees.
Site Compounds
Site compounds require access routes, temporary car parking and storage areas. Our range of geogids provide ground stabilisation by mechanically stabilising granular materials effectively. Geotextile provide separation functions when constructing unpaved access roads and parking areas.
Crane Pads / Piling Mats
Geogrids and geotextiles are ideal for temporary applications including stabilising weak ground for mobile cranes, piling rigs and working platforms. Geogrids mechanically interlock with well graded angular stone, reducing subbase thickness and increasing bearing capacity.
Wind farms access roads
Truckcell provides a permeable grass or gravel stabilised surface suitable for the heavy plant involved in the construction and maintenance access of wind farms sites.
Temporary Earthworks
Drainage is a major consideration in all Civil Engineering earthworks projects, including temporary works. Fildrain is a Fin Drain system that saves installation time and reduces costs compared to traditional stone based drainage layers.
Where temporary slopes and embankments are constructed, Geotexan provide a range of erosion control mats and geocells to confine fill material to reinforce the surface structure.
Specific design advice and guidance is available from our experienced in house technical team who will help ensure the right product is specified for your temporary works project.
Typical client profile
- Piling Contractors
- Foundation Engineers
- Civil Engineering Consultants
- Housebuilders
- Highways Engineers
- Rail Engineers
- Temporary Works Managers
- Main Contractors
Project Design Service
Submit your project design request via our Design Solutions page.
