Glossary of terms

Mass Gravity Retaining Walls

   A wall that is placed in front of an unstable slope to stop the slope collapsing and which depends on its mass to resist the pressures from the unstable slope.

Soil Reinforcement

   A technique which involves the introduction of synthetic geogrid elements into the ground, which makes the ground perform better than it does in its natural state; standing steeper, accommodating greater loads, distributing loads and settling less. Geogrids can be made of steel or polymer geogrids which interact with the soils compacted upon them.

Piled Embankment

   An embankment constructed upon soft soils, or soils that do not offer appropriate bearing capacity, will be prone to settlement. Building the embankment upon piles stops this happening as the embankment loads are transferred into the piles and thus into a more structurally competent strata. Ultra-high strength geogrids, placed beneath the embankment and just above the piles, help to spread loads into the piles, enabling the piles to be spaced out more, saving cost and materials.

Capping
   When a landfill or mine works is exhausted, it needs to be capped to completely encapsulate the contaminated / degrading waste material within. The capping works consist of a package of materials to seal, protect and drain the top of the landfill structure. Finally some mechanism of establishing vegetation on the capping is often included.

Transverse Structures

   Transverse structures are any structures that are perpendicular (or generally “not-parallel”) to the flow of a river or watercourse. Transverse structures can fully or partially cross the river or watercourse and can include, river groynes, weirs, culverts or dams. Bridges can also be considered a transverse structure and the effects that they have on the river (eddies, current changes and erosion at columns).

Dynamic Barriers

   A rockfall protection barrier (also known as a “catch fence”) that is designed to progressively deflect upon impact by a rock mass. These structures are designed as a ‘kit’ which should have been tested in accordance with specific protocols (e.g. ETAG 027 Guideline). Components within the fence absorb the impact energy and depending on the size of the rock mass, the barrier may be permanently deformed and would require maintenance. The residual height of the fence after impact, and the deflection of the barrier during impact are critical factors to the designer of these solutions.

Soil Bioengineering

   A technique that involves the integration of plant matter into more structural interventions. For example, a gabion wall used to provide long term stability to a river bank could include soil bioengineering techniques, designed to establish vegetation within and on the gabion. It allows a designer to have the long-term reliability of a structure (designable, tried and tested), with the aesthetic and ecological benefits of vegetation.