Ground Anchors are a load transfer system designed to transfer the forces applied to it into a competent stratum.
Used in a wide variety of applications in the civil engineering and construction sectors, Ground Anchors retain structures such as Bored Piles Walls, Sheet Pile Walls, Basements, Bridge Foundations, Marine Structures and for temporary works during construction phase works.
Ground Anchors can be installed into all types of ground conditions and at various angles to suit the requirement of the structure it is retaining.
Ground Anchors: Active and Passive
Active Anchors are pre-tensioned before the it takes up the load, which prevents distortion to the structure.
Passive Anchors are only tensioned by the structure itself applying load to it.
Anchors are designed to be either Temporary or Permanent, with Temporary Anchors having a design life of 2 years.
Permanent Ground Anchors can have a lifespan of 120 years if they have Double Corrosion Protection Applied (DCP). DCP is defined in BS8081 and consists of factory pre-grouted encapsulation of the bar within a corrugated plastic sheath. Galvanising is a method of providing single corrosion protection providing an extended design life.
Ground Anchors Tendons come in various forms:
Solid Thread Bars – ranging from 15mm up to 75mm Diameter with Ultimate loads up to 4572 kN
Hollow Bars - ranging from 25mm up to 103mm diameter with ultimate loads up to 3700 kN
Strand Anchors - 15.7mm Diameter Compacted Strand. Single Strands have an Ultimate Load of 300 kN. You can install between 1 and 30 Strands per Anchor bundle.
Removable Strand Anchors are strand anchors with a built-in rupture point of 220 kN. When this load is applied the strand can then be removed.
GFRP Cuttable Bar Anchors are 32mm Diameter Glass Fibre Reinforced Polymer bars with an ultimate load of 320kN, these can be installed as single bar anchors or Multi Bar bundles.
Ground Anchor installation is carried out by the drilling of a borehole, the installation of the tendon and grouting of the tendon in the borehole. The two main methods we use are Rotary Percussive Drilling(Top Hammer) and Down The Hole Hammer (DTHH).
Top hammer drilling can be carried out using air or water to flush the material from the borehole. We use this method to install self-drill hollow bars, allowing us to advance the anchor bars to depth then grout through the hollow stem in the bars.
Down the Hole Hammer bore holes are created using an air driven hammer drilling system. With this method we simultaneously install Temporary or Permanent casing while advancing the borehole. This is used when the soils are not stable. Once a better stratum is reached we can advance the bore hole using open hole drilling.