THE PLATIPUS CONCEPT
The Platipus Anchoring System is well proven in the field of Civil Engineering, Utility Services, Tree Anchoring and tie-downs as a lightweight, cost effective alternative to traditional techniques. Hundreds of thousands of Platipus Anchoring Systems have been installed worldwide in an increasing range of applications.



Platipus produces lightweight, high capacity anchoring systems, in a wide range of materials and sizes. They are quick and easy to install using simple tools and plant. The anchors are driven into the ground and proof loaded to precisely the load required using powered or manual jacks. They are then ready to use immediately with no waiting time, e.g., for concrete to cure. Thus, significant savings can be made in comparison to traditional methods, in terms of time and money.

INSTALLATION
There are three main stages to the installation of an anchor system. These same principles apply to all sizes of installation using a variety of light, medium or heavy installation equipment. The hand installation of a lightweight system is illustrated below.



Stage 1   Drive the anchor into the ground to the required installation depth.

Stage 2   Remove the drive rod from the body of the anchor in the ground, either by hand or using rod-removing equipment.

Stage 3   Loadlock the anchor into its full working position and proof load, by applying a load to the tendon.

LOAD LOCKING



Due to the design and shape of the anchor and the position of the tendon, when a load is applied the anchor will rotate in the ground by up to 90° and loadlock.

In dry granular material, the anchor will normally loadlock within its own body length. In a saturated clay material, this loadlock distance can be expected to increase by up to three times. The distance an anchor system travels through the ground during loadlocking and proof loading is known as extension and is normally measured in mm.

As additional load is applied to the anchor system, the body of soil ahead of the anchor is compressed and tends to bond along the shear angle of the soil. This provides resistance to any further anchor movement. The size and spread of this body of soil can be visualized as being a truncated cone or frustum. This soil is referred to as the Frustum Cone.

THE FRUSTUM CONE
A typical granular material consists of different particles that interlock, bond and compact when subjected to a load. Coarse sands (ranging from 0.6mm to 2mm) and gravels (coarser than 2mm) are generally of this composition. Typical shear angles for non-cohesive granular soils range from 30° to 50°.

The Platipus anchor system performs exceptionally well in granular material as the interlocking, bonding and compaction serves to create a frustum cone of large size and volume.

The actual size and volume of a frustum cone will largely be determined by:

• * The type of soil in which the anchor system is installed
• * The condition of the soil in terms of water content, voids, mechanical strength and shear angle
• * The size of the anchor used
• * The load applied; and
• * The depth of installation

In free draining, non-cohesive granular soil (good soil), as indicated above and illustrated in the diagram on the left, the larger shear angle increases the volume of the frustum cone created, the load achieved and its resistance to being pulled out.

In cohesive, saturated clay (poor soil with a typical shear angle of between 0° and 20°), the volume of the frustum cone created, the load achieved and its overall resistance to being pulled out will be reduced (as illustrated on the left). Nevertheless, even with a shear angle of 15° to 20°, it is still possible to achieve satisfactory loads with the Platipus system.

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