Root system

The average pile-driving depth for conventional piles is approx. 1.6-2.0 metres.

This depth is often a problem, particularly in the case of landfills, sites with ground monuments, stony plots and conversion areas with underground obstacles such as concrete and wall remains:

• Sealed landfills usually have a sealing film at a depth of approx. 80 cm, which is intended to safely drain off any gases that arise. This film must not be penetrated and the permitted pile-driving depth is reduced to a range of only 70 cm. This automatically rules out the use of conventional piling posts.
• Stony soils usually solidify and compact with increasing depth. In many cases, a closed rock slab is reached after less than one metre. Driving in normal piles is impossible here without cost-intensive pre-drilling.
• Groundwater conditions: The soil survey(s) also takes into account the groundwater conditions, which can influence the stability and longevity of the foundations.
• Conversion areas such as former barracks, industrial sites or railway facilities often have a long history and have often been built on with various buildings over the course of decades of use. These buildings were usually demolished to a depth of approx. 1.0 metre below ground level. Remaining foundations, pipes and sewers were then usually simply pushed in. Here too, it is impossible for the supports to penetrate to a depth of 1.6 metres.

The basic functional principle of foundations based on driven profiles is the friction between the ground and the surface of the profile. The vertical pull-out forces play a primary role here. The PV modules act like a sail that can be subjected to airflow from two sides. An inflow from the south ensures that the supports are pressed in (compressive load). 

An inflow from the north causes the supports to be pulled out (suction load).

Dutch marshland, landscapes with boggy soils, very sandy ground or terrain with a very high moisture content, such as floodplains and flood plains, cannot be built on using conventional driven piles or concrete foundations (risk of subsidence). 

Root systems offer a remedy here. The functional principle of "friction" is extended here by the angled guidance of the soil nails. These are not aligned directly in the effective direction of the support loads, but at an angle of approx. 45° to them. This allows additional soil to be activated and the load-bearing capacity to be significantly increased.

This function allows protection against both sinking in and pulling out and is realised with long soil nails on a project-specific basis.

Saline marsh soils, contaminated conversion areas or soils with a high pH value ensure extremely rapid removal of the zinc coating on conventional driven piles. At the same time, project planners and general contractors are under high cost pressure. This means that countermeasures such as stainless steel supports or concrete foundations are often ruled out. 

Our root systems provide a remedy here: only the relatively small soil nails and no other components are located in the ground. Form-Tec is therefore able to offer powder-coated or thick galvanised soil nails very cost-effectively and efficiently. 

Are you planning to use the system for a a lifetime in critical ground conditions? No problem! In contrast to conventional driven posts, ground spikes can be replaced at any time and at low cost.