Soil nailing

Using jetcrete or nails to temporarily or permanently secure construction pits and breaks between different terrain heights in granular soil or rock has been a proven construction technique for many years. PORR Spezialtiefbau GmbH has played a major role in this development and has its own general design approval for this method. 

In granular soil and loose rock, we arrange the nails to create a monolithic body that safely absorbs the earth pressure forces that occur. In solid rock, the nails act as dowels to prevent rock wedges from slipping or tipping. The surface is sealed using jetcrete, which we calibrate to match the earth pressure forces. We use modern calculation methods to determine what the optimum arrangement and dimensioning of the securing elements should be.

Common uses for jetcrete and soil and rock nails:

• Temporary construction pit systems
• Stabilising slopes and embankments, in some cases also with anchored nets
• Repairing concrete
• Special lightweight load-bearing structures
• Stabilisation during tunnelling works
   

• The jetcrete process can be adapted to every type of terrain. It can be combined with a soil nailing system to protect against debris and landslides.
• Large areas can be secured quickly and economically.
• Dry mix process: flexible and inexpensive. It can also be used in confined spaces.
• Wet mix process: This method can be used to secure large areas in a very short time. It generates very little dust.
• Steel fibres can be added to the mix, eliminating the need for conventional reinforcement.
• It can be freely shaped and adapted to the structural design.
• Jetcrete can also act as a fire retardant.
   

Standards and regulations

Jetcrete is dimensioned in accordance with:

• DIN EN 14487
• DIN 18551

When testing the load-bearing capacity, the reinforced concrete slab is checked for bending (uniaxial or biaxial) and shear force in order to calculate the steel reinforcement to be inserted. In soil nailing, the punching shear forces are also investigated.

The soil nails can be applied for temporary (< 2 years) or permanent (> 2 years) use. When they are installed for permanent use, the steel supporting element is fitted with an anti-corrosion system consisting of a plastic ribbed tube injected with grout.

Further details are specified in our DIBt-issued general type approval issued:
Z-20.1-104 Stump-Franki soil nailing system.

We ensure high execution quality with:

• Individually coordinated instructions
• Our own DIBt general type approval for soil nailing Z-20.1-104
• Compliance with the requirements of DIN EN 14487 and DIN 18551
• In-house production of the micropiles in Germany
• In-house and third-party production monitoring
• Clear processes governed by our quality management system in accordance with DIN EN 9001:2015
• Verification of the theoretical pull-out resistance of the soil nails based on professional pile test loads on 3% of all nails
   

There are two design variants with different advantages:

• Dry mix process: A flexible and inexpensive process that can also be applied in confined spaces.

• Wet mix method: This method allows large areas to be secured in a very short time while generating very little dust.