We supply grouted anchors in the form of strand anchors and bar anchors. A further distinction is made between:
Temporary anchors / short-term anchors
Service life up to two years
Temporary anchors with a service life of up to two years according to the DIN EN 1537 standard are indispensable for low-deformation construction pit production. Anti-corrosion protection is governed by the standard. Type approval is therefore no longer required for these systems, only for the method used to tension the anchors. Both single-rod and strand anchors are used as temporary anchors.
Extending the period of use in exceptional cases
In some cases, the two-year period of use may be exceeded. Special solutions must be defined in these cases. Our specialist engineers can provide solutions tailored to the individual problem. For example, anti-corrosion protection can be specifically improved at the anchor head and greased strands can be used for strand anchors.
Permanent anchors secure slopes and breaks in the terrain in the long term. This means that particularly high demands are placed on the durability of the load-bearing element and the implementation. In addition to the protection of the load-bearing element during transportation and installation, special attention is paid to the careful execution of anti-corrosion protection measures on the anchor head. These processes are defined and taught in detail at Stump-Franki. Construction site personnel and tensioning specialists are especially familiarised with and trained in the expert production of permanent anchors.
High anchor forces
We have a wealth of experience in the production of permanent anchors with high anchor forces up to characteristic forces of 7,500kN. Series production in our own facilities and consistent quality control during execution ensure a high level of security.
Economical and flexible
The external flushing system enables us to extract drilling cuttings as efficiently as possible. The grouting section is produced cleanly with an uneven surface (root effect). This helps us to achieve rapid construction progress and thus work at a low cost, thanks to the high daily output. Transportation, assembly and dismantling can all be carried out quickly thanks to the compact equipment and minimal site facilities. In this way, even small projects can be implemented economically and flexibly throughout the country.
Pressure sensitive drilling
For sites that have not been proven to be free of explosive ordnance
Sites that have not been proved to be free of explosive ordnance pose a particular challenge. In this case, we use our drilling rig for pressure-sensitive drilling. Sample drillings are conducted across the suspected areas in the company of an expert in accordance with section 20 SprengG in order to obtain a drilling permit. Stump-Franki has a special permit for this in accordance with section 7 SprengG. This means that we can implement your project – even in areas that are difficult to investigate – safely, straightforwardly, and in compliance with the regulations of the respective federal state regarding the handling of explosive ordnance.
Solutions for subsoils with poor load-bearing capacity
If only minor forces can be transferred to the ground (e.g. in clay) via grouted anchors, construction pits are often designed to include bracing. Staggered anchors, however, offer a safe and economical alternative.
How does a staggered anchor work?
Staggered anchors have the fixed anchor lengths of the individual strands arranged at different depths in the borehole, but these come together in a single anchor head. All the strands are tested in a specially designed acceptance test and the anchor is then prestressed and secured. The arrangement of the fixed anchor lengths of the strands at different depths ensures that the subsoil is optimally utilised and not overloaded. This allows higher anchor forces to be achieved in the same borehole.
Removal design and patented process for economic dismantling
In addition to existing or planned underground transportation and utility facilities, construction schemes in inner-city areas increasingly involve orders to remove grouted anchors, in part or in full. Different systems are available for this purpose. The most suitable system must be selected according to the surrounding ground and the length of the grouted anchors. Our specialist engineers will be happy to assist you with the selection process as early as the planning phase to ensure safe removal during the execution phase.
Stump-Franki employees have optimised the removal processes and developed a patented procedure from this.
Drilling start point below the groundwater level
Experience and expertise for safe execution
High groundwater levels in cities and the construction of deep and dense trough construction pits in coastal areas call for an individual adaptation of the design: In this case, grouted anchors are produced with attachment points that are significantly below the groundwater level. The design and manufacture of these anchors must be carried out with particular care. Our teams have many years of experience and maintain a constant exchange of knowledge, so that even boreholes with several bars of counterpressure from the surrounding groundwater can be carried out safely.
Producing anchors below groundwater level by enclosing the construction pit requires preparatory measures as early as during the production of the construction pit wall as a sheet pile or diaphragm wall. Our expert teams will be happy to assist you early on to ensure safe implementation.