Our approvals and type approvals.
PORR Spezialtiefbau GmbH has a large number of its own general building inspectorate approvals. Every customer can rest assured that we can fulfil any construction task, no matter how special, thanks to our technical expertise.
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Soil nailing Stump system.
The temporary or permanent securing of steep slopes and excavations with soil and rock nails is a major focus of PORR's special civil engineering activities. We have significantly influenced and further developed these tried-and-tested construction methods, which have our own general building authority approvals, since their market launch.
The arrangement of tensile round rods, so-called nails, makes it possible to create a monolithic body in loose rock that safely absorbs the earth pressure forces that occur. GEWI steels are used as load-bearing elements, which are coated with a ribbed tube injected with a cement suspension as corrosion protection for long-term use.
Depending on the application, it is also possible to use cuttable tensile elements made of glass fibres, so-called GRP elements, or self-drilling nails for securing during tunnelling. The surfaces of the loose rock secured by soil or rock nails are then stabilised using a statically designed and reinforced shotcrete shell. Our engineers use state-of-the-art calculation methods to determine the optimum arrangement and dimensions of the stabilising elements to be used.
Jet grouting Stump Jetting.
PORR Spezialtiefbau GmbH was one of the first holders of a general building authority approval for jet grouting in Germany. Thanks to the continuous further development of the individual components, we guarantee a high level of execution reliability.
With the publication and introduction of DIN EN 12716:2019-03 "Execution of special civil engineering works - Jet grouting; German version EN 12716:2018" as a technical building regulation, the planning and execution of load-bearing elements using jet grouting or high-pressure injection is regulated (see MVV TB, No. 1.2.2.7). A general type approval is no longer required. The use of subsoil improvement methods is permitted by the building authorities and does not require a type approval. You can find out more about the building inspectorate framework on the website of the Deutsches Institut für Bautechnik.
The jet grouting method is used for
- Underpinning
- sealing slabs
- Section sealing
- Sealing blocks
- retrofitting foundations
- soil improvement
Permanent anchorStump-Duplex.
The patented Stump Duplex Anchor was the first permanent anchor to receive general technical approval in Germany and was the first permanent anchor to be exempted from the obligation for subsequent monitoring. For over 40 years, this permanent anchor system has been used as a permanent anchor for more than two years.
The Stump Duplex anchor is a pressure tube anchor in which the force is transferred into the grout body via the rear end of the grout body. A pressure tube, the so-called duplex tube, serves as the force transmission element. The anchor steel tension member is not connected to the grout body. As the grout body transfers the force from the anchor end into the ground via compressive forces, cracking in the grout body and a resulting reduction in force transmission between the grout body and the existing ground is not to be expected.
Rock strand anchorStump rock anchor.
This best documents the progress and status of modern anchor technology when used in rock. Application is generally limited to cases where the entire length of the force application is in the rock. In addition, it is also possible to use Stump rock bolts in other ways with the approval of a geotechnical expert.
Even in particularly difficult soil and rock formations, the use of special grouting techniques means that a reliably load-bearing heavy-duty anchor can be used.
Milestones in further development.
In any case, the work on the Eder dam wall represented a milestone in the development of the Stump rock anchor. The Eder dam wall was secured against uplift using 104 type 6-34 permanent strand rock bolts with a working load of 4,500 kN. The test loads were up to 12,500 kN with anchor lengths between 68 and 73 metres. The boreholes had to be drilled carefully in the area of the dam wall and with maximum accuracy throughout. At 0.5 %, the drilling deviations were still below the strict tolerance of 1 % drilling deviation.
To produce these rock anchors, it was first necessary to drill a core hole with a diameter of 146 mm. This was followed by widening the diameter to 276 mm. By injecting rock and masonry on a cement basis, we achieved targeted tempering of the area, especially in the force application area of the anchors. This was verified by means of WD tests. The anchors were installed using a special deflection construction and a mobile crane to prevent damage to the corrosion protection of the anchor.
To tension the anchors, we used a tensioning jack specially made for this case. We equipped 10 of the 104 installed anchors with load cells and fibre optic sensors for permanent anchor monitoring. The anchor heads of all anchors are designed in such a way that anchor force measurement and, if necessary, retensioning of the anchors is possible at any time.
The securing of a large cliff body on the Kammereck cliff, between St. Goar and Oberwesel, was carried out by installing 23 permanent rock anchors, each with a working load of 2,000 kN. The rock massif is located directly above the busy federal roads B9 and is undercut by a Deutsche Bahn tunnel. The up to 40 metre long permanent anchors each consist of 23 individual strands and were arranged on two reinforced concrete bars. The working load was applied in two stages - first with 1,350 kN, then with 2,000 kN. We continuously monitored the deformation of the rock massif using multiple extensometers.
HLV pole PORR special civil engineering system.
HLV piles are pipes made of ductile cast iron, joined together from partial lengths to form the total pile length. The partial lengths are connected to each other via the pile's own ductile cast iron pile sockets or via special coupling elements and driven into the ground by pile drivers. The driving process creates a rigid, positive and non-positive connection. Depending on the soil conditions, a driving spike or driving shoe is used to drive the pile into the ground.
So-called ductile piles are used either grouted or ungrouted as compression and/or tension piles. They can also be installed vertically or inclined up to a depth of 55 metres.
They are available in the following specifications:
- Diameters of 118 and 170 mm
- Load transfer up to 1,400 kN
Stump compact anchorfor rock and soil.
Compact anchors, also known as grouted anchors, are used in a wide range of applications. One of the most common forms of application is the temporary securing of construction pits for less than two years.
Permanent anchors or permanent anchors, such as the strand compact anchor, have proven their suitability for anchoring tent roofs, bridges, slopes and retaining structures. However, this technology can also be used efficiently and economically for smaller projects. One example of this is the pylon bracing of the tent roof construction for the all-weather swimming pool in Velbert.
Compact anchors are also used in bridge construction, for example in the construction of the Kylltal bridge, where 58 anchors with a working load of 2,700 kN had to be installed on each side to transfer the forces from the cantilever construction. On one abutment side of the bridge, it was only possible to produce the anchors for the foundation to be anchored from a much lower working level than the later foundation. For this foundation work, it was necessary to extend this anchor by around 7 metres after production, as well as to form a coupling point, as is known from prestressed concrete. To ensure quality, the entire work at the coupling points was extensively monitored.
Stump strand pressure pipe anchorfor soil and rock.
Pressure tube anchors, such as the Stump strand pressure tube anchor, are so-called grouted anchors. The anchor force to be transferred into the subsoil is transferred from the steel tension member via a steel pressure tube from the anchor base to the grout body for introduction into the subsoil. The remaining space between the steel tension member and the pressure pipe is filled with a viscoplastic corrosion protection compound.
This anchor system combines the great flexibility of the strand load-bearing elements with optimum force transmission via the pressure pipe.
In addition, the Stump strand pressure pipe anchor is ideal for confined installation conditions.
Composite pile PORR special civil engineering system.
The PORR composite pile system can be used as a single-rod pile for compressive and tensile forces of up to 2,574 kN. The load-bearing element is a round steel bar with threaded ribs rolled onto both sides, which are arranged along the entire length. Coupling also makes it economically feasible to use the bonded pile for room heights of up to 2 m.
The rolled-on threaded ribs are used for the friction-locked connection of anchor pieces and anchor nuts, for coupling individual pile sections using threaded sockets, as well as for improving the bonding effect to the surrounding cement stone in the force transmission area. The profiling of the load-bearing element enables exact fixing in the pile head area as well as any extension of the pile projection using approved connecting parts. Provided with corrosion protection in accordance with the associated general building inspectorate approval, the composite pile can also be used as a tension pile for load-bearing forces of up to 990 kN.
The design of the pile allows proper pile fabrication even at minimum installation heights of approx. 2 metres. When installing a post-injection system, it is also possible to specifically improve the existing soil in the force application area by means of post-grouting.