KRINNER Ground Screws
The unique one-piece Krinner-developed hammered and hardened conical screw is excellent for penetrating through the soil. The shape, material used and spiral angle are ideal to cut the screwcutter into the soil.
Krinner Ground Screw Installation Method
KRINNER ground screw drilling machines boast torque of 5,000 Nm and thus are eligible to install screws up to 220cm of length into any kind of soil, including bedrock. The machines enable for excellent verticality to be retained while drilling. Changes in subsoil may be approached by the means of adjustable pressure force or torque. When drilling, rather solid soil may appear (for instance loess or grown sediment) and in such case it is convenient to use a pre-drilling disrupter. This disrupter will create beds for the ideal installation. If the situations requires it and the soil encountered is pure rock a diamond crown locking ring drill powered by compressor will be used. These machines are capable of installing 150 to 250 screws/working day within one workgroup (for instance: 1 MW requires 750 screws).
KRINNER Measuring Equipment
Prior to the installation of the screws each prospective customer is provided with a free soil test. This test should determine the ideal technology of driving the screw into particular soil type and how this will be reflected in the constructions statics. Simultaneously, the test analyzes possible dangers that might come up during drilling and provide adequate values for the bearing capacity certificate. This certificate is a part of the construction-base supply and should serve as an important document for the funding institution. Our measuring equipment is a part of our know-how and has been tested by a certified laboratory. The values obtained are considered binding and evidential.
Using Anchors – Guidelines
The below added table provides average/typical values in case the anchor is applied into soil the depth of 1 meter.
Example: 60mm anchor applied through arable land/loose soil into middle clayed soil the depth of one meter can reach the values of 20 kN – 25 kN.
If anchors are to be applied into impenetrable soil (such as claystone), a sprocket hole must be equipped with a core in such a way that the anchor can be screwed in into the hole and subsequently secured mechanically or injected.
| Soil type | SPT value | 60mm anchor (weight load/1 m mikropile) | 100mm anchor (weight load/1 m mikropile) | ||
|---|---|---|---|---|---|
| Tensile strength (kN) | Pressure (kN) | Tensile strength(kN) | Pressure (kN) | ||
| Arable land/loose soil | 0 – 5 | 5 | 8 | 7 | 10 |
| Soft clay | 1 – 4 | 7 | 10 | 10 – 20 | 15 – 25 |
| Middle clay | 4 – 8 | 10 – 15 | 15 – 20 | 25 – 35 | 30 – 40 |
| Impermeable clay | 8 – 20 | 25 – 30 | 30 – 40 | 40 – 60 | 70 – 90 |
| Soft sand clay | 1 – 4 | 7 | 15 – 20 | 12 – 15 | 15 – 20 |
| Middle sand clay | 4 – 8 | 15 – 25 | 25 – 30 | 30 – 35 | 40 – 50 |
| Impermeable sand clay | 8 – 20 | 25 – 30 | 40 – 50 | 40 – 50 | 70 – 90 |
| Boulder clay | 4 – 15 | 18 – 25 | 25 – 30 | 20 – 25 | 25 – 30 |
| Limestone | 20+ | 50 | 50 | 150 | 150 |
| Hard clay | 50+ | 50 | 50 | 150 | 150 |
| Rock | 50+ | 50 | 50 | 150 | 150 |
| Agglutinated limestone | 0 – 5 | 5 | 9 | 8 | 12 |
| Soft limestone | 5 – 10 | 12 | 18 | 19 | 25 |
| Impermeable limestone | 10 – 40 | 50 | 50 | 135 | 150 |
| Limestone rock | 40+ | 50 | 50 | 150 | 150 |
| Gravel | 20 – 40 | 10 – 20 | 30 – 40 | 15 – 30 | 40 – 60 |
| Gravel bed | 30 – 50 | 30 – 40 | 30 – 40 | 20 – 60 | 150 |
The information given above is for informative purposes only.
