For areas where ground conditions are very difficult and demanding, Normet designed an innovative, patented bolt combining the features of the Self Drilling Anchor (SDA) and D-Bolt®.
Normet produces two types of anchor taking into consideration design and load bearing capacity. For the North American mining market, Normet designed the bolt to reflect Nevada mine conditions. We call this the Self-Drilling Dynamic Bolt SDDB® – Nevada type. The anchor is a 2400 mm long self drilling hollow bar made from a single piece seamless tube with a diameter of 32 mm. The thread is ISO R32 rolled with uneven length from each side. The bolt is typically used for single length applications although it can be extended with coupings to reach the desired length where necessary.
Our second bolt type is the Self-Drilling Dynamic Bolt SDDB® – Nordic type. This model of anchor is similarly structured of 32 mm seamless tube but differs in its properties compared to Self-Drilling Dynamic Bolt SDDB® – Nevada type. the Noridc type is slightly stronger, threaded sections shorter and even on each side of the tube. This type of anchor has been designed for multiple extensions using couplings. This results in strong anchor points allowing the smooth section of the tube to deform and elongate under load. The anchors are loaded when the rock dilates with the smooth sections between the anchors stretching, which is the same principle of the standard D-Bolt®.
Both type of Self-Drilling Dynamic Bolt SDDB® can be post-grouted with conventional cementitious grouts or with specially designed pumpable resin such as TamPur RBG (Rock Bolt Grout).
- Possibility to install in single pass operation in fissured and fractured ground