Hollow stem augers
The use of Hollow Stem Augers is an optimal method of casing in advance allowing dry cased drilling in simple rotation without the use of drilling fluid such as air, water or drilling mud. Our auger robots manufacture these models in large series and the particularity of our hollow augers lies in their octagonal connection for a better distribution of the torque thus avoiding the risks of breakage known with the standard models in circular connection.
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The hollow auger system is designed to drill and install casing simultaneously in dry conditions in gravelly or non-homogeneous soil, such as sand and gravel. This technique, which is widely used around the world, makes it possible, in particular, to quickly install micropiles, insert core samplers through the auger, or install piezometers without impacting the environment.
The Apageo hollow augers are manufactured with octagonal connections, a major advantage over basic circular connection hollow augers. This allows the torque of the drill to be distributed over the whole octagon and not just over 2 screws in the case of circular connection augers, thus avoiding breakage and low productivity.
In a standard configuration (auger + rod), once the desired depth is reached, the lower string of rods and its tool are removed to clear the interior space of the auger. At this point, it is possible to fit the borehole with equipment, take samples beyond that depth, or simply continue drilling within the effective bore diameter.
When using a lost tool, the inner drill string and its tool are replaced by a three-blade lost tool mounted on the hollow auger cutting head, thereby preventing sediment from entering the augers. Once the desired depth is reached, the borehole is immediately cased, allowing for the installation of micropiles, piezometers, or other equipment to be placed in the borehole.
We offer a range of 4 standard sizes of hollow augers, defined by their inner and outer diameters:
- 66 x 140 mm (inner Ø x outer Ø)
- 82 x 175 mm (inner Ø x outer Ø)
- 111 x 194 mm (inner Ø x outer Ø)
- 159 x 254 mm (inner Ø x outer Ø).