 Drilled casings is one of most popular piling methods for foundations in urban areas. Today consultants are increasingly interested in utilizing DTH hammers in foundation construction. At the same time they are increasingly concerned about the use of compressed air which might cause damage to surrounding structures due to air leakage or overdrilling. To meet this challenge, Atlas Copco has developed a new system and is now proud to present Elemex flushing control casing drilling system.
Use of DTH drilling systems in foundation construction gives plenty of benefits; high productivity, straight holes and deep hole drilling capacity, just to mention a few of them. However, when working close to existing foundations the method poses one great challenge - controlling the removal of cuttings from the hole with compressed air. The flow of compressed air needs to be strong enough to transport the cuttings up to the surface but must not escape into the surrounding ground or remove excessive soil. This issue is most demanding in sensitive ground conditions. In clay, the compressed air can escape to surrounding working foundations and weaken the adhesion between soil and load-bearing elements. This brings a risk for sudden settlements. In sand, excessive flushing can unconsolidate the ground, decreasing the capacity of existing friction piles, which in turn might cause pile buckling and settlements.
Controlling air escape puts high demands both on the drill rig operator and the casing drilling system itself. Conventional systems push air straight into the ground, which is a feature derived from rock drilling applications where the rock face needs as much air as possible to be cleaned efficiently. However, in overburden drilling conditions flushing should be just intense enough to get cuttings out from the hole, but not more.
Thanks to the extended ring bit, the air flow is redirected across the bit face, resulting in an efficient flushing without air escaping to the surrounding ground.
The new and reliable Elemex systemminimizes the air escape to the surrounding ground as the high pressure air never faces the ground directly. The unique concept behind the Elemex design is built on redirection of the air flow. Once the air reaches the bit face, it is blown against the extended ring bit walls which redirects the flow across the face. This way, the air pressure is decreased just enough to allow an efficient flushing of the bit face without escaping to the surrounding ground. By utilizing the Elemex system, not only do you get peace of mind from knowing that neighbouring structures are kept intact and people around the worksite are safe, you also get all the benefits from DTH drilling for maximized productivity. With Elemex no special operator's training is needed to control the air flushing intensity; Elemex takes care of that for you. During our extensive testing program, consultants on the field have measured the ground water level variation, and with Elemex there has been none to show. Neither have there been any settlements of the surrounding buildings recorded.
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