Application of rotary drilling rig in super deep and large diameter pile drilling in deep bouldery formation

Abstract:

In the construction of super deep and large diameter bored piles for bridges, the high torque full-hydraulic circulating drilling rigs are usually used with roller bits to drill holes and air lifting reverse circulation to clean the holes. However, for deep and thick bouldery strata, it needs to break the cobbles when drilling, and there are some disadvantages such as low drilling efficiency, high construction cost, drill pipe blockage, slurry leaking, borehole collapse. In view of the above-mentioned shortcomings, the rotary drilling rig was chosen to drill holes with the wall protected by bentonite mud. Reliable plugging measures were taken for the leakage of the bouldery layer and the hole was cleared twice by air lifting reverse circulation to ensure the thickness of the sediment at the bottom of the hole. The construction efficiency has been greatly improved; and the construction period has been greatly shortened which saved construction costs, and ensured the quality of the pile foundation.

Key words:deep bouldery stratum; super deep large diameter bored pile; rotary drilling rig; slurry leakage