In-situ drilling system with dust disposal and overload control.

摘要

An apparatus and method is provided for substantially continuously drilling and disposing of drill cuttings and dust to minimize airborne contamination while providing protection against overload. A drill stem with a bit is advanced by a drill head to form the drill hole. A flushing mechanism utilizes vacuum or pressurized water for flushing the cuttings and dust from the drill hole for disposal. A transducer monitors the negative or positive gauge pressure. A controller is utilized to regulate the rate of drilling dependent on the signal level of the pressure being monitored. In the preferred embodiment utilizing air, the passage in the drill stem removes the cuttings/dust and is connected to a transfer duct, which in turn is connected to a filter and the intake side of a blower. The controller is programmable to establish the optimum rate of feed of the drill head. The rotary motion of the drill bit can also be regulated by the controller. Preferably, the threshold level to determine an approaching overload is in the range of 10% to 20% over the normal gauge pressure of 0.5-4 inches Hg. The feed of the drill stem and/or the rotation is slowed or stopped in an approaching overload condition, and automatically reestablished once the condition is past. In the alternative embodiment, the pressurized water flows through the passage in the drill stem and bit forming a slurry with the cuttings/dust. The slurry flows around the drill stem/bit and is deposited outside the drill hole.