High-efficiency construction technology of long auger drills in sandy gravel strata

The construction difficulties of conventional long auger drills in sandy gravel strata are mainly manifested as drill sticking, drill burying and severe mechanical wear. To address these problems, a series of improvements were made to the drilling tools and drilling operations of long auger drills, mainly including the following aspects: enhancing the torque of the power head of long auger drills to enable drilling in sandy gravel strata containing large-sized boulders; adding the reverse rotation function to the power head to allow independent adjustment after drill sticking or burying; strengthening relevant components such as drilling tools (drill pipes, alloy cutting bits, variable diameters, etc.), front and rear backplanes (including slips), casings and screws to make them adapt to the construction intensity; adjusting construction parameters such as rotational speed and footage speed according to actual conditions during drilling to achieve the effect of one-time hole and pile formation. Through practical tests, 5 sets of modified configurations of long auger drills suitable for construction in different sandy gravel strata were proposed, which can provide a reference for engineering applications.