1. When the drilling bucket rotates too quickly, driving the mud to scour the borehole walls, or if drilling is too deep in one go, the gravel inside the drilling bucket is squeezed out from the drainage outlet and flung to the gaps in the borehole walls, causing the drill to get stuck;

2. Protruding stones on the borehole walls cause radial sticking of the drill;

3. Wear of the drill teeth leading to the drill getting stuck;

4. Deviation of the borehole leading to the drill getting stuck;

5. Collapse of the borehole burying the drill;

6. Reduction in diameter causing the drill to get stuck.

Preventive Measures for Drill Sticking

1. The depth of drilling in one go should be strictly controlled, it should not be too deep, generally not exceeding one-third of the height of the drilling bucket. This can prevent rocks from falling from the top of the borehole and avoid the formation of significant frictional resistance between the drilling chips squeezed between the barrel of the drilling bucket and the borehole walls.

2. During the drilling process in gravel soil layers, the rotation speed should not be too fast. A fast rotation speed will drive the mud inside the borehole to scour the borehole walls at high speed, causing the walls to crumble (e.g., solitary rocks) and get stuck in the drilling bucket.

3. During the process of lifting the drill, the lifting speed should not be too fast, and at the same time, it should be rotated at a low speed to prevent objects protruding from the borehole walls from getting stuck in the drilling tools.

4. When making the drill bit, attention should be paid to the size of the drilling barrel; the diameter of the drilling barrel should generally be at least 150px smaller than the diameter of the borehole. During use, the drilling bucket should be repaired in time, and the side teeth and edge teeth of the drill head should be replaced or welded in time after wear, to ensure the size of the borehole. The wear-resistant blocks on the outside of the drilling bucket should be repaired or replaced with steel bars in time after wear, to ensure the gap between the drilling bucket and the borehole walls. At the same time, it should be ensured that the drill head hook is effective to avoid accidental unhooking.

5. To prevent protruding stones on the borehole walls, during the process of lifting the drill, it should be lifted as slowly as possible while also reversing the drilling bucket. When encountering protruding stones on the borehole walls causing radial sticking, a spiral drill head should be used first to loosen the protruding stones before drilling again. If encountering larger protruding stones, a rock core drill must be used, rotating back and forth to cut off the protruding stones on the borehole walls.

Common Methods for Handling Drill Sticking

1. After a drill sticking incident occurs, do not increase the lifting force to rapidly and forcefully lift the drill. An effective method is to repeatedly lift and lower the drilling bucket at the initial position of the incident, simultaneously rotating the drilling bucket in both directions until the foreign objects become loose and fall off, and then lifting the drilling bucket.

2. Direct lifting method, using a crane to directly lift upwards.

3. Clearing around the drilling bucket, namely using underwater cutting or reverse circulation methods to clear the sediment around the drilling barrel, and then lifting.