When the pile location is uncertain, the drilled soil should be cleared promptly. Pile tilt can be addressed by controlling the verticality of the drill rod and monitoring the offset using a plumb bob or pointer. Drilling process control should be based on the designed pile length and instantaneous current value, as the current changes instantaneously when the drill bit passes through different soil layers.
For pile end damage and pile breakage, the operation of lifting the drill and pumping the mixture should be coordinated. After the drill bit reaches the designed hole depth, drilling should be stopped and the drill rod lifted 30-50 cm. Pump the mixture for 10-30 seconds before lifting the drill rod. The lifting speed should be controlled at approximately 2 meters per minute.
Pipe blockage is related to the workability of the mixture and the operation. The slump of the mixture should be controlled at 18 ± 2 cm, and the mixing time should be no less than 2 minutes. During transportation, the material container should be continuously rotated, and excessive changes in pipe diameter and bends should be avoided. Hole drift is prone to occur in saturated silt and fine sand layers; methods such as alternating piles or skipping rows can be used.
