Working Logic of Rotary Drilling Rigs: Full Process Analysis from Drilling to Hole Completion

Drill Bucket Positioning and Hole Alignment

Before construction, the rotary drilling rig calibrates its attitude via the slewing platform, mast and levelling system, and aligns the drill bucket precisely with the preset pile position. The operator lowers the mast steadily to place the drill bucket on the ground, and verifies that the hole centre and verticality meet pile foundation specifications to set a benchmark for subsequent drilling. This step controls the positional accuracy of the entire pile hole and marks the start of pile quality management.

Rotary Drilling and Soil Collection inside the Bucket

Driven by the torque and pressure of the drill rod, the drill bucket rotates to cut soil, sand or soft rock, and the cut material continuously enters the bucket. Different tools such as sand grab buckets and pick buckets can be swapped for clay, silt, gravel and other strata. The feed pressure and rotation speed are coordinated to boost efficiency while minimising disturbance to the hole wall and lowering the risk of hole collapse.

Bucket Lifting and Soil Discharging for Cyclic Operation

Once the bucket is full of spoil, the main winch lifts the drill rod and pulls the bucket out of the hole. The machine slews to the spoil discharge area outside the hole, and the bottom gate of the bucket opens to unload soil. After unloading, the slewing platform returns, and the bucket is lowered again to the hole bottom to resume drilling. The cycle of drilling, lifting, slewing and discharging repeats to deepen the hole continuously.

Hole Trimming and Hole Wall Stabilisation

Bentonite slurry wall protection or dry casing support is applied during drilling to stabilise the hole wall and prevent collapse and shrinkage. When approaching the designed depth, the drilling speed is reduced to carefully trim the hole bottom and clean sediment, controlling sediment thickness to meet design requirements and prepare for reinforcement cage lowering and concrete pouring.

Final Hole Inspection and Hole Completion

Drilling stops when the designed depth, diameter and verticality are achieved. Inspections of hole depth, diameter and wall condition are carried out. Once all indicators pass acceptance, the hole-forming process is finished. The rig can move to the next site, and the working handover for reinforcement cage installation and concrete pouring follows.