Views: 0 Author: Site Editor Publish Time: 2025-10-09 Origin: Site
The rotary drilling rig is an efficient equipment for drilling foundation piles in construction projects. Its core operation is accomplished through four main steps: "rotary cutting - soil extraction and lifting - soil discharge and reset - repeated drilling". It is particularly suitable for foundation construction such as cast-in-place piles and continuous walls. The following breaks down its working logic into "four steps" and elaborates on key details to make the operation principle clearer:
Equipment in place + Drilling preparation (ensuring foundation support and determining hole accuracy)
Before operating the rotary drilling rig, "positioning + stabilization" must be completed to prevent subsequent drilling deviation or equipment tilt. The core actions include:
Site leveling and hardening: Remove debris from the working surface, and if the ground is soft, lay steel plates / crushed stones to prevent the drilling rig from sinking;
Precise positioning: Use the built-in GPS / total station on the machine to align the center of the drill bucket with the design coordinates of the pile foundation (the error should be ≤ 5cm), and adjust the verticality of the drill pipe (calibrated by the horizontal level and verticality monitoring system, with a verticality deviation of ≤ 1%);
Drill bucket selection and debugging: Select the drill bucket according to the soil layer type (use "Double-bottom sand dredger" for clay layers， "rock-bonding bucket" for sand and gravel layers， and "torque cone drill" for rock layers)， and check if the opening and closing mechanism and hydraulic system pressure of the drill bucket are normal.
Rotary cutting + drilling to create holes (the main operation, relying on "rotary force + downward pressure" to break up the soil)
Rotary cutting: Start the rotary motor of the drill pipe (with a torque of several hundred to several thousand kN·m), and the drill bucket rotates at high speed along with the drill pipe. The teeth (made of hard alloy) cut into the soil layer, while the hydraulic system applies "downward pressure" to the drill pipe to force the drill bucket to drill deeper underground;
Hole wall protection (optional operation): If encountering sandy layers or plastic flow soil layers, it is necessary to inject mud (silt + water) into the hole or insert a steel casing simultaneously. The mud pressure / casing is used to prevent the hole wall from collapsing (the mud liquid level should be 1-2 meters higher than the groundwater level);
Depth monitoring: The display screen of the machine body shows the drilling depth in real time (calculated by the drill pipe length scale + sensor). When the "single soil extraction depth" (usually 1-2 meters, depending on the capacity of the drill bucket) is reached, the drilling stops.
Drill bucket lifting + soil removal and debris clearance (soil extraction and output to avoid soil accumulation in the hole)
After the drill bucket is filled with soil, the debris needs to be removed from the hole. The process focuses on "smoothness + speed" to prevent disturbance of the hole wall or debris from falling back into the hole:
Drill bucket closure: First, rotate the drill rod in the reverse direction for 1-2 turns to make the "opening and closing flaps" at the bottom of the drill bucket automatically close (locked by mechanical clamps) to prevent debris from leaking out during lifting;
Drill rod lifting: Start the lifting hydraulic system and slowly lift the filled drill bucket to above the ground (the lifting speed is adjusted according to the length of the drill rod to avoid excessive speed which may cause the machine to shake);
Debris removal: Move the drill bucket to the designated "debris storage area" or above the transport truck, operate the hydraulic rod to open the opening and closing flaps of the drill bucket, and the debris will be automatically discharged by gravity;
Loop operation + final hole acceptance (until meeting the standards, ensuring the quality of the pile foundation)
Loop hole formation: After discharging the soil, reset the empty drilling bucket and re-align the hole position. Repeat "Step 2 (drilling) - Step 3 (discharging soil)", until the depth indicated by the drill rod reaches the designed value (for a 30m pile, it needs to be cycled 15-30 times, depending on the capacity of the drill bucket);
Depth / Diameter inspection: Use "tape measure + heavy hammer" to measure the actual hole depth (the deviation should be ≤ +10cm / -5cm), and use "diameter gauge" to detect the diameter of the hole wall (ensuring it conforms to the designed pile diameter and avoiding shrinkage / expansion);
Cleansing of the hole: If the sediment thickness at the bottom of the hole exceeds the limit (such as ≤ 5cm as designed), use the "silt removal bucket" for secondary silt removal, or inject clean water to circulate and replace the mud until the silt meets the standards;
Through the above four steps, the rotary drilling machine can efficiently complete the formation of pile foundations. Its core advantages are "adaptability to various soil layers (from clay to moderately weathered rock), fast hole formation (2-3 times faster than traditional impact drills), and high verticality of the hole wall", and it is widely used in foundation construction of building construction, bridges, subways, etc.
