Views: 0 Author: Anna Publish Time: 2025-12-23 Origin: Site
Power Output: The engine drives the power head through a hydraulic system, converting mechanical energy into torque (unit: kN·m) and rotational speed (unit: rpm). Torque is the core power to overcome stratum resistance, while rotational speed affects drilling efficiency;
Torque Transmission: The power head transmits torque to the drill bit through the drill pipe. Drill pipes are divided into friction drill pipes (suitable for soft soil/medium-hard strata with a torque transmission efficiency of approximately 60%) and interlocking drill pipes (suitable for hard rock strata with a torque transmission efficiency of over 90%). Hard rock strata rely on high-efficiency interlocking drill pipes to avoid power loss;
Cutting and Crushing: Drill bits are selected according to geological types (auger buckets, sand fishing buckets, cutter roller bits, etc.). They cut, extrude or crush the stratum through rotational torque — soft soil layers rely on "rotary excavation and soil discharge" of auger buckets, while hard rock layers rely on "torque crushing" of cutter roller bits;
Soil Extraction and Pile Formation: The cut rock and soil are collected into the drill bit cavity, and the drill bit is lifted out of the hole through the hoisting mechanism to unload the soil. The cycle is repeated to complete pile formation. Throughout the process, torque must be accurately matched with stratum hardness and drill bit type to avoid "insufficient torque for rock breaking" or "excessive torque wasting energy consumption".
For mid-rise building projects with pile diameter ≤ 1.2m and pile depth ≤ 30m, 150kN·m torque is sufficient. Equipped with ordinary auger buckets, the drilling speed can reach 1.2-3m/min;
For sand layers requiring mud wall protection, torque can be increased to 180-200kN·m, combined with double-layer casing technology to reduce collapse risk.
For high-rise building projects with pile diameter 1.2-1.8m and pile depth 30-50m, 250-300kN·m torque is the optimal choice. Equipped with dense-tooth auger buckets, it can handle cobbles with particle size 8-10cm;
For strongly weathered rock layers, switch to "low rotational speed (10-20rpm), high torque" mode, control torque at 300-350kN·m, and use conical tooth cylindrical bits with a drilling speed of approximately 0.3-0.5m/min.
For super high-rise projects with pile diameter ≥ 1.8m and pile depth ≥ 50m, models with torque ≥ 400kN·m are required, equipped with interlocking drill pipes (40% higher torque transmission efficiency than friction drill pipes) and cutter roller bits;
When drilling moderately weathered rock layers, torque needs to be increased to 450-550kN·m. Lift the drill to check bit wear every 0.5m of drilling, and replace immediately if the tooth tip wear exceeds 10mm;
For extreme hard rock conditions (such as granite), extra-large drilling rigs with torque over 600kN·m can be selected, combined with hydraulic impact devices to improve crushing efficiency by 50%.
Balance between Torque and Pile Diameter/Pile Depth: Torque must increase synchronously with pile diameter — for every 0.3m increase in pile diameter, torque is recommended to increase by 80-100kN·m; when pile depth exceeds 50m, due to drill pipe self-weight attenuation, 10%-15% torque redundancy should be reserved.
Constraints of Site Conditions: For narrow sites (width ≤ 2.5m), select crawler-type low-torque drilling rigs (such as XR120); for soft foundation sites, select models with ground contact pressure ≤ 80kPa to avoid increased site reinforcement costs.
Cost-Effectiveness Adaptation: For short-term projects (≤ 30 days), renting small-torque drilling rigs by day is more cost-effective; for long-term projects (≥ 60 days), selecting medium and large-sized drilling rigs by month can reduce costs by 20%-25%.
Soft soil layer: 180kN·m torque + auger bucket, drilling speed 2m/min;
Sand layer: 220kN·m torque + sand fishing bucket, mud specific gravity 1.25;
Strongly weathered sandstone: 300kN·m torque + conical tooth cylindrical drill;
Moderately weathered sandstone: 320kN·m torque + cutter bit, drilling speed 0.2m/min.
