Views: 0 Author: Site Editor Publish Time: 2025-10-14 Origin: Site
The rotary drilling rig, with its efficient hole-making capability (able to complete up to 2-3 times the number of holes per day compared to traditional equipment), high hole-making quality (with smooth hole walls and a verticality error of no more than 0.5%), and strong environmental friendliness (with less slurry usage and lower noise), has become the core equipment for bridge pile foundation construction. It is particularly suitable for deep and large-diameter pile construction under complex geological conditions.
Construction Preparation:
Clear the site and level it. Select the drilling rig based on the diameter of the pile and the geological conditions; Prepare bentonite slurry (with a viscosity controlled within 18-22 seconds); Install steel casing pipes (with a burial depth of ≥1.5m, 30cm above the ground, and a center deviation of ≤5cm).
Drilling Construction:
After the drilling rig is in place, calibrate the verticality. In soft soil layers, use low-speed and slow drilling to prevent well collapse; in hard rock layers, replace the alloy tooth drill bit and control the drilling speed; Monitor the hole diameter in real time. If there is a shrinkage hole, re-drill immediately.
Installation of Reinforcement Cage and Pipe:
The reinforcement cage is made in sections (with a single section length of ≤12m). The welding joints are offset from the main reinforcement positions. During installation, use a crane to lower it smoothly; The pipe needs to undergo a water-tight test (with a pressure of ≥0.6MPa), and during lowering, keep it centered, with the bottom 30-50cm away from the bottom of the hole.
Concrete Pouring:
Before pouring, clean the hole (with a sediment thickness of ≤5cm). Use the pipe method for continuous pouring. The initial pouring volume ensures that the pipe burial depth is ≥1m, and the subsequent burial depth is controlled at 2-6m to avoid broken piles.
Drilling deviation：
After the drilling rig is in place, it is calibrated using a level instrument. During the drilling process, the verticality is checked regularly. When encountering isolated rocks, the direction of the drill bucket is adjusted to avoid hard impacts.
Cave wall collapse:
Increase the viscosity of the mud (to 22-25 seconds) and slow down the drilling speed; when the collapse is severe, fill with clay to re-drill the hole.
Uncertain determination of the bearing stratum:
Based on the geological investigation report, take samples before reaching the designed depth for verification, and observe the rock layer interface with the on-site camera.
Underwater concrete pipe blockage:
Use crushed stones with a particle size of ≤ 40mm, control the slump of the concrete (18-22cm); check the pipe for no deformation before pouring to avoid prolonged pauses.
Excessive sludge:
During cleaning the hole, use an inverted circulation drilling machine for secondary cleaning; measure the sludge again before pouring, and continue cleaning until it meets the standard if it exceeds the limit.
During the construction of the pier foundation of a bridge across the river, a rotary drilling machine was used to handle the 40-meter deep sandy and pebble soil layer. By optimizing the mud ratio (adding CMC thixotropic agent) and adopting the segmented drilling technique, the qualification rate of hole formation reached 100%, and the construction period was shortened by 20%. In the future, the rotary drilling machine will develop towards intelligence (automatic verticality control, remote monitoring) and large size (suitable for piles with diameters of 3 meters or more), further enhancing its adaptability to complex working conditions.
