In bridge engineering construction, the quality and efficiency of pile foundation construction directly determine the overall progress and safety of the project. In the approach bridge project of a certain river-crossing bridge, by selecting the Sany SR235-C10 rotary drilling rig as the core construction equipment, the construction difficulties of pile foundations under complex geological conditions were successfully overcome, achieving remarkable results of a 15% reduction in construction period and a 12% reduction in comprehensive cost, providing valuable experience for similar projects.
The approach bridge section of the project required the construction of 126 pile foundations with a diameter of 1.8 meters and a depth of 55 meters. The geological conditions were complex, with miscellaneous fill, silty clay, strongly weathered sandstone and other soil layers distributed in sequence, and the groundwater level was relatively high. The traditional impact drilling rig construction plan was estimated to take 120 days, which was difficult to meet the overall project milestone requirements. After demonstration by the technical team, the Sany SR235-C10 rotary drilling rig was selected as the main equipment. Its rated torque of 235kN·m and adjustable speed range of 5-26rpm can adapt to the drilling needs of different soil layers.
During the construction process, the technical advantages of the rotary drilling rig were fully exerted. For the strongly weathered sandstone area, by adjusting to the low-speed and high-torque mode and matching with alloy tooth drill bits, a drilling efficiency of 1.2 meters per hour was achieved, which was nearly 3 times higher than that of traditional equipment. In the silty clay layer, the high-speed mode was switched and the intelligent soil dumping function was activated. With the help of the equipment's main hoist lifting speed of 70m/min, the retention time in the hole was greatly reduced, and the risk of hole collapse was effectively lowered. At the same time, the SANY-ADMS intelligent system equipped with the equipment monitored the drilling verticality in real time, and the pile verticality deviation was controlled within 0.3% through long guidance technology, which far exceeded the specification requirements.
While achieving efficient construction, the energy-saving and reliability advantages of the equipment were prominent. The project adopted 3 rotary drilling rigs for parallel operation. The ISUZU EFI engine equipped with the rig, combined with the hydraulic system power optimization technology, reduced the average daily fuel consumption of a single equipment by 18 liters compared with similar equipment, and no major equipment failures occurred during the entire construction process. To address the groundwater level issue, the technical team adopted a "follow-up while drilling" mud wall protection process in line with the drilling rig construction rhythm. With the advantage of rapid hole formation of the drilling rig, the mud soaking time was reduced, and the mud consumption was lowered by 30%.
Finally, the construction of 126 pile foundations was completed in only 102 days. The inspection showed that the proportion of Class I piles reached 98%. This case fully proves that rotary drilling rigs can achieve dual improvement in quality and efficiency through accurate adaptation to geological conditions and intelligent adjustment of construction parameters. In future bridge pile foundation construction, it is necessary to further optimize equipment selection and construction technology in combination with engineering practice, so as to give full play to the technical advantages of rotary drilling rigs.
