Recently, good news came from the site of the Ningpan section of the Yanjiang Expressway project: to solve the problems of low efficiency and high construction risk in square pile hole excavation, the project team set up a special task force and, after multiple trials, successfully achieved mechanized square pile driving using Yutong rotary drilling rigs.


　　The Yanjiang Expressway runs from Xinshi in Yibin, Sichuan, to the Panzhihua section, with a total length of 452 kilometers and a total investment of 88.6 billion yuan. It is the largest single-investment expressway project in China since the founding of the People's Republic, a major project under the national strategy of the "Belt and Road," and a major supporting project for the "Yangtze River Economic Belt." Its tunnel ratio and the types and number of special-structure bridges are the highest in Sichuan Province's expressways, and the route layout is extremely difficult, with extremely arduous construction conditions.

　　To build this project into a high-quality model project, engineers spent countless days and nights trekking over mountains and rivers, conducting on-site surveys, and repeatedly deliberating. The Ningpan section of the Yanjiang Expressway has complex geological conditions, alternating ridges and valleys, high mountains and deep valleys, and high-risk, steep roads. In the construction of bridge piles, compared with conventional cylindrical pile foundations, square piles offer better load-bearing performance and greater safety.


　　Traditional square piles involve manual hole excavation, which carries high construction risk, has low hole-forming efficiency, and is easily affected by geological conditions. This project team improved the construction process: pilot excavation by multi-hole drilling with a rotary drilling rig, hole forming with a rectangular edge trimmer, and hole cleaning and spoil removal with the rotary drilling rig. Faced with the new process, the project team set strict requirements for product reliability, stability, safety, intelligence, and other indicators when selecting construction equipment. After comparisons among multiple parties, Yutong rotary drilling rigs were ultimately used for construction.


　　Despite the new process, high requirements, and heavy tasks, the Yutong rotary drilling rig remained stable, rose to the challenges, lived up to expectations, and delivered excellent results. Facing complex working conditions—square piles with a diameter of 2m*3m, a pile depth of 25m, and red sandstone strata—the Yutong YTR430TD rotary drilling rig completed one pile in 2 days. Compared with the traditional process, which takes 16 days to complete one pile, the Yutong rotary drilling rig increased hole-forming efficiency by 70% in a straight line, demonstrating Yutong's style with high quality in the Yangtze River Economic Belt.