Recently, the Sichuan-Tibet Project Department of Sinohydro Bureau 14 completed the pouring of the last main pile foundation, pile 81-4#, for the Niyang River Grand Bridge. With this, all pile foundations for the bridge, an early-phase project of the Sichuan-Tibet project, have been completed, achieving the first-stage goal of 'fast bridge, stable tunnel'.

Quick Mobilization, Excellence from the Start

On November 10, 2020, construction began on the section of the Sichuan-Tibet project undertaken by Sinohydro Bureau 14. The company pooled its resources, selected elite personnel, and formed an iron-clad team. Under the leadership of General Manager Fan Kaiping, they mobilized quickly and worked tirelessly, adhering to the overall approach of 'scientific planning, technical support, ecological protection, and safety and reliability'. They established a reasonable and meticulous multi-threaded construction plan, ensuring progress daily, weekly, monthly, quarterly, and annually, and vigorously pursued production and operation.

On December 28, the No. 1 batching plant for the Niyang River Grand Bridge passed acceptance, becoming the first batching plant on the entire line to do so. Four days later, on December 31, 2020, the first pile foundation of the Niyang River Grand Bridge was poured, marking that the offline works of the bridge were on track.

Looking back at 2020, Sinohydro Bureau 14 shouldered heavy responsibilities and was the first on the entire Sichuan-Tibet project to complete land acquisition and demolition, temporary facilities, and on-site access roads. The world's longest under-construction inclined shaft—the Ba'nongqugou inclined shaft—was holed through 35 days ahead of schedule; the central laboratory received the first green card on the entire Sichuan-Tibet line; the Linzhi Town adit adopted the 'zero slope cutting' technique, entering early and exiting late, protecting the Tibetan ecology while holing through 5 days ahead of schedule; and in 2020, the project department completed a cumulative output value of 88,882,659 yuan. In the 'Excellent from the Start, Victory in the First Battle' labor competition of the Sichuan-Tibet project, they won first place in the Tibet section and third place on the entire line, becoming the unit with the highest completed output value on the entire line, and were awarded the titles of 'Winning Unit', 'Camp Construction Demonstration Unit', and 'Standardized Batching Plant Demonstration Site'. This brought a successful conclusion to 2020 and opened a glorious and magnificent 2021.

Leading Construction, Striving for Excellence

2021 is the opening year of the 14th Five-Year Plan, the 100th anniversary of the founding of the Communist Party of China, and the 70th anniversary of the peaceful liberation of Tibet. The Sichuan-Tibet Project Department of Sinohydro Bureau 14 keeps in mind the important instructions of General Secretary Xi Jinping on the commencement of the Sichuan-Tibet project, bases itself on the new development stage, implements new development concepts, builds a new development pattern, adheres to seeking progress while maintaining stability, further improves construction production efficiency, and strictly controls quality, safety, and environmental protection during construction, determined to achieve the 'five plus three' construction goals of the Sichuan-Tibet project.

For the Niyang River Grand Bridge, which crosses the mother river of Linzhi—the Niyang River—and connects the Linzhi EMU Depot and the Sejila Mountain Tunnel, with 859 pile foundations and a total length of 3,837.59 meters, the project department invested at peak construction 7 rotary drilling rigs, 3 percussion drills, 10 truck cranes, 10 excavators, up to 100 construction workers, and more than 20 management personnel, vowing to build the Niyang River Grand Bridge into a benchmark project.

From December 31, 2020, to July 25, 2021, the pile foundation construction of the Niyang River Grand Bridge took 226 days and was successfully completed.

During this period, facing the construction challenges of six in-water bridge structures from pier 49# to 75# of the Niyang River Grand Bridge, as well as the high cost of slag transport from later tunnel excavation, the project department repeatedly studied the design drawings of the bridge and the on-site topography, geology, and hydrological conditions, and decided to build a construction trestle bridge on the downstream side of the Niyang River Grand Bridge to assist in the construction of the in-water bridge structures and provide a convenient channel for subsequent tunnel slag transport. Once the plan was approved, the project department immediately organized construction. The 1,260-meter-long steel trestle bridge began construction on December 10, 2020, and was fully connected by January 31, 2021, taking only 52 days. The rapid completion of the steel trestle bridge laid a solid foundation for subsequent work.

In organizing construction, the project department comprehensively considered many factors affecting progress and eliminated them one by one. In response to the large flow of the Niyang River during the Linzhi flood season, which affected the construction of the in-water bridge structures of the grand bridge, the project department gave full play to its organizational advantages and adopted a multi-line parallel management process. During the construction of the steel trestle bridge, priority was given to completing the construction of the in-water bridge structure sections to ensure that in-water operations were completed before the flood season arrived. 'Heaven rewards the diligent.' On March 15, all six in-water pile foundations were completed, four months before the arrival of the Linzhi flood season at the end of July.

'Lucid waters and lush mountains are invaluable assets.' Considering the fragile ecological environment of the Tibetan region, Sinohydro Bureau 14 always regards 'environmental and water conservation work' as a top priority in the construction of the Sichuan-Tibet project. They formulated the 'Construction Method for Bored Cast-in-Place Piles with Rotary Drilling Rigs in Complex Strata' to guide the pile foundation construction of the Niyang River Grand Bridge. During slurry preparation, a 'Black Whirlwind' mud-water separator was used to separate sand and mud from the slurry generated during bored pile construction, adjusting the sand content and specific gravity of the slurry to prepare high-quality slurry. The generated mud residue and drill cuttings discharged from drilling were transported to a designated spoil ground for standardized disposal and were strictly prohibited from being discharged into the Niyang River or irrigation canals, avoiding the impact of construction on local water quality.

Gathering Strength, Overcoming Difficulties

Since the start of construction, all employees of the project department have braved hardships, overcome the extreme cold climate of the plateau with low oxygen, heavy snow and freezing, and strong winds, and eliminated adverse factors such as transportation difficulties and the COVID-19 pandemic. With the urgency of 'starting is a decisive battle', they actively responded to the call, unified their thinking, organized scientifically, deployed meticulously, and worked day and night.

Up to now, the project department's construction has experienced adverse natural conditions such as winter construction and flood season construction. Party members and young League members have closely united around the core leadership of the project department, played an exemplary role, been proactive, and offered suggestions. They coordinated planning from multiple aspects including material supply, construction progress, construction quality, construction safety, and environmental and water conservation. Taking the construction of the Niyang River Grand Bridge as an example, project management personnel kept a close eye on the site. From the deputy manager in charge down to the migrant workers, they worked day and night, ensuring the quality of pile foundation formation from steel cage processing, slurry performance, hole formation quality, and concrete performance. During shifts, they ate and lived at the work site, ensuring the efficient and stable progress of the pile foundation construction of the Niyang River Grand Bridge with a high sense of responsibility.

In the pile foundation construction of the Niyang River Grand Bridge, obtaining construction permits for piers 82# and 83#, located within the restricted construction area of the Milin Airport Expressway, was once a major problem for the construction personnel. However, project management personnel faced the difficulties and actively sought solutions. They invited a third party to assess the impact of pile foundation construction on the stability of the expressway subgrade and the resulting driving safety issues. After confirming that the construction impact was small and obtaining a safety assessment certificate, they actively contacted the Autonomous Region Development and Reform Commission, the expressway management department, and relevant Linzhi departments to obtain construction permits. At the same time, they quickly organized personnel to seize the schedule and minimize the disturbance time to the expressway.

Just after solving the problem of disturbing the expressway at piers 82# and 83#, piers 80# and 81# faced the dilemma of high-voltage lines restricting the use of machinery. Pier 80# passes under a 35 kV high-voltage line, and pier 81# passes under a 110 kV high-voltage line. The 17-meter-high high-voltage lines made the 24-meter-high rotary drilling rigs unable to meet the safe construction distance. To ensure safe construction and build a safe project, the project department did not wait or rely on others but decisively adopted percussion drilling. At the same time, they shortened the length of single-section steel cages, increased the number of steel cages, and limited the height of cranes to ensure construction safety. Although the construction period was extended, under the construction philosophy of 'life first, safety first', this was the optimal solution after balancing schedule and cost.

Keeping the Mission in Mind, Making Persistent Efforts

As of July 25, the Sichuan-Tibet Project Department of Sinohydro Bureau 14 has not only completed the pile foundation construction for the Niyang River Grand Bridge. The pouring of 73 pile caps for the grand bridge has been completed, accounting for 66%, and the pouring of 35 pier shafts has been completed, accounting for 32%. The project department will keep its mission in mind, promote the high-starting-point, high-standard, and high-quality development of the Sichuan-Tibet project, adhere to scientific, safe, and green construction, and build the Sichuan-Tibet line into a road of happiness and prosperity.