A gentle breeze carrying the fragrance of soil and green grass swept across the Huanxi River, where golden rapeseed flowers on both banks swayed in the wind, as if cheering on the workers toiling diligently.

This is the construction site of Pile Foundation No. 65-7 of the Huanxi River Grand Bridge, Section 5 of the newly built Chengdu-Chongqing Middle Line Railway (Sichuan Section), undertaken by China Railway Major Bridge Engineering Group. Under the brilliant sunshine, the drilling rig buried its "head" deep into the bosom of the earth—the 5,505th pile foundation was precisely "rooted" here.

The Huanxi River Grand Bridge under construction

A large number of piles and a long construction front, crossing major rivers, approaching villages and existing railway lines—these are the characteristics and difficulties of pile foundation construction in Section 5 of the Chengdu-Chongqing project. "This is not only a tough technical battle but also a test of overall coordination capability—we must finely manage the construction of more than 5,000 pile foundations, cross complex terrain, and find a balance among environmental protection, people's livelihood and schedule," Wan Mingmin, chief engineer of the sub-division of the Section 5 project department, told this reporter.

Faced with these difficulties, how did the bridge builders find solutions?

The two main piers of the Tuojiang River Grand Bridge, like strongmen, support the weight of the entire bridge. Their designed bearing capacity reaches 90,360 tons, equivalent to the total weight of 1,506 fully loaded heavy trucks (assuming each truck carries 60 tons at full load).

The pile foundations are deeply rooted underground, providing solid support for the main piers. The greater the bearing capacity of the main piers, the higher the requirements for the length and diameter of the pile foundations, which makes the main pier pile foundations of the Tuojiang River Grand Bridge 50 meters long and 2 meters in diameter.

Preparation before drilling of the pile foundation of Pier No. 2 of the Tuojiang River Grand Bridge

The overburden layer of the main pier pile foundations of the Tuojiang River Grand Bridge is a pebble layer, alternately passing through the strongly weathered and weakly weathered zones of mudstone intercalated with sandstone and sandstone layers. The pebble layer is prone to hole collapse, and drilling in the weakly weathered rock layer is difficult, which brings severe challenges to pile foundation construction.

"The pebble layer is like a torn sack full of glass marbles—as soon as the drill bit pushes the marbles aside and drills down, the surrounding stones come clattering into the hole; the weakly weathered rock layer is like a piece of hard and tough leather candy—it looks like there are cracks to drill through, but once you really penetrate it, you find not only great resistance but also very slow progress, just like digging out frozen, rock-hard leather candy with a spoon, which is extremely laborious and easily wears out the drill bit," Wan Mingmin explained to this reporter.

Preparation before drilling of the pile foundation of Pier No. 2 of the Tuojiang River Grand Bridge

Once there is a problem, a solution must be found.

Technician Sun Haoyang recalled that during the construction of the main pier pile foundations, Wan Mingmin pointed at the casing and passed on his experience: "This casing is like armor for the pile foundation. When drilling through the pebble layer, we use a barrel drill to drill in like turning a screw, keeping the stones outside the barrel wall to prevent hole collapse; when drilling into the rock layer, we switch to a rock-embedded drill bit and enlarge the hole in layers, which saves effort and is efficient. This is the construction method of barrel drilling for hole excavation and staged hole enlargement."

At that time, Sun Haoyang marveled at how fast the machine cleaned the hole, and Wan Mingmin patiently answered: "The key lies in using a 'mud pump + conduit + self-made suction disc' to extract sediment, filtering stones through a mud separator, and recycling the mud, which greatly improves the hole cleaning time."

By optimizing the construction plan for the main pier pile foundations of the Tuojiang River Grand Bridge, the project department perfectly solved the problem of hole formation for large-diameter pile foundations.

Green water and blue sky, with sparkling waves. Before the Dragon Boat Festival, students from the Jianyang Water Sports School were vigorously rowing on the Tuojiang River, preparing for the upcoming Dragon Boat Festival race.

The towering tower cranes, the winding trestle bridge, the standing pier shafts and the diligently training students form a beautiful picture combining motion and stillness.

To protect this lucid water and lush mountains, the project department has put in a lot of effort.

On the riverbank at the construction site of the Tuojiang River Grand Bridge, a dust and noise environmental monitoring system and toxic gas detection devices are installed, monitoring the surrounding environment in all directions 24 hours a day.

The Tuojiang River Grand Bridge under construction

Under the trestle bridge, a blue buoy caught this reporter's eye. This is the water quality monitoring buoy set up by the project department in the Tuojiang River, monitoring the water quality of the Tuojiang River at the main bridge site 24 hours a day.

"The construction of the Tuojiang River Grand Bridge involves water operations, which requires us to monitor changes in water quality in the construction area in real time. We protect the water quality of the construction area through automatic monitoring and early warning of environmental and water conservation," Wan Mingmin looked at the main pier and continued: "In addition, during the construction of the main pier pile foundations of the bridge, we used environmentally friendly mud; to prevent mud overflow, we adopted an 'internal and external dual circulation' measure. The 'internal circulation' means connecting each casing in series to ensure that mud does not overflow, maximizing the protection of the Tuojiang River's water quality from pollution."

For engineering projects, building a harmonious enterprise-locality relationship is the top priority for achieving efficient project advancement and resource integration.

Just as he stepped onto the trestle bridge, Liu Wei, the Party-mass coordinator of the project department, received a phone call.

"There's a traffic jam on the road, and our equipment can't get through."

"Okay, okay, I'll be right there!"

Liu Wei looked calm and strode down the bridge. His demeanor revealed a kind of confidence, as if the problem would be readily solved once he arrived at the site. 

Equipment entering the site must pass through County Road Y174, which cuts across Shizhong Town. The county road is narrow, with houses on both sides, making congestion easy; moreover, the entry and exit of large vehicles occasionally arouse dissatisfaction among some local residents, so Liu Wei is often needed to coordinate.

Flag-presentation ceremony by the Hefeng Town Government, thanking the project department for building a road for the elderly Li Yangxian and for its care for the residents of Hefeng Town

Before long, the vehicle carrying the equipment arrived smoothly at the construction site. How could such a thorny problem in others' eyes become "a piece of cake" for Liu Wei? This reporter curiously asked him for his "secret."

Liu Wei did not answer directly; instead, he talked about the early land acquisition and demolition work of the project.

"Everything is difficult at the beginning. At first, the local residents did not understand the project, and even less understood us. They were resistant and unwilling to communicate."

"So how did you break through?" this reporter asked.

"No matter how well you say it, it's better to do it well," Liu Wei recalled. "At that time, I visited them door to door again and again and got to know many local residents. For example, Grandpa Li of Wugui Village, who had been ill for years and was frail, lived in an adobe house with cracks in the walls, the widest being four or five centimeters. When it rained, the room was like a 'water curtain cave.' After learning about the situation, led by comrades from the Wugui Village Committee, we visited him to repair his house and brought condolence supplies."

"Grandpa Li Yangxian of Niuxinshan Village in Hefeng Town is 92 years old this year and has difficulty walking. The dirt road in front of his house is full of potholes, making travel even more difficult on rainy days. After learning about this, we arranged for the First Division, the closest to Hefeng Town, to pave a brand-new concrete road for the elderly man..."

Liu Wei (second from left) leading project department staff and Jianyang City Shizhong Town Government staff to visit Grandpa Li of Wugui Village

Listening to these heartwarming stories, this reporter suddenly understood—perhaps the so-called "secret" is nothing more than exchanging sincerity for true affection.

"People's hearts are made of flesh. If you truly think of them, they can naturally feel it," Liu Wei also told this reporter. "At the end of last year, Grandpa Wang of Huopen Village in Hefeng Town accidentally started a fire while cooking with firewood, trapping him and his wife. Fortunately, the dump truck driver of our earthwork transport team discovered the fire in time and reported it to the project department. The project department immediately arranged personnel and equipment to bring the fire under control and finally cooperated with the fire brigade to successfully rescue the elderly couple. Now Grandpa Wang praises our project department to everyone he meets."

By sincerely doing practical things for local residents, over time the project department and the residents naturally became "one family" that understands and supports each other.

"Though the road is long, traveling will bring us to the destination; though the task is difficult, doing it will lead to success." Among the nine sections of the newly built Chengdu-Chongqing Middle Line (Sichuan Section), Section 5 ranks second in the number of pile foundations, but with the wisdom of adapting to every situation and indomitable perseverance, the Section 5 project department ultimately took the lead in completing all pile foundation construction tasks. In the subsequent construction, the builders of China Railway Major Bridge Engineering Group will continue to overcome difficulties, meet various challenges with practical work, and keep leading the way.