Build a certificate of "big country granary"! The first-phase silo project of Grain and Oil Logistics Center in Tianjin Lingang Economic Zone was successfully capped.
Cang Li Shi, the world is safe. To ensure national food security! "Ensuring food security has always been a top priority for the national economy and people’s livelihood. It is necessary to study and improve food security policies, take capacity building as the foundation, and realize grain storage on the ground and grain storage in technology."
At the wharf of the grain and oil base in Tianjin Lingang Economic Zone, a freighter loaded with soybean, wheat and other grain and oil raw materials from overseas is unloading. After the fresh materials are disinfected and squeezed by equipment, golden soybean oil flows out, and the "Fulinmen" on the dining table of thousands of households is born.
Recently, the second-stage general contracting project of the first-stage silo of Tianjin Lingang Economic Zone, which was installed and built by China Construction, was successfully capped and passed the main acceptance. As the first link of the "front dock and back factory" of Tianjin Lingang grain and oil industry, the project consists of eight reinforced concrete silos. After completion, the storage capacity of soybeans can reach 288,000 tons. By then, Tianjin Lingang Grain and Oil Industrial Park will become the largest grain, oil and food processing base in the north, providing a strong guarantee for food security and stable food supply for residents in the north. It is expected to be officially put into operation in April next year.
Deeply rooted and tamped the granary "chassis"
Tianjin Lingang Economic Zone is located in the shallow beach area at the mouth of Haihe River. It is a port born from land reclamation and belongs to muddy coastal zone with poor geological and hydrological conditions. The silo has an outer diameter of 28 meters and a height of 44 meters. It is the first step for the project team to build a stable "people’s rice bowl" by making the "Eight Giants" firmly located on the dock and ensuring a solid foundation.
Before the start of construction, the project department organized experts to conduct on-site surveys for many times. After design, research and discussion, it was finally decided to adopt the pile mat foundation method. First, the bored pile technology was used to pile piles, and then the circular raft foundation was laid to stably support the silo "body". Due to the huge volume of silos, the deepest pile foundation needs to be drilled to 43 meters underground, but the maximum distance between silos is only 2 meters wide, which is always at risk of collapse. After repeated research and demonstration, the installation team of China Construction decided to set 40 supports around the foundation pit to fix the ground of the built silo to prevent the ground from collapsing during excavation. With the continuous operation of five pile drivers for 24 hours, the project team laid 1120 cast-in-place piles in only 36 days, laying a solid foundation for the silo.
After the pile foundation is "stabilized", it is necessary to lay a raft foundation with a thickness of 1.7 meters. The project team innovatively used the channel steel welded support system to replace the traditional reinforced horse stool and set up the "skeleton" of the raft, which solved the problems of large welding amount and high cost of the reinforced horse stool, and it was convenient to disassemble and assemble, which improved the construction efficiency. Before pouring concrete, the project team embedded 3 temperature measuring points and 15 wire probes in each silo. After pouring, external temperature measuring equipment was connected to monitor the concrete temperature at the corresponding position, and the cracking of mass concrete was effectively prevented by covering the concrete surface with felt and storing water. The project team completed 8800 cubic meters of concrete pouring in just one month, and the huge silo was "sitting like a clock".
Consolidate the foundation, expand the new and build a stable grain "protection warehouse"
The silo is composed of silo wall, funnel and silo roof. Considering the small space and limited working surface, the project team decided to adopt slip-form technology for the construction of silo wall. The double silos slide up at the same time, every 30 cm is poured, and when the concrete is initially set, the formwork will be lifted once, which is not only complicated and technically difficult, but also that once the slipform is opened, it can not be interrupted day and night, and any link will have an impact on slipform construction and silo quality.
In order to ensure the construction quality, every time it is lifted, the inspection personnel should carefully check whether the slip-form platforms of the two silos are deformed and whether the levelness and verticality are consistent. After 24-hour continuous construction and close cooperation of all disciplines, the concrete of eight silos was nearly 9,600 cubic meters, which was finally poured in 40 days, and the silo "body" construction was completed 7 days ahead of schedule.
The top of the silo is conical shell, which is the last step of the main construction and the most difficult "hard bone". Because the warehouse roof is constructed at an altitude of 44 meters, the constructors have no working platform to stay on. The conventional method is to build a full-house supporting frame to assist the construction. However, the traditional full-house supporting frame has a large volume, a lot of turnover materials and a long erection period, which affects the construction progress. Zhao Yafei, the chief engineer of the project, repeatedly studied and analyzed the bearing capacity and stability of the supporting system, and calculated it for more than 100 times. Finally, he innovatively developed a set of Bailey frame supporting system assembled construction platform, which consists of corbel, central column, jacking and Bailey. The installation and disassembly of the platform is simple and quick, which not only speeds up the construction progress, ensures the quality, but also reduces the construction cost and shortens the construction period by 45 days. This innovative technology has also won the national patent.
Ingeniously adhere to the "safety defense line" of building granaries
Kong Fanfeng, the project manager, has been stationed in Tianjin Lingang Wharf for six years. He led nine young people with an average age of 28 who were responsible for the electromechanical installation of the first phase of the silo, but the main construction area of the silo was also their "blank area". "Let’s build the silo, and the country’s big granary will be solid." This young team braved the wind and waves and fought against the sky to explore and crack the "construction password" of the granary.
It is said that the construction of the wharf depends on the weather, especially the sea breeze and rain in summer, which "beat" the wharf wildly, which brings great difficulties to the construction. The sliding formwork construction of the warehouse wall is in midsummer, so the project department prepares rain-proof materials in advance and adds sandbags for flood control at the low-lying places on the site in advance. Seeing that the slip-form casting is about to be completed, suddenly the sky is cloudy and thunder is rolling, and the raindrops as big as beans fall, and the dock instantly opens the "sea-watching mode". The rain is getting heavier and heavier, and the poured concrete has not completely solidified, and it is mixed with rain and flows out with "black water".
"So concrete and template stick together? The platform must be lifted by 50 mm every 30 minutes to separate the formwork from the poured concrete! " Zhao Yafei, the chief engineer of the project, couldn’t sit still. He rushed to the hydraulic console against the strong wind, neglected the umbrella, and controlled the sliding formwork body to move up slowly through the console. When other people saw it, they also ran into the rain, picking up the plastic sheets for rain protection in one hand and holding the plates next to them in the other. Qi Xin worked together to set up a "protective shed" on the hydraulic console. Everyone tacitly accepted Zhao Yafei’s "baton" and stuck to it in the rain to ensure that the sliding formwork moved up at a constant speed.
After the rain cleared, the project team immediately conducted a comprehensive "physical examination" on the strength of concrete, two tower cranes and 108 jack equipment to ensure that the sliding formwork body climbed steadily. The cold sea breeze stung their dark and cracked hands, and the waves were surging, beating their ingenious granaries. After 18 months of persistence, the installation team of China Construction completed the main construction task with high quality and efficiency.
Establish a "big country granary" to protect food security. The installation of state-owned enterprises helps to build a world-class grain and oil terminal with the highest degree of modernization in China! (Sun Li Shen Ruying Hong Yan)