The development of engineering materials is the most important driving force and key support for the technological progress of traffic engineering structures. Under the influence of a new round of scientific and technological revolution, how to use new materials and technologies to enhance the ability of transportation integration and innovation has become the key to energy conservation and carbon reduction.
Since the 18th National Congress of the Communist Party of China, China's transportation construction has changed from the pursuit of speed and scale to the focus on quality and efficiency, which also puts forward higher requirements for transportation infrastructure. Under the guidance of the Ministry of Transport, in 2017, Guangdong launched the creation of the "Ping An Centennial Quality Project" for highway and water transportation throughout the province, intending to provide a "Guangdong model" for the national counterparts through technological innovation and contribute "Guangdong wisdom" to the construction of a transportation power.
In order to do a good job in the work related to the "Ping An Centennial Quality Project", the Guangdong Provincial Department of Transportation has set up a special leading group to promote the creation of quality projects as a whole. At the same time, strengthen the mechanism guarantee to provide technical guidance and institutional guarantee for the construction of quality projects. According to statistics, from 2018 to 2020, the Guangdong Provincial Department of Transportation issued a total of 22 relevant systems and 25 guidelines and standards.
Behind the policy blessing is Guangdong's determination to be a pioneer.
How to promote the high-quality development of transportation infrastructure has long been deployed by the General Office of the Ministry of Transport. Previously, the General Office of the Ministry of Transport issued the "Ping An Centennial Quality Project" Construction Research and Promotion Plan (hereinafter referred to as the "Plan"). The work objectives of the program have long been clear, requiring materials, design, process methods, equipment, monitoring, maintenance and information technology as the research direction, focusing on special seminars and academic exchanges, promoting laboratory and physical engineering verification, and gradually forming a set of technologies and standards suitable for the durability of engineering construction, so as to continue to provide technical support for the construction of high-quality transportation infrastructure with durable quality, safety and reliability, economic and environmental protection, and a century-old heritage.
In order to effectively build the "first kilometer" for the high-quality development of transportation infrastructure, the Guangdong project team selected for the "Ping An Centennial Quality Project" has made positive explorations focusing on three aspects: safety and reliability, quality and durability, and economic and environmental protection.
The road surface will cool down
The road can absorb and degrade the exhaust fumes of the car and cool it down on its ownSounds like a fantasy.
The Congpu Expressway, which was selected as the first batch of demonstration projects for the creation of Ping An Centennial Quality Project in Guangdong Province, is such a highway that will absorb and degrade automobile exhaust and cool down by itself.
The total length of the Congpu Expressway is 6171 km, implemented in two phases. Among them, the first phase of the project opened to traffic is about 3962 kilometers, starting from Zhongheli, Taiping Town, Conghua District, connecting Daguang Expressway, Jiebei Expressway, Foqing Cong Expressway North Section, passing through Zhongluotan Town and Taihe Town, Baiyun District, and ending at Changping Community, Changling Street, Huangpu District, connecting the North Second Ring Expressway and Guangshan Highway, with 8 interchanges, the whole line adopts the design speed of 100 kilometers per hour, two-way 6 lanes of highway technical standards.
In the process of the construction of Congpu Expressway, Guangzhou Communications Investment Group took the initiative to benchmark the requirements of the construction of a strong transportation country and a strong transportation province, closely focused on the aspects of "green beauty, wisdom and quality", comprehensively carried out technological innovation and management innovation, and strived to build benchmark projects and quality projects. In terms of solving the hazard treatment of automobile exhaust, the exploration and application of exhaust degradation cool pavement from Congpu Expressway solves the technical problem of pavement degradation of urban automobile exhaust from the principle and technology, reduces the peak temperature value of each surface layer by more than 5, and effectively alleviates the "heat island effect".
This "cool pavement" can improve the summer environment of the highway, especially after the summer rain, or in areas that are often sprinkled with water, in addition to cooling down, the air humidity can be continuously adjusted to increase environmental comfort.
High performance emulsified asphalt plant mixing cold recycling technology
The Shenzhen-Shanxi Expressway Reconstruction and Expansion Project is one of the first batch of demonstration projects for the creation of "Ping An Centennial and Quality Project" announced by the Ministry of Transport. As a key project that has attracted much attention, the Shenzhen-Shanxi Expressway Reconstruction and Expansion Project attaches great importance to green environmental protection and circular development in the process of project promotion.
As the largest and longest highway reconstruction and expansion project in Guangdong, the original old pavement will produce a large amount of asphalt pavement milling material, which will be stacked or discarded at will not only occupy land, but also bring environmental pollution, and at the same time, the stone and asphalt resources in the waste material have also caused a lot of waste.
How to maximize the use of old road materials?The "green trick" of the Shenzhen-Shanxi Expressway Expansion Project is to recycle waste materials and turn waste into treasure, and maximize the utilization of old road resources through advanced "intelligent manufacturing" technologies such as bulk industrial solid waste utilization and waste concrete aggregate comprehensive utilization technology, and the transformation, upgrading and reuse of traffic safety facilities.
Approximately 7For example, the project uses high-performance emulsified asphalt plant cold recycling technology to achieve 100% recycling and 60% high-value utilization of old pavement materials.
In addition, the project also introduced the first crushed stone finishing production line in Guangdong to achieve resource reuse while ensuring quality. At the same time, the production line is equipped with a powder tank, with a dust removal efficiency of up to 99%, realizing the green production of no dust inside and outside the whole processing process.
The steel-UHPC composite bridge deck improves the durability of the project
In 2020, the Fulong project was awarded the "Key Science and Technology Project" by the Ministry of Transport and the first batch of "Ping An Centennial Quality Project" to create a demonstration project list.
In view of the characteristics of orthogonal shaped steel bridge deck that is easy to crack, the steel-UHPC composite bridge deck used in the main girder of Foshan Fulong Xijiang Bridge Project is the world's first to use UHPC as the main load-bearing component of the long-span cable-stayed bridge, which can effectively solve the problem of bridge deck cracking and durability that has plagued the engineering community for a long time.
So what kind of material is UHPC?UHPC, is a kind of ultra-high performance concrete, which is composed of cement, fine sand, fine aggregate, steel fibers and chemical additives, commonly known as liquid metal. Its compressive strength is up to 150MPa, which is about 4 times the strength of conventional concrete. The durability and weathering performance of UHPC far exceeds that of other structural engineering materials (steel, aluminum, plastic, etc.).
As a new engineering structural material, UHPC has many engineering applications, including a variety of bridge structures for pedestrian bridges, highway and railway bridges, to improve bridge span diameter or reduce bridge height-span ratio, to achieve rapid bridge construction and to improve bridge durability and life.
Through a large number of investigations and analyses of the use and research of steel-concrete composite slab light structures at home and abroad, the main bridge of Fulong Xijiang Bridge innovatively adopts steel box girder + (8mm) thin steel plate roof + (15cm) UHPC light composite bridge deck structure as the main load-bearing component of the cable-stayed bridge to solve the problems of bridge deck cracking and durability.
In response to this innovative design, the construction team, together with Tsinghua University, Hunan University, Wuhan University of Technology, Changsha University of Science and Technology and Foshan Transportation Science and Technology, jointly undertook the work of "Research on UHPC Key Technologies of Fulong Xijiang Bridge".
Based on the mechanical performance of the steel-UHPC lightweight composite bridge deck, the research team carried out full-scale model tests of a set of Charpy-UHPC composite bridge decks and a set of continuous steel-UHPC composite bridge decks, focusing on their static properties such as bearing capacity, stiffness and crack resistance. The test reveals the failure mode and the whole process behavior of the steel-UHPC composite bridge deck, which lays a foundation for the establishment of related theoretical calculation methods.
At the same time, based on the cross-section analysis method and plastic calculation theory, the research team deduced the calculation formula of the flexural bearing capacity of the steel-UHPC composite bridge deck, and proposed and verified the bending stiffness calculation method of the steel-UHPC composite bridge deck.
Application of foam lightweight soil in port area
The fourth phase of the Nansha Port Area Project of Guangzhou Port is a key project of Guangdong Province and Guangzhou City, and it is also the first batch of "Ping An Centennial Quality Project Creation Demonstration Projects" announced by the Ministry of Transport. The total investment of the project is estimated at 697.4 billion yuan, and the construction period is from 2018 to 2022. The project is located in the central excavated port pool of Longxue Island in Nansha District, covering an area of about 120 hectares, close to the first phase of the Nansha project on the southeast side, Nansha Port Station of Nansha Port Railway on the southwest side of the land area, and across the sea from the expansion project of the grain general wharf on the north side. The project will build 4 berths for 100,000-ton container ships, 12 berths for multi-purpose container barges and 4 berths for working ships, with an annual design capacity of 4.9 million TEUs.
In order to further implement the concept of "sponge city", the fourth phase of the Nansha Port project is the first large-scale application of four new technologies in the field of domestic water transportation engineering construction, such as comprehensive pipe trenches, foam lightweight soil, large steel pipe composite sheet piles, and straw drainage boards, to build a fully automated wharf with high quality.
The new material foam lightweight soil was applied to port engineering on a large scale for the first time in China, and its practice has attracted much attention in the industry. In terms of its function, the new foam lightweight soil material has the advantages of energy saving and environmental protection, simple construction and light structure, and the new material foam lightweight soil is more used in highway construction, especially in the process of expanding and reconstructing the expressway, the use of foam lightweight soil instead of traditional materials, can not only further improve the construction quality of the project, but also achieve the purpose of improving engineering safety and environmental protection. At the same time, the use of foam lightweight soil materials for construction can also achieve the purpose of reducing settlement and controlling costs.
In order to control the common quality problem of uneven settlement, the backfill behind the wharf structure of the fourth phase of Nansha Port Project adopts foam lightweight soil to replace the traditional sand and gravel, which is lightweight, and the heaviness is much smaller than that of the general fill, and its strength and gravity can be adjusted, with the characteristics of gelling and self-erection, which increases the safety and stability coefficient of the port project. The application of new structures and new materials is the highlight of the construction of the fourth phase of the Nansha project, and it is also the concrete embodiment of Guangzhou Port's efforts to create a century-old quality project of Ping An.
Smart installation
The South-Central Expressway spans the two cities of Guangzhou and Zhongshan, with Zhuhai in the south, Jiangmen in the west, and Shenzhen in the east, with a total length of 324 kilometers, is an important passage across the Pearl River water system, an important project to open up the main road of the Guangdong-Hong Kong-Macao Greater Bay Area Expressway. The project is planned to be completed and seamlessly connected with the Shenzhen-Zhongshan Corridor in 2024, further enhancing the role of Guangzhou as the core engine and the connection between the Zhongshan node, and making the connection between the urban agglomerations in the Greater Bay Area closer.
In 2021, the South-Central Expressway project became one of the first batch of demonstration projects of the Ministry of Transport's "Ping An Centennial Quality Project", which requires the project to create results in terms of engineering safety and durability.
As an important control project connecting Guangzhou and Zhongshan, the South-Central Expressway Hengmen Xite Bridge is the largest single-tower monolithic steel box girder cable-stayed bridge under construction in China.
Among them, the total height of the pagoda-type cable tower of the Hengmen West Bridge is 210 meters, which is equivalent to the height of a 70-story building. At the same time, the overall hoisting of the whole section of the Hengmen Xite Bridge is difficult to determine the center of gravity, the difficulty of hoisting attitude control, and the difficulty of each part hoisting can only be successful once.
To this end, the South-Central Expressway project innovates the construction process of "intelligent bending of tower column reinforcement mesh and on-site tire frame method assembly into a whole" steel bar parts, independently develops the flexible manufacturing of steel bar parts of ultra-high concrete bridge towers and the key construction technology of intelligent tower building, and successfully applies the industrial production of semi-finished steel bar products of the cable tower, the rapid assembly and forming of steel bar parts, and the high-altitude hoisting and docking of the whole segment to the construction of the tower column of the Hengmen Xite Bridge.
According to reports, under this self-developed hard-core technology, the on-site binding of steel bars has been increased from a 7-day section in the previous scheme to 1The 5-day section realizes the intelligent installation of "mechanized reduction and intelligent substitution", which greatly reduces the personnel and operation time of tower column reinforcement aerial work, and reduces the risk.