The mountains are undulating and the forest is boundless. The Pingnan Expressway passes through the mountains and forests like a giant dragon. Yang Chao, the chief engineer of the Pingnan Expressway Project of the First Navigation Bureau, pointed to the bridge and said, "With the guarantee of the quality of the bridge deck, the highway we build can be called a high-quality project."
The Pingnan Expressway contracted by the First Harbor Engineering Bureau and the Second Highway Engineering Bureau is an important part of the "vertical 10 lines" in the planning of the Guangxi highway network, with a total length of about 85 kilometers. After completion, it is of great significance to promote the construction of the new land and sea channel in the west and promote the economic and social development of the Baise revolutionary base. When the high-speed construction crosses the mountains, 51 bridges will be built for the bid section undertaken by the First Navigation Bureau. Due to heavy rain in mountainous areas, large temperature difference between day and night, and perennial wind and rain on the bridge surface, if the quality control of bridge deck pavement is not good, it is very easy to crack, which will bring serious safety hazards. "This is a way to connect people in mountainous areas to become rich, and there must be no quality problems." Yang Chao proposed to build a model for the whole line at the beginning of the project construction.
The smoothness and crack control of bridge deck pavement is the key to high-quality construction of asphalt concrete pavement. The traditional bridge deck pavement is vibrated by manual hand-held vibrators and then paved. The flatness of the bridge deck depends on workers and is difficult to be standardized. To this end, the project introduces intelligent paver equipment, which emits infrared light through the laser transmitter, feeds back to the laser receiver after encountering obstacles, and then the control system adjusts the height of the oil cylinder, so that the machine always operates according to the infrared plane emitted, to ensure the paving smoothness. However, during the test, the team found that when encountering a longitudinal undulating road surface, it is necessary to manually install a stable running track for the paver to ensure that the paver is always in the same plane, which is time-consuming and laborious. It is also easy to cause elevation error due to human adjustment.
After consulting a large number of data, Yang Chao found that ultrasound can achieve all-round detection from point to surface. Following this idea, the R&D team installed an ultrasonic control system on the basis of the laser paver and made an induction line on the bridge deck. After the ultrasonic wave returned when it was blocked, the automatic adjustment of the paving height in millimeter level was realized through the control system. The manual track laying is omitted, and the operation quality and efficiency of the paver are significantly improved. Just when everyone was overjoyed, the news from the front poured cold water on everyone.
Originally, the paver does not have the ability to vibrate and lift concrete in depth. "Vibration and slurry extraction directly affect the compactness and strength of concrete, so it is not allowed for the construction personnel to follow the equipment and push the vibrating scraper to vibrate, which is difficult to ensure the vibration quality," said Yang Guotai, the construction worker.
At this time, the car wiper attracted Yang Chao's attention: the wiper can move regularly. If the vibrating scraper is also fixed to the paver in sections, can it imitate manual operation? The R&D team installed a vibration scraper on the paver's pusher. After many tests, the best vibration frequency was found according to the equipment's traveling speed, which can not only reduce the labor input, but also greatly improve the vibration effect.
In the mountains after the rain, the air is mixed with the fragrance of soil. The bridge with a total length of 157 meters and a width of 31.5 meters completed the whole bridge deck pavement construction in less than 11 hours, and only six workers were employed in the whole process. For the crack prevention of the bridge deck, the team first laid a layer of transparent film on the road surface to prevent the water from evaporating instantaneously and being polluted by the soil on site. At night, when the mountain area cools down, a layer of geotextile with good water permeability is paved, which can not only spray regularly for protection, but also provide thermal insulation, providing "double insurance" against cracking. "The bridge deck concrete is vibrated and compacted, and the elevation and flatness are also beautiful." Zhu Zuobao, the chief dispatcher who has worked for more than 20 years, praised this.
Now, with the help of intelligent "robot" and "one film and one cloth" maintenance method, the qualified rate of the bridge deck pavement flatness is more than 98%, and the qualified rate of the protective layer is more than 97%. There is no crack or water accumulation, and it becomes the observation object of the whole line of bridge deck quality learning.
source
Traffic Construction Report
First Navigation Bureau
Welcome to reprint and indicate the source
news from：//new.qq.com/rain/a/20220714A05HM200
The Pingnan Expressway contracted by the First Harbor Engineering Bureau and the Second Highway Engineering Bureau is an important part of the "vertical 10 lines" in the planning of the Guangxi highway network, with a total length of about 85 kilometers. After completion, it is of great significance to promote the construction of the new land and sea channel in the west and promote the economic and social development of the Baise revolutionary base. When the high-speed construction crosses the mountains, 51 bridges will be built for the bid section undertaken by the First Navigation Bureau. Due to heavy rain in mountainous areas, large temperature difference between day and night, and perennial wind and rain on the bridge surface, if the quality control of bridge deck pavement is not good, it is very easy to crack, which will bring serious safety hazards. "This is a way to connect people in mountainous areas to become rich, and there must be no quality problems." Yang Chao proposed to build a model for the whole line at the beginning of the project construction.
The smoothness and crack control of bridge deck pavement is the key to high-quality construction of asphalt concrete pavement. The traditional bridge deck pavement is vibrated by manual hand-held vibrators and then paved. The flatness of the bridge deck depends on workers and is difficult to be standardized. To this end, the project introduces intelligent paver equipment, which emits infrared light through the laser transmitter, feeds back to the laser receiver after encountering obstacles, and then the control system adjusts the height of the oil cylinder, so that the machine always operates according to the infrared plane emitted, to ensure the paving smoothness. However, during the test, the team found that when encountering a longitudinal undulating road surface, it is necessary to manually install a stable running track for the paver to ensure that the paver is always in the same plane, which is time-consuming and laborious. It is also easy to cause elevation error due to human adjustment.
After consulting a large number of data, Yang Chao found that ultrasound can achieve all-round detection from point to surface. Following this idea, the R&D team installed an ultrasonic control system on the basis of the laser paver and made an induction line on the bridge deck. After the ultrasonic wave returned when it was blocked, the automatic adjustment of the paving height in millimeter level was realized through the control system. The manual track laying is omitted, and the operation quality and efficiency of the paver are significantly improved. Just when everyone was overjoyed, the news from the front poured cold water on everyone.
Originally, the paver does not have the ability to vibrate and lift concrete in depth. "Vibration and slurry extraction directly affect the compactness and strength of concrete, so it is not allowed for the construction personnel to follow the equipment and push the vibrating scraper to vibrate, which is difficult to ensure the vibration quality," said Yang Guotai, the construction worker.
At this time, the car wiper attracted Yang Chao's attention: the wiper can move regularly. If the vibrating scraper is also fixed to the paver in sections, can it imitate manual operation? The R&D team installed a vibration scraper on the paver's pusher. After many tests, the best vibration frequency was found according to the equipment's traveling speed, which can not only reduce the labor input, but also greatly improve the vibration effect.
In the mountains after the rain, the air is mixed with the fragrance of soil. The bridge with a total length of 157 meters and a width of 31.5 meters completed the whole bridge deck pavement construction in less than 11 hours, and only six workers were employed in the whole process. For the crack prevention of the bridge deck, the team first laid a layer of transparent film on the road surface to prevent the water from evaporating instantaneously and being polluted by the soil on site. At night, when the mountain area cools down, a layer of geotextile with good water permeability is paved, which can not only spray regularly for protection, but also provide thermal insulation, providing "double insurance" against cracking. "The bridge deck concrete is vibrated and compacted, and the elevation and flatness are also beautiful." Zhu Zuobao, the chief dispatcher who has worked for more than 20 years, praised this.
Now, with the help of intelligent "robot" and "one film and one cloth" maintenance method, the qualified rate of the bridge deck pavement flatness is more than 98%, and the qualified rate of the protective layer is more than 97%. There is no crack or water accumulation, and it becomes the observation object of the whole line of bridge deck quality learning.
source
Traffic Construction Report
First Navigation Bureau
Welcome to reprint and indicate the source
news from：//new.qq.com/rain/a/20220714A05HM200
