1 project overview
The contract section from Dejiang to Wuchuan expressway DWTJ- 1 starts from Qianjia Tujia Township, Dejiang County, with the starting pile number K0+000, and connects to expressway, Dejiang County along the river. Traffic conversion is realized by setting up Qianjia Hub, which serves Dejiang County, with the terminal pile number YK6+755, the total length of 6.739km, the subgrade width of 24.5m, two-way four lanes, the designed driving speed of 80 km/h, and the main quantities: earth and stone works of 2,004,600 m3, tunnels of 3,358 m/2 and bridges of 2,655 m/6. A total of 645 T-beams are prefabricated in this project (including 560 30mT beams and 85 40mT beams). Ensuring the quality of precast T-beam is an important link to ensure the engineering quality. Intelligent maintenance system of precast concrete beam and slab is adopted to ensure the maintenance quality of beam and slab.
Two characteristics
(1) After the maintenance pipeline layout is completed, start the intelligent maintenance system with one key, and the whole cycle maintenance construction will be completed automatically. (2) Covering the concrete periphery in time, shading and moisturizing, monitoring the surrounding environment and surface temperature and humidity of the beam body in the whole process, automatically judging and controlling the completion of highway maintenance, guiding the release of hydration heat in time, and preventing the occurrence of early maintenance cracks. (3) Self-controlled hot water boiler is used for winter maintenance, and concrete construction can be carried out at lower temperature in winter, which can speed up the construction progress and shorten the construction period.
3 process principle
3. 1 Technical Principle of Intelligent Maintenance System The intelligent maintenance system for cement concrete is mainly composed of three parts: wireless temperature and humidity measuring terminal, system host and maintenance terminal (scaffold, pipeline and nozzle). The main engine of the system is composed of controller, variable speed frequency converter, power distribution system, multistage vertical pump, temperature and humidity sensor, pressure sensor and other components to ensure that any nozzle maintains a spray pressure of 0.20MPa.
3.2 Wireless Temperature and Humidity Terminal The wireless temperature and humidity terminal is arranged on the surface of the concrete structure to be maintained, and the temperature and humidity of the beam surface can be monitored at any time. When the temperature and humidity exceed the set value, the maintenance system should be controlled to start spraying maintenance. The wireless transmission distance of the terminal exceeds 300m, data is transmitted every 30s, and it has its own wireless battery, which can be used continuously for 3 years.
3.3 The composition of the system host ① controller: This component controls the frequency converter to adjust the rotating speed of the multi-stage vertical water pump to adjust the water supply pressure according to the detected temperature and humidity conditions and the release rate of hydration heat, so as to ensure the spraying effect of the nozzle. ② Speed-regulating frequency converter: This part is used to control the rotating speed of the vertical multistage water pump to adjust the pressure and flow, and adjust the outlet pressure, so as to realize the energy-saving effect of frequency conversion. ③ Power distribution system: used to supply power to all electrical components. ④ Vertical multistage water pump: used for water supply and pressurization. ⑤ Temperature and humidity sensor: used to detect the ambient temperature and humidity. ⑥ Pressure sensor: used to detect the water pressure value of water supply. 3.4 Composition of curing terminal (1) The spray pipe adopts PP-R water supply pipe with strength of 1.6MPa and pipe diameters of φ25 and φ32. (2) The nozzle is made of double nozzles made of plastic, which can be divided into two types: fixed angle and 360 adjustable. (3) Maintenance of scaffolding: galvanized pipes with φ32, φ40 and wall thickness of 2.5mm are used, and they are designed and processed according to the types of beams.
4 key points of construction operation
4.65438+ Water intake points shall be reasonably distributed according to the site composition and structural position to meet the requirements of water intake distance. The beam yard will set up a catchment area according to the terrain, and the water after maintenance will be collected in the catchment area for precipitation and recycling. 4.2 Set the placement position of intelligent curing host. The intelligent curing instrument should be placed in the center of each component and structure to be cured, so as to reduce the water loss during curing water transportation. If it is used in precast beam yard, it should be prefabricated in batches in a planned way to reduce the movement of the maintenance host. The place where the intelligent therapeutic instrument is placed should be located on a flat ground. During use, umbrellas should be used to protect from rain, and there should be no water on the ground.
4.3 Manufacture of maintenance pipeline and maintenance shed ① Manufacture of maintenance pipeline: According to the external dimensions of components and structures to be maintained, design the layout of maintenance pipeline and the spacing of nozzles to ensure that the spray maintenance area covers the concrete surface to be maintained. The nozzle adopts double-head high atomization nozzle, and the curing radius is greater than 1.0m (2). Fabrication of maintenance scaffolding: According to the external dimensions of different components and structures, design maintenance covered scaffolding, using φ32 and φ40 steel pipes (wall thickness is 2.5 ~ 3 mm). 4.4 Connect the pipeline, connect the power supply, and connect the pipeline between the maintenance instrument host and the component or structure to be maintained; Connect the pipeline between the water intake point and the intelligent maintenance instrument. 4.5 Set a wireless temperature and humidity terminal on the beam slab or prevent the wireless temperature and humidity terminal from being used to test the temperature and humidity on the beam surface.
4.6 Start the maintenance host and set the maintenance parameters. After the system starts, open the distribution box door and touch screen, and set the maintenance parameters. Target pressure value: point out the water pressure value of the nozzle, and determine the last nozzle and the pressure value of 0.2MPa according to the calculated head loss. Minimum temperature: 5℃ according to the specification requirements. In winter, if the program is lower than 5℃, the system will automatically spray hot water, and in summer, if the program is lower than 5℃, the system will not start. When connecting or disconnecting the boiler, the control program should be updated. Maximum temperature: usually set to 40 ~ 45℃. Maximum humidity: usually set above 90%. Clock-controlled spraying time: that is, the time to start spraying maintenance every time, which is set to 2 ~ 4min； according to the number of nozzles; Clock maintenance stage setting: divided into three stages, 1 stage is 1 day; The second stage is the second day to the third day, and the third stage is the fourth day to the end of maintenance. You can set the clock-spraying frequency in different stages, such as 1 stage, 30 minutes/time during the day and 60 minutes/time at night. Press the channel button corresponding to a beam maintenance pipeline on the control panel to immediately start the full-cycle maintenance construction. 4.7 After the curing of the concrete beam and slab to be cured reaches the curing age, press the control button of the corresponding channel on the control panel of the curing host, and the indicator light will go out, and the curing will end immediately. Scaffolds and pipes are moved to other beams for maintenance.
5 quality control
(1) Establish quality assurance system, implement quality responsibility system and ensure construction quality. (2) After the initial setting of precast concrete beam and slab pouring and formwork removal, the maintenance pipeline shall be installed immediately and spraying maintenance shall be started. When formwork maintenance is needed, the maintenance scaffolding shall be covered, and spray maintenance shall be started immediately after slurry collection. (3) The nozzle spacing on the spray maintenance pipeline is 1.0 ~ 1.5m to ensure that the spraying range covers all areas of the concrete surface, and the angle of each nozzle can be manually adjusted. (4) Concrete shall be covered immediately after form removal in winter to ensure that the temperature difference between the concrete surface and the surrounding environment does not exceed 20℃. (5) When the ambient temperature is lower than 5℃ in winter, the main engine of the maintenance system should be used together with the automatic hot water boiler, and sprayed with hot water for heat preservation and moisture preservation. (6) Generally, the curing period should not be less than 7d, and the concrete with special needs should be extended as appropriate according to the environmental temperature and humidity, cement varieties and additives. (7) During the whole curing process, water and electricity should be kept unblocked, and the main engine filter should be cleaned regularly and the curing nozzle should be tested.
6 safety measures
Strengthen training to improve the safety awareness of all participants. Safety precautions for concrete intelligent curing system (1) The three-phase power supply should be connected by a professional electrician. In the power supply box, the general letter L stands for live wire. (2) The stainless steel wheel of the main engine of the intelligent maintenance system must be pressed on a solid ground to eliminate static electricity on the grounding conductor. When installing equipment on site, the wheel shall not be hung. (3) It is forbidden to start the intelligent maintenance system without water, and it should be stopped immediately when there is no water. (4) When the intelligent maintenance system is used outdoors, its top surface must be covered with rain and sun protection measures. (5) When the ambient temperature is lower than 0℃, the system host should stop running.
7 Environmental protection measures
The waste water, waste slurry and waste residue generated in the construction can't be misplaced, and should be treated according to regulations. The maintenance beam yard is provided with a water collection channel and a confluence pool, and the sprayed maintenance water flows down from the beam slab to be maintained, and is collected through the confluence channel, and then enters the confluence pool for precipitation to be used as maintenance water again.
8 Resource saving
The use of advanced and economical construction equipment not only improves the advanced and intelligent technology, but also promotes the standardization and refinement of management and saves various expenses. It has changed the backward technology of manual maintenance in the past, improved the maintenance quality of concrete, reduced pollution and protected the ecological environment. It reduces the number of people who carry out complicated procedures of construction technology, and the procedures replace them, thus improving work efficiency.
9 benefit analysis
9. 1 technical advantages
(1) Monitor the ambient temperature and humidity and the beam surface temperature and humidity in real time, and automatically implement the maintenance measures according to the monitoring results, so that the on-site concrete curing conditions tend to the standard curing room, and realize the standardization, refinement and intelligence of on-site concrete curing. It overcomes the problem that it is difficult to guarantee the actual measurement times and actual maintenance times of artificial temperature and humidity measurement. (2) According to the set procedure of hydration heat release, guide the smooth release of hydration heat. (3) According to the specifications and established procedures of the maintenance scheme, standardize the maintenance construction and spray reasonably. (4) The curing process is standardized and reasonable, with high concrete strength and few cracks. (5) After the system runs, the whole-cycle maintenance construction can be automatically completed, and a plurality of beams with different ages can be automatically maintained at the same time.
9.2 Economic benefits
The equipment can be used for more than 8 years after one-time investment. Compared with traditional manual maintenance, intelligent maintenance can achieve full-cycle maintenance once installed, which can improve work efficiency by more than 5 times and save labor by 70%. At the same time, the maintenance quality has been improved qualitatively, which ensures the temperature and humidity during the maintenance of concrete members on site, avoids the occurrence of maintenance cracks as much as possible, reduces the maintenance cost of the later structure, and produces immeasurable economic benefits. 9.3 The maintenance quality of social benefit concrete is the key process to ensure the safety and durability of concrete members and the lifeline of structural safety. Controlling the temperature and humidity in the process of concrete curing by automatic and intelligent means can improve the safety and durability of concrete members, change the traditional manual maintenance method and realize the improvement of technology and technology, which has good social benefits.
10 conclusion
The intelligent curing system of cement concrete is adopted in the site, and it is used together with the automatic hot water boiler. Changing manual maintenance into intelligent mechanical automatic maintenance improves the maintenance efficiency and quality, promotes the construction progress, prolongs the service life of concrete members, saves the later maintenance cost, and has good economic benefits, social benefits and popularization prospects.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd