| Large volume concrete plays a rather important role in medium and large construction projects such as bridges.The structural cracking problem caused by temperature stress during concrete casting and forming is of great concern,when the temperature stress exceeds the ultimate tensile strength of the concrete,the concrete will produce cracks.Due to the very complex hydration reaction and numerous influencing factors in the actual project,temperature control during the construction period of mass concrete has been a key research area.Controlling the key temperature indicators during concrete casting and forming within the standard range can effectively reduce the risk of temperature cracks in concrete.In order to realize intelligent through-water temperature control during the construction period of large volume concrete,this paper innovatively designs an industrialized intelligent control platform based on adaptive cascade fuzzy control algorithm,and the main research contents for the design of this intelligent control platform are as follows:(1)Based on fuzzy control theory,a variable-domain cascade fuzzy control algorithm is designed for bulk concrete through-water temperature control.The three key parameters of concrete lining temperature difference,temperature change rate and inlet water temperature are integrated and compounded for two-level fuzzy reasoning to form an intelligent closed-loop bulk concrete through-water temperature control algorithm.In order to verify the feasibility of the through-water temperature control algorithm,several sets of comparative simulation experiments were conducted based on the existing through-water cooling algorithm,and the analysis of the joint simulation results according to "GB/T 51028-2015" standard showed that the designed adaptive cascade fuzzy control algorithm can maintain the temperature difference between the concrete internal and inlet water below 25 ℃ below,in the concrete cooling zone,the cooling rate does not exceed 2(℃ / day),on the basis of this effective cooling of concrete,the results are in line with the "GB/T 51028-2015"(2)The system architecture of the industrialized intelligent control platform for mass concrete was constructed,while the circuit schematic of the main control board was designed and the PCB layout was drawn,taking into account the hardware needs of the system.After on-board testing,the intelligent control platform can effectively monitor,process data and control the temperature of six layers of concrete at the same time.The existing equipment put into actual engineering use for more than one month of continuous normal operation,to verify the reliability of the designed architecture and the main control hardware.(3)Based on the embedded microcontroller platform and the real-time operating system,the software program of the intelligent temperature control platform for large volume concrete was designed.The main research and design contents are as follows,allocating the resources of the microcontroller,creating several task programs according to the operation mechanism of the intelligent temperature control system,writing device drivers for each peripheral device of the temperature control platform one by one,and then writing driver call programs within each task program,and the tasks run together to complete the corresponding functions.(4)The data collected by the intelligent temperature control platform,which has been put into use in the actual concrete casting project,is analyzed according to the indexes of the bulk concrete temperature measurement and control standard "GB/T 51028-2015".The graphs of concrete internal temperature,concrete external temperature and water inlet temperature were drawn.The maximum temperature difference between the concrete internal and inlet water is 24.6℃ and the maximum cooling rate of concrete is 1.59(℃ /day),which meet the requirements of "GB/T 51028-2015" and verify the effectiveness of the intelligent temperature control platform in the actual concrete casting project. |
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