Research On Thermal Shrinkage Control Of Super-Length Concrete Structure In Construction Period

With the development of China,the city's demand for comprehensive and multi-functional buildings continues to increase,urban land resources have become increasingly tense,and ultra-long basements and super-large structures have emerged.The super-sength basement structure is greatly affected by temperature,shrinkage and creep during the construction phase,often resulting in safety and durability problems.Therefore,it is very necessary to conduct long-term monitoring and control research on the temperature shrinkage of the ultra-long concrete construction stage in the basement.Based on the background of Chengdu Jincheng Plaza Underground Comprehensive Interchange Service Center,this topic carried out field measurement of the temperature and deformation on the south side of the first batch of projects(park and ride area),and obtained the actual thermal stress of the project Field distribution,combined with Midas / Gen to establish a finite element model,in-depth study of the effect of temperature on the thermal stress and deformation of the structure,guide the subsequent construction of the project,and also provide temperature analysis and temperature and shrinkage control for such ultra-long basement structures For reference,project research has important theoretical significance and practical value in engineering.The main conclusions drawn by the paper are as follows:1.After a period of on-site monitoring,the temperature of the concrete changes with the ambient temperature during the entire process of all the measuring points;the changes in the stress and deformation of the concrete gradually increase with time;2.After comparing the actual measurement and simulation at the current stage of the project site,during the construction stage of the diverting water section on the south side of the parking lot of the transfer service center,the temperature stress is The overall structure of the parking lot has less influence,and the structure has better integrity;3.The temperature difference of heating has little effect on the temperature effect of the ultra-long concrete in the basement,while the temperature difference of temperature decrease has a great influence on the temperature effect of the ultra-long concrete in the basement.The greater the temperature drop,the greater the temperature stress and deformation on the ceiling of the basement.It can be selected in a period of low temperature,which is convenient for controlling the pouring temperature of concrete,and prevents the structure from being subjected to excessive cooling temperature difference,thereby causing greater temperature stress.Properly extending the closing time of the post-pouring zone between the flow sections can also reduce the effect of concrete shrinkage on the temperature effect of the structure;4.Through finite element simulation,calculate the influence of different post-sealing zone sealing methods(sequential sealing,pairwise sealing and relative sealing from the north-south section)on the temperature stress during the construction process,and compare and analyze the use of sequential sealing and relative sealing from the south-north section The closing method of post-casting zone can effectively reduce the adverse effect of temperature effect on the construction of ultra-long concrete in the basement.