Research On Seamless Construction Techniques Of Super Long Mass Concrete Box Foundation

The temperature load of mass concrete box foundation on the casting phase caused by the hydration heat and its shrinkage property will produce great thermal stresses, which will cause hazardous cracks if design and construction are inappropriate. In the past, codes adopted expansion joints and post-pouring zone to solve the problem of temperature stress and shrinkage stress. Due to such reasons as the integrity of the building and structure, function of use and demand of a limited time for a project, we put forward the requirement of seamless construction to the super long mass concrete box foundation. The research on the seamless construction of super long mass concrete box foundation, which was out of the prescript of codes, was relatively deficient and its application was limited greatly. The design and construction mainly depended on past practical experiences, which caused a large number of wastes and hidden dangers in projects. So this research in this paper has important actual project value.Based on the summarization and analyses of the current researches at home and abroad, combined the theory of concrete strain-cracking with the seamless construction technique of super long mass concrete box foundation of Bao-steel Group 1780mm steel rolling house, the paper discusses the feasibility on seamless construction theory of super long mass concrete box foundation and puts forward the sequential construction method and its comprehensive technique measures of seamless construction. The main research contents include the following several respects:(1) Analyzing the t heory of srtain-cracking and stress calculation method of super long mass concrete box foundation, selecting calculation modal that is closed to super long concrete box foundation, and calculating interval construction [L] of seamless construction, and proving the feasibility theoretically.(2) According to the relation between shrinkage, creep, temperature and concerte srtess, depending on the seamless construction technique of super long mass concrete box foundation of Bao-steel Group 1780mm steel rolling house, the cracking fracture checking computation on the construction stage was carried on.(3)On the base of the design, materials, construction and temperature to stress test in suit, analyzing the cracking control measures of seamless construction of mass concrete box foundation. The practice of Bao-steel Group 1780mm steel rolling house shows seamless construction super long and super wide mass concrete box foundation with general concrete, which has no. deformation seam, no repour strip and no special material, can reach good result in cracking control by the sequential construction method, optimization design, material control, concrete curing without increasing the cost or extension.