The principle of skip bin method makes full use of the principle of "resistance to release" that concrete is easy to release internal stress before its performance is unstable and it is not completely solidified within 5 ~ 10 days. It divides the building foundation or large-area concrete plane mechanism into several areas, and carries out construction according to the principle of "block planning, block construction, layered pouring and integral molding". Its mode is the same as checkers, that is, pouring one section at a time. The interval between two adjacent sections shall not be less than 7 days, so as to avoid strong temperature difference and drying effect at the initial stage of concrete construction, and thus there is no need to leave post-cast strip. The comprehensive technical measures of skip bin method have successfully solved the problem of crack control and seepage control of super-long, super-wide and super-thick mass concrete without joints.
Main technology
(1) Based on the principle of "resistance at the same time, resistance first, resistance first", the "skip block" is scientifically divided through analysis, and comprehensive measures are taken in terms of materials, structure and construction management to strictly control the early cracks in concrete.
(2) Long walls are equipped with small-diameter high-density horizontal reinforcement outside the main reinforcement, and the bottom plate is covered with steel mesh to increase the crack resistance of concrete.
(3) Choose low shrinkage cement, optimize concrete mix ratio and strictly control cement dosage, so as to effectively control concrete temperature stress and reduce concrete shrinkage and deformation.
(4) Strictly control the silt content and concrete slump of coarse and fine aggregates in concrete raw materials to further improve the tensile strength and ultimate tensile deformation of concrete.
(5) Strengthen information construction, and adopt temperature measurement method to realize temperature control. Comprehensive sanitary measures, such as plastic film moisturizing and straw bag insulation, should be taken to backfill and cover the soil as soon as possible, slow down the temperature, give full play to the stress relaxation of concrete and reduce the constraint stress. The theoretical analysis of crack control carried out in this achievement includes strength and deformation analysis. Close contact with engineering practice: the temperature stress of concrete is not linear with the length of structure, and the cracks of super-long structure concrete are controllable. Super-long, super-wide and super-thick mass concrete structures are not provided with deformation joints and post-pouring zones. Using conventional concrete without any expansion agent and adopting "comprehensive technical measures of block jumping and pouring" can effectively control harmful cracks in concrete and ensure the safety of engineering crack resistance. Compared with the common construction methods at home and abroad, it is innovative and breaks through the provisions of domestic norms on the allowable spacing of deformation joints of underground long walls.