泵送混凝土结构施工期温控防裂研究

Temperature and Crack Control of Pumping Concrete Structure during Construction

针对泵送混凝土结构施工期易开裂的问题,从减小温差和约束出发,采用三维不稳定温度场和应力场的有限单元法及水管冷却离散算法,对某泵送混凝土结构施工期防裂方法进行数值计算分析。计算结果表明:表面保温性能越好,结构早期内外温差越小,表面拉应力也就越小,但拆模后表面和后期内部的拉应力也越大;吊空模板技术、缩短间歇时间和设置后浇带等施工方式对减小约束、防止结构后期裂缝有利;合理保温和水管冷却是防止裂缝产生的有效措施。

For controlling the crack of pumping concrete structure in the period of construction, the effects of some control measures, which being considered from the perspective of decreasing temperature different and constraint, were simulated by the 3D-FEM of unstable temperature and stress fields and the discrete algorithm of cooling pipe for a pumping concrete project. The results show that： （a） the better the insulation, the smaller internal and external temperature different and surface tensile stress at early stage, but the larger tensile stress in surface after form removal and in internal at later stage; （b） construction methods such as using suspension formwork, shortening interval time and setting late poured band are useful to decrease constraint and control later cracks; and （c） reasonable insulation and pipe cooling are effective method to control cracks.