薄壁箱型混凝土结构施工期温度裂缝控制

Thermal Cracking Control of Thin-walled Box Concrete Structures during Construction Period

针对薄壁箱型混凝土结构特点及施工期易产生裂缝的问题,采用三维有限单元法仿真计算某拱式渡槽拱圈的一个浇筑段温度场和应力场,据此研究裂缝成因及开裂机理并提出相应的控制措施。结果表明,薄壁箱型混凝土结构早期的内外温差及腹板和横隔板的约束作用是产生裂缝的主要原因,而采用塑料板保温的温控防裂措施能有效预防裂缝的产生,且塑料板厚度越大,防裂效果越好。

In view of the characteristics of thin-walled box concrete structure and the problem of cracking easily during the construction period,the 3-D FEM was adopted to simulate and calculate the thermal field and stresses field of a pouring section of an arch-shaped aqueduct.Accordingly,the causes and mechanism of cracks were studied and the corresponding control measures were put forward.The results show that the temperature difference between the surface and interior of thin-walled box concrete structure and the restraint action of web and transverse diaphragm are the main factors influencing the occurrence of cracks.The exterior thermal insulation is the effective measure to prevent the concrete structure from cracking,and the greater the thickness of plastic sheets,the better the anti-crack effect.