无缝设计在水工大体积结构混凝土中的应用

The Application of Continuous Welded Design to Mass Concrete Hydraulic Structures

形成大体积混凝土温度裂缝的原因有内部约束应力和外部约束应力两种情况.当内外温度差大于25℃时,表面混凝土抗拉强度抵挡不住这种应力,就会产生表面裂缝.泵送混凝土由于水泥用量多、单位用水量大、砂率高和掺化学外加剂等特点,使混凝土干燥收缩,产生裂缝的几率增大.对此提出UEA补偿收缩混凝土的无缝设计施工方法,实施结果表明,该方法对控制高强度、大流动性条件下的大体积泵送混凝土温度裂缝是有效可靠的,其他种类的水工大体积混凝土的温度控制与裂缝预防也可借鉴此方法.

The reason of forming concrete cracks comes from interior constraint stress and external constraint stress. When the temperature difference between interior and external exceeds 25℃, then the tensile strength of concrete can not resist this king of temperature stress. As a result the cracks of concrete are produced. Pumping concrete with much more cement, unit water consumption, sand rate and additives compared with common concrete, so the probability of dry contraction and cracks propagation increase. A new continuous welded design method by use of UEA offset contraction concrete is put forward. The practical result indicates that it is effective to prevent cracks propagation in pumping concrete with high pouring strength, flow and large mass. This construction method also provide support to other mass concrete hydraulic structures.