高寒地区水工混凝土防护修复技术与应用

高寒地区水工混凝土建筑物处于超大温差、极端低温、强辐射、大风、干燥等复杂条件,混凝土结构容易产生以冻融破坏为代表的劣化病害,防护修复技术是常用的劣化防治措施之一。通过有限元方法对冻融循环作用下水工建筑材料劣化过程及影响规律进行了模拟计算。结果显示,在周期变温荷载作用下,孔隙水结冰产生的冻胀应力是导致混凝土耐久性降低的主要因素。除了改善混凝土本体抗冻性外,还应采用表面防渗处理,如表面涂层防护,以控制混凝土内部含水量和冻胀应力,提高抗冻融能力。介绍了高寒地区水工建筑物防护修复材料的选择原则、种类特点和施工工艺,总结了防护修复技术在高寒地区的典型工程应用,为高寒地区水利水电工程维护提供了一定的参考借鉴,并从材料性能、配套设备、工艺拓展、标准制定4个方面进行了展望。

Protection and Repair Technology for Hydraulic Concrete in High and Cold Region: Research and Application

Due to complex conditions such as large temperature difference, extremely low temperature, strong radiation, strong wind and drying, hydraulic concrete structures in high and cold region are prone to suffer from deterioration diseases represented by freeze-thaw damage. Protection and repair technology is a commonly used preventive measure against deterioration. The degradation process and the law of influence on hydraulic building materials under freezing-thawing cycle are simulated by finite element method. Results suggest that the frost heave stress caused by freezing of pore water is the main factor leading to the decrease of its durability under cyclic varying temperature-caused load. In addition to improving the antifreeze capacity of concrete, surface anti-seepage treatment such as surface coating protection should also be taken to control the interior water content and frost heaving stress in concrete and to improve freeze-thaw resistance. Moreover, the selection principles, types and characteristics as well as construction techniques of protective repair material for hydraulic structure in high and cold region are summarized, and some typical engineering applications of protective repair technology in high and cold region are introduced for reference. The development trends of material performance, equipment, technique extension, and standard formulation are also discussed.