浆砌石坝体溶蚀评价及防治对策探讨

溶蚀导致浆砌石坝体材料强度降低、孔隙率增大、渗漏严重，对大坝安全构成威胁。本文探讨了砂浆的溶蚀机理，提出了根据水质分析和侵蚀性评价、强度检测、水泥浆体成分分析和其中钙离子的溶出量分析等方法来评价浆砌石坝溶蚀程度的方法。在运用该方法对广东省某浆砌石坝进行溶蚀的危害程度评价时发现该工程环境水具有软水的溶出型侵蚀、泛酸型侵蚀和碳酸型侵蚀，部分水样达到强腐蚀等级。同时，砂浆抗压强度低、孔隙率大，水泥浆体中的钙离子含量偏低，随渗漏水流失的钙离子数量巨大，因此，溶蚀已经对坝体材料造成了一定的破坏，且这种影响随时间而增大。最后提出在上游面作防渗层并用改性水泥砂浆和净浆进行灌浆防渗补强处理的防治对策。

Evaluation method and protection measure for leaching corrosion of masonry dams

The mechanism of leaching corrosion is studied theoretically. On this basis the methods for evaluating the level of corrosion according to the leaching water quality, strength of cement mortar, constituent of cement hydration production and quantity of dissolved Ca2+ are proposed. These methods are applied to evaluate the leaching corrosion level of a typical masonry dam in Guangdong Province, China. The examination of water quality shows that corrosions due to soft water, acid or carbonic acid exist, some water specimens even contain high corrosive material. lt is also found that the compressive strength of the mortar is low and porosity is high. Furthermore, the content of Ca2+ in cement paste is low. All these information shows that leaching corrosion result in remarkable erosion of the dam. For preventing further erosion a waterproof layer placed on the upstream face of the dam is recommended to minimize the leaching.