西南某隧道衬砌混凝土中的硫酸盐腐蚀破坏分析及对策

A Case Analysis of Tunnel Lining Concrete under Sulfate Attack and It's Countermeasures

为掌握实际服役条件下隧道结构衬砌混凝土的硫酸盐腐蚀劣化特征与机制,通过对西南某隧道衬砌混凝土样品的力学、耐久性能测试以及微观分析,发现该隧道混凝土所遭受的腐蚀破坏由硫酸盐侵蚀造成,且腐蚀破坏程度严重。腐蚀产物类型与混凝土所处位置相关,在衬砌表层和开裂、剥落的混凝土中腐蚀产物主要以钙矾石和石膏为主,在衬砌与地面交接处的糊状混凝土中则以碳硫硅钙石为主。分析结果表明:混凝土自身密实性不足和其使用大量石灰石原料是出现严重腐蚀破坏的主要原因。建议从混凝土原材料组成优选、配合比设计、施工养护和表层防护等多方面来提高隧道衬砌混凝土抗硫酸盐侵蚀破坏能力。

The test of mechanical properties and durability performance and microscopic analysis are made on lining concrete samples of a tunnel in Southwest China,so as to learn the characteristics,mechanism and influencing degree of sulfate attack.The analytical results show that the inadequate compactness and large amount of limestone used for concrete are the main causes for sulfate attack.The authors suggest to make a proper selection of concrete raw materials and rational mixing proportion design and carry out curing and surface protection technologies to improve the anti-sulfate attack capacity of lining concrete of tunnel.