高原多年冻土区隧道湿喷混凝土施工技术

Tunnel Wet Concrete-shot Technology in Permafrost Region

在青藏铁路昆仑山隧道成功使用湿喷混凝土作为临时支护。通过试验和经济比选确定选用A类防冻剂、D′类速凝剂和聚丙烯纤维材料,确定水泥与骨料的比为1∶3 4,水泥用量在470kg·m-3～480kg·m-3之间,砂率为60%;水灰比为0 42～0 47。在高原缺氧环境下使用适用于低温环境的喷射机械,采取温控措施,确保喷射时拌和物温度不低于10℃,加强检查,可以保证高原冻土隧道混凝土喷射质量。

Through test and economic comparison, the wet concrete shot in tunnel which is used as a temporary support in Kunlunshan tunnel on Qinghai-Tibet Railway, uses class A anti-freeze agent, class D′ fast coagulator and polypropylene fiber material, and adopts the ratio of 1∶3.4 for the cement and aggregates. The use of cement is between 470 kg·m^(-3)-480 kg·m^(-3), the rate of sand 60%, and the ratio of water vs. sand and cement 0.42-0.47. Ejecting machines adaptable to low temperature and low oxygen content are used. Temperature control measures are taken to ensure that the temperature of the mixed material at ejection is not lower than 10℃. With inspection strengthened, the quality of concrete-shot in permafrost tunnel can be guaranteed.