水泥改良前后土体热物理参数试验研究

目前，软土地区地铁隧道端头加固往往采用化学加固后辅以人工冻结，关于典型土层水泥改良前后土体、含盐土体、含盐土层水泥改良前后土体的热物理和力学特性室内试验的研究还很少，缺少相关试验参数。结合南京地铁10号线过江隧道盾构始发工程，对始发端头典型的两种土质进行了水泥改良前后土体热物理参数的室内试验。试验表明:不同土质不同温度下导热系数和容积热容均随着水泥掺量和龄期的增大而减小，常温下的导热系数明显低于-10 ℃时的导热系数，常温下的容积热容明显高于-10 ℃时的容积热容;常温下不同土质的导温系数随水泥掺量的增大而线性增大，而-10 ℃时不同土质的导温系数随着水泥掺量的增大而缓慢减小，不同土质不同温度的导温系数均随龄期的增大而增大，常温下的导温系数明显低于-10 ℃时的导温系数。最后给出了数值分析时端头土体热物理参数的建议取值并经现场验证取值正确可行。

Experimental Study on the Thermo-physical Property of Pre and Post Cement-soil

Recently supplemented by artificial freezing method after chemical reinforcement is the main method to improve the soil at the ends of subway tunnel in soft clay area, but the relevant test parameters of thermo-physical and mechanical characterisitics of pre and post cement-soil, salt soil, pre and post cement-salt-soil are few. Based on the shield launching project of the crossing-river tunnel of Nanjing Subway Line 10, the thermo-physical property of the two typical soils were tested before and after the cement improvement. The experiment shows that: The conductivity coefficient and volumetric heat capacity of different soils and different temperature decreases with both the increase of cement content and curing time. The conductivity coefficient at normal temperature is evidently lower than that at -10 degree while the volumetric heat capacity at normal temperature is evidently higher than that at -10 degree. At normal temperature, the conductivity coefficient of different soils linearly increases with the cement content; however, it slowly decreases with the cement content at -10 degree. The conductivity coefficient of different soils and different temperature increases with the curing time and it is evidently lower at normal temperature than that at -10 degree. Finally the parameter values of thermo-physical using in numerical analysis were proposed and they are verified by site.