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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。
At present, the reinforcement of the subway tunnels in soft soil areas is often reinforced by chemical reinforcement followed by artificial freezing. Before and after the improvement of typical soil cement, the thermal physical and mechanical properties of the soil before and after the improvement of the soil, salty soil, There are few studies on the test, and the relevant test parameters are lacking. Combined with the starting project of shield tunnel of Nanjing Tunnel on Line 10, indoor thermal physical parameters of soil before and after cement improvement were tested on the two typical soil types at the beginning of the project. The results show that the thermal conductivity and volumetric heat capacity of different soil temperatures decrease with the increase of cement content and age. The thermal conductivity at room temperature is obviously lower than the thermal conductivity at -10 ℃. The volume at room temperature Heat capacity was significantly higher than -10 ℃ when the volumetric heat capacity; temperature coefficient of different soil at room temperature with the increase of cement content increases linearly, and -10 ℃ when the different soil thermal conductivity with the cement content While the temperature coefficient of different soil temperature increased with the increase of age. The temperature coefficient at room temperature was obviously lower than the temperature coefficient at -10 ℃. Finally, the recommended values of the thermal physical parameters of the tip soil are given and the values are validated on the spot.