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对火灾高温下隧道衬砌结构周围饱和软黏土的热传导特性进行了试验研究,旨在进一步探讨作用于隧道结构上的荷载变化,以便准确评价其安全状态。采用热探针程序法(美国材料与试验协会(ASTM)确定土体和软岩导热系数的标准方法),应用自行研制的高温土体导热系数测定仪测定了上海淤泥质黏土在高温下的导热系数。试验分别测定了不同温度及不同含水率条件下土样的导热系数,并以KD2导热系数测定仪作为校准仪器对试验结果进行了校正。试验结果表明:导热系数随着温度的升高而增大,且其增大的速率随温度的增加而减小,特别是对含有机质的淤泥质黏土因有机质的高温分解而使得这种降低更加明显;此外,在不同高温下土体导热系数随含水率的增加而增大。
The thermal conductivity of saturated soft clay around the tunnel lining structure under fire and high temperature was studied in order to further explore the changes of load acting on the tunnel structure in order to accurately evaluate the safety status. The heat probe method (ASTM standard method for determining the thermal conductivity of soil and soft rock) was used to determine the thermal conductivity of Shanghai silty clay at high temperature using a self-developed high-temperature soil thermal conductivity meter coefficient. The thermal conductivity of soil samples under different temperatures and different moisture contents were measured respectively. The KD2 thermal conductivity detector was used as a calibration instrument to calibrate the test results. The experimental results show that the thermal conductivity increases with the increase of temperature, and its rate of increase decreases with the increase of temperature, especially for organic silt clay which is degraded by the pyrolysis of organic matter Obviously; in addition, the thermal conductivity of soil increases with the increase of water content under different high temperatures.