基于现场热响应测试方法的地下岩土热物性分析

Analysis of Soil Thermal Properties with In-Situ Thermal Response Test Method

目前获取导热系数的主要方法是现场热响应试验,但该方法缺乏统一的技术标准,导致计算结果可比较性差,难以应用。笔者开展了不同热响应试验设备的原位热物性测试系列试验,分析了测试与数据处理方法对测试结果的影响,探讨了试验过程中需要注意的问题。结果显示：为减少试验误差,两次热响应试验测试的时间间隔不应少于10d;应尽量避免循环水与岩土介质以外的其他介质产生热量交换;对于恒热流热响应试验,导热系数值与舍弃时间（1.0~12.0h）成正相关关系;而对于定进回循环水温差的热响应试验,导热系数值与舍弃时间（0.0~12.0h）成负相关关系;舍弃时间大于12.0h时,导热系数变化趋于稳定。按统一标准舍弃前12.0h的测试数据进行导热系数计算,6家单位的导热系数计算值都在2.2~2.8W/（m·℃）范围内,测试结果合理可靠。

At present,in-situ thermal response test is widely used to measure thermal conductivity parameter in engineering.However,due to the lack of unified technical standard of the test,results obtained from in-situ test have unsatisfactory reliability.Our main aim is to analyze the effects of test methods and data processing on the results of the tests.Series of in-situ tests were carried out by using various of thermal response equipments in a special test well.Results show that in order to reduce experimental error,time interval between two thermal response tests should not be less than 10 days and circulating water should be prevented from heat exchange with other media（except for geotechnical media）.For thermal response tests with steady input power,the value of thermal conductivity is positively correlated with times not used（1.0-12.0h）.On the other hand,for thermal response testswith steady temperature difference,the thermal conductivity value is negatively correlated with times not used（0.0-12.0h）.It is also found that the value of thermal conductivity is stabilized with times not used（12.0h）.According to the uniform standard with times not used（12.0h）,the values of thermal conductivity of the six units are all within 2.2-2.8 W/（m·℃）,and the test results are reasonable and reliable.