换热孔回填材料含水率特征变化规律及其对热物性影响研究

通过设计“量筒法”代替环刀法和选用热重法,分别测量地下水渗入换热孔内回填材料的饱和含水率和残余含水率,用滤纸法测量基质吸力与含水率数据,然后基于含水率计算出不同深度下回填材料热特性参数。结果表明,高吸力值时材料的含水率更低,假设饱水带最高点为地下水位线0点,在距地下水位线100 m处仅有3.6%含水率;对比软件模拟数据与实测点,发现所选用的设计方法与拟合结果相近;与干实回填材料相比,受地下水渗入的换热孔下段靠近水位线处蓄热能力更强,温度变化相对延迟,但导热能力和热扩散能力都有所减弱,中上段蓄热和导热能力减弱,但热扩散能力增强。

STUDY ON VARIATION PATTERN MOISTURE CONTENT OF BACKFILL MATERIAL BOREHOLE AND ITS INFLUENCE ON THERMAL PROPERTIES

In this paper, the water saturation and residual water content of the backfill material in the boreholes were measured by the thermogravimetric method. The "graduated cylinder approach" was adopted to replace the ring knife method in this study. The matrix suction and water content were measured by the filter paper method. Based on the moisture content, the thermal characteristic parameters of the backfill material at different depths were calculated. The results showed that the greater the matrix suction, the lower the water content. Assuming that the highest point of the saturated zone is the water table, there is only 3.6% of water saturation at a distance of 100 m from the water table. Comparing the simulation results with the measured points, it shows that the measured results from the design method used matches the fitting results; compared with dry backfill material, the lower section of the borehole infiltrated by groundwater has a higher heat storage capacity near the water table, and the temperature change is relatively delayed. However, the thermal conductivity and thermal diffusion capacity are both affected. The heat storage and heat conduction capacity of the upper middle section is weakened, but the heat diffusion capacity is strengthened.