膨润土组合试样的热传导和水分迁移规律试验研究

Experimental study on heat conduction and water migration of composite bentonite samples

缓冲材料砌块接缝作为高放废物处置库工程屏障系统中潜在的薄弱部位必须被深入研究。为此,利用研制的试验装置测定了进水前与进水后两种情况下高庙子(GMZ)膨润土组合试样不同位置处的温度和体积含水量随时间的演化规律,并根据试验结果得到了组合试样接缝愈合后的热传导系数和水力传导系数。试验结果表明膨润土组合试样内部温度的变化主要受温度边界的影响,而其内部水分的变化对其影响较小。在短时间内,加载水力边界条件仅使得靠近水力边界处的土体的体积含水量大幅度增加,而对其它位置影响较小。由于受到温度边界的影响,靠近温度边界位置处的土体的体积含水量随时间逐渐降低。愈合后接缝位置的导热性能和渗透性能够满足高放废物处置库工程屏障的要求。

The joints of composite blocks of buffer materials as potential weak parts in the engineering barrier system of high-level radioactive waste(HLW)repository must be studied in depth.Therefore,the evolution of temperature and volumetric water content with time at different locations of Gaomiaozi(GMZ)composite bentonite samples before and after simulated water inflow is measured by using the developed experimental devices.According to the experimental results,the thermal conductivity and hydraulic conductivity of the joint location after healing of composite samples are obtained.The experimental results show that the change of the internal temperature of the composite bentonite samples is mainly affected by the temperature boundary,and the change of the internal water has small effects on it.In a short period of time,the loading of hydraulic boundary conditions only makes the volumetric water content of the soil near the hydraulic boundary increase significantly,but has small effects on other locations.Affected by the temperature boundary,the volumetric water content of the soil near the temperature boundary gradually decreases with time.The thermal conductivity and permeability of the joint location after healing can meet the requirements of the engineering barrier of the HLW repository.