温度对GMZ膨润土的膨胀性能影响研究

Effects of temperature on swelling characteristics of GMZ bentonite

在25℃,40℃,60℃和90℃的蒸馏水中对高庙子(GMZ)膨润土进行了膨胀性能试验。由于在试验条件下渗透膨胀占主导地位,GMZ膨润土的膨胀性能随温度的升高而增大,其中最大膨胀率随温度线性增加,而膨胀力随温度呈指数增加。压实GMZ膨润土的膨胀性能可用em=Kp^(D-3)表示。N2吸附试验结果表明温度对GMZ膨润土的表面分维D基本没有影响。在渗透膨胀条件下,采用扩散双层模型计算发现膨胀系数K与温度T_(c)之间存在线性关系,并且通过GMZ膨润土和Bikaner膨润土的膨胀试验进行了验证。将K–T_(c)线性关系与e_(m)–p分形关系相结合,提出了温度作用下GMZ膨润土膨胀性能的一种简便定量评价方法。

The buffer/backfill performance of bentonite–based materials may be affected by the influences of temperature fields,thereby leading to uncertainties in the safe operation of repositories.In order to address this issue,the swelling tests on Gaomiaozi(GMZ)bentonite are carried out in distilled water at 25,40,60,and 90°C.The results show that the swelling of GMZ bentonite increases with the temperature,owing to that the osmotic swelling dominates the swelling of compacted GMZ bentonite under the experimental conditions.The maximum swelling strain increases linearly with the temperature,whereas the swelling pressure increases exponentially with the temperature.The swelling characteristics of compacted GMZ bentonite can be expressed as em=KpD-3.According to the results of N2 adsorption tests,the fractal dimension,D,of GMZ bentonite is unaffected by the temperature.Calculated by the diffuse double layer model under osmotic swelling,a linear relation is found between the montmorillonite swelling coefficient K and the temperature Tc,which is verified by the swelling tests on GMZ bentonite and Bikaner bentonite.Combining the linear K-Tc relation and the fractal em-p relation,a simple method for evaluating the swelling of GMZ bentonite affected by the temperature is proposed.