高庙子膨润土悬浮液的抗冲蚀流变特性

Antierosion Rheological Characteristics of Gaomiaozi Bentonite Suspension

摘要:

采用流变仪对高庙子膨润土悬浮液在不同水固比、掺加盐溶液类型及浓度的条件下的抗冲蚀流变特性进行了研究，得到了各种情况下膨润土悬浮液的屈服应力，再结合Stoke公式计算了引起膨润土悬浮液冲蚀的初始水流速度.研究表明：随着水固比的增加，膨润土流变曲线逐渐下移；对于水固比小于5.0的膨润土悬浮液，当剪切速率较小时呈现假塑性流体特征，而当剪切速率达到一定值时，流变曲线斜率趋于定值；对于水固比大于5.0的膨润土悬浮液，则始终表现为假塑性流体特征, 且随着水固比的增大，膨润土悬浮液牛顿流体特征逐渐增强；随着NaCl浓度的增加，膨润土悬浮液屈服应力先减小后增大，而随着CaCl2浓度的增加，膨润土悬浮液屈服应力则不断减小；引起膨润土悬浮液发生冲蚀破坏所需的最低水流速度在10-4~10-2 m?s-1范围内.

关键词:膨润土;冲蚀;流变性;屈服应力

Abstract:

The rheological characteristics of Gaomiaozi(GMZ) bentonite suspension with different watersolid ratio, salt type and concentration were investigated by using Brookfield DVIII rheological device, and the yield stresses of bentonite suspensions were obtained from rheological curves, then the yielding initial water velocity was calculated with a consideration of the Stoke law. The results showed that the rheological curves of bentonite suspension moved lower with the increase of watersolid ratio. For the bentonite suspension with a watersolid ratio below 5.0, the suspension presented a characteristic of pseudoplastic fluid when shearing rate was slow, while the rheological curve slope tended to be constant when shearing rate exceeded a certain value. For the bentonite suspension with a watersolid ratio above 5.0, the suspension gradually presented a characteristic of newtonian fluid with the increase of watersolid ratio; when the concentration of NaCl solution increased, the yielding stress of bentonite suspension firstly decreased and then increased, while the yielding stress would be reduced all through the test with the increase of CaCl2 solution’s concentration; the yielding initial water velocity of bentonite suspension was between 10-4~10-2 m?s-1 under the condition in this study.

Key words:bentonite; erosion; rheological characteristic; yield stress