挤压、剪切作用在增稠现象中的作用研究

学者们一般认为浓厚颗粒悬浮液的稠化现象与颗粒间的剪切作用有关,然而有研究者发现,在冲击试验中,颗粒间的挤压作用可能是悬浮液的稠化主要原因。为了区分挤压和剪切行为在浓厚颗粒悬浮液稠化现象中的作用,本文设计了拖球、拖片的对比试验,并且考虑了围压及加载速率的影响。研究结果表明,在稠化过程中,颗粒间的挤压作用占据了主导地位,即颗粒间的挤压作用比剪切作用更容易造成浓厚悬浮液的增稠。围压的存在会影响挤压和剪切的作用力,围压的增大对增稠现象有明显的促进作用；相比于剪切作用,挤压作用对加载速率的促进作用更加敏感。

Experimental study on compression and shearing behaviorin particle suspension

Shear behavior between particles is often employed to explain the large resistance when thickening happens in the particle suspension. However, some researchers suspected that the compression is responsible for the larger stress in experiment which the suspension is impacted by an impactor and lead to thickening. To clear the difference between compression and shear behavior in particle suspension, the pulling sphere and sheet experiments are designed. A series of tests are carried out under the conditions of different speeds and confining pressures in muddy clay. According to the experimental results, the compression stress is much larger than the shear stress under the same condition, and more likely to arouse thickening phenomenon than shear. And it is also known that the existence of confinement can also promote the compression or shear stress and the larger confining pressure is, the easier it is to give rise to a compression thickening phenomena. Moreover, we observe that the compression or shear stress increases with the increase of the pulling speed and the compressive behavior is more susceptible to pulling speed than shear action. Our research reveals that the thickening phenomenon should be divided as two kinds, the compression and shear thickening.