无纺织物过滤黏土的梯度比试验及机理研究

Gradient ratio tests and filtration mechanism of cohesive soil-geotextile system

采用2种土工织物和黏土进行梯度比试验,并通过试验后黏土试样微观结构的电镜扫描,从微观上认识土工织物过滤黏土机制。结果表明:在土工织物过滤黏土的过程中,初期梯度比会快速上升,达到峰值后,织物-黏土体系淤堵情况逐渐缓解,透水性相对改善,梯度比下降并趋于稳定;在过滤过程中靠近织物的黏土中会发生细颗粒穿过土工织物逃逸的现象,这是织物-黏土体系的透水性改善的内在机制;过滤后的黏土主要以聚粒形式存在,结构较疏松,在靠近织物的黏土中出现较大的孔隙;不同孔径和工艺的土工织物过滤黏土机制相同,但淤堵程度不同。

Two kinds of geotextiles were used to do the Gradient Ratio（ GR） tests of a clay-geotextile system,and the Scanning Electron Microscope（ SEM） technique was adopted in this study to observe the microstructure of clay after K tests. The objective of this study focuses on the clay filtering mechanism of geotextile from the microscopic point of view. Research results show that：（1） During the clay filtering process of geotextile,the gradient ratio rises rapidly at the initial stage,while after reaching the peak,the gradient ratio drops and tends to be stable with the gradual improvement of the permeability of geotextile-soil system;（ 2） Some fine clay particles close to the geotextile pass through and escape from the textile during the filtration,which should be the intrinsic mechanism of the permeability improvement of geotextile-soil system;（ 3） The filtered clay is mainly in the form of poly grain texture with loose structure and larger pores in the clay appear near the geotextile;（ 4） Geotextiles with different pore sizes and technologies have the same mechanism of clay filtering,while the extents of clogging are different.