分散性黏土是一种特殊土,具有易被水冲蚀的特性。随着国内外土石坝发展迅速,心墙土的选择范围也不断扩大,能否选用分散性黏土作为心墙填料以及分散性黏土在反滤层保护下防渗效果如何,是工程设计中十分关心的问题。针对某水利枢纽2个料场的心墙料取样开展了与分散性有关的试验研究,通过针孔、碎块、孔隙水溶液及双比重计4种室内试验鉴定方法对心墙料的分散性进行判定。对分散性心墙料掺加不同比例的水泥或生石灰进行了改性,并对改性前后的心墙料渗透特性和反滤保护措施效果进行对比研究。试验成果表明料场的部分心墙料具有分散性;2个料场的土料在水泥掺量3%或者生石灰掺量3%～5%的情况下,基本可以消除土料的分散性;经过掺水泥或石灰等方式改性的心墙料比未掺改性材料的心墙料能承受的水力比降更高;在合适的反滤料保护下,分散性黏土能承受较高的水力比降,在裂缝等不利情况下有良好的自愈能力。

Dispersive clay is a special soil which can be washed out by water easily. With the development of earth and rockfill dam, the range of choosing core material expands correspondingly. Dispersive clay as core material and its seepage-proofing effect under the protection of filters are issues concerned in engineering design. In this research we collected core materials from two stock grounds of a hydro-junction and conducted laboratory tests using pinhole, fragment, pore water solution and double areometers to determine the dispersibility of core material. By mixing different ratios of cement or quick lime, we modified the dispersibility of the core materials and compared their permeability and filter protection effect before and after modification. Results reveal that by mixing 3% of cement or 3%-5% of quick lime we can eliminate the dispersibility of the core materials from the two sites. Moreover, core material modified by cement or quick lime could bear higher hydraulic gradient than non-modified material does. Under the protection of proper filtration material, dispersive clay could bear high gradient, and has good self-healing ability in the presence of fissures.