基于黏性土分散机制的分散性土化学改性研究

分散性土具有遇水易分散的特性，可导致堤坝等水利工程的冲蚀破坏。基于黏性土分散机制的研究，选用AlCl3? 6H2O、MgCl2?6H2O、CaCl2及CaO作为分散性土的化学改性材料，采用针孔试验和碎块试验对其改性效果进行判别和比较。试验表明，上述改性材料均可将分散性土改性为非分散性土，显著提高土体的抗冲蚀能力。结果说明：在分散性土中掺加高价态阳离子的可溶性盐，通过置换土粒表面钠离子或降低土体碱性，减小颗粒扩散层的厚度，可抑制土体的分散性，从而达到改性的目的；根据黏性土分散机制以及改性试验结果，提出了分散性土化学改性的原则，即改性材料中含有高价态的可溶性阳离子，或改性材料呈酸性，且环境友好，价格低廉，施工方便。

Study of chemical modification of dispersive clay based on mechanism of dispersivity of cohesive soil

Getting erosion is the characteristic of dispersive clay which would cause series of damages to hydraulic projects like dams. AlCl3?6H2O, MgCl2?6H2O, CaCl2 and CaO were selected as chemical modification materials of dispersive clay based on the mechanism of dispersivity. The judgments and comparisons of soil samples were made using pinhole tests and crumb tests. Tests show that with the modification materials selected above, the ability against erosion of dispersive clay was improved; and the dispersive clay would turn into non-dispersive. The results indicate that cations with higher valence state mixed into dispersive clay could reduce the diffusion layer by replacing sodium ions in soil particles surface or by lessening soil alkaline; as a result, it plays a role in modification. According to mechanism of dispersivity and the results of modification test, the chemical modification principles of dispersivity are put forward; modification materials contain cations with higher valence state or pH is acidic. Materials should environmental friendly and have lower price, and also facilitates the construction,