pH值变化对昆明红土击实特性的影响

The effects of pH value variations on compaction characteristics of Kunming laterite

以昆明红土为研究对象,选取盐酸和氢氧化钠调节浸润液的p H值,考虑浸润时间的影响,采用轻型击实和微结构试验方法,研究p H值变化对昆明红土击实特性的影响。试验结果表明,p H值和浸润时间的变化改变了红土的击实特性和微结构特性,引起红土最佳击实指标和微结构参数的变化。浸润时间一定,随着p H值增大,在偏酸性和偏碱性条件下,红土的最大干密度存在极大值,最优含水率减小;对应击实红土的微结构图像呈现出密实性增强、孔隙率减小、颗粒数增大的特征,从酸性到碱性过程,微结构图像呈现出密实性变差、孔隙率增大、颗粒数减小的特征。p H值一定,不论偏酸性还是偏碱性,随浸润时间延长,红土的最大干密度存在2个极大值和1个极小值,碱性条件下最大干密度的极大值、极小值大于酸性条件下的相应值,最优含水率则相反。p H值和浸润时间对红土击实特性的影响可以用p H影响系数和浸润影响系数来衡量,可以从盐酸和氢氧化钠与红土颗粒之间的化学反应过程来解释。

Taking Kunming laterite as the research object,this paper selects the hydrochloric acid and sodium hydroxide to adjust the p H value of the infiltration solution,considers the influence of infiltration time,researching the effects of p H value change on the compaction properties of Kunming laterite with the methods of light compaction and microstructural. As the test shows,changes in p H value and infiltration time changed the compaction properties and microstructure properties of laterite,causing a change in the optimum compaction index and microstructural parameters of laterite. In acidic and alkaline conditions,if infiltration time is a fixed value,with the p H value increases,the maximum dry density has a great value and optimum water content decreases of laterite; microstructure image of compacted laterite corresponds to exhibit enhanced dense,pore ratio decreases,the number of particles increases features,from acidic to alkaline process,the microstructure image showing the feature of dense deteriorated,porosity increases,the number of particles reduced.If p H value is a fixed value,regardless of acidic or alkaline conditions,there are two maximum and a minimum values in laterite＇s maximum dry density with infiltration time prolonging. The maximum dry density＇s maxima and minimum values in alkaline conditions is greater than the corresponding values in acidic conditions,the optimum water content is the opposite. The p H value and infiltration time impact on the compaction characteristic of laterite can be measured by p H influence coefficients and infiltration influence coefficients,explain the process from the chemical reaction between hydrochloric acid,sodium hydroxide and laterite particles.