固化盐渍土抗冻融性能的研究
Investigation on resistance to freezing-thawing effect of solidified saline soil
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摘要: 针对我国西北地区广泛分布的硫酸盐–氯盐盐渍土,设计了两种试验方法:无压力四周给水冻融法和无压力单向给水冻融法,观察固化盐渍土的抗冻融能力。结果显示在不同冻融条件下试件的破坏模式不同。运用土水势分析了冻融过程中水分迁移的动力和传输形式,研究表明:无压力四周给水冻融条件会导致土水势中出现压力势分势,由于压力势的存在,水分率先在试件的外围部分集中饱和,从而形成表层剥蚀;无压力单向给水冻融则消除了压力势的影响,水分得以高度分散而不能局部集中,当整个试件的含水率达到临界值时,试件发生整体的粉碎性破坏。固化剂掺量会影响固化盐渍土的抗冻性能,但足够长的养生期是提高固化盐渍土的抗冻融性能的关键性因素。Abstract: Two freezing-thawing tests under the conditions of all-around(I) or one-dimension(II) water-supplying to samples without pressure were designed to investigate the resistance to freezing-thawing effect of solidified sulfate-chloride type saline soil widely distributed in the northwest of China.It was shown that different failure patterns were caused by different freezing-thawing conditions.The conception of soil water potential was used for the analysis and explanation of driving force and form of water migration in solidified soil body in either test.The condition of test I brought pressure potential in total soil water potential.Presence of pressure potential led to water concentration in outer part of sample first so that the surface layer of sample was eroded by expansion of ice.But the pressure potential disappeared under the condition of test II so that water could fully diffuse all over the whole solidified soil body.The sample was not smashed up unless the water content reached the critical value.Resistance to freezing-thawing effect of solidified soil was influenced by the dosage of soil stabilizer.However,enough curing period was a key factor for it.