粗颗粒盐渍土工程特性研究进展

从盐渍土的分布状况出发, 阐述了合理利用粗颗粒盐渍土的环保性和重要性; 基于单因素盐胀试验结果, 结合多因素交互作用下的盐胀试验, 分析了土、水、盐、温、力5要素对粗颗粒盐渍土盐胀量的影响效果; 通过现场和室内溶陷试验结果对比, 概括了粗颗粒盐渍土溶陷特性的典型规律; 梳理了不同工况下粗颗粒盐渍土冻融循环试验成果, 完善了粗颗粒盐渍土现有的改良方法, 提出了粗颗粒盐渍土工程特性的研究方向。研究结果表明: 粗颗粒盐渍土的物理力学性质与其颗粒组成和含盐量关系密切; 地域不同, 粗颗粒盐渍土的颗粒级配亦有所差别; 温度、含盐量、含盐类型、含水率、初始密度和上覆荷载均是影响粗颗粒盐渍土盐胀量的重要因素, 且存在一定的交互作用; 建议在将粗颗粒盐渍土用作路基填料时, 应充分考虑各个因素对盐胀量的影响, 有效利用具有抑制盐胀作用的因素; 现场和室内溶陷试验均是测定盐渍土溶陷率的有效方法, 但粗颗粒盐渍土室内溶陷试验需要在考虑土体颗粒粒径效应的基础上完善、规范; 冻融循环试验可近似模拟粗颗粒盐渍土的实际工况, 直观反映其温度、水分与变形等规律, 但在进行试验方案设计时, 需综合考虑实际工程中的各种环境因素, 不同因素的组合对冻融循环试验结果影响较显著; 在进行粗颗粒盐渍土工程特性改良时, 应充分利用现场材料, 火山灰、粉煤灰等具有较好的改良效果; 应建立水-热-盐-力四场全耦合模型以进一步完善粗颗粒盐渍土盐胀机理。 

Research progress on engineering properties of coarse-grained saline soil

Based on the distribution of saline soil, the environmental protection feature and the importance of rational utilization of coarse-grained saline soil were expounded. In view of the single-factor salt expansion test results, combined with the multi-factor interaction salt expansion test, the effects of five factors such as soil, water, salt, temperature and force on the salt expansion of coarse-grained saline soil were analyzed. According to the comparison of on-site and laboratory collapse test results, the typical laws of collapse characteristics of coarse-grained saline soil were concluded. The results of the freeze-thaw cycle test of coarse-grained saline soil under different working conditions were also summarized, and the existing improvement methods of saline soil were refined. The research directions of engineering characteristics of coarse-grained saline soil were proposed. Research result shows that the physical and mechanical properties of coarse-grained saline soil are related to its particle composition and salt content. The granule gradation of coarse-grained saline soil is also different in different regions. Temperature, salt content, salt type, moisture content, initial density and overburden load are all key factors that affect the salt expansion of coarse-grained saline soil, while certain interactions occur among these factors. It is suggested that when coarse-grained saline soil is used as a subgrade filler, the influence of various factors on salt expansion should be carefully considered, and the factors that inhibit salt expansion should be effectively utilized. Both on-site and laboratory collapse tests are identified as effective methods to determine the saline soil collapse rate. However, the laboratory collapse tests need to be improved and standardized with consideration of the particle effect of coarse-grained saline soils. The freeze-thaw cycle test can approximately simulate the actual working conditions and directly reflect the laws of temperature, moisture and deformation of coarse-grained saline soil. In the design of test scheme, various environmental factors in the actual project should be comprehensively considered, and the combination of different factors has a significant impact on the freeze-thaw cycle test results. When improving the engineering properties of coarse-grained saline soil, the on-site materials should be fully utilized, and volcanic ash and fly ash have better improvement effects. Establishing a four-field fully coupled model of water-heat-salt-force is considered as a fundamental step to improve the salt expansion mechanism of coarse-grained saline soil.