宁夏地区硫酸盐渍土工程特性试验研究

发布时间：2018-10-12 09:31

【摘要】：硫酸盐渍土作为一种特殊土,广泛分布于世界各地区,我国硫酸盐渍土主要分布于西北地区。宁夏地处西北内陆干旱-半干旱地区,区域内气候干燥、蒸发强烈、温差巨大,从而形成了特有的内陆寒旱区盐渍土,其中,硫酸与亚硫酸盐馈土的分布较多。硫酸盐渍土具有盐胀、溶陷及腐蚀等特性,工程建设中这些特性的危害比湿陷性黄土还大。随着西部大开发战略及“一带一路”的深入实施,在宁夏地区进行的水利、公路、铁路及房建等工程会不断增多,这必将遇到硫酸盐渍土问题。因此,对硫酸盐渍土工程特性的分析研究显得特别的迫切与必要。本文选取宁夏吴忠市红寺堡地区的硫酸盐渍土作为试验用的原料土,以室内人工制备的硫酸盐o,土为研究对象,就压实度、含盐量、含水率、温度变化对硫酸盐渍土强度、盐胀、压缩以及氯化钙、粉煤灰改良硫酸盐o,土盐胀特性进行了试验研究。通过研究得到以下结论:(1)压实度与含水率在一定范围内对粘聚力有增强作用,但超过某个临界值会降低粘聚力,含盐量与冻融循环次数对粘聚力具有减小作用。各因素对粘聚力的影响较大,内摩擦角受上述各因素的影响较小。(2)对于硫酸盐o,土的盐胀率,含盐量影响显著,其他因素影响不显著,含盐量对盐胀率具有增大作用;对于压缩系数,含盐量影响极显著,冻融次数影响显著,其他因素影响不显著,含盐量与冻融次数增加都会增大压缩系数。(3)单侧降温条件下,硫酸盐渍土的起胀温度随含盐量增加而增大。随温度降低,盐冻胀过程表现为四个阶段:35～5℃之间属于纯盐胀阶段,5～5℃之间属于调整阶段,-5-10℃之间属于盐冻胀阶段,-10～-25℃之间属于稳定阶段。(4)通过常温下改良硫酸盐o,土盐胀的试验,得到粉煤灰的最优掺量为20%,Cacl2的最优掺量宜为2%,Cacl2对盐胀的抑制效果较为明显。本文通过对宁夏地区硫酸盐o,土工程特性的室内试验研究,为硫酸盐o,土地区的工程建设提供参考与技术支持。
[Abstract]:As a special soil, sulphate soil is widely distributed in all parts of the world, and sulphate soil is mainly distributed in northwest of China. Ningxia is located in the arid and semi-arid region of northwest China. Its climate is dry, evaporation is strong, and the temperature difference is huge, thus forming the special saline soil in the inland cold and arid region, among which, the distribution of sulfuric acid and sulfite fed soil is more. Sulfate saline soil has the characteristics of salt expansion, dissolution and corrosion, which are more harmful than collapsible loess in engineering construction. With the implementation of the strategy of western development and Belt and Road, the number of water conservancy, highway, railway and house construction projects in Ningxia will increase, which will inevitably meet the problem of sulphate saline soil. Therefore, it is urgent and necessary to analyze and study the engineering characteristics of sulphate saline soil. In this paper, sulphate soil in Hongsibao area, Wuzhong City, Ningxia was selected as the raw material soil for the experiment. The sulphate soil prepared in laboratory was taken as the research object. The strength of sulphate soil was affected by the change of compaction degree, salt content, moisture content and temperature. The characteristics of salt swelling, compression, calcium chloride and fly ash modified sulfate and soil salt swelling were studied. The conclusions are as follows: (1) compaction and water content can enhance the cohesion in a certain range, but beyond a certain critical value, the cohesion will be reduced, and the salinity and the number of freeze-thaw cycles will decrease the cohesion. Each factor has a great influence on the cohesion, but the angle of internal friction is less affected by the above factors. (2) for sulfate, the salt expansion rate of soil, the salt content has a significant effect, but the other factors have no significant effect, the salt content has an increasing effect on the salt expansion rate; For the compression coefficient, the effect of salt content is very significant, freezing and thawing times are significant, other factors are not significant, the increase of salt content and freeze-thaw times will increase the compression coefficient. (3) under the condition of unilateral cooling, The swelling temperature of sulphate saline soil increases with the increase of salt content. As the temperature decreases, The process of salt frost heaving shows four stages: 35 鈩，

本文编号：2265626