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冰川冻土 ›› 2018, Vol. 40 ›› Issue (1): 86-93.doi: 10.7522/j.issn.1000-0240.2018.0011

• 寒区科学与技术 • 上一篇    下一篇

冻融循环对硅酸钠固化黄土力学性质的影响

侯鑫1,2, 马巍1, 李国玉1, 周志伟1, 黄永庭1,2   

  1. 1. 中国科学院 西北生态环境资源研究院 冻土工程国家重点实验室, 甘肃 兰州 730000;
    2. 中国科学院大学, 北京 100049
  • 收稿日期:2017-07-16 修回日期:2017-09-23 出版日期:2018-02-25 发布日期:2018-04-13
  • 通讯作者: 马巍,E-mail:mawei@lzb.ac.cn E-mail:mawei@lzb.ac.cn
  • 作者简介:侯鑫(1987-),男,山东泰安人,2013年在莫斯科国立罗蒙诺索夫大学获硕士学位,现为中国科学院西北生态环境资源研究院在读博士研究生,从事岩土工程研究.E-mail:286693463@qq.com
  • 基金资助:
    国家自然科学基金项目(41630636);甘肃省科技重大专项计划项目(143GKDA007);国家重点研发计划项目(2017YFC0405101)资助

Effects of freezing-thawing cycles on mechanical properties of loess solidified by sodium silicate

HOU Xin1,2, MA Wei1, LI Guoyu1, ZHOU Zhiwei1, HUANG Yongting1,2   

  1. 1. State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2017-07-16 Revised:2017-09-23 Online:2018-02-25 Published:2018-04-13

摘要: 硅酸钠作为一种灌浆材料,常被用于湿陷性黄土的固化工程。冻融循环会影响季节冻土区固化黄土的结构,从而导致其力学性质发生变化。以兰州黄土为研究对象,分别对冻融循环前后掺量为3%的硅酸钠固化黄土进行压汞试验和力学强度试验,从强度、刚度、能量耗散和土体微观孔隙结构等方面探讨冻融循环作用对硅酸钠固化黄土力学特性的影响。结果表明:一方面,冻融作用会增大土中平均孔隙直径,降低微孔隙含量,导致土样产生裂隙;另一方面,硅酸钠反应生成的Na+在水分梯度作用下迁移至土样和裂隙表面并重结晶,上述作用破坏了土颗粒间胶结,最终大幅度劣化了固化黄土力学性能。随着冻融次数的增加,硅酸钠固化黄土无侧限抗压强度在单轴加卸载过程中的能耗值、弹性变形量和滞回环回弹模量均呈现下降趋势,冻融20次后强度降幅高达85.33%,而能耗均值与回弹模量均值分别为未冻融状态下的8.68%和20.70%,即固化土消振性与刚度大幅劣化。鉴于此情况,季节冻土区盐渍黄土硅酸钠的固化处理措施应慎重使用。

关键词: 硅酸钠, 黄土, 冻融循环, 强度, 加卸载, 压汞法

Abstract: As a reinforcement reagent, sodium silicate is often used in the solidification of collapsible loess. In seasonally frozen soil region, the freezing-thawing cycles affect the structure of solidified loess and lead to the change of its mechanical properties. Taking Lanzhou loess as the object of study, the mercury intrusion porosimetry and mechanical tests are carried out respectively before and after freezing-thawing cycles on the loess solidified with 3% sodium silicate. The results showed that freezing-thawing cycles increased the average pore diameter in loess and reduced the content of micropores, resulting in cracks in samples. On the other hand, the Na+ produced by the reaction of sodium silicate migrated to the surface of fractures and samples under the moisture gradient, and caused recrystallization. The above effects destroy the cementation between the soil particles and eventually deteriorated the mechanical properties of the solidified loess substantially. The data showed that with the increase of freezing-thawing cycles, the unconfined compressive strength of sodium silicate solidified loess reduced, the energy consumption, and resilience modulus of hysteresis loops in the process of uniaxial loading and unloading showed a downward trend. After 20 freezing-thawing cycles, the strength decreases by as much as 85.33%, and the average value of energy consumption and the resilience modulus are 8.68% and 20.70% of the values in the initial state respectively. It means that the vibration and stiffness of the solidified loess are greatly deteriorated. For saline loess, sodium silicate should be used with caution in seasonally frozen soil region.

Key words: sodium silicate, loess, freezing-thawing cycles, strength, loading-unloading, mercury intrusion porosimetry

中图分类号: 

  • TU444