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冰川冻土 ›› 2019, Vol. 41 ›› Issue (5): 1115-1121.doi: 10.7522/j.issn.1000-0240.2019.0321

• 冻土与寒区工程 • 上一篇    下一篇

冻融条件下非饱和路基土的强度及微观特性研究

崔宏环1,2, 秦晓鹏2, 王文涛2, 王盼盼2   

  1. 1. 河北省土木工程诊断、改造与抗灾重点实验室, 河北 张家口 075000;
    2. 河北建筑工程学院, 河北 张家口 075000
  • 收稿日期:2019-07-14 修回日期:2019-09-16 发布日期:2020-02-24
  • 通讯作者: 秦晓鹏,E-mial:754018156@qq.com. E-mail:754018156@qq.com
  • 作者简介:崔宏环(1974-),女,河北张家口人,教授,2017年在北京交通大学获博士学位,从事非饱和土与路基路面工程本构模型研究.E-mail:cuihonghuan729@163.com
  • 基金资助:
    国家自然科学基金项目(51878242);河北省研究生创新资助项目(CXZZ2019150);张家口市科学技术与地震局指导项目(1811009B-17);河北建筑工程学院创新基金项目(XA201902)资助

Study on the strength and microscopic characteristics of unsaturated subgrade soil under freezing-thawing conditions

CUI Honghuan1,2, QIN Xiaopeng2, WANG Wentao2, WANG Panpan2   

  1. 1. Hebei Provincial Key Laboratory of Civil Engineering Diagnosis, Reconstruction and Disaster Resistance, Zhangjiakou 075000, Hebei, China;
    2. Hebei University of Architecture, Zhangjiakou 075000, Hebei, China
  • Received:2019-07-14 Revised:2019-09-16 Published:2020-02-24

摘要: 为探究非饱和路基粉质黏土在冻融条件下的强度及微观特性的影响,对路基非饱和粉质黏土进行了冻融循环试验、非饱和土直剪试验、氮吸附试验,结果表明:非饱和土强度随冻融循环的增加呈先减小后趋于稳定的趋势,冻结负温为-10℃黏聚力降低最明显,通过BET法求得试样经历不同外部条件影响后的比表面积值,根据氮吸附试验的等温线计算出非饱和路基土的分形维数,试验试样的比表面积与分形维数都随冻融循环次数的增加先增大后减小,冻融循环3次时达到最大值,随冻结负温的降低而降低。从微观的角度解释了非饱和路基粉质黏土经多次冻融循环后,基质吸力对非饱和土的黏聚力影响的原因。

关键词: 冻融, 非饱和路基土, 强度, 氮吸附, 分形维数, 微观特征

Abstract: In order to explore the influence of strength and microscopic characteristics of unsaturated silty clay in freezing-thawing conditions, freezing-thawing cycle test, unsaturated soil direct shear test and nitrogen adsorption test were carried out on the unsaturated silty clay in subgrade. The results showed that the strength of unsaturated soil decreases first and then tends to be stable with the increase of freezing-thawing cycle; when the temperature is -10℃, the cohesive force decreases most obviously; the specific surface area of the sample obtained by BET method is controlled by external conditions. According to the nitrogen isothermal adsorption test, the fractal dimension of unsaturated subgrade soil is calculated. The specific surface area and fractal dimension of the test sample first increase, then decrease with the increase of freeze-thaw cycles. The fractal dimension reaches its maximum when freeze-thaw cycles are 3 and decreases with temperature decrease. The influence of matric suction on the cohesion of unsaturated subgrade silty clay after several freezing-thawing cycles is explained from microscopic perspective.

Key words: freezing-thawing, unsaturated subgrade soil, strength, nitrogen adsorption, fractal dimension, microscopic characteristics

中图分类号: 

  • P642.14