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冰川冻土 ›› 2014, Vol. 36 ›› Issue (4): 922-927.doi: 10.7522/j.issn.1000-0240.2014.0111

• 冻土模型与冻土物理力学性质 • 上一篇    下一篇

冻融循环作用对黄土微结构和强度的影响

倪万魁, 师华强   

  1. 长安大学 地质工程与测绘学院, 陕西 西安 710054
  • 收稿日期:2014-03-01 修回日期:2014-06-05 发布日期:2014-08-23
  • 作者简介:倪万魁(1965-),男,宁夏固原人,教授,1999年在西安工程学院获博士学位,现主要从事岩土工程及地质灾害方面的研究.E-mail:nnwwkk@126.com
  • 基金资助:
    国家重点基础研究发展计划(973计划) 项目(2012CB026101);国家自然科学基金创新群体项目(41121061);中国科学院西部行动计划项目(KZCX2-XB3-19);国家自然科学基金重点项目(41030741)资助

Influence of freezing-thawing cycles on micro-structure and shear strength of loess

NI Wankui, SHI Huaqiang   

  1. Institute of Geological Engineering and Surveying, Chang'an University, Xi'an 710054, China
  • Received:2014-03-01 Revised:2014-06-05 Published:2014-08-23

摘要: 通过对洛川黄土在反复冻融作用下的电镜扫描观测、单轴压缩试验和三轴剪切试验,研究了冻融循环作用对黄土微结构和强度的影响. 结果表明:随着冻融循环次数的增加,黄土的原始胶结结构逐渐被破坏,颗粒重新排列,土的结构越来越疏松,同级压力下土体的孔隙比不断增大;冻融循环50次后土样的原始胶结已完全破坏,当压力超过自重应力时会产生很大的附加变形. 反复冻融作用使黄土颗粒之间原始固有胶结逐渐减弱,造成黏聚力不断降低. 同时,较大的团粒破碎,颗粒均一化,颗粒与颗粒之间的接触点增多,表现为内摩擦角不断增大. 多次冻融循环后,原状黄土的抗剪强度与重塑黄土的强度接近.

关键词: 黄土, 冻融循环, 微观结构, 孔隙比, 抗剪强度

Abstract: By taking the loess from Luochuan in Shaanxi Province to prepare specimens, a series of compression tests and tri-axial shear tests were conducted to explore the characteristics of micro-structure and shear strength of undisturbed loess with freezing-thawing cycles. The experimental results indicate that the initial cementation structure of loess is gradually broken to become more and more loose with increasing of freezing-thawing cycles, and the void ratio of loess continuously increases in the same press. The initial structure of loess is completely disrupted after 50 freezing-thawing cycles, and a great deal of deformation probably produce when the additional press is more than geostatic stress. Because of shortening the initial cementation structure of loess with repeated freezing-thawing cycles, cohesive force of loess constantly decreases, and internal friction angle increases by increasing touch points of inter-particles. Shear strength of the undisturbed loess under repeated freezing-thawing cycles will be close to that of remolded loess.

Key words: loess, freezing-thawing cycles, micro-structure, void ratio, shear strength

中图分类号: 

  • P642.13+1