摘要
冻融循环破坏了土的结构,降低了土的力学性能。完成了石灰固化土与纤维加筋固化土的冻融试验、无侧限抗压试验、扫描电镜(scanning election microscopy,简称SEM)观察与核磁共振(nuclear magnetic resonance,简称NMR)测试,探讨冻融循环对土的强度与微结构的破坏作用,以微结构指标评价土的抗压强度变化。结果表明:石灰固化土与纤维加筋固化土的抗压强度均随冻融次数的增加而降低,土的冻融破坏过程经历了降幅较大、降幅较小、降幅平缓与强度稳定4个阶段;含水率越大,冻融次数越多,纤维对土的增强效果越明显;掺加纤维延缓了微裂隙的形成与发展,降低了裂隙的贯通率;随着冻融次数的增加,孔隙率与孔径均增大,冻胀使得部分小孔隙联通为中孔隙和大孔隙。纤维对土的空间约束作用与筋土摩擦作用使得土的孔隙率与孔隙分布特征变化较小,纤维加筋固化土的强度与抗冻融性能优于固化土。
Freeze-thaw cycles destroy the structure of soil, resulting in a reduction in mechanical properties of soil. A series of tests on lime-soil and fiber reinforced lime-soil is completed, including freeze-thaw test, the unconfined compressive test, scanning election microscopy(SEM) test, and nuclear magnetic resonance(NMR) test. Based on the test results, the effect of freeze-thaw cycles on soil strength and microstructure index is discussed. The results show that the compressive strength of lime-soil and fiber reinforced lime-soil decrease with the increase of freeze-thaw number, and the four stages for soil strength variation are identified in soil failure process, i.e., large reduction, small reduction, slow reduction and stability. In the case of high moisture content and frequent freezing and thawing, it is more conducive to the reinforcement of soil by fibers. The addition of fiber delays the formation and development of cracks in soil, reducing the connection of cracks. With the increase of freeze-thaw number, the porosity and the pore diameter increase, as a result, a part of small pores connect into medium pores and large pores. The porosity and pore distributions of soil vary slightly under freeze-thaw cycles because of the spatial restraint effect of fiber on soil and the friction between fiber and soil,which result in the strength and freeze-thaw resistance of fiber reinforced lime-soil is better than that of lime-soil.
作者
魏丽
柴寿喜
刘著
王沛
李芳
WEI Li;CHAI Shou-xi;LIU Zhu;WANG Pei;LI Fang(Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment,Tianjin Chengjian University,Tianjin 300384,China;Key Laboratory of Mechanics on Disaster and Environment in Western China,Ministry of Education,Lanzhou University,Lanzhou,Gansu 730000,China;Lifetime Industrial(Tianjin)Co.,Ltd.,Tianjin 301700,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2022年第S02期163-170,182,共9页
Rock and Soil Mechanics
基金
天津市科技支撑重点项目(No.19YFZCSF00820)
天津市科技计划项目(No.20YDTPJC00930)
关键词
冻融循环
纤维加筋土
抗压强度
孔隙率
孔隙分布
freeze-thaw cycles
fiber reinforced soil
unconfined compressive strength
porosity
pore distribution
