不同长度纤维混掺水泥改良风积沙强度及微观结构研究  

The effects of different fiber lengths on the unconfined compressive strength and microstructure of cemented aeolian sand reinforced with hybrid fiber

作　　者：阮波[1] 赵洋 张向京 袁忠正 车玉富 路占海 RUAN Bo;ZHAO Yang;ZHANG Xiangjing;YUAN Zhongzheng;CHE Yufu;LU Zhanhai(School of Civil Engineering,Central South University,Changsha 410075,China;Guangdong Pearl River Delta Intercity Railway Co.,Ltd.,Guangzhou 510330,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]广东珠三角城际轨道交通有限公司,广东广州510330

出　　处：《铁道科学与工程学报》2024年第12期5242-5251,共10页Journal of Railway Science and Engineering

基　　金：中国铁路乌鲁木齐局集团有限公司科技研究开发计划课题(WLMQ-KGHZGS-HRTL-GGB-2020-0032);国家自然科学基金资助项目(51978672)。

摘　　要：混掺纤维土可以利用不同长度纤维特性进行优势互补,从而提高土体强度,增强延性。以和若铁路为工程背景,对沿线风积沙进行纤维水泥改良,以满足铁路路基基床表层填料要求。通过无侧限抗压强度试验及扫描电镜试验,研究不同长度聚丙烯纤维混掺对水泥改良风积沙试样微观结构和无侧限抗压强度影响。混掺纤维掺量为8‰和10‰,纤维长度有3,6和12 mm共3种规格,按1∶3、1∶1和3∶1比例混掺,水泥掺量5%。采用锤击法制作成直径和高度均为50 mm的圆柱体试样,标准养护7 d龄期后进行无侧限抗压强度试验,在破坏后的试样上取4个样品,制作成边长1 cm的立方试件进行扫描电镜试验。结果表明,不同长度纤维混掺水泥改良风积沙试样较单掺纤维试样的峰值应力、残余应力及延性系数明显增大,而峰前应力增长速率与峰后应力衰减速率显著减小。混掺纤维试样无侧限抗压强度较单掺纤维试样增大12%~46%。混掺纤维掺量从8‰增大到10‰,混掺纤维试样无侧限抗压强度增大10%~13%。混掺纤维试样延性系数随12 mm长纤维的纤维掺量增加而增大。3 mm短纤维与12 mm长纤维混掺的水泥改良风积沙试样的孔隙定向概率熵随长纤维占比的增大而增大,而孔隙率与孔隙平均丰度则相反。3 mm短纤维与12 mm长纤维按照1∶3混掺试验组的无侧限抗压强度最大,对应的孔隙率、孔隙平均丰度最小,孔隙定向概率熵最大。混掺水泥改良风积沙试样无侧限抗压强度与孔隙率、孔隙平均丰度均呈线性负相关。研究成果对风积沙地区铁路路基基床表层填料的设计和施工有借鉴意义。Soil reinforced with fiber can make use of the advantages of different lengths of fibers,and the strength and ductility of the soil are improved.The different lengths of fibers and cement were used to reinforce the aeolian sand from the Hotan-Ruoqiang Railway to meet the requirements of surface filler of the railway subgrade bed.The effects of different polypropylene fiber lengths on the unconfined compressive strength(UCS)and microstructure of samples that were cemented aeolian sand reinforced with hybrid fiber(CASRHF)cured on the seventh day.They were studied by the UCS and scanning electron microscope(SEM)tests.The total fiber content of two different lengths of hybrid fibers that reinforced cemented aeolian sand was 8‰and 10‰.Fibers with different lengths of 3,6,and 12 mm were used in the test and mixed according to the ratio of 1∶3,1∶1,and 3∶1.Cylindrical specimens with diameter and height of 50 mm were made by hammering method.The specimens were placed in a standard curing room and then placed in a universal testing machine for the UCS test.Finally,the compressed specimens were sampled for the SEM test.The results show that the peak stress,residual stress,and ductility index of the samples which were cemented aeolian sand reinforced with different length hybrid fiber are significantly higher than those of the samples with single fiber length,while the pre-peak stress growth rate and post-peak stress decay rate are significantly reduced.The UCS of CASRHF samples increases by 12%~46%compared with that of single fiber samples.The UCS of CASRHF samples increased by 10%~13%when hybrid fiber content increased from 8%to 10%.The ductility coefficient of CASRHF samples increases with the content of 12 mm long fiber.The pore orientation probability entropy(POPE)of CASRHF samples with 3 mm fiber and 12 mm fiber increases with the proportion of 12 mm fiber,while the porosity and average pore abundance(APA)are opposite.The UCS of CASRHF samples is negatively correlated with porosity and APA.The research result

关 键 词：铁路路基基床 混掺纤维 纤维长度 混掺比例 风积沙 无侧限抗压强度 孔隙丰度 孔隙定向概率熵 

分 类 号：TU441[建筑科学—岩土工程]