冻融损伤过程中纤维加筋土的抗压性能与裂隙演化  

Compressive properties and crack evolution characteristics of fiber reinforced soil under freeze-thaw cycling

作　　者：魏丽[1] 杨光[1] 尚军 柴寿喜 Wei Li;Yang Guang;Shang Jun;Chai Shouxi(Tianjin Key Laboratory of Soft Soil Characteristics and Engineering Environment,Tianjin Chengjian University,Tianjin 300384,China;School of Geology and Geomatics,Tianjin Chengjian University,Tianjin 300384,China)

机构地区：[1]天津城建大学天津市软土特性与工程环境重点实验室,天津300384 [2]天津城建大学地质与测绘学院,天津300384

出　　处：《土木工程学报》2024年第4期81-91,共11页China Civil Engineering Journal

基　　金：天津市科技计划项目(20YDTPJC00930)。

摘　　要：冻融损伤土的微观结构,土中产生微裂隙,宏观上表现为土的力学性能下降。文章完成了石灰固化土和纤维与石灰加筋固化土的冻融试验、无侧限抗压强度试验、CT扫描试验,分析冻融损伤过程中石灰固化土和纤维与石灰加筋固化土的抗压性能与裂隙演化特征,评价纤维对提高土的抗冻融性能的积极作用。结果表明:石灰固化土、纤维与石灰加筋固化土的抗压强度与破坏应变均随冻融次数的增加呈阶段性下降,即降幅较大阶段、降幅较小阶段和强度基本稳定阶段,纤维加筋显著提高了土的抗变形性能;土的压实度越大,纤维加筋提高土的力学性能就越明显;冻融过程中,裂隙主要分布在试样的表面、上部和下部,面裂隙率随扫描层数的增加呈先减小后增大的变化规律;纤维与石灰加筋固化土的体裂隙率、裂隙长度均值、裂隙宽度均值均小于石灰固化土,纤维加筋延缓了裂隙的形成、发展与连通。纤维与石灰加筋固化土的抗压性能与抗冻融性能显著优于石灰固化土,纤维加筋减弱了冻融土的微观结构损伤程度。Cracks and mechanical properties degradation of soil can be observed when the structure of the soil is damaged by the freeze-thaw cycling.In order to evaluate the degree of freeze-thaw damage of lime soil(L-S)and fiber reinforced lime-soil(F-L-S)based on the compression performance and crack evolution characteristics,a series of tests on L-S and F-L-S,including freeze-thaw cycling test,the unconfined compressive strength(UCS)test,and computed tomography(CT)test wereconducted.And theeffect of fiber reinforced on the freeze-thaw resistance of soil was discussed.The results showed that the UCS and failure strain of L-S and F-L-S decreased with the rise of freeze-thaw cycles for the whole stress change.The deformation resistance of soil was significantly enhanced by adding fibers.The higher the degree of compaction,the more obvious the fiber reinforcement effect on improving the mechanical properties of soil.Under freeze-thaw cycling,the cracks were mainly distributed on the surface,upper and lower parts of the specimen,and the crack ratio of section decreased first and then increased with the rise of scanning layers.The crack ratio of body,crack length and crack width of F-L-S were all smaller than those of L-S.The addition of fiber delayed the generation,development,and connection of cracks in soil,and reduced the crack ratio,crack length and crack width.The compressive performance and freeze-thaw resistance of F-L-S were better than those of the L-S.Adding fiber into the soil could effectively weaken the microstructure damage of soil under freeze-thaw cycling.

关 键 词：固化土 纤维加筋土 冻融损伤 抗压性能 裂隙演化 

分 类 号：TU443[建筑科学—岩土工程]