冻融循环作用对F1加固黄土强度与微观结构的影响研究  

Effects of Freeze⁃thaw Cycles on the Strength and Microstructure of F1⁃solidified Loess

作　　者：谢嘉豪 李建东 王旭[1,2] 张延杰[1] 蒋代军[1] 王兴为[1] XIE Jiahao;LI Jiandong;WANG Xu;ZHANG Yanjie;JIANG Daijun;WANG Xingwei(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;National and Provincial Joint Engineering Laboratory of Road&Bridge Disaster Prevention and Control,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070 [2]兰州交通大学道桥工程灾害防治技术国家地方联合工程实验室,甘肃兰州730070

出　　处：《防灾减灾工程学报》2023年第6期1445-1453,共9页Journal of Disaster Prevention and Mitigation Engineering

基　　金：国家自然科学基金项目(51868038);甘肃省基础研究创新群体项目(21JR7RA347)资助。

摘　　要：冻融循环作用显著影响固化剂加固效果和固化土物理力学特性。为研究冻融循环作用对F1加固黄土强度与微观结构特性的影响,对不同掺量、不同冻融次数的F1固化黄土试样开展三轴不固结不排水试验及电镜扫描试验,探讨冻融前后F1加固黄土抗剪强度参数及微观孔隙结构变化规律。研究发现,F1可显著改善黄土持水特性和压实特性。当F1掺量为0.3 L/m3最佳掺量时,与黄土相比,F1固化黄土塑限和最优含水率分别减少2.65%和7.22%,液限和最大干密度分别增大7.92%和9.83%;F1显著增大黄土黏聚力与内摩擦角。0次和15次冻融循环时,与未冻融黄土相比,0.3 L/m3掺量F1固化黄土的黏聚力分别增大36.82%和16.64%,内摩擦角分别增大16.92%和4.63%;与黄土相比,冻融循环15次时F1固化黄土中微孔隙增大6.28%、小孔隙减少17.84%,孔隙面积比和平均分形分维数分别减小了20.4%和0.67%,表明经F1固化后黄土形成更加稳定的层状堆叠结构,显著改善冻融循环作用下微、小孔隙的演化和发育,提高密实度、增强力学性能和抗剪强度。Freeze-thaw cycles significantly affects the consolidation effect and the physical and mechan-ical properties of solidified soil.In order to study impact of freeze-thaw cycles on the strength and mi-crostructural properties of F1-solidified loess,triaxial unconsolidated-undrained loess tests and elec-tron microscopy scanning tests were carried out on F1-solidified loess samples with varying FI dosag-es and freeze-thaw durations.These tests aimed to explore the shear strength parameters and changes in the microscopic pore structure of F1-solidified loess before and after freeze-thaw cycles.The study revealed that F1 can significantly improve the water-holding and compaction properties of loess.At the optimum dosage of 0.3L/m3,the plastic limit and optimum moisture content of F1-solidified loess are reduced by 2.65%and 7.22%respectively,while the liquid limit and maximum dry density are in-creased by 7.92%and 9.83%respectively.F1 significantly increases the cohesion and internal friction angle of loess.At 0 and 15 freeze-thaw cycles,compared with unfrozen thawed loess,the cohesion of F1-solidified loess with 0.3L/m3 content increased by 36.82%and 16.64%respectively,the internal friction angle increased by 16.92%and 4.63%respectively.compared with the loess,the microporosi-ty in F1-solidified loess increased by 6.28%and small porosity decreased by 17.84%at 15 freeze-thaw cycles.Additionally,the pore area ratio and average fractal dimension decreased by 20.4%and 0.67%respectively.These changes indicate that the loess forms a more stable laminated stacking structure af-ter F1 curing,which significantly improves the evolution and development of micro and small pores under freeze-thaw cycles,increases the compactness,enhances the mechanical properties and shear strength.

关 键 词：冻融循环 黄土 F1离子固化剂 抗剪强度 微观结构 

分 类 号：TU443[建筑科学—岩土工程]