冻融循环作用对F1加固黄土强度与微观结构的影响研究
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谢嘉豪(1997—),男,硕士研究生。主要从事黄土地区地基处理与基础工程方向的研究。E-mail:11200279@stu.lzjtu.edu.cn

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TU443

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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


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

    Abstract:

    Freeze-thaw cycles significantly affects the consolidation effect and the physical and mechanical properties of solidified soil. In order to study impact of freeze-thaw cycles on the strength and microstructural properties of F1-solidified loess, triaxial unconsolidated-undrained loess tests and electron microscopy scanning tests were carried out on F1-solidified loess samples with varying FI dosages 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 increased 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 microporosity 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 after 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.

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谢嘉豪,李建东,王旭,张延杰,蒋代军,王兴为.冻融循环作用对F1加固黄土强度与微观结构的影响研究[J].防灾减灾工程学报,2023,43(6):1445-1453

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  • 收稿日期:2022-06-16
  • 最后修改日期:2022-08-24
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  • 在线发布日期:2024-01-11
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