Abstract Although natural fibers can improve the strength behavior of frozen-thawed soil, the reinforcing mechanism is still not fully understood. To investigate the effects of freeze-thaw cycles on the strength of natural fiber-reinforced soil, unconfined compression tests, single-fiber pull-out tests and scanning electron microscopy (SEM) tests under 0, 3, 5, 10, 15, and 20 freeze-thaw cycles were conducted on cotton straw fiber-reinforced soil. It was found that the unconfined compressive strength (UCS) of fiber-reinforced soil decreases exponentially with the number of freeze-thaw cycles. In addition, fiber reinforcement weakens the softening degree of frozen-thawed soil under unconfined states. The UCS reduction in fiber-reinforced soil under freeze-thaw conditions is smaller than the strength reduction at the fiber-soil interface because fiber reinforcement is mainly governed not only by the fiber-soil interface but also by the spatial stress network established by discrete fibers. The complex spatial stress network, which improves the reinforcement of the fibers, is monitored by SEM after freeze-thaw cycles.

中文翻译：

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冻融循环对秸秆纤维增强土无侧限抗压强度的影响

摘要 虽然天然纤维可以提高冻融土的强度行为，但其增强机制仍不完全清楚。为了研究冻融循环对天然纤维增强土强度的影响，无侧限压缩试验、单纤维拉拔试验和扫描电子显微镜 (SEM) 试验在 0、3、5、10、15 和在棉秆纤维增强土壤上进行了 20 次冻融循环。结果表明，纤维增强土的无侧限抗压强度（UCS）随着冻融循环次数呈指数下降。此外，纤维增强减弱了冻融土在非侧限状态下的软化程度。冻融条件下纤维增强土的 UCS 减少小于纤维-土壤界面处的强度减少，因为纤维增强不仅受纤维-土壤界面的控制，还受离散纤维建立的空间应力网络控制. 在冻融循环后，通过扫描电镜监测改善了纤维增强的复杂空间应力网络。