春融期,受冻融影响,季冻区边坡极易出现浅层热融滑塌现象,为研究春融期生态边坡的稳定性,通过室内冻融界面直剪试验,将根系简化为主根型,对比分析了素土及根-土复合体冻融界面处土体的抗剪强度指标变化规律;结合数值模拟,对比分析有无冻融界面试样塑性区的剪切破坏情况,建立模型,计算植物根系穿过冻融界面土体时的边坡安全系数。结果表明:随冻融次数增加,素土冻融界面土体抗剪强度损伤程度大于根-土复合体,素土及根-土复合体冻融界面处土体黏聚力均降低,而摩擦角均增加;冻融界面试样的剪切塑性区主要于正融区土体内发展,且剪切塑性区体积明显大于无冻融界面试样;根系穿过冻融界面土体时,显著提高冻融界面土体的抗剪强度,增强春融期边坡的稳定性。研究成果可为季冻区生态边坡工程的设计、施工和维护提供有效的科学依据。
Abstract
In spring thawing period, slopes in seasonal frozen zone is susceptible to shallow slide due to thermal thawing. To investigate the stability of ecological slopes during this period, laboratory direct shear tests were conducted on the freeze-thaw interfaces of plain soil and root-soil composites. The root system was simplified as taproot type. The variation in shear strength indices of both soils was compared and analyzed. Through numerical simulation, the shear failure in the plastic zone of samples in the presence or in the absence of freeze-thaw interface was analyzed, and a model was developed to calculate the safety factor of slope stability when plant roots penetrate the freeze-thaw interface. Results indicate that as freeze-thaw cycles increase, the damage to the shear strength of plain soil at the freeze-thaw interface is greater than that of root-soil composite. Additionally, the cohesion of soil at the interface decreases, while friction angle increases for both plain soil and root-soil composite. The shear plastic zone of samples with freeze-thaw interface primarily develops within the soil body in the normal thawing zone and exhibits a significantly larger volume compared to samples with no freeze-thaw interface. By passing through the freeze-thaw interface, roots significantly raise the shear strength of the soil, thus enhancing the slope stability in spring thawing period. These findings provide a scientific foundation for the design, construction, and maintenance of ecological slope projects in seasonal frozen regions.
关键词
根-土复合体 /
冻融循环 /
冻融界面 /
直剪试验 /
边坡稳定性
Key words
root-soil composite /
freeze-thaw cycle /
freeze-thaw interface /
direct shear test /
slope stability
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