赵影, 毛雪松, 张腾达, 等. 2022. 季节冻融条件下新型筏板地基承载特性的模型试验研究及数值分析[J]. 工程地质学报, 30(3): 772-783. doi: 10.13544/j.cnki.jeg.2021-0421.
    引用本文: 赵影, 毛雪松, 张腾达, 等. 2022. 季节冻融条件下新型筏板地基承载特性的模型试验研究及数值分析[J]. 工程地质学报, 30(3): 772-783. doi: 10.13544/j.cnki.jeg.2021-0421.
    Zhao Ying, Mao Xuesong, Zhang Tengda, et al. 2022. Model test and numerical analysis of bearing characteristic of new raft foundation under seasonal freeze-thaw condition[J]. Journal of Engineering Geology, 30(3): 772-783. doi: 10.13544/j.cnki.jeg.2021-0421.
    Citation: Zhao Ying, Mao Xuesong, Zhang Tengda, et al. 2022. Model test and numerical analysis of bearing characteristic of new raft foundation under seasonal freeze-thaw condition[J]. Journal of Engineering Geology, 30(3): 772-783. doi: 10.13544/j.cnki.jeg.2021-0421.

    季节冻融条件下新型筏板地基承载特性的模型试验研究及数值分析

    MODEL TEST AND NUMERICAL ANALYSIS OF BEARING CHARACTERISTIC OF NEW RAFT FOUNDATION UNDER SEASONAL FREEZE-THAW CONDITION

    • 摘要: 岛状冻土地区地基经历季节冻融后土体强度急剧降低,道路上易产生不均匀沉降现象,本文提出了新型筏板结构用于岛状冻土地区道路。为了研究岛状冻土地区新型筏板地基的承载特性,本文通过对室内新型筏板地基模型进行冻融,采用分级加载试验和数值模拟方法,分析了新型筏板地基的承载特性,及冻胀融沉对地基模型的沉降特性、内部应力分布及筏板应变分布规律的影响。结果表明,新型筏板的承载作用极大地缓解了地基变形量,且整体上减小了一定深度范围内的地基应力,由此说明筏板是作为地基“加固结构”的形式存在;筏板较大的刚度使承受荷载向外围传递,降低了筏板中心位置处地基反力;新型筏板应变呈中间大两边小的U型分布,且纵向应变高于横向应变,说明变形更多地沿筏板纵向传递;冻融对土体结构产生严重破坏,导致地基沉降大幅增加;筏板-土体系统作为荷载的主要载体,当土体强度衰减时,筏板应变随之增大;冻融循环造成地基一定深度范围内应力的增加,与冻融循环作用深度范围一致,且随着荷载水平的增加影响程度愈加显著。此外,数值模拟结果与试验结果具有较好的一致性,本文数值模拟方法可用于分析新型筏板地基受力特征。

       

      Abstract: The strength of foundation in island frozen soil decreases sharply as the frozen soil thaws,which leads to uneven settlement of the subgrade. Hence,we propose a new raft structure for the highway in island frozen soil area in this paper. In order to study the bearing characteristics of the new raft foundation,the freeze-thaw cycle,ramp load tests and numerical simulation method are applied on the new raft foundation model. We analyze the bearing characteristics of the new raft foundation and how the freeze-thaw cycle affects the deformation and the stress distribution of foundation model and the strain of the new raft structure. The results show that the bearing effect of the new raft greatly alleviates the foundation deformation and reduces the foundation stress within a certain depth,which indicates that the raft exists as a "reinforced structure" of the foundation. The larger stiffness of the new raft allows the load to be transmitted to the periphery,reducing the foundation reaction force at the center of the raft. The strain of the new raft presents a U-shaped distribution with large in the middle and small on both sides. Meantime,the longitudinal strain is higher than the transverse strain,indicating that the deformation is transmitted more along the longitudinal direction of the raft. The soil structure is seriously damaged by the freeze-thaw cycle,resulting in a significant increase in settlement of foundation. The raft-soil system shares the upper load,and the raft strain increases while the soil strength decreases. Besides,the increase of stress in a certain depth range of the foundation caused by freeze-thaw cycle is consistent with the depth range of freeze-thaw cycle action,and the degree of influence becomes more obviously with the increase of the load level. In addition,the numerical simulation results are in good agreement with the experimental results,which indicates that the numerical simulation method can be used to analyze the mechanical characteristics of the new raft foundation in island frozen soil area.

       

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