摘要
为探究冻土热-力耦合效应对铁路重力式桥墩抗震性能的影响规律,采用热-力耦合方式建立了土-桩基础-桥墩相互作用下三维实体有限元模型,并利用拟静力模型试验结果对其进行验证.在此基础上,探讨了地表温度和融化层厚度变化对桩基础铁路重力式桥墩抗震性能的影响规律.研究结果表明:采用热-力耦合方式建立的土-桩基础-桥墩有限元模型预测结果与拟静力试验结果吻合较好,能够有效模拟其水平地震荷载作用下的非线性响应;随着地表温度的降低,土-桩基础-桥墩体系的极限水平承载能力、初始刚度和累计耗能均会增大,但桩基础桥墩的侧向位移能力会出现一定程度的降低;随着季节冻土层融化深度的增加,土-桩-桥墩体系的极限水平承载能力、整体刚度退化和累计耗能曲线均出现大幅下降趋势,其中表层冻土融化深度从0cm增加到5cm时桩基础桥墩的抗震性能减弱幅度较为严重.
Abstract
This study aims to provide a theoretical basis for selecting salt-tolerant maize varieties for seed production and saline-alkali soil cultivation in Zhangye City.Four maize varieties-Huadan 86,Pengyu 17,SK567,and Henong No.1-were used as materials.The seeds were treated with different NaCl concentrations(100,200,300,400,and 500 mmol/L),with dis-tilled water as a control,to assess germination indices,seedling morphology,and physiological indices.The results indicated that low salt concentrations had minimal impact on the seed germination rate of the four maize varieties,while high NaCl concen-trations significantly reduced the germination rate of Henong No.1.As NaCl concentration increased,germination potential,rela-tive germination index,and relative seed vigor index decreased significantly.The morphological growth of plant height,leaf length,and root length was inhibited,although the inhibition in Henong No.1 was relatively slower.Higher NaCl concentrations led to significant differences in proline content between varieties and the control group,with the highest proline content observed at 500 mmol/L NaCl,especially in Henong No.1.MDA content and relative conductivity also increased with rising NaCl concen-trations across all varieties,with SK567 showing the highest MDA content and Henong No.1 the lowest.Relative conductivity rose rapidly in Pengyu 17 and Huadan 86,but more gradually in SK567 and Henong No.1.Considering the effects of salt stress on germination,seedling growth,and physiological indices,Henong No.1 demonstrated the greatest salt tolerance,followed by SK567,Pengyu 17,and Huadan 86.
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