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针对青藏高原多年冻土区路基在地震作用下出现大量破坏这一实际问题,以G214公路工程地质条件为基础,以西宁台站、大武台站、都兰台站等实测地震加速度数据作为边界条件,建立有限元模型,计算地震荷载下多年冻土区路基动力学响应。计算了-0.2℃、-0.5℃、-0.8℃年平均地温工况下路基动力响应,并以此为基础研究温度对路基动力响应影响;以1、4、7、10月温度场计算结果为依托,计算了不同季节工况对路基动力响应影响;以5、10、15m高填路基为样本,通过动力分析,确定填方高度对路基动力响应影响;同时考虑阴阳坡效应对路基稳定性影响,对比分析阴阳坡侧动力响应差异,并对比分析各因素对路基动力稳定性影响权重,确定其中主要因素。研究结果表明:地震荷载作用下,填土高度对路基稳定性的影响大于季节及温度的影响;受路基阴阳坡效应的影响,阳坡侧路基位移峰值大于阴坡侧,路肩处阳坡侧水平位移峰值比阴坡侧高42.9%,阳坡侧坡脚水平位移比阴坡侧高42.8%;10月份为路基体受力及变形最不利季节,冻土地温越高,路基顶面及坡脚点位移幅值越大,且地温对坡脚点位移的影响大于路基中心点;在地震作用下,有明显阴阳坡效应的多年冻土路基坡脚位移差别较大,路基阳坡侧较阴坡侧有更高的失稳风险。
Aiming at the practical problem of massive destruction of subgrade in permafrost region on the Qinghai-Tibet Plateau under seismic action, based on the engineering geological conditions of G214 highway, the measured seismic acceleration data such as Xining station, Dawu station and Dulan station are taken as the boundary conditions , The finite element model is established and the dynamic response of subgrade in permafrost region under earthquake load is calculated. The dynamic response of subgrade at -0.2 ℃, -0.5 ℃ and -0.8 ℃ is calculated. Based on this, the influence of temperature on dynamic response of subgrade is studied. The calculated results of temperature field at 1, 4, 7 and 10 are Relying on it, the influence of different season conditions on subgrade dynamic response was calculated. Taking 5, 10, 15m high subgrade as sample, the influence of subgrade height on subgrade dynamic response was determined by dynamic analysis. At the same time, , Comparative analysis of yin and yang slope dynamic response differences, and comparative analysis of various factors on the dynamic stability of roadbed weight, to determine the main factors. The results show that under the action of seismic load, the effect of fill height on the stability of subgrade is greater than that of season and temperature. Under the influence of the Yin-Yang slope effect of subgrade, the peak displacement of sunny-side embankment is larger than that on the shady slope side, The displacement peak is 42.9% higher than the shady side and the horizontal displacement of the slope on the sunny side is 42.8% higher than that on the shady side. In October, the most unfavorable season is the stress and deformation of the roadbed. The higher the ground temperature of the frozen ground, The larger the amplitude of point displacement is, and the effect of ground temperature on the displacement of footing point is greater than that of the embankment center. Under the action of earthquake, the difference of foot displacement of permafrost subgrade with obvious yin-yang slope effect is larger, The side has a higher risk of instability.