高原地区路基地震液化数值模拟研究

在青海玉树地震之后,有大量路基出现由于液化而导致的病害问题。以青海S308线结古—曲麻莱段公路路基变形为例,通过FLAC3D数值模拟软件还原该路基在地震中的变形破坏过程,得出如下结论:(1)无地下水情况下,边坡出现明显塑性屈服的振动强度是0.6g,塑性屈服首先发生在填土厚度较薄的路基两端。(2)若砂土完全饱水,随振幅的增加,饱和砂土层液化趋势逐渐增强。振幅小于0.3g时砂土层没有液化。振幅为0.4g时5s以后砂土层出现液化;振幅大于0.5g以后,从振动的开始就出现了液化。(3)下伏饱和砂土的路基动力破坏机理为:饱和砂土层近地表处屈服屈服区在饱和砂土层中向中部扩展饱和砂土层屈服贯通饱和砂土层完全屈服填土后部首先破坏填土破坏区在填土-砂土界面向下扩展填土后部地表屈服开裂破坏区在填土内扩展。至最终破坏时,填土中后部大范围开裂屈服,但填土前部依然保持完整。

Numerical Simulation of the Earthquake Liquefactionof a Roadbed in a Plateau

The roadbed in a plateau is impacted by seasonal freezing and thawing; compared with those of plains, of the liquefaction factors of roadbeds in a plateau are more complex. Taking Qinghai S308 knot ancient qumarleb section of highway roadbed deformation for example, reducing the roadbed in the earthquake devastated by FLAC^3D process simulation software, the following conclusions can be made:(1) In the absence of groundwater conditions, slope obvious plastic vibration strength yield is 0.6g, plastic yielding occurs first in the subgrade fill thinner ends. (2) If the sand is completely saturated with water, liquefaction gradually occurs with increasing amplitude. When the amplitude is less than 0.3g, the sand layer is not liquefied. At an amplitude of 0.4g, the sand layer liquefies 5 s later. At amplitudes greater than 0.5g, the vibration from the beginning, there have been liquefied. Saturated sand embankment power (3) the underlying failure mechanism is:saturated sand layer near the surface of the yield →yield zones in saturated sand layer through→yield saturated sand layer to the middle layer is completely saturated sand expansion→yield first, fill the rear area damage undermine→fill fill-sand interface extends down→fill rear surface cracking yield expansion in the destruction zone backfill. At the final destruction, filling cracks in the rear of the large-scale yielding, but filling the front remains intact.