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基于对负温条件下青藏铁路高温不稳定多年冻土区桥梁桩基础的缩尺模型振动台试验,明确了动荷载作用下模型桩-土界面和两桩中间土体存在温度升高响应。在此基础上,考虑天然状态和地震荷载作用下地温升高两种条件,运用动力有限元方法,对青藏铁路清水河特大桥桩基础进行了地震响应分析。计算表明,在高温状态下(-1℃以上),多年冻土的地基及桩基础在地震荷载作用下的动态响应对温度的升高异常敏感;在50年超载概率2%的青藏人工波作用下,因桩基础的相对位移增大了地基与桩基础间的滑移、脱离现象,特别是高温状态下地基与桩基础间的变形出现了明显的不稳定滑移,影响了整个桩基础的稳定性。
Based on the shaking table test of the scale model of the bridge pile foundation in the high temperature unstable region of the Qinghai-Tibet Railway under the negative temperature condition, the response of the temperature rise of the model pile-soil interface and the two middle soil bodies under the action of dynamic load is clarified. On this basis, considering the two conditions of natural state and the increase of ground temperature under the earthquake load, the dynamic response of the pile foundation of Qingshuihe Extra Large Bridge of Qinghai-Tibet Railway was analyzed by dynamic finite element method. Computation shows that at high temperature (above -1 ℃), the dynamic response of the foundation and pile foundation of permafrost under earthquake load is sensitive to the increase of temperature. In the past 50 years, the Qinghai-Tibet artificial wave with an overload probability of 2% , The slippage and detachment between foundation and pile foundation are increased due to the relative displacement of pile foundation, especially the unstable deformation of the deformation between foundation and pile foundation under high temperature, affecting the whole pile foundation stability.