高速铁路桩承式路基土拱安定性分析

Shakedown Analysis of Soil Arch in Piled Embankment of High-speed Railway

高速铁路桩承式路基中土拱的动力稳定性直接影响到路基的应力分布、累积变形,进而影响其服役性能,而目前研究中动荷载对土拱退化、失稳的影响缺乏定量描述。在Hewlett土拱物理模型的基础上考虑附加循环荷载的作用,分析桩承式路基桩顶、桩间土的受力状态,并结合土拱的破坏失稳模式,利用安定理论构造最佳残余应力场,研究拱脚稳定性随动荷载变化的弹性、安定、破坏阶段,给出弹性极限荷载pe、安定荷载psd、临界破坏荷载pp的求解方法,计算结果与模型试验规律相符。通过安定荷载确定土拱在长期循环荷载作用下不发生累积变形破坏的荷载临界值,其对桩承式路基结构设计具有指导意义。

Soil arch in pile-supported embankment of high-speed railway is inevitably affected by long-term cyclic dynamic loads. Its stability under dynamic loads directly affects the stress distribution and accumulated deformation of the embankment, further affecting its service performance. However, current studies involving soil arch stability mainly focused on limit state analysis under static load and rarely presented quantitative description on the influence of dynamic loads on the degradation and collapse of soil arch. In this paper, based on the soil arch model of Hewlett and considering the effect of additional cyclic loading, the force-bearing features of pile top and soil among piles were analyzed. The optimum residual stress field was constructed using the shakedown theory in combination with the failure mode of soil arch. The elasticity, shakedown and failure stage of the stability of the arch foot under cyclic load were distinguished with the theoretical calculation of critical loads pe, psdand ppproposed in this paper. The results indicated that the regularities reflected by calculation values were in agreement with the model test. The critical value of the cumulative deformation failure of soil arch under long-term cyclic loading can be determined by the stability load, which is of guiding significance for the design of the pile supported embankment structure. © 2016, Editorial Office of Journal of the China Railway Society. All right reserved.