青藏高原多年冻土地区铁路路基工程动力稳定性分析

Dynamic Stability Analysis of Railway Embankment Engineering in Permafrost Regions of the Qinghai-Tibet Plateau

摘要:

科学合理地分析铁路路基块石层在机车荷载作用下的动力传递机理，对于多年冻土区路基工程稳定性预测有着重要的指导意义，同时对于在青藏高原多年冻土地区建设高坝大库等重要水利工程的动力稳定性分析也具有重要的借鉴作用。通过选取青藏铁路北麓河段典型块石路基结构开展机车通过实时强震动测试，获得了机车通过时的实时加速度数据。在现场测试的基础上，基于有限元分析软件, 运用二维非线性动力响应分析方法对多年冻土区块石路基结构在机车荷载作用下动力传递特性、位移响应特性和应力应变特性进行了数值模拟分析，并通过对比分析素土路基的动力响应特征，科学分析青藏铁路路基块石层在机车荷载作用下的动力传递机理。研究结果表明，块石层的铺设可以有效限制机车荷载产生的加速度向路基深处传递，减小机车振动对路基结构的影响，有助于保护冻土路基的稳定性；块石层的铺设可以较好地减小机车荷载作用下路基的沉降变形，在相同机车荷载作用下块石结构路基的最大沉降量仅为0.9 mm，而素土路基的最大沉降量可达1.9 mm；块石层的铺设可以改变机车荷载作用下路基内部的应力应变状态，使得路基内部最大主应力增大，而最大剪应变幅值、范围均减小。

Abstract:

Analyzing the dynamic transfer mechanism of the plain-fill railway embankment under locomotive loading in a scientific and reasonable manner is of primary importance for stability prediction of the embankment，especially in the permafrost regions.It also provides a valuable reference for the construction of significant water conservancy projects，such as large dams and reservoirs，in the permafrost regions of the Qinghai-Tibet plateau. Based on the strong motion observation tests at the Beilu River segment in the permafrost region，the nonlinear dynamic finite element method was applied to the numerical calculation of the plain-fill and block-stone embankments to analyze the influence of the block-stone layer.The results show that vibration transmission can be controlled through the block-stone layer，which can decrease the effect of vibration on the stability of the embankment.Meanwhile，the vibration settlement from train-induced vibrations mainly occurs in the roadbed；the maximum displacement of the block-stone embankment can reach up to 0.9 mm，which is less than the displacement of the plain-fill embankment.The maximum principal stress of the block-stone embankment is greater than the plain fill embankment，however，the amplitude and the range of maximum shear strain is smaller.