重复列车荷载作用下季节性冻土区桥墩-基础场地振动特性及长期变形分析

VIBRATION CHARACTERISTICS AND LONG-TERM DEFORMATION ANALYSIS OF BRIDGE PIERS-FOUNDATION SITES IN SEASONAL FROZEN SOIL REGION UNDER REPEATED TRAIN LOAD

基于高速列车运行引起的轨道-桥梁-桥墩-季节性冻土区场地的地面振动和沉降问题,选取哈大高速铁路铁岭至四平段某桥墩及周围基础场地为测试段,对实测数据从时域和频域两方面进行分析,研究了桥墩及周围不同场地的振动特性,结果表明:桥墩和基础场地的振动特性存在很大的差异,基础场地对振动有放大效应,且不同基础场地对振动的放大效果也明显不同。结合实测概况建立了桥墩-基础场地有限元数值模型,分析桥墩及基础场地在不同季节的振动传播特性,以及基础场地土体内部的应力分布情况,并利用累积塑性应变模型对重复列车荷载作用下季节性冻土区基础场地的沉降变形进行分析,发现场地振动加速度峰值随与桥墩距离R的增大而衰减,且在冻结季的振动衰减速度明显小于非冻结季的;基础场地地表的累积沉降在距桥墩R=0.5 m处最大,且随着列车荷载作用次数的增加而增加,最后逐步趋于稳定。

Based on the ground vibration and settlement of track-bridge-pier-seasonal frozen soil site caused by high-speed train operation,we selected a pier and surrounding foundation site of Tieling-Siping section of HarbinDalian high-speed railway as the test site.The measured data are analyzed in time domain and frequency domain.And we studied the vibration characteristics of piers and surrounding sites.The results show that the vibration characteristics of bridge pier and foundation site are quite different,and the vibration amplification effect of different foundation site is also significantly different.Combining with the survey,we established the finite element numerical model of pier-foundation site.We analyzed the vibration propagation characteristics of pier and foundation site in different seasons and the stress distribution in the soil of foundation site.We used the accumulated plastic strain model to analyze the settlement and deformation of the foundation site in seasonal frozen soil region under repeated train loads.It is found that the peak vibration acceleration of site decreases with the increase of the distance R from the pier,and the vibration attenuation rate of freezing season is obviously lower than vibration attenuation rate of non-freezing season.The cumulative settlement of the ground surface of the foundation site is the largest where the distance from the bottom of the pier is 0.5 m.The permanent deformation of foundation site caused by train loading increases with the increase of the times of train load,and the deformation tends to be stable with the increase of time as well.