基于桥墩基础场地土体参数的高速列车振动敏感性分析

Vibration sensitivity analysis of high-speed trains based on soil parameters of pier foundation sites

桥墩侧堆积填土及其物理力学和几何参数对列车振动传播的有重要影响。本文以哈大高铁的铁岭—四平段某桥墩及右侧堆积填土和基础场地为研究对象,建立有限元模型,同时定义“振动变化有效值”,并结合灰色关联度理论,利用现场实测和数值模拟方法揭示桥墩侧堆积填土及其参数对振动传播的影响规律。通过研究分析主要得到以下结论:(1)桥墩顶端支撑垫石的振动特性与堆积填土和基础场地的振动特性具有不同的性质,堆积填土和基础场地对列车振动有明显的放大效应;(2)堆积填土侧的振动加速度级要大于未填土侧的,且在堆积填土的边界位置会出现反弹现象;(3)堆积填土侧的振动加速度级随着堆积填土弹性模量的增大而增大,其密度和泊松比对振动传播几乎没有影响;在距桥墩1 m之内,随着阻尼比的增加堆积填土侧的振动加速度级增大,当大于1 m时,随着阻尼比的增大而其振动加速度级减小;(4)随着堆积填土长度的增加振动加速度级增大,而堆积填土高度变化的范围内,存在一个最优值,使得堆积填土侧的振动加速度级最小,同时,桥墩侧堆积填土的各个参数对地面振动的敏感性大小为:弹性模量>长度>阻尼比>高度>密度>泊松比。

The alluvial filling soil on the side of bridge piers and its physical,mechanical,and geometric parameters have important effects on train vibration propagation.Taking a pier and its adjacent alluvial filling soil and foundation site along the Tieling-Siping section of the Harbin-Dalian high-speed railway as the research object in this study,a finite element model was established,and the“effective value of vibration change”was defined.Combined with the theory of gray relational degree,the field measurement and numerical simulation method were used to reveal the influence of the alluvial filling soil and its parameters on vibration propagation.The following conclusions are obtained through the analysis.(1)Vibration characteristics of the supporting pad stone at the top of the pier are different from those of alluvial filling soil and the foundation site,which have amplification effects on the train vibration.(2)The vibration acceleration level of the alluvial filling side is larger than that of the unfilled side,and a rebound phenomenon will be observed at the boundary position of the alluvial filling soil.(3)The vibration acceleration level increases with the elastic modulus of alluvial filling soil,and its density and Poisson’s ratio hardly affect the vibration propagation.Within 1 m from the pier,the vibration acceleration level increases with the damping ratio;when the distance is larger than 1 m,this level decreases with the increase in the damping ratio.(4)The vibration acceleration level increases with the length of the alluvial filling soil,and its height demonstrates an optimum value,which minimizes the vibration acceleration level on the side of the alluvial filling soil.Meanwhile,the sensitivity of each parameter of alluvial filling soil on the pier side to the ground vibration is in this order:elastic modulus>length>damping ratio>height>density>Poisson’s ratio.