地铁列车引起的地基振动及浮置板减振研究

发布时间：2018-06-30 04:30

本文选题：2.5维有限元 + 地铁　；参考：《浙江大学》2013年硕士论文

【摘要】：近几年来轨道交通的高速发展引起的环境振动和路基不均匀沉降问题日益凸显。过大的环境振动影响了沿线居民的正常生活,以及沿线一些有精密仪器的实验室和设备工厂,另外也可能会破坏沿线的一些不能承受过大振动的历史性建筑；而列车的长期运营后引起的路基不均匀沉降会使振动加剧。所以轨道交通引起的振动问题和沉降问题被越来越多的学者关注。本文首先运用已有的2.5维有限元方法,引入多层阻尼边界,通过计算带有一定激振频率移动矩形荷载下土体中的振动响应,与半解析解方法进行对比,以验证本模型在计算动静荷载下场地振动的正确性。之后把列车荷载考虑为移动常荷载,再加以一定的激振频率来分析不考虑车辆和轨道耦合的情况下单轮荷载通过时和整车荷载通过时隧道结构以及周围土层中的振动响应特征。为了表征这一结果,在地表和土层内部分别选择了若干个观察点。分析后发现列车的速度以及激振频率对场地中的振动响应有着重要的影响。当荷载考虑为移动常荷载时,在地表上引起的竖向位移响应范围较窄,而当荷载附加较低激振频率时,地表上引起的竖向位移响应范围较广,如果附加的激振频率较高时,那么地表上的竖向位移响应范围又会变窄。为了较真实有效地模拟列车通过时引起的振动问题,考虑了轨道的不平顺性,并把列车车体和轨道进行耦合。轮轨接触力通过四分之一车体模型来计算,模型中轨道不平顺采用单个余弦不平顺。在此种模型下分析了轨道不平顺的波长和幅值以及隧道壁厚和埋深对列车荷载引起的振动响应的影响。分析后发现隧道壁厚对地表振动的影响较小,而隧道埋深和轨道不平顺的波长和幅值对地表振动的影响跟列车速度有关。为了评估浮置板轨道的减振效果,本文进一步建立了2.5维浮置板轨道分析模型,模型中浮置板轨道中的钢轨和轨道板均采用欧拉梁来模拟,扣件和轨道板下钢弹簧在沿轨道方向进行均化处理,并采用弹簧-阻尼系统来模拟。浮置板轨道结构的刚度可通过与下面隧道结构接触的节点整合到下面有限单元中。文中首先分析了浮置板轨道的减振特性,然后分析了土层和隧道结构参数,浮置板轨道参数(钢弹簧刚度和浮置板单位长度质量)以及轨道不平顺参数(不平顺波长和幅值)对浮置板轨道减振效果的影响。为了更能真实地考虑轨道不平顺性,本文引入美国不平顺轨道谱,并通过三角级数方法展开成不平顺的空间分布,这样轨道的不平顺就可认为是由多个余弦不平顺组成。通过对由每个余弦不平顺下引起的轮轨接触力进行叠加,可以得到实际不平顺轨道下的轮轨接触力。本文中采用此模型分析了高铁和地铁两种工况,分析过程中考虑了不同的轨道平顺性条件以及不同的列车速度。
[Abstract]:In recent years, the environmental vibration and uneven settlement of roadbed caused by the rapid development of rail transit have become increasingly prominent. Excessive environmental vibration affects the normal life of residents along the route, as well as some laboratories and equipment factories with precision instruments along the route, and may also destroy some historic buildings along the route that cannot withstand excessive vibration; The uneven settlement of roadbed caused by long-term operation of train will aggravate the vibration. So more and more scholars pay attention to the vibration problem and settlement problem caused by rail transit. In this paper, the existing 2.5 dimensional finite element method is used to calculate the vibration response of soil under the moving rectangular load with a certain frequency, and the results are compared with the semi-analytical method. In order to verify the correctness of the model under static and dynamic loads of the site vibration. Then the train load is considered as moving constant load, and the vibration response characteristics of tunnel structure and surrounding soil layer are analyzed without considering the coupling of vehicle and track. In order to represent this result, several observation points were selected in the surface and the soil layer respectively. It is found that the speed and exciting frequency of the train have an important influence on the vibration response in the field. When the load is considered as moving constant load, the response range of vertical displacement on the surface is narrower, but when the load is attached with lower excitation frequency, the response range of vertical displacement is wider, if the additional excitation frequency is higher, Then the response range of vertical displacement on the surface will narrow again. In order to simulate the vibration caused by train passing effectively, the irregularity of track is considered, and the train body and track are coupled. The wheel / rail contact force is calculated by the 1/4 car body model, in which the track irregularity is a single cosine irregularity. Under this model, the influence of the wavelength and amplitude of track irregularity, tunnel wall thickness and buried depth on the vibration response induced by train load is analyzed. It is found that the influence of tunnel wall thickness on surface vibration is small, while the influence of tunnel depth and the wavelength and amplitude of track irregularity on the surface vibration is related to the train speed. In order to evaluate the vibration reduction effect of floating slab track, a 2.5 dimensional analysis model of floating slab track is established in this paper. In the model, Euler beam is used to simulate the rail and track slab in the floating slab track. The steel spring under the rail plate and fastener are homogenized along the track, and the spring damping system is used to simulate them. The stiffness of the floating slab track structure can be integrated into the following finite element by the nodes in contact with the tunnel structure below. In this paper, the vibration absorption characteristics of floating slab track are analyzed, and then the parameters of soil layer and tunnel structure are analyzed. The influence of track parameters (steel spring stiffness and unit length mass of floating slab) and track irregularity (irregularity wavelength and amplitude) on the vibration reduction effect of floating slab track. In order to consider the irregularity of orbit more realistically, this paper introduces the spectrum of irregularity orbit in the United States and expands it into the spatial distribution of irregularity by means of trigonometric series method, so that the irregularity of orbit can be considered as composed of several cosine irregularity. By superposing the wheel-rail contact force caused by each cosine irregularity, the wheel-rail contact force under the actual irregularity track can be obtained. This model is used to analyze the two working conditions of high-speed rail and subway. Different conditions of track ride comfort and different train speeds are considered in the process of analysis.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU435;U211.3

【参考文献】