【作者】 王宁；

【导师】 朱德兵；

【作者基本信息】 中南大学 ， 地球探测与信息技术， 2012， 硕士

【摘要】 基本不影响正常运营的路基在线加固和在线检测评估对于铁路系统维护意义重大。利用弹性波频响曲线变化特征检测路基状态具有工作效率高,可获得介质动力学参数等优点,是评价路基状态及加固施工效果的新方法,对于其理论依据和实际工作效果都需要有针对性的研究。本文从拟模态概念出发,概述了拟模态试验分析和数值模拟中所使用的交错网格有限差分算法的基本理论。参照铁路路基结构及典型病害特征,构建了正常状态和含软弱夹层的非桥涵铁路路基模型,分别利用场地抗震评价理论中的分层土自振频率公式和基于弹性波全波波场的正演模拟记录,计算了不同状态下路基结构的自振频率和频响特征曲线,计算结果表明含浅部软弱夹层的路基相比正常路基,其主频向低频方向移动。弹性波勘探系统为在铁路道碴面上直接进行路基质量检测提供保障。借助该系统,在朔黄铁路某工区完成了重载铁路软弱路基加固前后原位弹性波测试,其频响曲线变化特征与所获得地震映像剖面相符合,进一步证明了前文所述规律的存在。在常规地震勘探和探地雷达难以对超浅层路基结构进行评估时,基于路基状态频响特性分析的技术是一种可以尝试的技术手段。论文课题来源于国家高技术研究发展计划(863计划项目编号：2009AA11Z101)子课题七——“路基状态连续检测技术”。从弹性波动力学角度对铁路路基病害检测工作进行了研究,丰富了铁路路基检测评估的思路,为拟模态理论实践应用提供了支持。更多还原

【Abstract】 On-line reinforcement, testing and evaluation on railway bed is of great significance for the maintaining of railway system. The test based on the properties of elastic wave frequency response curve is a new method to evaluate the nature of bed and effect of reinforcement. The method has the advantages of bringing high efficiency and enabling testers to get parameters of medium dynamics. However, special researches should be made as to its theoretical foundation and practical effects.Starting from the concept of simulated modal, the author generally introduced the basic theory of staggered grid finite-difference algorithm used in simulated modal test analysis and numerical simulation. In light of the structures of railway bed and railway diseases, the author built a non-bridge and non-culvert bed model featuring soft rock strata for one and normal conditions for anther. The author also worked out the curves of natural frequency of vibration and of frequency response of bed structures under the two different conditions, with related formula of natural frequency of vibration of layered soil from the theory of Site Seismic Evaluation Theory and according to forward modeling records based on elastic double-wave field. The curves show that, compared with normal bed, the dominant frequency of the other kind of bed gradually becomes low.The elastic wave exploration system ensures the quality test of railway bed directly done on railway ballast surface. Relying on that system, the elastic wave tests were conducted on reinforced and unreinforced soft rock bed of heavy haul railways in a work area of Shuo-Huang Railway. Their frequency response curves match the profiles of earthquake image, which further proves the disciplines. And the method based on property analysis of frequency response is applicable, when normal seismic exploration and GPR can not accomplish the evaluation of railway bed containing very soft rock strata.The subject of the paper is the seven sub-subject of the National Hi-tech R&D Program—Continuous Test on Railway Bed (Program 2009AA11Z101belonging to863Program). The study was conducted on test of railway bed diseases from the angle of elastic wave dynamics. It expands the ways of test and evaluation of railway bed and provides support for application of simulated modal theory into practice.更多还原