工程场地弹性波拟模态分析技术研究

Study on quasi-modal method of elastic wave for engineering site

采用弹性波小排列观测系统,将岩土体简化为质量-弹簧-阻尼系统,分析"点源"激励多自由度的幅-频响应特征,提出了工程场地介质结构弹性波测试的振动拟模态试验分析方法.通过对物理模型的动力学和静力学参数的测试,建立起激励响应的频率与抗压强度、弹性模量的相关关系:随着弹性模量的增大,激励响应大的频带和主频明显向高频移动.研究表明在有效激励下运用单道记录拟模态结果即可快速定性评价岩土体物性变化,对工程场地岩土体的快速诊断具有重要意义.

Based on the small-scale observation system and the characteristics of the elastic wave, the response of the shallow and ultra-shallow rock vertical excitation is seem as one degree-of-freedom system, according to the systematical model of mass-spring-damping, the frequency response of the ＂point source＂ was analyzed, and the quasi-modal test and analysis theory of the wave-shock character of ultra- shallow elastic wave by effective excitation was build up. Comparising the elastic wave testing and static parameter testing of the model, the relationship between frequency of elastic wave and compressive strength, Elastic Modulus and the velocity of P-wave was obtained： the dominant frequency and frequency band of elastic wave was increased gradually according to the elastic parameters increased. The study indicates that quasi-modal testing can be described as a rapid method of physical properties indentification of rock and soil, it has important significance for evaluting the quality of engineering site rapidly and accurately.