Research On Micro-tremor Characteristics And Dynamic Response Of Loess Slope In Meixian, Baoji

The earthquake is one of the natural disasters with the greatest impact on human activities, which will release huge energy in a very short time, giving no time for people to hide or take measures, so it will usually cause heavy losses of lives and properties. The geological structure is relative complex in Baoji area, within which the topography is very different. In this area, there is a wide distribution of loess slopes, which tend to fail easily under earthquake action, so the problem of earthquake stability of loess slopes is urgent to be solved.The micro-tremor is a typical kind of full-band frequency source of vibration; compared to earthquake action, it is only different on amplitude, that is to say, the difference between micro-tremor and earthquake is just the magnitude of load. For an engineering site, no matter the input load is from the earthquake or micro-tremor, the selecting effect of frequency is similar, in other words, a certain engineering site will apparently select out and amplify a certain and narrow range of frequency. So, the research on the slopes respond to micro-tremor will benefit the earthquake stability of slopes a lot.This paper takes the Yang Jiacun loess slope in Mei Xian, Baoji as the object of analysis, measures its micro-tremor and analyzes its characteristics of dynamic respond. Using the software of ArcGIS, AutoCAD, Ansys and FLAC3D, based on the geo-exploration data, the paper constructs an initial model. Setting the analysis results of on-site measured micro-tremor as the target function, the paper simulates the micro-tremor respond by adjusting the dynamic parameters of the model again and again, and a relative rational model is obtained when the simulated spectrum fits the on-site measured micro-tremor spectrum best. Meanwhile the mode of vibration is analyzed and the predominant mode of vibration of this slope is achieved.Synthesizing the dynamic effect of earthquake action, adopting the concept of mean value acceleration, searching the critical acceleration causing the failure of the slope, compare it with the fortification acceleration of this area the dynamic stability factor is obtained. The research shows that, under the fortification earthquake acceleration, 50 years, 10% probability exceedance, its dynamic stability factor is 0.8, that is to say, under the fortification earthquake action of this area, the slope will have a risk of instability and failure.