Dissertation
Dissertation > Industrial Technology > Building Science > Soil mechanics,foundation engineering > Various types of soil and foundation > Loess and foundation

Study on the Characteristics of Seismic Subsidence Loess in Guanzhong Area

Author ZhuXia
Tutor FanWen
School Chang'an University
Course Geological Engineering
Keywords Undisturbed Loess Remodeling Loess Dynamic Shear Modulus Damping Ratio Loess Seismic Subsidence
CLC TU444
Type Master's thesis
Year 2011
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There is a significant seismic subsidence in the loess, what many examples and loess seismic subsidence damage studies have shown in the earthquake. Loess is widely distributed in the Guanzhong area., So it is extremely necessary that we make the seismic subsidence depth study of the nature of loess, It affects the loess areas of construction, has a great significance of the mitigation of seismic disasters.This research, which based on the Seismic Zoning project in Guanzhong area, focuses on problems of loess seismic subsidence.Firstly, a comprehensive analysis is taken about the topography, regional tectonics and earthquakes, lithology, hydrogeology and other aspects in the Guanzhong area. Meanwhile, the research on the loess material composition, microstructure and properties of engineering by using conventional geotechnical tests, grain size analysis, spectrum analysis, scanning electron microscope and other methods.On that basis, taking the dynamic triaxial tests on undisturbed loess and remolded loess by considering the influence of different factors, which including moisture content, density, consolidation stress, consolidation stress ratio, vibration times.etc. By finishing the test data analysis, There are several of factors having a certain impact on the loess dynamic shear modulus, damping ratio and seismic settlement by the test data analyzed. By comparing the effects of the undisturbed loess and remolded loess under the same conditions, found that remolded loess dynamic shear modulus be smaller than the undisturbed loess, that that remolded loess damping factor be larger than the undisturbed loess. The Seismic subsidence curve of the undisturbed loess is higher than the curve of the remolded loess. It’s obvious linear feature about seismic subsidence curves of remolded loess, resulting in larger residual strain than the undisturbed loess. It’s great effects in loess seismic subsidence that the native structure of loess.Making a quantitative analysis about the mathematical model of seismic subsidence curve, found that it is preferable using the quadratic mathematical model of nonlinear to be fitting both undisturbed loess and remolded loess, What is more that remolded loess fit better Correlation than the undisturbed loess. Afterwards, By using layerwise summation method, taking an example of seismic subsidence evaluation in the Loess Site of Xi’an.

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