Inversion Of Soil Structure By Microtremors

Compared with the single point-drilling exploration survey technology surface, wave exploration technique,as a new exploration method, has the advantages of low cost and convenience to use.At present, the method has been widely used in geotechnical engineering and earthquake engineering,in practice.Besides,it has become an important subject on a professional geophysical and geotechnical engineering interdisciplinary study.Firstly，this paper reviews the research progress of the surface wave survey exemplified technology at home and abroad, and makes a brief overview of the method’s theoretical basis.Secondly, the paper describes the data preprocessing method in the actual wave exploration and analyzes the advantages and disadvantages of methods about nature source and artificial source.Finally, I put forward research methods and ideas in this paper.In the layered media, Rayleigh wave dispersion curve is based on the forward algorithm. This paper realizes characteristics analysis of the parameters of the soil medium through Knopoff algorithm, obtain: in increasing soil layer, soft interlayer soil and hard interbedded soil layer, the area of shear wave velocity’s influence on the dispersion is the largest, and become the most important parameter in describing the soil structure.To inversion operation on site, given the density, thickness and p-wave velocity of each soil layer,only the theory of soil layer (including increasing soil, soft interlayer soil) of the shear wave velocity are analyzed in virtual inversion,and proves the feasibility and effectiveness of the genetic algorithm method. Then, by use of the aftershocks of the array to record data in tianjin, the paper adopts ESPAC method to the inversion of soil layers shear wave velocity,and evaluates the effect of inversion.In the end, I summarize the contents of this paper,describe the problems existing in the paper,and some suggestions to the future research works are present.