2D Seismic Simulation And Tomographic Technology Of Landslide

With the deepening of China's urbanization development process,the risk of landslide disasters caused by large-scale engineering construction has gradually increased.In addition,landslides caused by natural disasters such as earthquakes and extreme weather have also caused greater threats to people's lives,property and economic development.Among the many methods of landslide detection,geophysical exploration is the most economical,fast and effective method.Seismic tomography can identify landslides and landslides and is a common method used in landslide detection.However,in the application process of seismic tomography to detect landslide body,there are some problems such as insufficient selection of acquisition parameters,optimization of inversion parameters,and high subjectivity of velocity interface interpretation.In addition,the applicability of tomography lacks necessary analysis.Based on the classification of material composition,formation mechanism and scale of landslides in engineering geology,this paper generalized six types of landslide seismic geological models,including collapse type,expansion type,steep type,slow-slip type,step type and mezzanine.type.For the different landslide models,the two-dimensional simulation method based on wave equation is used to test the parameters of the observation system such as gun density,track distance,offset and excitation mode.The optimization method of observation parameters is discussed.Based on the two-dimensional seismic forward data of different landslides,the tomographic inversion was completed based on the pre-processing of observation system establishment and first-time picking;firstly,the comparison of initial model,ray density,iteration number and other parameters was carried out.The relevant parameters are preferred to ensure the accuracy of the inversion results of the velocity structure.Aiming at the continuous variation characteristics of the tomographic inversion velocity results,the velocity abrupt interface explains the multi-solution problem.Based on the assumption that the velocity depth is the fastest velocity position,the vertical gradient extremum is used to explain the landslide surface.The method solves the gradient in the vertical direction by the velocity after the inversion of the tomography,and selects the position with the largest gradient as the velocity interface,thereby determining the spatial shape of the sliding surface and the spatial characteristics of the landslide body.Interpretation error analysis,the absolute error of the absolute error and the overall thickness of the landslide model is less than 10 m,and the relative error is less than 10%.The method feasibility verification was carried out by selecting two-dimensional seismic data from Qinshui Xiaoling area.The tomographic,scattered-wave imaging,high-density electrical imaging results and comparative results of six seismic line data in the study area show that the tomographic results are consistent with the results of scattering wave imaging,resistivity imaging and actual drilling.Good,but for the sandwich type landslide body,the accuracy of the tomographic results is very large.This study shows that seismic tomography can identify geological anomalies with increasing speed in engineering geological exploration,and its accuracy can meet the accuracy requirements and feasibility.Strong;but under the condition that the speed is reversed,the applicability of the method is poor because the assumption that the speed of tomography increases with depth is not satisfied.