Research On 3D Geological Modeling Method And Application Of Chengdu Central City Based On Borehole Data

In the past decade,China's urban rail transit a qualitative leap,especially underground rail transit,the situation is by the increasing traffic pressure and the rapid development of our country's economic strength,in the next 20 years,underground will focus for the traffic transportation,to explore from the perspective of new acceleration of urban engineering geological research;In the case of Chengdu,a total of 12 subway lines will be built and put into operation by 2020,and 50 subway lines will be built or approved by 2050.This paper adopts statistical methods to summarize and analyze the stratigraphic profile of Chengdu,and at the same time,based on the borehole data after screening,adopts the model analysis method to carry out 3D geological modeling in GOCAD software for different scales of the central urban area of Chengdu,analyzes the distribution laws of each stratigraphic model and explores the engineering application of the model.The main results are as follows:1.Using data analysis and field investigation methods,the lithology of the entire area of Chengdu is explored on a plane,and the engineering geological map of Chengdu is drawn;on the vertical plane,the city center of Chengdu is used as a research area to conduct After discussing the stratum stratification,abandoning the previous method of stratifying the sand and pebble strata in accordance with the density of the latest stratum,and classifying it according to the latest stratum classification,and drawing a stratum histogram of the study area,which lays a solid foundation for the establishment of a 3D model.2.The methods of combining graphics with collected data,field survey and other methods were used to screen the data along the existing subway line.Finally,the drilling of Chengdu Metro Line 1,2,3,4,7,9,and 18 to the bedrock layer was all effective The data was modeled by the reservoir grid structure,and the purpose is to analyze the distribution of layers in Chengdu and the shape of undulating surface of bedrock layer in Chengdu,which was larger and more accurate than the previous model;At the same time in the study area to take out the local subway line 1,2,3,4 lines surrounded by the borehole distribution is more uniform,more wells as an example,the establishment of a fine structural model,in order to explore the application of the 3D model in the project;3.Using the model analysis method,the application of the three-dimensional model in engineering was explored: the reservoir grid structure model was used to reverse predict the thickness of the "virtual borehole" stratum,and the measured but unrecorded borehole points were used to validate the results,with minimal error,providing theoretical support for the location of the borehole and undesirable areas;By assigning further properties to the tectonic model and slicing the property model to analyze the properties of the target thickness stratum,the weak points and anomalous areas of the stratum were identified,illustrating the value of the tectonic model in engineering applications.