Research On 3D Visualization Fine Modeling Of Urban Quaternary Sedimentary Facies

With the development of geological information technology, as well as the proposition and construction of "Smart City" and "Glass Land", three-dimensional geological modeling technology are more and more receives people’s attention.3D geological modeling which is a basis of a series of geological application, such as geological spatial analysis, the simulation of geological process, the explanation of geological phenomenon the usage of underground space and the evaluation of mineral resources. It is not only important to seeking the combination between engineering construction and geological environmental conditions, but also important to improving the efficiency of urban planning, urban construction, urban management and the usage of underground space, and it is significant to seeking city maximum economic and environmental benefits.The topic of this dissertation is coming from the project "Fuzhou city (Minjiangkou area) geological environment information and data management service system" (Shorted form is Fuzhou urban geological information system) which is a kind of provincial and ministerial level cooperation project. This topic is studying on the technological and methods of the construction of 3D geological model, and directly facing the field of geo-information engineering frontier which is the study of urban 3D fine geological modeling method. The study, which is on the basis of existing 3D geological modeling technology and combining with the characteristic of urban geology, and its purpose is to find a new 3D geological modeling method, by which it can support reasonable urban planning, constructing and using of underground space.The construction purpose of urban 3D fine geological modeling is reproducing the underground structure of urban in 3D space as real as possible, so as to made the geologists could feel the underground geological body and geological structure directly and vividly, and its purpose is to improve the cognitive level about urban water resource and urban geological environment condition, and to support the planning, constructing of urban infrastructure and underground space, as well as the early warning and prevention of geological hazard.In this paper, aiming at the characteristic urban geological body and geological structure, as well as the requirements of 3D geological fine expression, it focus on the theory of putting the knowledge of sedimentology into the process of 3D geological modeling construction, probing the feasibility of constructing 3D geological model by using Triangulated Irregular Network (TIN) and Corner Point Grid model (CPG, a kind model of Irregular Hexahedral) which is a kind of hybrid spatial data model, proposing and realizing the solution of 3D Visualization Fine Modeling of Urban Quaternary Sedimentary Facies. The main idea of this solution is:firstly, building the quaternary sedimentary facies sections about the research area, by using the bore data and relative geological information and combining the quaternary sedimentary knowledge; secondly, vectorizing the sections and establishing the quaternary comprehensive stratigraphic framework model; thirdly, using the tool about TIN model transform to CPG model, and realizing the construction of 3D fine geological model; finally, programming the relevant function of spatial analysis.Basing on the up thoughts, the main results of this paper are as follows:(1) According to amount of bore data and surface geological data, merging fine stratums according to sedimentary knowledge, drawing the sections by combining plans and sections, and comparing them as well, analyzing the distribution of bedrock and four intervals characteristics of Fuzhou urban (Minjiangkou area) quaternary sedimentary environment and spatial-temporal evolution. These four intervals of quaternary in turn from old to new is:Pleistocene Series (indivision) residual soil and slope washes (Qpel)、Middle Pleistocene Series (QP2)、Upper Pleistocene (Qp3) and Holocene Series (Qh).(2) Basing on the analysis of sedimentary environment and sedimentary facies, it was drew 50 quaternary sedimentary facies sections and 4 quaternary sedimentary plans about Fuzhou. By using this way which basing on the analysis of sedimentary, it replaced a traditional way which are "sand to sand" and "soil to soil", and its merits are:firstly, it is easy to understand the structure of strata and the changes between sections; secondly, it is more reasonable and real on extrapolating and connecting between sections, so as to supporting the topology inference by given geological knowledge.(3) Proposing a new quaternary 3D geological fine modeling method which is basing on the knowledge of quaternary sedimentary and knowledge driven. Its main thinking is:firstly, building the quaternary sedimentary facies sections about the research area, by using the bore data and relative geological information and combining the quaternary’ sedimentary’ knowledge; secondly, vectorizing the sections and establishing the quaternary comprehensive stratigraphic framework model; thirdly, using the tool about TIN model transform to CPG model, and realizing the construction of 3D fine geological model; finally, by using the technique of vector shear constructing the form of the model. The model constructed basing on this method can better express the objective of underground geological body.(4) According to the requirement of urban quaternary 3D geological fine modeling, it proposed a constructing thinking and principle about hybrid spatial data model which are basing on TIN and CPG. The process is:constructing 3D structure-strata framework model by using TIN model, expressing fine geological structure by using CPG volumetric model; by using transform tool about spatial data model, it can transform the model from TIN to CPG. so as to achieve constructing 3D fine geological model.(5) Programming and realizing the transform algorithm which is used to transform spatial data model from TIN to CPG. First of all, make sure the definition model about stratigraphic sequence in TIN model corresponding with it in CPG model; when transforming, make sure the dividing way and dividing method of CPG model grid according to the boundary and direction of the model; finally, calculating spatial coordinates of each grid in CPG model by using the control grid, and taking advantage of*.GRDECL file format realizing the storage and expression of 3D geological fine model.(6) Proposing the constructing 3D fine geological method basing on CPG data model. In this method, it is basing on the structure-strata framework model which constructed by using TIN-CPG hybrid data model, and by using appropriate spatial interpolation algorithm, calculating the attribute data of each grid cell in CPG model, then according to the characteristic of *.GRDECL file format, writing these attribute data into attribute file, accordingly, it can realize the construction of 3D fine attribute data model.(7) Basing on the upon method and algorithm principle, it modeled a few quaternary 3D geological models in different size, they are; Fuzhou (Minjiangkou area) quaternary 3D structure-strata framework geological model, Fuzhou (Minjiangkou area) quaternary 3D fine geological model and Fuzhou university town area hydrogeology 3D fine geological model.(8) Basing on the accomplishment of construction principle, method studying and realization of 3D fine geological model, it developed the function of geological section and extracting space attribute grid cell. Geological section which means cut out the model in the direction of X, Y, and Z, and making the response sections; Extracting space attribute grid cell which means according to the parameters, extracting the corresponding grid cells in CPG model, and show them independently.In conclusion, in this paper, it referenced the state-of-the-art research results in the field of 3D geological modeling, according to the underground geology structure characteristics of urban quaternary, using the knowledge of sedimentary facies, solving the problem of heterogeneous geological structure fine expression in 3D structure-strata framework, designing and realizing it by using Visual C++ computer language. Its main innovation points are:1. According to the quaternary 3D fine geological modeling requirements, proposing TIN-CPG hybrid spatial data model, demonstrating and realizing this kind of spatial data model. Its main thinking is:constructing 3D structure-strata framework model by using TIN data model, choosing CPG data model to expressing 3D fine geological structure; then transforming TIN model to CPG model by using spatial data model transforming tool, so as to achieving the construction of 3D fine geological model.2. Proposing a method of constructing quaternary 3D fine geological model which is basing on sedimentary knowledge. In this method, firstly, it needs to compilation geological section and geological plans by analyzing sedimentary environment and sedimentary facies, then basing on these maps, according to the analysis results, making topological and reasoning construction by using TIN-CPG hybrid spatial data model. On account of the involving of sedimentary knowledge, the models are more conform to the real underground geological structure.In this paper, it aims at the problem that the geological content deficient on most of 3D geological models in 3D urban geological modeling currently, to this question, it proposed that putting sedimentary knowledge into the process of modeling, and applying the solution which is expressing the fine geological model by using TIN-CPG spatial data model. Besides, the results which are achieved had been used in the project of "Fuzhou urban geological information system". This solution has strong universality, and according to the different area of its own geological environment characteristics, the solution to be expanded and improved, it could be used in the relative geological field, such as oil & gas and metal mineral exploration, survey and design of water conservancy and hydropower engineering, survey and design of railway engineering, as well as in the field of geological hazard investigation.