Geological Engineering in complex geological bodies of various geological information can be seen as a function of three-dimensional space, using field measurement data respectively to establish appropriate surface fitting function, and use of computers to create a three dimensional geologic model, achieve the Visual expression of geological information in engineering rock mass distribution, increase awareness, guidance for geological rule of geological surveying and construction of projects and monitoring purposes. This article provides an analysis of three dimensional modeling and visualization of complex geological key technical problems and preliminary application in xiangjiaba dam area of three dimensional geologic modeling.
First, the preamble
Geological Engineering in complex geological bodies of various geological information can be gained through field exploration or monitoring devices record measured, but are generally scattered data, engineering workers in its engineering rock mass difficult to has a comprehensive and intuitive grasp of the distribution. Various geological information, including surface terrain, and groundwater bit, and formation interface, and fault, and section acting, and weathered with distribution, and intrusion body and the various Earth physical, and geochemical, and rock soil body of physical mechanical parameter or data of equivalent surface (line),, are can seen as is three dimensional space in the of function, using various field measured information respectively established corresponding of surface intends hop function, turn using computer established three dimensional geological model, reached intuitive to expression geological information in engineering rock soil body in the of distribution law, and improve for geological law of awareness, and guidance geological project of survey construction and the monitoring of purpose. Establishment of three dimensional model of geological engineering of complex geologic body, rock interface combined with a discontinuity, lifelike picture reflected the subsurface geological structure, for geological engineering workers analysis of engineering geology and rock-soil mass structures found law provides a new set of research methods and research methods.
Second, the complex geology of three dimensional modeling and visualization, and software development
Present situation of domestic research and development: TITAN three-dimensional modeling software was developed by Beijing Oriental technology Titan TITAN geo-a component of the integrated information system is based on modeling the ideological development of the framework, using parallel or parallel profile data to build arbitrarily complex three dimensional space of true three dimensional solid model of the shape object. TITAN three dimensional built die software of part has: (1) profile data processing module, established profile data, for established three dimensional entity model provides by series parallel of profile composition of framework data, data profile by polygon, and ring and point element composition; (2) corresponds relationship processing module, established profile Zhijian, and polygon Zhijian, and ring Zhijian and point Zhijian of corresponds relationship, for established three dimensional entity model provides profile between of one by one corresponds relationship, thus established built die element Zhijian in three dimensional space in the of contact; (3) model processing module, established entity model, with profile data and profile between of corresponds relationship established up three dimensional entity model, and can on model for arbitrary cutting, and calculation area and volume of processing. This software is only three-dimensional modeling and graphics engine, applied widely. However, when you face the specific professional, you need to add or expand the professional module, such as engineering geology module. Panoramic view of the current situation of research and development of several software, for geological engineering modeling and analysis of complex geological bodies targeted is not strong, did not fully reflect the particularities of geological engineering, geological engineering production and not be very good to meet actual needs of the research
Three complex geology, geological engineering modeling and visualization of three dimensional analysis of key technology issues
(A) discrete interpolation and data fitting
Geological information of the fitting and interpolation functions according to the actual survey data, measured data is more accurate, be more authentically depicting the geological model of the spatial distribution of the information. For the different geological information, use different fitting function. Surface topography measurement data (x, y coordinates and surface elevation z), buried depth of groundwater level measurements of surface generated graphics can be summed up in two-argument fitting and interpolation of the discrete data. Surface interpolation function has the following structure method, and is inversely proportional to the distance-weighted method, method of radial basis function interpolation, plane elasticity theory method of interpolation, which also applies to a single interface, geophysical data, continuous formation of rock and soil geochemical exploration data and spatial distribution of physical and mechanical parameters of rock mass.
(B) three dimensional data structures
Geological Engineering geologic body is generally irregular shape, curves and surfaces in computer graphics is always separately by many tiny line segments and small triangular surface approximation, to simulate the boundary of the lithology and rock surfaces, that interface and rock surface rock formation are the collections of many tiny line segments and small triangular surfaces. This requires that you must have a valid hierarchy of three dimensional data structures, such as geology and engineering geology in the space of points represented by the three-coordinate component of that tiny line segment is composed of its two endpoints, geological boundaries is made up of tiny line segments all part of the boundary, and rock surfaces made up of tiny triangular surface. Three-dimensional data structures to ensure effective realization of human-computer interaction and query.
(C) analysis of the surfaces and topology of three-dimensional intersection
Geological body in the exists large various level, including surface, and groundwater bit surface, and formation level,, dang appears formation not integration, and formation tip fight and groundwater out dew Yu Valley surface, scenario Shi, on natural will encountered surface between seeking cross of problem; geological body three dimensional model of upper boundary is surface surface, through mathematics method intends hop out of rock level or underground water level surface not should beyond surface surface, is beyond part not should display. Similarly, when you show when several strata, per stratum should be below a rock on its boundary. The other hand, when in profile graphs, geological boundaries of drawing was through the display profile and interface of various geological derived line of intersection. Intersect the surface intersection between geo-interface, and intersect two categories of geological profile and interface issues. From the perspective of geology, topology is the relationship between geologic objects form storage layer overlying the topology table, underlying and cross-cutting, such as stratigraphy and geological spatial relationships. Using visualization techniques can construct from a huge geological survey data for edges broken geological engineering stability and deformation of underground Chamber, played a key role in rock formations and structures, and displays the trend of its scope, and meet each other, help engineering personnel to correctly interpret the original data and provide decision support for geologic analysis of specific issues.
Four, three dimensional modeling of complicated geological entity and preliminary development and application of visualization technology
(A) geological engineering complex three dimensional modeling and visualization of geologic body
Based on discrete sampling data of plug value and intends hop of thought, is discrete data transformation for continuous curve surface, geological engineering, complex geological body three dimensional built die and Visual of of process is, from exploration database in the extraction various geological information of coordinates location and the rock soil body of physical mechanical parameter, through different of intends hop and plug value function get geological level (surface) and geological entity of three dimensional computer graphics display, expression geological information in research regional within of distribution law. After building the geological rock layers and geologic entity, from any angle to establish model and realization based on the specified section to, generate vertical inclination and angle sections.
(B) development and application of preliminary
Engineering survey and spatial databases to collect survey data into the data table, these data tables include not only the location of geological information data, attribute data is more important to provide. Lithology data tables, for example, requires entry hole termination depth of number, the starting depth, rock strata, layer thickness, lithology, stratigraphy code, rock to rocks, rock orientation, inclination, contact relationships, geological description and other data. With the development of engineering survey, can easily be modified to add and manage survey data. Xiangjiaba dam site engineering survey data, the establishment of a three dimensional geologic map at the right bank. To home dam a dam area bottom formation rock sexual combination for: fourth Department collapse breaking stacked property, Jurassic mudstone, and powder sand mass mudstone, and mud mass powder sandstone, three stack Department Shang Commission thick to giant thick layer shaped fine to in the grain sandstone, three stack Department Shang Commission thin to in the thick layer shaped powder sand rock, and powder sandstone, three stack Department Shang Commission in the thick to thick layer shaped in the rough sandstone. Stereogram drawn by limited engineering survey data, to better meet the precision of engineering geology.
Five, conclusions
Geological Engineering of complex geologic body modeling and visualization study of rock-soil mass structure in geological engineering, intuitive expression of geological information in geological engineering in rock-soil mass distribution laws and guidance of geological surveying and construction of the project is of great significance. Geology is a complex of engineering rock mass of irregular shape, there is a variety of geological rock layers and structure, full expression and rock formations and geological information structure, cutting each other, and combination relationship between location, geological engineering of complex geologic body modeling and visualization of three dimensional research is promising.
Reference literature
[1] Sun Guangzhong, engineering geology and geological engineering, s Sun Guangzhong, Seismologic press, June 1993
[2] such as Huang Dingcheng, Henan science and technology of the Chinese Earth science toward 21st century press, October 1995
[3] Zhang Mingding, of the systematic thinking of hydrogeology and engineering geology of the Northwestern Polytechnical University Press
复杂地质体三维建模
地质工程复杂地质体中的各种地质信息都可以看作是三维空间中的函数，利用各种野外实测资料分别建立相应的曲面拟合函数，进而利用计算机建立三维地质模型，达到直观地表达地质信息在工程岩土体中的分布规律、提高对于地质规律的认识、指导地质工程项目的勘测施工及监测的目的。本文分析了复杂地质体三维建模与可视化研究的关键技术问题,并初步应用在向家坝某坝址区的三维地质建模中。
一、前言
地质工程复杂地质体中的各种地质信息，可以通过野外勘探实测或监测仪器记录获得，但一般都是散乱数据，工程地质工作者很难对其在工程岩土体中的分布规律有一个整体和直观的把握。各种地质信息，包括地表地形、地下水位、地层界面、断层、节理、风化带分布、侵入体及各种地球物理、地球化学、岩土体的物理力学参数或数据的等值面(线)等，都可以看作是三维空间中的函数，利用各种野外实测资料分别建立相应的曲面拟合函数，进而利用计算机建立三维地质模型，达到直观地表达地质信息在工程岩土体中的分布规律、提高对于地质规律的认识、指导地质工程项目的勘测施工及监测的目的。建立地质工程复杂地质体的三维模型，处理岩层界面与结构面组合关系，逼真反映地下地质结构全貌，将为地质工程工作者分析研究工程地质现象和发现掌握岩土体结构规律提供一种崭新的研究手段和研究方法。
二、复杂地质体三维建模与可视化研究和软件开发动态
国内研究与开发现状：TITAN三维建模软件是由北京东方泰坦科技有限公司开发的TITAN地学综合信息系统中的一个组件，是基于框架建模的思想研制开发而成的，利用平行或基本平行的剖面数据建立起三维空间任意复杂形状物体的真三维实体模型。TITAN三维建模软件的组成部分有：（1）剖面数据处理模块，建立剖面数据，为建立三维实体模型提供由一系列平行的剖面组成的框架数据，数据剖面由多边形、环和点元素组成；（2）对应关系处理模块，建立剖面之间、多边形之间、环之间和点之间的对应关系，为建立三维实体模型提供剖面间的一一对应关系，从而建立建模元素之间在三维空间中的联系；（3）模型处理模块，建立实体模型，用剖面数据和剖面间的对应关系建立起三维实体模型，并且可以对模型进行任意切割、计算面积和体积的处理。此软件只是三维建模与图形处理的引擎，适用面广泛。但在面向具体专业时，需要添加或扩充专业模块，比如工程地质专业模块等。纵观国内外几种软件的研究与开发现状，对于地质工程专业的复杂地质体建模与分析的针对性不强，没有充分体现地质工程专业的特殊性，不能够很好地满足地质工程生产与研究的实际需要
三、地质工程复杂地质体三维建模和可视化的关键技术问题分析
（一）离散数据的插值与拟合
地质信息的插值和拟合函数要根据实际勘测数据建立，实测数据越丰富精确，得到的地质模型越能够真实描绘出这些信息的空间分布规律。对于不同的地质信息，需采用不同的拟合函数。地表地形测量数据(X坐标、Y坐标和地表高程Z)、地下水位埋深测量信息等的曲面图形生成可归结为双自变量离散数据的插值和拟合。空间曲面插值函数有以下构造方法，如与距离成反比的加权方法，径向基函数插值法，平面弹性理论插值法等，它们同样适用于单个连续地层界面、地球物理勘探数据、地球化学勘探数据以及岩土体物理力学参数在地质体空间的分布。
（二）三维数据结构
地质工程地质体一般是不规则形体，在计算机图形学中曲线和曲面总是分别通过很多微小直线段和微小三角面逼近，来模拟地层岩性界线和岩层曲面，即岩层界面和岩层曲面都分别是许多微小直线段和微小三角面的集合。这就要求必须具备有效的分层的三维数据结构，比如地质工程地质体空间中的点由有三位坐标分量表示，微小直线段由其两个端点组成，地质层面界线由所有属于该边界的微小直线段组成，而岩层曲面由微小三角面组成。有效的三维数据结构能够确保人机交互和查询的实现。
（三）曲面求交和三维拓扑结构分析
地质体中存在大量各种层面，包括地表、地下水位面、地层层面等，当出现地层不整合、地层尖灭和地下水出露于河谷地表等情形时，就自然会遇到曲面间求交的问题；地质体三维模型的上部边界是地表曲面，通过数学方法拟合出的岩层面或地下水位面不应超出地表曲面，即超出部分不应显示。同样的，当显示多层地层时，下面的每一岩层应以其上一岩层为边界。另一方面，在剖面图成图时，地质界线的绘制是通过显示剖面与各种地质界面求交所得出的交线。因此曲面求交包括地质界面之间的相交，和地质界面与剖面的相交两类问题。从地质学角度看，拓扑是地质对象间关系的表格，拓扑表存储层位间上覆、下伏和交切等的地层学关系及地质空间位置关系。利用可视化技术可以从庞大的地质勘测数据中构造出地质工程中对于边破稳定性和地下硐室变形破坏等起关键作用的岩层和结构面，并显示其范围、走向和相互交切关系，帮助工程地质人员对原始数据做出正确解释，继而为工程地质分析具体问题提供决策支持。
四、复杂地质体三维建模与可视化技术的初步开发与应用
（一）地质工程复杂地质体三维建模与可视化的
基于离散采样数据的插值与拟合的思想，即将离散数据转化为连续曲线曲面, 地质工程，复杂地质体三维建模与可视化的过程是，从勘探数据库中提取各种地质信息的坐标位置及岩土体的物理力学参数，通过不同的拟合与插值函数得到地质层面(曲面)和地质实体的三维计算机图形显示，表达地质信息在研究区域内的分布规律。生成地质岩层面和地质实体后，实现从任意角度观察建立的模型，实现根据指定的剖面走向、倾向和倾角生成垂直剖面。
（二）初步开发与应用
工程勘测空间数据库在收集整理现场勘测数据后录入各分项数据表，这些数据表不仅包括地质信息的位置数据，更重要的是提供属性数据。以地层岩性数据表为例，要求录入钻孔编号、岩层起始深度、岩层终止深度、层厚、岩性、地层代码、岩层走向、岩层倾向、岩层倾角、接触关系、地质描述等数据。随着工程勘测的进展，能够方便地修改补充和管理勘测数据。利用向家坝某坝址区工程勘测数据，建立了坝址区右岸三维立体地质图。向家坝某坝址区自上而下地层岩性组合为：第四系崩破堆积物，侏罗系泥岩、粉砂质泥岩、泥质粉砂岩，三叠系上统厚至巨厚层状细至中粒砂岩，三叠系上统薄至中厚层状粉细砂岩、粉砂岩，三叠系上统中厚至厚层状中粗砂岩。通过有限的工程勘测数据得出的立体图，能够较好地满足工程地质的精度。
五、结论
地质工程复杂地质体的三维建模与可视化研究对于地质工程岩土体结构的研究、直观表达地质体信息在地质工程岩土体中的分布规律和指导地质工程项目的勘测施工都具有重要意义。地质工程岩土体是复杂的不规则形体，存在各种地质岩性层面和结构面，完全表达地质信息及岩层和结构面间的位置、相互切割和组合关系，地质工程复杂地质体的三维建模与可视化研究是大有作为的。
参考文献
[1]孙广忠，工程地质与地质工程，孙广忠著，地震出版社，1993年6月第1版
[2]黄鼎成等，《走向21世纪的中国地球科学》河南科技出版社，1995年10月
[3] 张明定等，《水文地质与工程地质的系统思维》西北工业大学出版社，1993年12月
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