The Overground-Underground Integrated Modeling Based On City-Stability Evaluation

In the acceleration process of our digitalization construction, the natural geological environment and resource conditions directly restricts the layout and development of our country’s modernization construction. How to actually and accurately describe the earth, understand the earth, comprehend the geological features of our positions, and then provide the decision-making basis for economic construction, which is one of the primary missions in building the “Smart City”. And the three-dimensional(3D) geological modeling is its foundation.With the rapid development of the computer technology, 3D visualization technology and geospatial information technology, the research on city 3D modeling and visualization has been paid tremendous attention, and has become research focus in the field of 3D city and 3D geological simulation. Except planning the ground buildings and landscaping, the geological stability and security should also be fully taken into account during the urban construction. The integrated model integrating the ground and underground is essential for urban geological stability evaluation.Encompassing the related theories and technologies in these aspects of city 3D modeling method, 3D geological modeling method, 3D spatial data model, and 3D spatial data organization and management, the research is conducted. The detailed algorithm is given, and the bottom development, implementation and test are performed, including:(1)Research on multi-scale display mode of geological information. A variety of data are involved in when geological exploration personnel carry out various activities, and data of different scales are required according to different business activities. Different business activities have different data requirements and the data have strong scale characteristics. There are inevitable inherent relations between business activities and the scale. On the base of the multi-scale characteristics of geological data, from the perspective of the generalized scale operator, the multi-scale data display mode based on TSO matrix is proposed. The stratum surface is organized in accordance with TIN model, the Scale ID field is added in the stratum surface data structure, and then the stratum surface multi-scale control is realized.(2)Research on key techniques of formation model building. In view of different scale geological information such as point, surface and space, using coordinate transformation method, the unified expression of multi-scale geological information is achieved. Based on the study of the geological information structure characteristics, in consideration of the complexity of the geological structure, taking fault structure for example, a rapid construction technique of typical model of the complex geological structure is designed. The regional unbiased estimation interpolation method is designed to complete the interpolation operation of fault classification regions. Irregular grid data of each segmented region is built. Through boundary fitting, the geological model of complex geologic bodies based on TIN triangulation network is quickly built.(3)Research on the ground and underground integrated modeling technology. In order to solve the problem of urban ground and underground integrated modeling, utilizing the open source graphics library OSG, the secondary development is carried out to realize the integration display of formation model and the ground model. OSG is an object-oriented 3D visual simulation development kit and it not only contains extremely rich class library, flexible operation and superior performance, but also provides excellent support for LOD technology and multiple formats of model data like OpenFlight. 3D formation models and 3D drilling models are built with OSG and multi-layer DEM. At the same time, the models on the ground built by Creator are loaded. With space coordinates of drilling control points on the regional topographic map and drilling layout as reference, the ground models and the underground models are integrated. Questions like intersection, cracks will exist between the formation model and the model on the ground. Since the ground building model is established with terrain as reference and the top interface of the formation model is the ground surface that is the terrain, therefore, the intersection of the ground and underground model is actually the intersection of two terrain model. With the terrain of the model on the ground as reference, through intersection and clipping with the top surface of formation model, the seamless integration modeling of the model on the ground and formation model is achieved.(4)Research on geological stability analysis based on the integrated model. It mainly includes information query, pit slot excavation, formation smoke layer and measurement of 3D geological object and automatic generation technology of the topic maps.Taking advantage of geological modeling software at home and abroad, the ground and underground integrated software system prototype based on the city stability evaluation is developed in the development environment with Vega Prime, OpenGL and VC++ 6.0. The main functions like data import and export, interpolation processing, 3D geological modeling, integrated modeling and geological stability analysis are covered. The theoretical model and the actual geological data information test show that the system usage of geological evaluation in urban planning and design can be basically meet.