Feature-Based Modeling For Digital Underground Space

Great disadvantages appeared in Geotechnical Engineering result in the invisibility of the subsurface environment, which is now becoming visible with the tools of digitalization. Digitalization is becoming an efficient method to solve certain problems in urban underground space and geotechnical engineering. Among various techniques of digital underground space and engineering science (DUSES), modeling is absolutely the most important one. There are still some great challenges extruding in the difficulties of DUSES modeling: modeling the horizon with arbitrary boundaries in soft clay, the complicated underground structures and modeling the objects in a certain project in life-long term.After compared with the traditional methods of horizon modeling and advanced geometric modeling methods, feature-based modeling technique is chosen to be applied in the field of DUSES, and the objectives of this work are as follows:1. In Chapter 2, to deal with modeling on horizon interface with arbitrary boundary, 3 degree Bspline trend surface is adopted to fit borehole data points on different horizons at first. Secondly, with the help of topology existing in the 4 vertexes of the irregular grid unit, the nip-out points are interpolated. At last, the horizon interfaces with arbitrary boundaries are made by adding boundaries to trend surface with the method of B-Rep. Furthermore, interface update in local region is realized by making full use of the characteristic of localized modification.2. In Chapter 3, feature-based modeling for DUSES is put forward to modeling complicated underground constructions and architects efficiently. Firstly, the definition and category of features for DUSES are analyzed. Secondly, the concept model, modeling method and procedure this technique are presented thoroughly. In addition, temporal and spatial data organization and model representation of objects in underground space are achieved with the model of base state amendments.3. In Chapter 4, two program prototype systems have been worked out with the principle of feature based modeling techniques for DUSES. And in Chapter 5, some practical project modeling examples are accomplished to test and verify the modeling techniques and program.