Abstract: Three dimensional geological modeling is one of the basic tasks for the construction of "smart city", which involves urban-level geological range from hundreds to thousands of square kilometers. Because the urban geological model spans many geological units and the geological conditions are complex, the traditional three dimensional geological modeling methods have insufficient consideration of correct stratigraphic connections across different geologic units. A unified stratigraphic sequence method based on stratigraphic sedimentary sequence can identify the special condition such as stratum loss and stratum reversal, thus both the abnormal and the normal cases can be identified, avoiding incorrect interpolation in 3D geological modeling. By adding zero-thickness layers, the stratigraphic sedimentary sequence of all drilling holes can be completely consistent, and the match-up of stratum between drilling holes are constructed. In this paper, three special cases of stratum loss, reversal and repetition are discussed in detail, and this method is verified in different examples. The results can effectively make a clear judgment on the connection problems of various geological conditions in the three dimensional geological modeling in the urban. It can reduce the incorrect stratum connection in the three dimensional urban geological modeling with complex geological conditions and many geological units, and it provides efficient support for the development of "smart city".

Key words: urban three dimensional geological modeling, unified stratigraphic sequence, stratum loss, stratum reversal, stratum repetition