###### Abstract  
Three-dimensional (3D) geological models are currently needed and used independently for urban development. The main difficulty in constructing a 3D geological model of a shallow subsurface is to determine the stratigraphic distribution. Highly variable properties and geometries of geological units beneath lead to difficulty. It is key to find a practicable and efficient way to construct a model in practical work. This study takes Tongzhou District (Beijing) as a case; 476 boreholes (40 newly drilled and 436 existing engineering boreholes) were utilized combined with the cross-section method to construct an integrated 3D geological model. The framework and analyses contributed to the following applications: (1) High-quality information from new boreholes and existing engineering boreholes were used to define stratigraphy and build cross-sections. (2) The resulting geological model (up to 50 m beneath Tongzhou area) shows many details of the shallow subsurface. This includes 10 major layers which were grouped into three cyclothens representing cyclic sequences of clay, interbedded silt, sand, and gravel with variable quantities of lenses. (3) The new model was used as a tool to visualize the depth and geometry variations below ground and to characterize a large variety of properties (for example, the compression modulus analyzed in this paper) that each unit contains, and then to evaluate the underground geological conditions. (4) An analysis of a dynamic monitoring model based on the resulting 3D model indicated that the geological units (sand and silty clay) at depths between 30 m and 40 m, with an average vertical deformation of 0.97 mm, from July 2019 to September 2020, are suitable for underground construction, from the perspective of vertical stability in the study area. Monitoring models that take time into consideration based on a 3D framework will be further explored. three-dimensional geological model; shallow subsurface; geotechnical properties; cross-sections; urban underground space; monitoring station; Tongzhou District +
Footnote †: journal: _Sci._  
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are heterogeneous [7; 8]. Although the geological and geotechnical investigation method provides detailed information at discrete locations [8], soil properties can be highly variable in the vertical direction. Three-dimensional (3D) geological modeling is then developed as an effective method to describe such variability subsoils exhibit in both horizontal and vertical directions. In an urban setting, it is challenging to construct a 3D geological model. As an effective tool to visualize the urban subsurface [9; 10; 11; 12], 3D geological modeling has been developing quickly in the past decades [8; 13; 14; 15; 16; 17; 18; 19; 20]. This method can deliver a better understanding of the subsurface structures [21; 22; 23; 24; 25; 26] and portray the properties that are heterogeneously distributed within geological bodies [17; 27; 28; 29]. Additionally, a variety of 3D geological models has been constructed to aid resource evaluation [6; 9], to explore geological conditions [30; 31; 32; 33], and to study the geotechnical properties of the subsoils [7; 10; 34; 35] to promote understanding of shallow subsurfaces. Researchers from the British Geological Survey [2; 5; 12; 36; 37] have constructed a variety of 3D geological models at all scales from sites to cities to the UK landmass and continental shelf using various software tools and modelling approaches [38]; [PERSON] et al. [9] built a 3D geological model to establish the UUS quality level and distribution in Foshan city in Guangdong Province, China; [PERSON] et al. [33] constructed a 3D model of land subsidence to simulate groundwater flow aquifer system displacements in downtown Shanghai (China); [PERSON] et al.