Dong Ji ¹ Jing Hou ² Zhiliang Cheng ^1* Shuai Wei ¹ Yue Zhai ³ Wenhao Li ¹

• ¹ Weifang University, Weifang, China
• ² Qingdao Research Institute of Geotechnical Investigation and Surveying, Qingdao，China, Qingdao, China
• ³ Xiangyang Institute of Surveying and Mapping, Xiangyang, China, Xiangyang, China

The 3D geological model is crucial for geotechnical simulations and assessments in coastal urban environments with complex bedrock formations. This study presents a multi-scale 3D geo-logical modeling methodology for coastal bedrock cities. A double-weighted interpolation fit-ting method was proposed for the seamless integration of heterogeneous data sources, ensuring a smooth transition and maintaining accuracy in land-sea data fusion. A three-tiered coding system was developed for bedrock layers that effectively represents the degree of weathering, geological age, and lithological characteristics, addressing complexities and standardization issues in rock formations. Utilizing Qingdao as a case study, the proposed methodology has successfully facilitated the development of models across four scales. This includes a comprehensive city-wide model, five models designed for general application, two demonstration models, and a quintet of boutique zone models tailored to specific localities. The integration of 3D geological modeling with technologies like BIM, GIS, and IoT demonstrates significant potential in supporting coastal urban construction and geological disaster mitigation, contributing to the sustainable development of coastal areas.