Investigation,Evaluation And Modeling Research On Geological Environment Of Suzhou Ancient City

Under the influence of "big city disease",underground space development,as a new form of resource utilization for sustainable urban development,has become the current national development trend,especially in the core ancient urban areas where space resources are scarce,which is of great significance.The geological environment restricts the development and utilization of underground space.Therefore,conducting survey evaluation of geological environment and visualization of 3D geological modeling is the primary prerequisite for reasonable development.This paper used the ancient city of Suzhou as the research area to conduct geological environment survey evaluation and modeling research.The main work and research results are as follows:(1)Geological data of the ancient city of Suzhou was collected to find out and investigate the utilization of underground space.Based on the collected relevant regional geological data,a reasonable and unified division of the soil layers in the ancient city of 90 m and below is carried out.Important physical and mechanical parameters,hydrogeological conditions and unfavorable geological conditions of engineering geology in this area is clarified.Typical geological profiles of the study area were drawn and determined key geological information of the study area was determined.At the same time,in oder to build an underground environment information system in the ancient city,the distribution of underground space was calculated and underground communication channels were designed.(2)We studyed the definition of stratigraphic sequence,geostatistical methods,typical modeling methods in the 3D geological modeling method and determined the basic modeling ideas:build stratum modeling based on drilling data,establish a 3D stratum-groundwater model in the study area and underground space engineering and then form a threedimensional integration of underground space.Through model cut analysis,the results clearly reflect the distribution of rock and soil at different depths in different regions,thickness and depth of aquifers and distribution of underground space.Due to sparse boreholes and severe data discretization in the study area,the overall reliability of the study area model is theoretically different.In order to verify the reliability of the model,we selected areas with dense borehole data to perform borehole verification and profile verification respectively and selected different numbers of boreholes for modeling to verify the reliability of each group of models in groups.Then reliability evaluation standards for the study area was established which was used to evaluate reliability of the builded model.(3)According to the characteristics of ancient Suzhou city,analytic hierarchy process and expert survey method wad used to determine the three thematic layers of the geological environment influencing factors in the study area,quantify the index layers and obtain the weight coefficients of each indicator.Then the ancient city of Suzhou District geological environment index system was builde.We determineed the evaluation criteria for underground space development according to the mathematical evaluation model and divided the geological environment for underground space development into four levels:level I(suitable),level II(generally suitable),level III(less suitable)and level VI(unsuitable).With the help of Arc GIS spatial function analysis for visual analysis,the suitability of the shallow and sub-shallow geological environment of the ancient city of Suzhou is evaluated.The evaluation results provide scientific suggestions for the development path and location of the underground space of the ancient city of Suzhou.