Geological Environment Suitability Assessment Of Underground Space Development In Haidian District,Beijing

Underground space is an important new type of land and resources,which is non-renewable and irreversible.Once developed,it is difficult to recycle.Therefore,urban underground space development planning should be well done to make it reasonable and orderly developed.In the preparation of urban underground space development and utilization planning,the geological environment factor is the limiting factor of whether the underground space can be developed and utilized.Therefore,the development of geological environment suitability evaluation of underground space development is the premise of the preparation of urban underground space development planning and an important link to realize the rational and orderly development of urban underground space.According to the existing data,Haidian district,this paper analyses the geological factors that affect underground space development in the study area.In the research,8 evaluation indexs are selected from the 5 aspects of landform,engineering geology condition,hydrogeology condition,adverse geological process and ecological factors,such as ground gradient,soil type,soft soil layer thickness,phreatic water depth,water yield property,active faults,land subsidence and the surface waters.The analytic hierarchy process(AHP)was used to establish the evaluation index system and determined the weight of evaluation index.The geological environment suitability of underground space development in the study area was evaluated by comprehensive index method and spatial superposition function of GIS software.The spatial domain of this study is 50 m below the surface of Haidian district,which is divided into shallow layer(0~-10m),sub-shallow layer(-10~-30m)and sub-deep layer(-30~-50m).According to the above evaluation methods,the suitability of shallow,sub-shallow and sub-deep underground space in Haidian district was evaluated.The main research results are as follows:(1)The geological environment suitability for underground space development in Haidian district is divided into four grades: suitability(grade I),relatively suitability(grade II),poor suitability(grade III)and unsuitability(grade IV).The geological environment suitability for the development of shallow underground space is mainly I ~ II grade,accounting for 67.68%.The geological environment is good and it is generally suitable for underground space development.The restricted factors that affect the development of shallow underground space are soil type,ground subsidence,active fault and the surface waters.(2)The geological environment suitability of sub-shallow underground space development is mainly I ~ II grade,accounting for 67.31%.The geological environment conditions are relatively good,and the overall geological environment is more suitable for underground space development.The geological factors that restrict the development of sub-shallow underground space are soil type,water yield property,ground subsidence and active faults.(3)The geological environment suitability of sub-deep underground space development is mainly I~II grade,accounting for 56.23%.The geological environment conditions are general,which is generally suitable for underground space development.The geological factors that restrict the development of sub-deep underground space are soil type,water yield property,ground subsidence and active faults.This paper evaluates the suitability of geological environment for the development of underground space in Haidian district,which can provide reference for the preparation of the detailed regulatory planning of the development and utilization of underground space in Haidian district in the future.