Evaluation of urban underground space resources using digitalization technologies

Exploitation and utilization of urban underground space resources is gaining increasing attention in cities’sustainable development.Due to the attributes of fragility and irreversibility,urban underground space resources can be extremely vulnerable to damage and it is often difficult in restoring their original state once damaged.Therefore,scientific and reasonable evaluation of urban underground space resources is of vital importance in urban planning and development.This paper first describes the content and methods for the evaluation of urban underground space resources,and introduces the digitalization technologies to handle the problems of strong subjectivity,low efficiency and rough precision encountered when using traditional evaluation tools.Then,the related concepts and main technologies for digitalization were demonstrated and an intelligent GIS-based engineering geology system was built.Based on the drilling information in Changzhou City,stratum standardization and 3D modeling of strata,underground structures and pipelines were conducted in the built intelligent system.Finally,with the help of spatial overlay analysis in the GIS-based platform and a combination of other digitalization technologies,the urban underground space resources of Changzhou City were evaluated.Maps of geological suitability were produced,which provide scientific guidance and reference for the exploitation and planning of urban underground space resources in Changzhou City.In addition,site selection for key projects was conducted based on the evaluation results using this platform.

Comprehensive safety evaluation method of surrounding rock during underground cavern construction

The deformation instability of surrounding rock and the collapse of rock blocks are two common failure modes observed during the construction of underground caverns.Therefore,a comprehensive safety evaluation method(CSEM)of surrounding rock for application during underground cavern construction is presented in this paper.The method can be used to evaluate the deformation stability of surrounding rock and predict the collapse of rock blocks,rapidly.First,a deformation stability prediction and evaluation method(DSPEM)for rock mass is established.It combines the safety evaluation method based on a deformation statistical analysis and an inverse deformation prediction method using measured deformation data of surrounding rock.This approach possesses the unique characteristics of complementary and mutual verification.In addition,a comprehensive early-warning index system(CWIS)for assessing the deformation stability of surrounding rock is presented.It consists of three types of warning indicators and three levels of warning values.The earlywarning values can be adjusted reasonably by the prediction correction method according to the measured displacements.For the collapse of rock blocks controlled by structural surfaces,a rapid prediction method of rock block collapse(RPMBC)based on the block theory is then presented.Finally,combining the DSPEM,RPMBC,and CWIS,the CSEM of surrounding rock for assessing the safety of cavern construction is established.It can provide technical support for decision making on the safety of surrounding rock during the construction of underground caverns.