Research on risk assessment system for water inrush in the karst tunnel construction based on GIS: Case study on the diversion tunnel groups of the Jinping II Hydropower Station

•Two type models have been built for risk assessment of water inrush.•Model one is conducted by setting the weight using AHP.•Model two is made using the rock mass mechanics theories.•The risk assessment system of the Jinping II Hydropower Station has been developed.•Information extraction, model calculation and automatic mapping have been realized. This paper studies the risk assessment system for water inrush in the karst tunnel using geographic information system (GIS) technology to predict dynamically the water inrush risk and to develop appropriate protective measures. The risk assessment of the water inrush with geological flaws is conducted where the weight is set using the analytic hierarchy process (AHP) to establish the assessment models, whereas that with no geological flaws is made using the rock mass mechanics theories. The technical route to predict the water inrush risk is based on the geological data obtained prior to prospecting, and the prediction is introduced into the assessment system as background database. The geological and underground water data during construction are combined to correct the water inrush model parameters. The corrected parameters are used to update the basic database of the assessment, and the updated data are employed to assess the water inrush risk before construction. During this research, GIS is introduced into the specialized model of risk assessment of the water inrush. MAPGIS geographic information system software is selected as the basic platform of GIS, and VC++ is selected as the development tool. The assessment of the water inrush model adopted in the system is tested in water inrush cases in the auxiliary tunnel in Jinping II Hydropower Station. The results validate the reliability of the model. The system realizes a real-time assessment of the water rush in the karst tunnel by providing a relatively correct and direct geological basis for the design of waterproof tunnel excavation and offers a practical guide on safe tunnel construction.