Recognition Of Bad Geological Body In Karst Tunnel And Countermeasures For Construction Of Giant Cavity

With the rapid development of the Southwest,along with the construction of highways and railway networks,a large number of tunnel projects have emerged.However,due to the unique geological conditions of the southwestern region,the tunnel construction in this area has to pass through the karst development area.Therefore,bad geology such as karst has brought great safety risks to the construction.If we can grasp the geological situation in front of the tunnel and combine corresponding construction countermeasures,we can effectively avoid unnecessary karst disasters such as water inrush,mud outburst,and landslides,thereby greatly improving the safety of construction personnel.Relying on the Wen Quan tunnel project,this article uses Google-Earth,UAV tilt photography technology and multiple Advance detection methods to accurately locate the unfavorable geology in front of the tunnel.Through numerical simulation analysis of deep and complicated karst,the corresponding construction countermeasures are studied.The main work is as follows:Based on the study of regional geological data,master the history of sedimentary construction and tectonic evolution in the study area,use Google-Earth to implement the regional structure and stratigraphic interpretation of the study area,and restore the establishment of the ancient tectonic stress field accordingly.Use the UAV tilt photography technology to build a 3D geomorphic model,use ultra-high resolution images,and identify bad geological bodies in the tunnel area according to the theory of structural geomorphology.Understand the geological structure information background before tunnel excavation,thus laying the ground for physical exploration Theoretical basis.The EH4 magnetotelluric method is used to detect large karst structures near the tunnel route,and the TGS360 Pro detection system is used to conduct advanced detection in the cave.Under the guidance of the foregoing theory,the multiple solutions of geophysical exploration can be eliminated and the interpretation accuracy can be effectively improved.In the process of tunnel excavation,using geological cataloging and advanced drilling,on the one hand,further grasp the development of geological structures,enrich and check the aforementioned geological structure information model,and on the other hand,realize accurate detection of bad geological bodies.In this way,from the macro to the micro,from the rough investigation to the precise investigation,the progressive detection methods and evaluation concepts have been successfully implemented,and finally the accurate prediction of the karst disaster has been successfully achieved;Based on literature analysis and field investigation combined with geomorphological image interpretation technology,the karst development rules and characteristics of the tunnel site are summarized.Combined with domestic and foreign tunnel construction treatment methods for karst structures,preliminary countermeasures for karst structure construction of hot spring tunnels are proposed.For the giant karst caves detected during the construction of the Wen Quan tunnel,three representative sections were selected.Using the method of numerical simulation analysis,the stability of the karst cave and the mechanical state of the tunnel structure during the tunnel construction under different working conditions were studied.This optimized design and construction plan.