Study On Exploration And Prevention And Treatment Of Karst At The Bottom Of Shennong Tunnel In Taijiao Railway

Because there are many mountains in our country,the high-speed railway often passes through the complex geological environment,and the high-speed railway has more strict standards for the subgrade bearing capacity,compaction coefficient,compressive strength,deformation,settlement and other technical indicators,so the lithology,geological structure,karst development at the bottom of the tunnel directly affect the stability and firmness of the high-speed railway subgrade,while the subgrade The quality has a direct impact on the normal operation of the railway.In order to ensure the smooth and safe operation of the railway,a complete set of tunnel bottom karst exploration and treatment method is urgently needed.Based on Shennong tunnel of Taijiao railway,through geological investigation,HSP and GPR,this paper explores the karst development at the tunnel bottom,and uses computer to model the tunnel and surrounding rock to simulate the stress-strain state of the tunnel bottom before and after the treatment of karst holes.It is found that after the treatment of Karst holes,the stability is improved,and the deformation at the tunnel bottom becomes smaller,which meets the requirements of the specification.Therefore,the karst development is improved Grouting treatment is adopted in the area.After treatment,seismic imaging method and geological radar method are used for remeasurement respectively.It is found that karst holes and cracks at the tunnel bottom have been filled with concrete and the tunnel bottom has reached a dense state.It is proved that this method has good effect on the exploration and treatment of karst at the tunnel bottom.This paper mainly does the following research:(1)Combined with the geological data of the early exploration in the tunnel area,this paper uses the seismic imaging method to detect the karst disease at the tunnel bottom in three side lines.(2)On the basis of the seismic imaging method,the abnormal area detected is detected by the geological radar once more to determine the karst area and karst development.(3)ANSYS model is used to simulate the stress-strain state of the tunnel bottom when the tunnel bottom is loaded when the karst hole is not treated and the stress-strain state of the tunnel bottom when the tunnel bottom is loaded after the grouting and solidification of the karst hole.(4)After the grouting treatment of the karst holes at the tunnel bottom,the seismic imaging method and the geological radar method are respectively used to explore the tunnel bottom to verify whether the results of the karst treatment at the tunnel bottom meet the requirements of the specification.(5)This paper sums up a set of methods to explore and deal with the karst at the tunnel bottom.First,combining with the geological data,the seismic mapping method and the geological radar method,the development position,scale and the shape of the karst hole at the tunnel bottom are explored.Then,the stress-strain state of the tunnel bottom before and after the treatment is compared by numerical simulation.Next,the karst hole is grouted,and finally retested to verify the result of the karst treatment Fruit.