Analysis of Construction of Shallow Underwater Tunnel Based on Transient Characteristics of Excavation Unloading

In order to research the surrounding rock stability of shallow underwater tunnel at the action of dynamic unloading,according to numerical simulation and real-time monitoring data,three-benching tunnelling method of explosive excavation and combination excavation method of milling-dig and controlled blasting are chosen to analyze the influence of transient characteristics,dynamic effects and construction method on the dike by taking the Liuyanghe tunnel project in Changsha City for an example.The results show that combination excavation method of milling-dig and controlled blasting can control vertical disturbance of surrounding rock effectively and ensure safety and reliability of tunnel mining for unstable geologic river bed and dike,which has good practicability and popularization value in shallow underwater tunnel project.