Analysis Of Typical Water Inrush Types And Mechanism Of Subsea Tunnel

Throughout the history of tunnel and subsea tunnel construction in the world,water inrush disaster has always been one of the common disasters in the process of tunnel construction.Its occurrence frequency and damage degree rank in the forefront of all kinds of tunnel construction disasters.In view of this,this paper summarizes the types of water inrush disaster based on the.type of surrounding rock by studying the adverse geological characteristics of subsea tunnel.The characteristics of surrounding rock are generalized,the mechanical model is simplified and the minimum thickness of outburst layer is studied for two typical underwater tunnel water inrush disasters.Finally,the flow characteristics of the mud-water mixture in the tunnel affer the water burst disaster are analyzed.In this paper,the typical water inrush type and prevention mechanism of submarine tunnel are systematically studied by summarizing,theoretical analysis,numerical simulation and engineering cases.Combined with the construction of Qingdao subsea tunnel,the disaster conditions and mechanical mechanism of water inrush disaster are further studied.The flow situation after the disaster is simulated and analyzed.The main research contents are as follows:(1)The water inrush accidents in subsea tunnel are statistically analyzed,and the geological conditions,rock types,and the distribution of faults and fissures in the tunnel area where the accidents occur are summarized.The hydrogeological conditions,tunnel section design,buried depth and overlying sea water depth are sorted out.The inducement factors and characteristics of water inrush are summarized.The water inrush disaster is evaluated.The water inrush mechanism of subsea tunnel is analyzed from the disaster process,and the water inrush types of subsa tunnel are classified according to the water inrush mechanism.(2)Two typical water-inrush types of subsea tunnel are selected to analyze the physical,chemical,mechanical and biological influence factors by sea for the seabed surrounding rock.In view of the thickness of the upper overburden and the surrounding rock in front of the work face,the disaster-causing structural generalization model and the mechanical calculation model of the thickness of the outburst prevention layer are established.Combined with mechanical analysis and energy method,different types of outburst prevention layer calculation theories are established.The calculation method of the minimum safe thickness of the typical water inrush layer of subsea tunnel is determined.The influencing factors and transformation rules of the minimum outburst prevention layer are also discussed.(3)According to different excavation methods and water inrush position of tunnel,the common water and mud inrush condition of working face in different excavation process of double-hole tunnel is studied.The multiphase flow simulation of water inrush in tunnel is realized by FLUENT.The fluid flow pressure,velocity and volume fraction distribution of mud-water mixture in the subsea tunnel after the water inrush disaster are analyzed.The fluid flow characteristics in the tunnel after disaster are summarized,and the application value of the engineering example analysis scheme is given.