| At present,with the continuous progress of science and technology,advanced forecasting,advanced geological detection and other technologies continue to mature,the probability of major disasters in the construction process of underwater and undersea tunnels is generally low.However,since undersea tunnels are buried deep under sea water,compared with mountain tunnels,there are great difficulties in excavation construction,operation support,ventilation and exhaust,power transportation and late maintenance,etc.At the same time,deep-buried submarine tunnels should bear a large pore water pressure,which will pose a serious threat to the waterproof system.It is impossible to avoid water seepage completely for the undersea tunnel,so it is necessary to prevent water from the lining structure as far as possible by setting a reasonable waterproof scheme.At the same time,considering the bearing capacity of the lining structure and the overall stability of the tunnel surrounding rock,it is necessary to properly "unload" the water supply and deal with the relative relationship between "plugging-waterproofing" and "drainage-drainage".Based on Shantou Bay Undersea Tunnel,this thesis carries out the research on the prediction of submarine water inflow and optimization of prevention and drainage scheme.The main research contents are as follows:(1)The numerical simulation of the actual project is carried out based on the equivalent continuum mathematical model,and the submarine tunnel under different surrounding rock levels is studied.The reasonable seepage influence radius in FLAC3 D software was determined,and the corresponding numerical model was established to carry out fluid-structure coupling calculation.The distribution law of the seepage field in the stratum before tunnel excavation and the change of the seepage field around the tunnel after tunnel completion were summarized,and the distribution law of the seepage field in the undersea tunnel was revealed,which provided the basis for the theoretical derivation of water inflow.(2)By establishing the seepage model of the submarine tunnel,the theoretical formula between the circumferential water inflow and the seepage law of the submarine tunnel is deduced.Based on Darcy’s law,the correlation between pore water pressure and water inflow without grouting was derived,and the theoretical results of predicted water inflow were calculated and verified by compiling FISH language.Based on Darcy’s law,the theoretical prediction formula of water inflow related to pore water pressure under grouting conditions is derived.Meanwhile,the grey relation analysis is carried out on the seven factors affecting water inflow in the formula,and the sensitivity of the influence of several factors is sorted.(3)Based on Shantou Bay Undersea Tunnel project,combined with theoretical research,numerical simulation and practical engineering situation,optimize the anti-drainage system of undersea tunnel.Through the establishment of real three-dimensional models of Grade Ⅱ,Ⅳ and Ⅴ tunnels in the sea section of Shantou Bay Undersea Tunnel,and based on the main influencing factors proposed by grey correlation analysis,the relevant research of three kinds of anti-drainage systems in this section is carried out,namely,full undrained,half full drained and full controlled discharge.The seepage field form,seepage state and displacement field distribution of tunnel under different drainage systems are analyzed.At the same time,based on the results of grey correlation analysis,the grouting research is carried out on the undersea tunnel,and the influence law of grouting on the stability of the undersea tunnel is analyzed,and then the optimal waterproofing and drainage system of the undersea tunnel is obtained. |
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