Finite Element Analysis On Reinforcement Effect And Influencing Factors Of Hydraulic Tunnel By Sticking Steel

As an important part of water conveyance project,hydraulic tunnel plays a vital role in the whole project.However,many existing or constructed tunnels have different degrees and types of defects all the time,which lead to unfavorable conditions of stress concentration and excessive deformation of lining structure,shorten the service life of the tunnel,and even lead to tunnel collapse,causing major economic losses and even casualties.Therefore,it is very important to reinforce the tunnel effectively.Steel-bonded reinforcement is a reinforcement method which uses structural adhesive to bond steel plates on the surface of concrete members so that the steel plates and concrete members can bear together as a whole to improve the bearing capacity or rigidity of structural members.Many scholars at home and abroad have carried out research on bonded steel reinforcement technology,which mainly focuses on the specific engineering application and method of bonded steel reinforcement,as well as the experimental research and theoretical calculation analysis of bonded steel reinforcement for reinforced concrete beams.However,there are few studies on how bonded steel reinforcement plays a reinforcing role in hydraulic tunnel and how to achieve reinforcing effect.The study on the reinforcement effect and influencing factors of steel-bonded reinforcement for hydraulic tunnel is helpful to further understand the mechanical condition of steel-bonded reinforcement for hydraulic tunnel and is of great significance to promote the further application of Steel-bonded Reinforcement Technology in hydraulic tunnel.Therefore,based on finite element theory and taking actual project as an example,this paper studies the reinforcement effect and influencing factors of steel-bonded reinforcement of hydraulic tunnel by numerical simulation.The main research contents and results are as follows:(1)Taking Sankesong C Tunnel of Shenzhen Dongjiang Water Source Project as an example,the cracking nonlinearity and contact nonlinearity of lining concrete are simulated,a three-dimensional finite element model before and after reinforcement with bonded steel is established,and the linear and non-linear calculation results during the maintenance period and operation period of water shutdown of the tunnel are analyzed respectively.By comparing and analyzing the deformation,stress and cracking of lining before and after reinforcement,the stress and cracking of lining before and as well as the improvement of lining safety factor,the reinforcement effect of tunnel bonded steel is analyzed and evaluated.The results show that the bonded steel reinforcement can improve the overall stiffness and strength,improve the deformation of lining,restrain the cracking of lining concrete,the steel plate can help the lining bear partial tensile stress,the stress state of lining structure has been significantly improved,which is conducive to improving the safety of the structure,playing a very good role in the stability of the lining structure,and the bonded steel reinforcement effect is good.(2)The improvement of safety factor of lining after bonded steel reinforcement is analyzed.After reinforcement,the axial force and bending moment of the lining as a whole are reduced and the structural stress state is better.The safety factor of lining has been improved,the arch has been enlarged more,the side wall and bottom plate have been enlarged less,but the improvement of safety factor in the middle of side wall and bottom plate is particularly important,which makes the above parts change from not meeting safety requirements to meeting safety requirements.Side walls,corners of floors and floors are dangerous areas with low safety factors due to large internal forces,so reinforcement can be considered.Especially at the corner of the baseplate,the safety factor is the smallest,which is judged to be the most dangerous section.Near the corner of the baseplate,it is also the stress concentration area.Stress characteristics and reinforcement measures should be considered.The proper thickness of the steel plate in this area can be considered.In addition,the reinforcement design of this area should be paid attention to.(3)Aiming at the influencing factors of bonded steel reinforcement,taking the deformation,stress and cracking condition of lining as evaluation indexes,the influence of steel plate thickness,adhesive layer thickness and elastic modulus of steel plate on the reinforcement effect is analyzed and comprehensive optimization suggestions are put forward.The calculation results show that when the thickness of steel plate reaches 10 mm,it is slow to improve the deformation and stress of lining with increasing thickness of steel plate,but the cost of reinforcement increases a lot.At the same time,the steel plate should not be too thin and the stiffness of the thick steel plate is high,which can effectively limit the deformation of the lining and improve the stress state of the structure.Considering the reinforcement effect and economy comprehensively,it is suggested that the thickness of steel plate be 4mm-10 mm.According to the calculation results of deformation,stress and cracking of lining with different thickness of adhesive layer,2mm-3mm is more suitable for the thickness of adhesive layer.When the elastic modulus of steel plate is large,the stiffness and strength of the whole structure can be improved more effectively by bonded steel reinforcement,and the deformation and stress state of lining structure can be improved.Good improvement,but also can more effectively restrain concrete cracking.Therefore,when selecting steel plates for reinforcement,steel plates with large elastic modulus can be selected within a certain range.Taking Sankesong C Tunnel of Shenzhen Dongjiang Water Source Project as an example,this paper simulates cracking nonlinearity and contact nonlinearity of lining concrete by numerical simulation method,analyses the effect of steel-bonded reinforcement of hydraulic tunnel and the improvement of safety factor of lining by steel-bonded reinforcement,conducts research on influencing factors of steel-bonded reinforcement,and puts forward comprehensive optimization suggestions.It is expected to provide reference for reinforcement design and numerical analysis of similar projects and reduce the risk of cracking and destruction of hydraulic tunnel.