Finite Element Analysis Of Optimization Of Prestressed Concrete Layout For Shiplock Chamber

Locks are common navigation buildings,and more than 800 locks of various sizes have been built in China.The main body of the locks leakage phenomenon is common,of which the lock chamber structure seepage is one of the main common problems of the lock building,not only will have a negative impact on the structural safety of the lock building,upright high side slope rock stability,concrete structure durability,but also reduce the efficiency of water resources utilization.Pinglu Canal is an important part of the construction of the new western land and sea corridor,in which the three stepped hub projects of Madao,Qishi and Youth are proposed to adopt the water saving lock scheme,so the water stopping measures and water stopping effect of the locks are highly required.In this thesis,the effect of prestressing technology on concrete temperature stress and structural stress is studied by using three-dimensional finite element numerical analysis method,and the optimization analysis of concrete prestressing arrangement scheme of the lock chamber is carried out.The research contents and main conclusions are as follows:(1)The finite element method was used to simulate the construction process of large volume concrete locks and analyze the change law of concrete temperature with time during the construction stage of the lock chamber.It is found that with the exothermic hydration of cement,the internal temperature of concrete rises continuously and forms a large temperature difference with the surface,which is very easy to produce temperature stresses and lead to concrete surface cracking;numerical simulations are conducted separately for whether cooling water pipes are arranged in the construction stage of the lock chamber,which shows that the arrangement of cooling water pipes can significantly reduce the maximum temperature of concrete in the construction stage and the temperature difference between inside and outside of the lock chamber,which is conducive to reducing the appearance of temperature cracks in the lock chamber.(2)The effect of prestressing during the construction of the lock chamber is simulated and the effect of prestressing on the surface stress of the lock chamber structure is analyzed.It is found that applying pre-stress can reduce the tensile stress on the surface of the lock chamber structure,and when the spacing between slits of the lock chamber does not exceed 40m,applying pre-stress has a certain effect on reducing the tensile stress on the surface of the lock chamber structure,and has a certain effect on increasing the spacing between slits of the lock chamber and reducing leakage,and the effect of applying pre-stress is not obvious after the spacing between slits is greater than 40m.(3)Optimization analysis of the prestressing arrangement scheme for the bottom plate of the lock chamber.Through the comparison of 15 prestressing arrangement schemes,the best prestressing arrangement scheme for the bottom plate of the lock chamber is obtained:the spacing of prestressing tendons is 1.0m,and the prestressing tendons are 0.2m from the surface of the bottom plate of the lock.(4)Establish the finite element model of the lock chamber of the Madao hub,and carry out the three-dimensional finite element analysis of the temperature field and stress field of the lock chamber structure based on the prestressing technology.Comparing the displacement and stress of the lock chamber structure before and after the prestressing arrangement under three different working conditions,such as the completion period,the highest upstream navigable water level and the lowest downstream navigable water level,it shows that the optimum prestressing arrangement designed in this paper can reduce the tensile stress on the surface of the lock chamber structure under different working conditions when the slit spacing of the lock is 40m.