Study On Crack Propagation Simulation And Prevention Of Depressed Chamber Bottom Plate Under Reciprocating Loads

As the most widely used navigable building in inland river transportation engineering,ship lock is usually composed of lock chamber,lock head,gate,approach channel and corresponding equipment.The lock chamber structure can be divided into depressed chamber and separate type chamber according to the connection mode between the bottom plate and the lock wall.Depressed structure,also known as integral structure,is widely used because of its characteristics of good integrity,strong impermeability and uniform distribution of foundation reaction.The collapse of dock lock is not common and will cause serious loss.In view of the fact that there is no literature to study this problem,this paper uses the Extended Finite Element Method(XFEM)to analyze the causes of the collapse and destruction of the ship lock,and the crack propagation behavior in the structure is simulated.According to the simulation results and the existing experience,some suggestions for crack prevention and control of depressed chamber are put forward.The specific work contents and conclusions are as follows:1.The possible causes for the collapse and destruction of the lock are simulated and analyzed.It is considered that the main cause of the accident is the fatigue expansion of the initial damage caused by improper construction on the stratified surface under reciprocating water pressure,and the minor cause is the insufficient anchorage length of steel bars.2.Crack propagation behavior was simulated under different layer damage conditions.The results show that under the reciprocating water pressure,the initial damage in 2m layer will expand due to fatigue accumulation and eventually lead to structural failure.The crack propagation speed is faster when initial damage exists in 3m layer than when initial damage exists in 2m layer.When initial damage in 1.5m layer,the fracture hardly extends.3.According to the regular of crack propagation under various layered damage conditions of dock gate chamber structure,a crack prevention and control scheme of lengthening oblique and vertical steel bars at the same time is proposed.The numerical simulation proves that the extension of steel bar can not only delay the crack propagation speed,but also prevent the structure damage effectively.4.According to the stress characteristics of the depressed chamber,a crack prevention scheme is proposed to adjust the anti-scour structure.It is proved by numerical simulation that adjusting the anti-scour structure can improve the distribution of internal force and limit the crack propagation to prevent the structural failure.