With the upsizing and standardization of ships,the integral lock chamber which is suitable for high water head and high lock wall has been widely used.To explore the influence of the reserved wide joint on the internal force of the baseplate of the integral lock chamber,based on modified Mohr Coulomb model,this paper uses Midas GTS NX to perform finite element analysis of Guanqiao lock chamber.The results show that:1）The modified Mohr Coulomb Model has more advantages in describing soil deformation than Drucker Prager model.2）Compared with the absence of wide joint,the reserved wide joint can significantly reduce the hogging moment in the midspan of the baseplate.3）The later the time of closing joint is,the smaller the maximum of the hogging moment of the baseplate becomes.4）Considering the internal forces of the baseplate and the stability of the lock wall,when the level of the backfill soil behind the lock wall reaches the elevation of 35.5 m,the baseplate of Guanqiao lock chamber should fill the reserved wide joint.5）During completion and operation periods,the maximum of the sagging moment and hogging moment of the baseplate with reserved wide joint occur under the conditions of the completion and maintenance respectively,and the maximum and minimum of the foundation stress occur under the conditions of the high-water-level operation and maintenance respectively.