Crushing Characteristics of Mud Cakes Scoured by Cutterhead Jets in a Slurry Shield

Abstract

In this paper, the Edinburgh Elasto-Plastic Adhesion (EEPA) model is used to characterize discrete-element particles. Based on the coupling technology of the computational fluid dynamics (CFD)-discrete-element method (DEM), the Euler–Lagrange interface is used to realize the solid–liquid coupling of muck and slurry in order to establish the numerical analysis model of jet crushing mud cake, and the correctness of the model is verified by jet testing. In order to investigate the crushing characteristics of mud cake under hydrodynamic action, further research is conducted on the crushing process of mud cake under different amounts of adhesion, compaction strength, and adhesion strength by jet impact. The mechanism of jet scouring mud cake is revealed by the force of fluid on mud cake particles, the form of mud cake breaking, and its breaking effect. The research results show that when the change in the amount of mud cake is proportional to the change in the contact area of the cutterhead, the crushing amount of the mud cake by the jet remains unchanged at first and then decreases. Whether the mud cake can be broken under different compaction strengths depends on its shear strength and its elastic–plastic state. The adhesion strength of particles greatly influences whether the mud cake can be broken. When the surface energy of the adhesion strength parameter increases to 1,200 J/m3, the jet force is not sufficient to break the mud cake. The research in this paper can provide new ideas and methods to guide the design of the scouring system of the anti-mud-cake cutterhead.