Modeling of reinforced-concrete cutting with shield rippers using FEM-DEM-coupling method

•Dynamic analyses of ripper cutting RC pile were performed using FEM-DEM method.•Comparison between numerical results and experiments was conducted.•The damage characteristics of steel bars and concrete were analyzed.•A parametric analysis is conducted to assess the ripper cutting performance.•Some recommendations are made for the geometric design of ripper used for cutting RC. With the increase in the number of underground structures, it is common to encounter reinforced concrete (RC) pile foundations of existing buildings or bridges during shield machine tunneling in densely constructed urban areas. The cutting of RC piles with the shield machines is a challenging task due to cutter damage and cutting efficiency issues. In this paper, the interaction between a ripper and an RC was studied based on the FEM-DEM coupling method. A three-dimensional transient dynamic model of two typical rippers (angular ripper and curved ripper) cutting RC piles was established, respectively. In the FEM-DEM coupling model, the mechanical behavior of concrete was described via DEM, and the impact of steel bars in concrete was considered via FEM. In addition, an experimental verification was conducted to validate the effectiveness of the numerical results. The damage characteristics of the steel bars and concrete, and the force patterns of the rippers were analyzed. The influence of the geometric parameters of the ripper, including blade width, blade angle, and blade anterior angle on the cutting performance was also investigated through a parametric study. Some recommendations are made for the geometric design of rippers used for cutting reinforced concrete. The results of this study could provide some references for cutting RC obstacles with a shield machine. [Display omitted]