Improvements in DDA program for rockslides with local in-circle contact method and modified open-close iteration

Discontinuous deformation analysis (DDA) is capable of modeling rockslides with substantial debris flow. This study improves DDA modeling accuracy by introducing two important enhancements. Firstly, a local in-circle method is proposed to obtain round corners, which eliminates contact indeterminacy and the associated unreasonable sliding behaviors. The radii of the round corners prove having influence on motion modes and sliding distances, offering another perspective for back analysis. Secondly, the original open-close iteration (OCI) is modified to enforce stricter convergence criteria of contact analysis. Accurate contact states and friction forces are obtained using the modified OCI, which is conducive to more precise analysis of rockslides. Several numerical tests were conducted in validating the necessity and accuracy of these two improvements. The results also imply that rock blocks with rounder corners are more likely to cross bench slopes and exhibit longer sliding distances. By overcoming two critical issues in DDA, this work could contribute to rockslide analysis in rock engineering.