Discontinuous deformation analysis (DDA) is an efficient algorithm for calculating block system deformation and displacement. Citing Newmark integration in the structural dynamic differential equation and considering inertia force and damping force computation

DDA source code is improved so as to optimize adaptive step size. The convergence rates of linear acceleration method

constant acceleration method and average acceleration method in Newmark integration are investigated by comparative analysis; the principle of adding or deleting non-balance force is introduced; and a scheme is given to control the error range. Using the improved DDA method to simulate a coal and gas outburst during a coal seam excavating

the results have a good match with the investigation data. The improved DDA method with adaptive step size can provide a new way to deal with the dynamic calculation for block system.