SOME ISSUES IN DISCONTINUOUS DEFORMATION ANALYSIS FOR GEOTECHNICAL ENGINEERING
岩土工程不连续变形分析计算中的若干问题

Some key problems including energy dissipation,convergence criterion and simulation of construction procedure for geotechnical engineering in discontinuous deformation analysis(DDA) method are discussed.A linear viscous-type resistance is used to absorb the kinetic energy of the block system;and the equilibrium equations to contain damping term are derived by minimizing the total potential energy.The mechanism of the energy consumption by damping force is discussed;and three types of convergence criteria including displacement criterion,velocity criterion and acceleration criterion are defined to ensure convergence to the correct result for quasi-static analysis.According to the features of DDA,the problems of the excavating load and bolting load in the analysis of geotechnical engineering are studied.Two new algorithms to simulate sequential excavation for rock masses have been developed and implemented into the DDA program.Three typical numerical examples are calculated to demonstrate the capability of the DDA with the new extensions.The computational results show that the improved DDA has not only high accuracy and good convergence performance,but also is easily applied to practical engineering.