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Abstract The artificial boundaries in numerical analysis may introduce fictitious scattered waves，which inevitably affect the simulation results. The artificial boundary problem in the discontinuous deformation analysis (DDA) method had been investigated in detail. Firstly，the contributions to the DDA equations for nonreflecting boundaries(including the viscous boundary and the viscoelastic boundary) were deduced based on the Newmark method. Secondly，to accurately simulate the motion due to external source wave such as earthquakes，a free-field boundary in DDA was introduced. Lastly，the unified static-dynamic boundary was implemented in DDA to ensure the consistency of the transformation of the boundaries. The analysis of examples with the improved DDA program showed that each artificial boundary theory has been correctly implemented. The viscous boundary was found to be highly effective for the absorption of the reflection wave at the artificial boundaries，and the viscoelastic boundary adequately simulated the elastic recovery of the infinite domain. The DDA model with the free-field boundaries at both sides is better than that imposed by the viscous boundary. The DDA with the unified boundary can completely simulate the static and dynamic calculation process.
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2015, Vol. 34 
