Study On The Mechanism Of Main-Controlling Parameters In DDA And Its Application

DDA(Discontinuous Deformation Analysis)method is a new numerical analysis method proposed by Dr.Shi in 1980 s.Compared with other numerical method,DDA method shows great advantages in the simulation of block system owning the characteristics of large deformation and large displacement.It could evaluate the stability of rock mass by studying the displacement,deformation,and movement of block system.Since it was proposed,DDA has been paid great attention by scholars in the rock and soil mechanics field,who acknowledge that DDA has great potential in simulating the discontinuity and large deformation of rock mass.Until 2017,International Conference on Analysis of Discontinuous Deformation(ICADD)has been held 12 sessions successively,where improvement,application and validation of DDA method are still the important research topics.In this thesis,a simplified block contact model has been established based on DDA theory to carry out the influence of main-controlling parameters on the contact displacement.The similar simulations are carried out by the original DDA program and the FEM,and then the similarities and differences of these three methods are compared.It verified the effectiveness of the DDA and discussed the mechanism of main-controlling parameters.The research results mainly contain:(1)Some problems encountered in the computer programming of the two-dimensional DDA are discussed and the corresponding solutions are given.(2)A simplified block contact model based on DDA theory is established.The model was studied by analytical formula derivation in detail,which reveals the actual effects of time step,normal and shear spring stiffness on contact force and contact displacement.(3)The results by the DDA method are consistent with that by the analytical formulas.Similarly,the nearly same deformations and displacements are observed in the simulation by FEM.(4)According to the needs of analyzing the deformation of rock slope with bolt reinforcements,some adjustments to the DDA calculation program are carried out.Then it is applied to simulate the deformation of a slope in Southwest China and the influence of the bolts on the slope deformation is analyzed.