Research On The Rock Failure Process Analysis Method With RFPA-DDA Coupled Model

With the strong requirement of our economic development, a large number of geotechnical engineering projects have been constructed. In order to ensure project safety and reliability, it is necessary to evaluate the mechanical state of rock masses qualitatively and quantitatively during design, numerical simulation has become an indispensable method. Because of most natural rocks belong to interrupted media, their failure process transform from continuous media to non-continuous media, existing numerical simulation methods are unable to simulate the entire process of rock mass failure. Firstly, the DDA method has been improved in this thesis. What’s more, the DDA method is used to analyze the stress evolution during the rotating process of rock roof. Last, a DDD (Discontinuous Deformation and Displacement) method by combining the RFPA and DDA is proposed, the method is able to simulate the entire process from small deformation and fracturing to large displacement in rock masses. The works content is as follows:(1) As the original DDA method relies on manual joints to input, this will need a larger workload, and DDA method has no interactive features and lack of the preprocessing and postprocessing functions. In this paper, we can model conveniently by introducing the methods of Ansys and Geocad to divide mesh, and the postprocessing has been increased the dynamic display function. After modification, user-friendly interface has been achieved by using pull-down menus and dialog windows combined form in the new program, we name the improved DDA method as NDDA method.(2) By combining the theoretical formulas and DDA numerical simulation method, the stress evolution of key blocks in "Masonry beam" structure during the process of turning has been analyzed, the results showed a good fit between the two methods. According stress we researched the instability rule and mode on the key block, sliding instability is more easily to occur in the early stage of rotational deformation or larger roof breakage, with the rotation angle increases, the rotation instability will occur.(3) By analyzing the mechanics characteristics and damage characteristics of rocks and using appropriate destruction criterion, on the basis of the source program of the DDA and RFPA, the DDD method has been developed to simulate the entire process from small deformation to large displacement in rock masses, this method has been used to simulate rock movement and slope instability. In the simulation of strata movement we demonstrated of sliding and rotation type instability process by numerical methods for the first time, providing support for the "masonry beam" theory; the DDD method is adopted to model the landsliding process of a slope and reproduce the entire process from deformation, crack initiation, propagation, coalescence and sliding, after that, displacement and stress evolution has been analyzed in order to study the slope stability and find more secure supports of slope.