Research On Rock Fracturing Process And Coupled Hydro-Mechanical Effect Using An Elasto-Plastic Cellular Automaton

With the development of mining engineering in deep underground, side slope engineering and nuclear waste disposal etc, people in the world encounter numerous rock mechanical problems during engineering construction. Some fatal engineering disasters occur from time to time. Research on rock failure mechanism as well as hydro-mechanical coupling characteristics is the key to solve and control the engineering disasters. In order to solve these issues, based on elasto-plastic theory, Biot theory and cellular automaton self-organized theory, an elasto-plastic cellular automaton model is built to study rock fracturing process and coupled hydro-mechanical effect. The EPCA (Elasto-Plastic Cellular automaton) code and HM-EPCA (Hydro-Mechanics coupling analysis with Elasto-Plastic Cellular automaton) code for rock failure process simulation are developed to study the failure mechanism of heterogeneous rocks with and without consideration of hydro-mechanical effect. The following contents are included in this thesis:1. According to CA local action theory, solid CA updating rules are built on the basis of equilibrium equation, consistent equation and Darcy's law, fluid continuity equation to solve problems related to rock mechanics, seepage field and coupled hydro-mechanics.2. An EPCA (Elasto-Plastic Cellular automaton) model is built to simulate the failure process of heterogeneous rocks on the basis of elasto-plastic theory and cellular automaton self-organization theory. The basic thought for simulating rock failure process as well as heterogeneous model of rock material and acoustic emission during failure process is presented. An EPCA code is developed in Visual C++ environment.3. By using EPCA code, the failure process of heterogeneous rocks under uniaxial compression is conducted. The mechanical behavior and Kaiser effect of AE under cyclic loading is investigated. The EPCA code is used to study the effect of heterogeneity, H/W ratio of rock specimen and sample size etc. on the failure process of rocks. The failure processes of rocks under tensile loading such as direct tension and indirect tension, including notched brazilian disc and three points bending, are studied and the results are well agreement with experimental results.4. By introducing the linear combination of stress and strain loading control method, the EPCA model is used to simulate the failure process of rocks to obtain not only Class I curves, but also Class II curves. The mechanism of Class II behavior is discussed.5. An HM-EPCA (Hydro-Mechanics coupling analysis with Elasto-Plastic Cellular automaton) model is built on the basis of EPCA model, by introducing hydro-mechanical coupling model. An HM-EPCA code is developed in Visual C++ environment.