伯格斯模型参数调试与岩石蠕变特性颗粒流分析

岩石作为地下工程的主要研究对象，其物质组成和所赋存的复杂地质环境使其具有明显的流变特性。基于三维颗粒流程序(PFC3D)，采用由开尔文模型和马克斯伟尔模型串联组成的伯格斯（Burgers）流变模型，通过控制变量法，分析了伯格斯模型中弹性系数(Em和Ek)、黏性系数(?m和?k)和摩擦因数f对瞬时强度特性和流变特性的影响；分析得出数值试样的瞬时强度特性主要受马克斯伟尔体弹性系数Em和摩擦因数f影响：弹性模量和单轴抗压强度与Em和f均呈正相关，泊松比与Em呈正相关，与f呈负相关；而流变特性与各参数均呈现负相关性。在此基础上，进行了红页岩分级增量蠕变试验的模拟，通过与室内蠕变试验结果的对比，验证了PFC3D中的伯格斯模型用于岩石蠕变试验模拟的可行性，并将该方法用于分级增量循环加卸载蠕变试验和三轴蠕变试验数值研究。该研究内容是利用离散单元法研究岩石流变特性的一种新的尝试。

Parametric analysis of Burgers model and creep properties of rock with particle flow code

As a main research object in underground engineering, rock has obvious rheological properties due to its material composition and complicated geological environment. Applying Burgers constitutive model (which is formed with a series of Kelvin model and Maxwell model) to particle flow code in three dimensions (PFC3D), this research analyzes the impact of different parameters (including elastic coefficients Em and Ek, viscosity coefficients ?m and ?k, and friction factor f ) on the instantaneous and rheological properties. The controlling variable method is used. Conclusions can be drawn as follows. The instantaneous strength properties are mainly affected by Maxwell’s elastic coefficient Em and friction factor f . The elastic modulus and uniaxial compression strength have positive correlation with Em and f . However, Poisson’s ratio is positively correlated with Em and negatively correlated with f. Meanwhile negative correlations are observed among rheological properties and these parameters. Based on these conclusions, a staged increment loading creep experiment of red shale is simulated. Comparisons with results from laboratory experiments prove the feasibility of Burgers constitutive model in PFC3D for creep experiments. At the same time, this method is used in staged increment cyclic loading and unloading experiment and triaxial creep experiment. This research is also a new attempt to analyze creep properties of rock material with discrete element method.