颗粒形状及定向排列所导致的初始各项异性对胶结岩土材料的力学特性影响明显。为提出具有微观力学机制的胶结岩土材料各向异性强度准则,基于规则排列的椭圆颗粒集合体,通过微观力学解析模型建立了规则排列椭圆颗粒集合体的等效格构模型,将颗粒接触特性赋予至对应的格构梁,并采用考虑胶结尺寸影响的非线性微观屈服准则定义了格构梁的破坏。通过对代表性单元的失稳状态进行力学分析,提出了以微观参数(颗粒形状参数、接触参数)和沉积方向角表示的宏观各向异性强度解析解和对应强度参数的宏微观关联解。通过离散单元法(discrete element method,简称DEM)为基础的数值模拟验证了解析解的正确性。研究结果表明,所提出的强度解析式能较好地反映初始各向异性对胶结岩土材料力学特性的影响,宏微观定量关联解析解揭示了颗粒形状、规则排列方式所导致的初始各向异性以及粒间接触特性对宏观力学行为的定量影响规律。
Abstract
The initial anisotropy resulting from particle shape and granular arrangement significantly influences the mechanical behaviors of cemented geo-materials. To establish an anisotropic strength criterion for cemented geo-materials that incorporates micromechanical mechanisms
we utilize regularly arranged elliptical particle assemblies. By employing a micro-analytical model
we develop an equivalent lattice model for these assemblies
assign particle contact properties to the corresponding lattice beams
and apply a size-dependent nonlinear yield criterion to describe beam breakages. Through mechanical analysis of the instability state of the representative volume element
we propose macroscopic strength and corresponding strength parameters expressed in terms of microscopic parameters (particle shape parameters
contact parameters) and the tilting angle. The correctness of the analytical solution is verified through numerical simulations based on the discrete element method. The results demonstrate that the proposed strength analytical formula can effectively reflect the influence of initial anisotropy on the mechanical properties of cemented geo-materials. The macro-micro quantitative correlation analytical solution reveals the quantitative influence of initial anisotropy caused by particle shape and regular arrangement