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耦合了非饱和多孔多相介质有限元模型和颗粒介质离散元(DEM)模型,提出了以宏、细观尺度分别耦合Biot-Cosserat连续体模型和离散颗粒集合体模型的连接尺度方法来分析非饱和含液颗粒材料的力学渗流耦合问题。根据被动空气压力假定和对空间离散孔隙水质量守恒方程的约化,从非饱和土有限元控制方程的基本未知量中消去了孔隙水压力,而将其取作有限元积分点上定义取值的内状态变量,进而建立了节点未知量仅包含固相线位移和转角的非饱和Cosserat多孔连续体约化有限元数值模型。基于连接尺度方法(BSM)宏、细观尺度数值过程的解耦计算的特点,对宏、细观两尺度数值模型的时域积分分别采用隐式Newmark方法和显式中心差分法,且取不同时间步长以提高计算效率。与全域采用DEM的精细分析方法相比,本文BSM在保证计算精度的前提下可大幅节省计算时间。在不考虑湿化效应的边坡稳定算例中,在得到类似计算精度条件下它比全域采用DEM节省计算时间高达86.65%。二维边坡稳定算例结果验证了本文连接尺度方法的有效性,以及在揭示含液颗粒结构细观破坏机理上的优点。数值算例结果显示,边坡承载能力因降雨大幅下降约50%,这表明本文发展的计及伴随湿化过程的颗粒材料结构中饱和度及吸力分布演变及其对结构破坏失效影响的非饱和颗粒材料多尺度计算模型是很有必要的。
Coupled with the finite element model of unsaturated porous multiphase media and the particle medium discrete element (DEM) model, the connection scale method of coupling Biot-Cosserat continuum model and discrete particle assembly model with macroscopic and mesoscopic dimensions is proposed to analyze the non- Mechanics Seepage Coupling Problems of Saturated Liquid Particles Containing Particles. According to the assumption of passive air pressure and the reduction of the mass-discrete pore water mass conservation equation, the pore-water pressure is eliminated from the basic unknowns of the governing equations of unsaturated soils and is taken as the definition of the finite element integral point Then, a finite element numerical model of Unsaturated Cosserat porous continuum with unknown nodes and only solid-line displacement and rotation angle is established. Based on the characteristics of decoupling calculation of macro-scale and meso-scale numerical processes in connection scale method (BSM), the implicit Newmark method and explicit center difference method are used respectively for the time-domain integrals of macro-and micro-scale numerical models. Time step to improve computational efficiency. Compared with the detailed analysis method using DEM in the whole world, BSM in this paper can save the calculation time greatly while ensuring the accuracy of calculation. In the case of slope stability without considering wetting effect, it can save up to 86.65% of the computation time by using DEM in the whole area under similar calculation accuracy. The results of the two-dimensional slope stability test validate the validity of the connection scale method and the advantages in revealing the mechanism of meso-failure of liquid-bearing particles. The results of numerical examples show that the slope carrying capacity dropped sharply by about 50% due to rainfall. This indicates that the evolution of saturation and suction distribution in the structure of granular material with wetting process and the non-saturation of its influence on structural failure Multi-scale calculation model of granular materials is necessary.