基于离散-连续耦合的尾矿坝边坡破坏机理分析

在连续介质力学有限差分数值模拟的基础上,选取有代表性的局部区域进行基于有限差分与离散元的离散-连续耦合分析。采用上述方法模拟了某尾矿坝边坡在尾矿冲填前后潜在滑移带附近的宏细观力学特征。模拟结果显示,对于耦合和非耦合模型中的连续域两种方法的计算结果基本一致,但离散域的存在可以对滑移带形成过程的细观力学特征,如力链分布、土体细观组构发展等进行分析,研究边坡破坏的细观机理。研究表明,在滑移带形成过程中,滑移带内外土体各向异性的发展明显不同：随着荷载的施加,潜在滑移带内土体颗粒发生了较明显的位移,应力主方向发生了明显转动。颗粒的转动改变了带内组构的分布,并逐渐形成剪切滑移带,造成边坡失稳。滑带外土体虽然应力主方向发生了一定的偏转,但剪应力变化不大。采用的离散-耦合分析方法可以分析边坡在渐进破坏过程中滑移带形成的细观力学机理。

Failure mechanism analysis of tailing dams based on coupled discrete and continuous method

Based on the numerical results from the finite difference method (FDM), a representative local area is selected to conduct discrete-continuous coupling analysis using FDM and discrete element (DEM). The macro-scale and meso-scale mechanical responses of a tailing dam slope before and after filling are simulated by using the above model. The numerical results indicate that for the continuous domain, the results are almost the same using non-coupled method and coupled method. The meso-scale mechanical response in the slip bands, such as distribution of force chain and development of soil fabric, can be analyzed by using the discrete domain to discuss the meso-mechanism of failure of tailing dams. The research shows that in the formation of slip bands, the soil anisotropies in and out of the slip bands are obviously different: with the increasing load, soil particles in the potential slip bands have significant displacement. The main direction of stress has a significant rotation. The rotation of particles changes the fabric distribution, which contributes to the formation of slip bands and the slope instability. The main direction of stress of soil outside the bands rotates to some degree, while the shear stress changes little. The proposed discrete-continuous coupling method can analyze the meso-mechanism of formation of slip bands during slope progressive failure.