In this study, Bonded Block Models (BBMs) are used to investigate the pillar damage mechanisms and rock-support interaction in massive-to-sparsely-fractured rockmasses. Hypothetical granite pillar models of width-to-height (W/H) ratio of 1, 2 and 3 are developed, and the input parameters are constrained by matching the stress-strain response of the BBMs to the stress-strain curves from FLAC3D models that were previously calibrated to an empirical pillar strength database. Two different block representations are also considered – elastic and inelastic. It was found that inelastic blocks are necessary to capture the behavioral transition from strain-softening to pseudo-ductile with increase in pillar W/H.

Post-calibration, different rockbolt combinations are tested in the BBM and their influence on the pillar strength and lateral deformations are analyzed. It was found that as the support density is increased, the peak pillar strengths also increase but the effect is dependent on the W/H. Deformation of the outer stress-fractured region and bulking systematically decreased with increasing support density, but the exact trend evolved as the pillars were loaded to various points on their stress-strain curves. Lastly, a BBM pillar was developed with explicit intra-block fracturing capability (i.e., individual blocks could break) and the support analysis was repeated. The goal was to understand if the continuum representation of damage within the inelastic blocks led to some underestimation of the rock-support interaction mechanism. It was ultimately concluded that the continuum inelastic representation of smaller-scale damage within individual blocks allows for a more appropriate representation of the rock-support interaction than the explicit intra-block representation.

在这项研究中，使用粘结块模型（BBM）来研究大规模到稀疏裂隙岩体中的柱破坏机理和岩-支撑相互作用。建立了宽高比为1、2和3的假想花岗岩柱模型，并通过将BBM的应力-应变响应与FLAC3D模型的应力-应变曲线相匹配来约束输入参数之前已根据经验支柱强度数据库进行了校准。还考虑了两种不同的块表示形式-弹性和非弹性。已经发现，随着柱子W / H的增加，无弹性块对于捕获从应变软化到伪延性的行为转变是必要的。

校准后，在BBM中测试了不同的锚杆组合，并分析了它们对立柱强度和侧向变形的影响。发现随着载体密度的增加，峰值柱强度也增加，但是效果取决于W / H。随着支撑密度的增加，外部应力破裂区域的变形和膨胀系统地减小，但是随着支柱被加载到应力-应变曲线上的各个点，精确的趋势逐渐演变。最后，开发了具有明显的区块内部压裂能力（即单个区块可能破裂）的BBM支柱，并重复进行了支撑分析。目的是要了解非弹性块内破坏的连续表示是否导致岩石-支撑相互作用机制的某些低估。