Grouting is a widely used technique in underground engineering by enhancing mechanical properties of jointed rock mass. Understanding the shear characteristics of jointed coal mass after grouting reinforcement is crucial for optimizing grouting parameters and advancing grouting mechanism. This study proposed a grout-filled jointed coal (GJC) direct shear discrete element model (GJCS-DEM). The model consists of coal matrix, grout-filled layer, and coal-grout interface. Parallel bond model (PBM) was adopted on intact coal matrix and grout-filled layer, while smooth joint model (SJM) was utilized to model deform behavior of interface in this model. Then, microscopic parameters determination method for SJM in GJCS-DEM has also been introduced and all the parameters for PBM and SJM were calibrated. After that, the proposed approach was validated through the good agreement between strength and failure characteristics of numerical and experimental direct shear test results of specimens with different grouting materials. Finally, the validated GJCS-DEM was applied to investigate effect factors of shear mechanical propertied for GJC specimens. As the grout-filled layer height and joint sawtooth dig angle increases, both peak and residual strength increases, while the failure pattern varies. The work here can offer valuable insights for grouting efficiency improvement in engineering practices.

中文翻译：

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基于离散元法的注浆充填节理煤直剪力学特性研究


灌浆是地下工程中广泛使用的一种技术，它通过提高节理岩体的力学性能。了解注浆加固后节理煤体的剪切特性对于优化注浆参数和推进注浆机理至关重要。本研究提出了一种灌浆填充节理煤 （GJC） 直接剪切离散元模型 （GJCS-DEM）。该模型由煤基质、灌浆填充层和煤-灌浆界面组成。在完整的煤基质和灌浆填充层上采用平行粘合模型 （PBM），同时采用光滑节理模型 （SJM） 对界面的变形行为进行建模。然后，还介绍了 GJCS-DEM 中 SJM 的显微参数测定方法，并对 PBM 和 SJM 的所有参数进行了校准。在此之后，通过不同注浆材料试件的数值和实验直接剪切试验结果的强度与破坏特性的良好吻合，验证了所提方法的有效性。最后，应用验证的 GJCS-DEM 研究 GJC 试件剪切力学特性的影响因素。随着灌浆填充层高和接缝锯齿挖掘角度的增加，峰值强度和残余强度都会增加，而破坏模式会发生变化。这里的工作可以为工程实践中的灌浆效率提高提供有价值的见解。