Simulation study on the damage evolution of rock by Two-Step wedge cut blasting under high in-situ stress

This study investigates the two-step wedge cut blasting technique, crucial for deep hard rock excavation under high stress. Our research assumes that this method significantly influences rock damage and fragmentation under varying stress conditions. Data from numerical simulations and experiments reveal the following:

First-stage cutting initiates cracks and local damage in the cut area, while second-stage cutting propagates these cracks, forming a wider damage zone around the cavity. Under hydrostatic stress exceeding 20 MPa, radial crack growth is restricted, with damage concentrated near blast holes, exhibiting uniform compressive cracks. In non-hydrostatic fields, cracks grow in diverse directions with intersecting patterns. High in-situ stress enhances the efficiency of explosive energy usage, resulting in more complete rock breakage and a larger cavity volume. The non-hydrostatic field shows higher energy-release efficiency than the hydrostatic one, creating a wider failure-extension area.

These findings indicate that stress conditions considerably affect rock fragmentation and cavity formation in two-step wedge cut blasting. The data was obtained through calibrated numerical models in LS-DYNA and experimental tests, ensuring reliability. This research offers valuable insights for optimizing blasting design in deep hard rock excavation under high stress, providing both theoretical understanding and practical guidance for improving efficiency in such challenging environments.

本研究针对高应力（high stress）条件下深部硬岩开挖（deep hard rock excavation）中至关重要的两步楔形掏槽爆破技术（two-step wedge cut blasting）展开探究。本研究假设，在不同应力条件下，该方法对岩石损伤与破碎效果具有显著影响。通过数值模拟（numerical simulations）与实验获取的数据揭示如下规律：
第一阶段掏槽（first-stage cutting）会在掏槽区域萌生裂纹（cracks）并引发局部损伤（local damage），第二阶段掏槽（second-stage cutting）则会扩展这些裂纹，在空腔周围形成范围更广的损伤带。当静水应力（hydrostatic stress）超过20 MPa时，径向裂纹扩展（radial crack growth）受到限制，损伤集中于炮孔（blast holes）附近，呈现出均匀分布的压缩裂纹（compressive cracks）特征。在非静水应力场（non-hydrostatic field）中，裂纹会沿多方向扩展并形成交错分布的形态。高地应力（in-situ stress）能够提升炸药能量利用率（explosive energy usage），使得岩石破碎（rock breakage）更为充分，空腔体积（cavity volume）更大。非静水应力场的能量释放效率（energy-release efficiency）高于静水应力场，可形成范围更广的破坏扩展区域（failure-extension area）。
上述研究结果表明，应力条件对两步楔形掏槽爆破的岩石破碎效果与空腔成型具有显著影响。本研究的数据通过LS-DYNA中的校准数值模型（calibrated numerical models）与实验测试获取，确保了结果的可靠性。本研究可为高应力深部硬岩开挖的爆破设计优化提供宝贵见解，为这类高难度施工环境下的效率提升提供理论认知与实践指导。