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<p>Preformed defects (pre-cut grooves, pre-drilled holes) reduce rock-breaking energy via the free surface effect. However, with laser-assisted rock breaking, the coupling mechanism between defect properties (type, parameters) remains unclear; particularly, the synergistic verification using macro–micro experiments and numerical simulations is still lacking. Taking granite as the object, this study conducted single-point/mobile laser irradiation experiments on defective samples and established a coupled grain-based model, cohesive zone model, and thermal–mechanical damage (GBM-CZM-TMD) numerical model (incorporating real mineral distribution and cohesive elements). Experiments quantified four thermal crack types and rock-breaking parameters via thermography and microscopy; the model reproduced thermo-mechanically coupled crack evolution to validate experiments. Results show pre-cut grooves (linear defects) guide thermal cracks more effectively than pre-drilled holes (point defects). Under single-point irradiation, optimal efficiency and minimal energy consumption occur at 20&#xa0;mm groove spacing and 15&#xa0;mm hole spacing. Under mobile irradiation, grooves have a 15&#xa0;mm critical spacing, with minimal energy consumption at 25&#xa0;mm. Temperature gradients drive rock-breaking (shear craters and tensile cracks), and the model has a ≤  ± 10% quantitative error. This study provides theoretical support for laser-assisted hard rock excavation parameter optimization.</p>

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The Effect of Pre-cut Grooves and Pre-drilled Holes on Laser-Induced Fracturing of Granite

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Zhengkuo Ma,
  • Chunshun Zhang

摘要

Preformed defects (pre-cut grooves, pre-drilled holes) reduce rock-breaking energy via the free surface effect. However, with laser-assisted rock breaking, the coupling mechanism between defect properties (type, parameters) remains unclear; particularly, the synergistic verification using macro–micro experiments and numerical simulations is still lacking. Taking granite as the object, this study conducted single-point/mobile laser irradiation experiments on defective samples and established a coupled grain-based model, cohesive zone model, and thermal–mechanical damage (GBM-CZM-TMD) numerical model (incorporating real mineral distribution and cohesive elements). Experiments quantified four thermal crack types and rock-breaking parameters via thermography and microscopy; the model reproduced thermo-mechanically coupled crack evolution to validate experiments. Results show pre-cut grooves (linear defects) guide thermal cracks more effectively than pre-drilled holes (point defects). Under single-point irradiation, optimal efficiency and minimal energy consumption occur at 20 mm groove spacing and 15 mm hole spacing. Under mobile irradiation, grooves have a 15 mm critical spacing, with minimal energy consumption at 25 mm. Temperature gradients drive rock-breaking (shear craters and tensile cracks), and the model has a ≤  ± 10% quantitative error. This study provides theoretical support for laser-assisted hard rock excavation parameter optimization.