Objective Traditional laser thermal rock breaking technologies suffer from high energy consumption and a limited damage depth. To overcome these challenges, this study proposed a novel mechanical rock breaking method based on high-pressure plasma shock waves induced by short pulsed lasers, aiming to transform a thermodynamics-dominated rock breaking mechanism into a dynamics-dominated mechanism.
Methods and Results Under the Abaqus/Explicit explicit dynamics framework, this study constructed a finite element model to simulate the interactions between nanosecond laser-induced shock waves and rocks. The accurate loading of shock wave pressure in the spatial and temporal domains was achieved using the VDLOAD user subroutine. Under the typical parameter combination—a peak pressure of 3 GPa, a pulse width of 20 ns, and a spot diameter of 4 mm, this study systematically simulated and revealed the dynamic behavior of the propagation of laser-induced shock waves in rocks, along with the two-stage mechanisms of dynamic rock damage. Specifically, in the shock wave loading stage, an instantaneous high stress (Mises stress: up to 2 706 MPa) was generated on the rock surface; in the stress wave propagation stage, the reflection and superposition of the waves within rocks led to cumulative damage and ultimately rock material scaling. Furthermore, multiple comparative simulations were designed by systematically adjusting the peak pressure (1‒5 GPa), pulse width (20‒200 ns), and spot diameter (2‒6 mm). With the damage volume as the assessment metric, the sensitivity of these parameters to the rock-breaking effect was investigated. The results reveal that under the typical parameter combination, a single laser shock led to the formation of a nearly conical damage zone on the rock surface, with a diameter of 4.3 mm, a depth of 5.8 mm, and a damage volume of 27.8 mm³. The parameter sensitivity analysis indicates that the peak pressure exhibited a limited impact on the damage volume (increase rate: below 5.5%). In contrast, the pulse width and spot diameter exerted significant influence, representing dominant factors controlling the rock-breaking efficiency.
Conclusions The rock-breaking efficiency of laser-induced shock waves depends predominantly on the spatiotemporal distribution and control of the stress wave energy. The collaborative optimization of the pulse width and spot diameter can effectively regulate the rock damage under similar single-pulse energy, thereby achieving low energy consumption and high efficiency in rock breaking. Overall, this study provides a novel approach for the exploitation of deep hard rock resources.
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