Development and experimental verification of a new model for predicting laser-induced rock cutting slit depth

High-energy laser beams have a powerful ability to induce rock fragmentation, but there is still a lack of suitable calculation methods to quantitatively predict the laser-induced rock cutting slit depth. This work aims to provide a new predictive model for the quantitative determination of the laser rock cutting slit depth. In this paper, based on the energy consumption model of laser-induced rock breaking, the prediction model of laser cutting slit depth is creatively established by comprehensively considering the factors affecting laser cutting slit depth, such as laser power, moving speed, and spot radius. Then, relying on the three kinds of rocks exposed in the second phase of the Xinjiang water supply project, which is the longest water conservancy tunnel in the world, the prediction model is verified by laboratory tests, and the variation rules of slit depth, width and specific energy with laser parameters are explored. The results show that the slit depth of laser rock cutting is directly proportional to the laser power and inversely proportional to the moving speed and the defocusing amount. The prediction error for cutting slit depth of the model is less than 10% for palimpsest alkali feldspar granite, and less than 15% for granitic shallow granulite and siliceous schist. Under the same laser condition, the cutting slit depth of siliceous schist is about 25% larger than that of the other two kinds of rocks for its high content of plagioclase. The prediction model and experimental rules proposed in this paper are expected to further promote the application of laser cutting technology in the field of auxiliary TBM rock breaking.