Fig. 1. Schematic of laser assisted TBM rock-breaking principle^[31]

Fig. 2. Stress module of rock-breaking with laser-assisted^[48]

Fig. 3. Experimental principle for laser scanning of rock^[50]

Fig. 4. Temperature and stress distribution^[21]. (a) Temperature distribution of pulse laser (0.2 s);(b)stress distribution of pulse laser (0.2 s); (c) temperature distribution of continuous laser (0.4 s); (d) stress distribution of continuous laser (0.4 s); (e) temperature distribution of composite laser (0.2 s); (f) stress distribution of composite laser (0.2 s)

Fig. 5. Relationships between the breaking efficiency increase ratio, cutter wear decrease ratio, and laser parameters^[26]. (a) Breaking efficiency increase ratio; (b) wear decrease ratio

Fig. 6. Concept map of laser-assisted TBM tunneling^[26]

Fig. 7. Relationship of rock-breaking specific energy with cutter-hole space^[51]

Fig. 8. Relationship of rock-breaking specific energy with cutter-groove space^[54]

Fig. 9. Sandstone surface morphology at different laser scanning speeds^[50]

Fig. 10. Analysis of sandstone composition^[50]. (a) XRD analysis of sandstone; (b) XRD analysis of glass

Fig. 11. Side-view topography of granite irradiated horizontally by laser^[56]

Fig. 12. Axial stress-strain curve of granite^[56]

Fig. 13. Macro-fragmentation process observed on rock samples during indentation with laser hole spacing of 2 mm and cutter-hole spacing of 8 mm^[52]

Fig. 14. Rock-breaking process with cutter-groove spacing of 5 mm^[54]

Fig. 15. Variation of crushing ratio energy consumption with cutter-hole spacing^[52]

Fig. 16. Variation of crushing ratio energy consumption with cutter-groove spacing^[54]

Fig. 17. A new structure of rock-breaking TBM with laser-assisted^[24]

Fig. 18. A modular laser and water jet assisted rock-breaking TBM^[58]

Fig. 19. A type of shield tunneling machine based on composite laser perforation^[25]

Fig. 20. A rapid analysis device for laser probe quartz detection^[60]