TBM Tunnelling Parameters and Efficiency Correlation Analysis Using Full-cycle Data: A Case Study from the High-altitude Guxue Power Station Tunnel

Based on the full-cycle main control parameters and downtime statistics of the TBM used in the Guxue Power Station Tunnel, this study systematically analyzed the correlation between TBM tunnelling parameters, the evolution law of tunnelling efficiency, and the influencing mechanisms under high-altitude environments. The results indicate that the penetration rate and advance rate exhibit a very strong positive correlation (R²=0.860), serving as the core factor controlling tunnelling efficiency. Low temperatures in high-altitude areas increase the brittleness coefficient of granite/diorite, leading to brittle spalling as the main rock-breaking mode. This results in an extremely weak correlation between total thrust and penetration rate (R²=0.102), the rock-breaking advantage of the "rotational speed-penetration rate coordinated control" is obvious. The average TBM utilization rate is 27.17%, it shows distinct phased characteristics in construction efficiency. The tool replacement is the most frequent cause of downtime (35%), while TBM maintenance accounts for the longest total downtime (19%), significantly impacting progress. The average advance (7.285 m) and utilization rate (33.61%) of night shifts are higher than those of day shifts (5.569 m, 26.99%)., Workers in the hypoxic environment on the day shift are engaged in multiple tasks (maintenance, coordination), leading to cumulative fatigue; in contrast, the night shift focuses on tunnelling, demonstrating significant advantages in work efficiency and thus becoming the core period for efficient operation.