Abstract: In the light of the HC evaluation system in the Code for Geologic Investigation of Water Resources and Hydropower Engineering, a model of predicting the advance rate of double shield Tunnel Boring Machine (TBM) is established based on analysing the correlations between the net penetration rate and utilization rate of TBM and the HC score through statistical analysis of field measured data. The double shield TBM construction of water conveyance tunnel of Lanzhou water source project is taken as a case study. Results reveal 1) a quadratic function relationship between net penetration rate and HC score with the correlation coefficient reaching 0.84. With the decrease of HC score, the net penetration rate shows an increasing trend. 2) There is also a quadratic function relationship between TBM utilization rate and HC score, with the correlation coefficient being 0.82. With the increase of HC score, the utilization rate increases first and then decreases. 3) When HC score ranges between 41 and 46, the advance rate of TBM peaks with the daily tunneling distance reaching 45 m. When HC score is smaller than 41, advance rate decreases along with the decline of HC score. When HC score is greater than 46, advance rate reduces with the increase of HC score. 4) The predicted advance rate is in good agreement with the actual construction speed, with an average error of 5.2% and a maximum error less than 10%, indicating that the prediction model is reliable and can be used to predict the advance rate of double shield TBM.

Key words: double shield TBM, HC score of surrounding rock classification, utilization rate, net penetration rate, advance rate, prediction model