Abstract:

The rock quality designation (RQD), joint space and joint characters of diversion tunnel of CCS Hydropower Station in Ecuador bored by doubleshield TBM are obtained by rock mass rating (RMR), uniaxial compressive strength calculated by rebound test, observation of tunnel wall and working face through shield gaps and cutterhead gaps and rock slag and tunneling parameters. Seven indexes, i. e. rock rebounding value, surrounding rock integrity, RQD, cutterhead thrusting force, cutterhead torque, content of sheet rock slag, and seepage volume of groundwater, are selected and assigned by comprehensive analysis. The surrounding rock classification standards are established; and the classification of surrounding rocks is carried out by summation method. The classification results show that the selected seven indexes can overcome the difficulties of comprehensive geological sketching when using doubleshield TBM, meet the rapid construction requirements and reflect the surrounding rock accurately. In other words, the classification results are reliable. 

Key words: CCS Hydropower Station in Ecuador, diversion tunnel, doubleshield TBM, surrounding rock classification