Abstract:

TBM tunneling method has many advantages, such as high speed, high efficiency, high safety and being environmental friendly. Due to the bad geological adaptability of TBM method, however, the TBM tunneling efficiency may be affected by the engineering geological conditions. Therefore, it is of great necessity to study the engineering geological conditions of the project before TBM tunneling is started. In this paper, the engineering geological conditions of the headrace tunnel of CCS hydropower station in Ecuador are analyzed in terms of uniaxial compressive strength, abrasiveness and intactness of the rocks and it is concluded that TBM method has good engineering geological adaptability in the project. Furthermore, engineering geological problems that may be encountered in TBM tunneling in the project, including rockburst, collapse in fault and fracture zones, serious deformation of soft rock, water inflow, high ground temperature and harmful gases, are analyzed and countermeasures are proposed. 

Key words: CCS hydropower station in Ecuador, TBM, headrace tunnel, engineering geological condition, prevention measure, construction countermeasure