The Engineering Geological conditions of the Qingling-Dabashan Sector of the Water Diversion Project from the Three Gorges Reservoir to the Yellow River
三峡水库引水工程秦巴段工程地质条件研究

Based on investigations into regional crust stability, active faults, engineering geological conditions and important engineering geological problems of the Qingling-Dabashan sector of the water diversion project from the Three Gorges Reservoir to the Yellow River, the authors divided the region into six segments from the difference of engineering geological conditions, namely, I-the sedimentary rock segment in northeast Sichuan basin, II- the segment of arc faults and folds in the southern part of the Daba Mountain, III- the segment of faults and karsts in the Daba Mountain, IV-the mid-low metamorphic rock segment in the southern part of the Qingling Mountains, V-the segment of dense faults and high metamorphic rocks in the Qingling Mountains, VI-the segment of Quaternary sediments in Weihe basin. Of them, the I and VI segments have the best engineering geological conditions, while the III and V segments possess the worst conditions. There exist more important engineering geological problems in III and V segments than in other segments. Rock blasting, water bursting and intense deformation in tunneling of deep-long tunnels make up the important engineering geological problems. It should be noticed that strong rock burst can occur near the highest peak in the Qingling Mountains, and that intense water gushing may occur in the Daba Mountain area. According to a comparative analysis of regional geological setting, crust stability, line-engineering geological conditions and important engineering geological problems of the three lines at the Qingling-Dabashan sector, it is held that the midline project is better than the west-line and the east-line projects.