Abstract: The main strata in Qiandao Lake water distribution project are sandstone and quartz sandstone with high quartz content, shallow overburden and multiple faults, among which grade Ⅳ surrounding rock accounted for 52%. The construction period of the project is tight, and the demand for tunnel boring machine(TBM) advance rate is high. Based on such special geological conditions, the TBM selection and targeted design are conducted for Qiandao Lake water distribution project. The doubleshield TBM is adopted, the cutterhead is designed with highstrength box structure, the disc cutters are arranged in nonlinear way, and the cutter spacing and muck outlet are optimized. By controlling the exposed length of cutterhead, enhancing the ability of cutterhead to expand, adopting main drive lifting design, large torque and large thrust design, the grade Ⅳ broken surrounding rock and fault can be driven. The smallhole diameter TBM logistics and transportation platform is optimized. The engineering practice results show that the TBM cutterhead design has high reliability and can guarantee efficient rockbreaking performance. The overall perfectness ratio is up to 97% and the machine advanced 3151.58 m in 92 days. Additionally, the TBM has successfully advanced through grade Ⅳ fractured rock and faults effectively and quickly with all systems running in favorable conditions.

Key words:

Qiandao Lake water distribution project, TBM selection, doubleshield tunnel boring machine, treatment measures for unfavorable geologies