Abstract：All the comparative projects of diversion tunnel line in “nine-nine” Daban area are all through mid and lower Pleistocene strata in the Quaternary. For the granular structure of Quaternary strata，unified classification standard and method have not been established in China at present. The tunneling conditions in these strata play a dominant role in the choice of the design scheme. Therefore，the prototype examination holes are arranged on the top of the lower Pleistocene strata，which have relatively poorer tunneling conditions at the tunnel entry. Based on the monitoring of overall process of excavation and deformation after excavation for the prototype examination holes，the stability and deformation characteristics of the surrounding rock of tunnel are studied；and the result offers a scientific reference to the design and supporting of tunnel.
