Abstract: Stress measurement data is in lack in Northern Xinjiang’s Altai region. We tested the stress field of a deep water diversion tunnel in this region by using hydraulic fracturing method. Test result and analysis reveal that the tested stress field is tectonic stress type and the maximum horizontal principal stress orientation is NNE, which is in consistency with the focal mechanism solution. Moreover, it reveals that the ratio of average horizontal stress to vertical stress changes no smaller (close to 1.0)in the depth of more than 300 m. We should strengthen the research on tectonic stress field in deep area and pay attention to the application of in-situ measurement means to improve the macroscopic understanding of regional stress field.

Key words: deep tunnel, geo-stress, North Xinjiang area, tectonic stress field, hydro-fracturing method