Geostress field plays an important role in the stability of tunnel surrounding rock. Based on the in-situ stress results and geological conditions in the cracked area of the secondary lining concrete of the Qinling water conveyance tunnel from Hanjiang-to-Weihe, three-dimensional hydraulic fracturing method was used to analyze the in-situ stress of the surrounding rock in Qinling tunnel. The results show that the maximum principal stress on the cross section of the horizontal hole is 16.3-37.9 MPa and the minimum principal stress on the cross section is 2.4-9.1 MPa in the horizontal drilling depth range of 9.2-26.6 m. In the vertical drilling depth range of 3.8-20.7 m, the maximum horizontal principal stress is mainly 21.5-30.5 MPa, the azimuth average is N57°E, and the minimum horizontal principal stress is mainly 12.7-16.5 MPa. The maximum and minimum and the spatial maximum principal stress are 24.3 MPa, 14.4 MPa and 24.6 MPa respectively, which are nearly horizontal distribution. The stress field of surrounding rock at the test site of tunnel rock mass is mainly horizontal stress and the rock mass stress is classified as "high in-situ stress".

water conveyance tunnel  /  geostress test  /  hydraulic fracturing method  /  plastic deformation