Abstract：To study the distribution，values and directions of rock stresses，the plane and three-dimensional stresses in the riverbed and mountain massif are measured in field by hydraulic fracturing method in V-shaped river valley. The direction of the measured maximum horizontal principal stress is NW40°–60°，the value of the maximum horizontal principal stress is near to 40 MPa，and the minimum horizontal principal stress is about 20 MPa. The in-situ stress has been released as river valley unloaded and unloaded zone has been formed above 80 m around river valley shallow depth. The stresses concentration happens in the depth of 90–130 m；and the typical “stresses fold”of V-shaped river valley has been formed. Three-dimensional in-situ stress measurement is conducted at three points with different depths in cavity PD27. The results indicate that the three-dimensional principal stress increases with the depth increasing. The maximum and minimum principal stresses are double of their values from the first point to the third one. The orientation and trend of the principal stresses in three points are consistent. With the increase of the cavity depth，the inclination of the maximum principal stress becomes steeper gradually，which indicates that the contribution of the gravity is more dominant. The maximum and minimum principal compressive stresses in the tunnel cross section are obtained by stress analysis. The possibility of rockburst is analyzed combining the rockburst criterion. Analysis shows that the rockburst is controlled by the maximum difference stress in the tunnel cross section.
