Abstract: This paper discusses the geostress distribution of slope in deep-cutting gorge in Southwest China. Based on 95 test data of spatial stress and 50 test data measured using the method by adit-wall stress restoration from 10 large-scale hydropower projects in Southwest China. The change discipline of geostress field along with vertical depth and horizontal depth can be counted and analysed. Furthermore, the characteristic of geostress field in superficial zone of slope can be discussed according to the magnitude of principal stress and the change rule of dip angle. The results show that: (1) The stress field can be divided into two parts: superficial zone(0-300 m) and deep zone(>300 m) from macroscopic perspective. (2) The magnitude of principal stress and the dip angle is extremely volatile in superficial zone; the magnitude of principal stress and the dip angle in deep zone is stable. The magnitude of maximum principal stress is between 15 and 30 MPa; the magnitude of minor principal stresses is between 5 and 12 MPa; the dip angle is ranged from 0 to 30°, It is apparent that the magnitude of maximum principal stress is 1.5-3.5 times than minor principal stresses. (3) The change characteristics are that the principal stress magnitude in superficial zone changes from low to high and fluctuates violently before to stability while the dip angle of maximum principal stress is transferred from the nearly parallel with slope to high-variability, and then the two gradually shift to a consistent state with deep zone.

Key words: geostress field, high steep canyon slope, Southwest China