Abstract: The valley stress field of Jinping I stage hydropower station is regressively computed based on investigating geological conditions. The in-situ test data and the calculation results that were explored by predecessors are considered and comparatives analysed during the regression simulation process. The geological section III is served as research object; and it is meticulously generalized; then a numerical model with complex geological structure is established. At the same time, the river development history is investigated. Then the evolution processes of bank slope frontier and weathering rock belt are designed based on the river cutting speed and timespan during every river terrace. Through many regression calculations, the stress trial method is chosen. Through analyzing Jinping tectonic characteristics, in-situ geostress data and predecessor’s results, the 12 MPa and 8 MPa uniform stress are decided to apply on model boundary after many trial computations. The regression simulation results are the best one, when the uniform stresses of 12 MPa, 8 MPa are applied on two vertical boundaries of the sixth river terrace model with the gravity stress field. A comparative analysis between the simulated results and the measured geostress data is carried out. It is shown that the magnitude and distribution depth of the stress concentration zone at the bottom are both fitting with a high precision between the calculation results and in-situ stress data. Through analyzing Jinping valley stress field features, it is shown that the stress distribution is not symmetric between left and right bank slopes. The stress distribution in the left bank is more complex due to the influence of fault and macular dikes tending to outward. In left bank the stress strong differentiation zone and unloading scope are both deeper than right bank.

Key words: valley stress field, valley evolution, stress partition