Mechanisms of Interaction Between an Arch Dam and Abutment Slope Using Physical Model Tests

In southwestern China, the stability of high-steep slopes in large-scale hydropower projects has become a key technical challenge that constrains the safety of construction and operation. Based on a geological survey of the large-scale rock block in the Jinping-I Hydropower Station left bank, the entire system of the dam and its abutment slope is defined as the study subject. The mechanisms of interaction between the arch dam and the abutment slope during the construction stage, the impoundment stage and the structural plane strength-weakening stage are investigated using physical model tests. (1) During the excavation stage, the early-stage excavation has a significant impact on the huge rock block, whereas the impact of later-stage excavation is relatively small. (2) During the impoundment stage, the dam foundation is under hydraulic load. Therefore, the huge rock block moves away from the slope due to the arch thrust. (3) During the structural plane strength-weakening stage, both sides of the structural planes develop a relative displacement, and the massive rock block slips slightly. Moreover, the strain of the dam is slightly different from the situation in the normal impoundment stage. The majority of the downstream plane is under tension, indicating that a decline in the bedrock strength of the left bank dam abutment results in deformation of the dam towards the mountain body, the riverbed and the top part of the dam crest.