Method for Analyzing the Evolution Characteristics of in Situ Stress Field Considering Rheology and Degradation: A Deeply Incised Valley in Qinghai-Tibet Plateau, Case Study

The in-situ stress field in deeply incised valleys is an important factor to be considered in major construction projects on the Qinghai-Tibet Plateau. The resulting in-situ stress has a complex distribution and large magnitude due to rapid river erosion. Considering that the few actual measured in-situ stress values are insufficient to meet the needs of understanding the regional in-situ stress field and its evolution, this research proposes a method, the Svisc model, to study the distribution and evolution characteristics of the in-situ stress field and applies it to a case study of the Jinping-I Hydropower Station. The results show that the Svisc model, which considers the rheological and degradation properties of the rock mass, applies strength parameters that change from peak to residual values rather than remaining constant with rock mass degradation during the downcutting process of valleys. The stress adjustment depth obtained is deeper, and the current in-situ stress field values are higher overall according to the Svisc model. This model is more effective than conventional methods to simulate the long-term evolution of valleys.