Retrospective case example using a comprehensive suitability index (CSI) for siting the Shisan-Ling power station, China

The purpose of this paper is to present a retrospective case example of using the rock engineering systems (RES) methodology to site a pumped storage power station in China. With such a siting problem, there are many interacting factors governing both the site and the specific underground position of the powerhouse. The RES approach, based on an interaction matrix for semi-quantitative characterization of the factors and their interactions, is used to develop a comprehensive suitability index (CSI). In this way, the factors governing the geological and rock mechanics related factors are structured and evaluated. Additionally, the complexity of the decision making process is condensed to the CSI values for different potential sites and underground locations, a higher CSI value indicating a more suitable site.The retrospective analysis uses information from the investigations made during the actual site investigation and design work for the Shisan-Ling Power Station, China — which has been constructed. For the first stage, site selection for the overall engineering arrangement, 11 parameters concerned with geology, geomorphology, engineering layout, environment, cost and construction are taken into account. After comparison of site options in conglomerate, andesite and limestone formations, the conglomerate formation proved to be most favorable — because it has the highest CSI value. For the second stage, specifically locating the underground powerhouse, another seven parameters associated with faults, joints, groundwater, etc. are evaluated. As a result, position II proved to be the most favorable location for the powerhouse. Since these were the same conclusions reached during the actual investigations, this retrospective application of the CSI demonstrates the value of the RES methodology and associated indices for assisting in rock engineering design.