Abstract: The natural topography of karst regions is favorable for pumping and storage projects, however, karst development creates heterogeneous engineering geological rock groups, which can compromise project stability. Therefore, accurately estimating the mechanical characteristics of such heterogeneous rock masses in karst areas is crucial. Existing methods for estimating rock mass mechanical parameters fail to adequately quantify dissolution-induced heterogeneity, referred to here as dissolution characteristics. This study analyzes the impact of dissolution on rock masses and introduces the dissolution rate, inhomogeneity coefficient, and degree of variation to characterize these dissolution-induced features. A method for preparing karst rock samples is proposed, and rock samples with specific karstification characteristics are prepared for uniaxial compression tests. The findings reveal a negative exponential relationship between mechanical parameters and dissolution rate. Additionally, the inhomogeneity coefficient and degree of variation influence these parameters by modifying dissolution impact coefficient, establishing a relationship expression linking mechanical parameters to dissolution characteristics. A field method for quickly determining dissolution characteristic indices is developed. By integrating the Hoek-Brown criterion with the established relationship expression, a rapid estimation method for mechanical parameters of heterogeneous rock masses in karst areas was created. The method is applied to the upper reservoir site of a proposed pumped storage power station in Hubei Province’s karst region, demonstrating the validity of the estimated mechanical parameters and the strong engineering applicability of the developed method.

Key words: heterogeneous rock formation, rock mass dissolution characteristics, uniaxial compression test, Hoek-Brown criterion, rock mechanical parameters, rapid estimation