Point Load Strength Test Power Index of Irregular Sandy Dolomite Blocks

The point load strength test index (I_s(50)) rapidly determines the tensile strength and the uniaxial compressive strength of rocks. It is necessary to analyze the power index (m) of I_s(50) when conducting a point load test (PLT) on irregular rock blocks. In this study, sandy dolomites from the Sinian Dengying Formation (Z_bd_n) and Doushantuo Formation (Z_bd) in the Yuxi section of the Central Yunnan Water Diversion Project were analyzed for their physical and mechanical properties. PLTs were performed on dolomites with different geological origins and weathering degrees, and the m-values were determined through statistical methods and regression analysis. The results showed that the logP–logD_e² curve exhibits a negative slope, and the m-value and its correlation coefficient (R²) increased with the decreasing weathering degree. For similar weathering conditions, the R² of the Z_bd_n dolomites was higher than that of the Z_bd dolomites. The error analysis indicated that the obtained m-values were highly accurate for the dolomite with different geological origins and weathering degrees. Casting slice identification tests further confirmed that the dolomite pore structure and density, connectedness, and specific mineral composition were the primary factors influencing the m-value.