Abstract:

To get the reasonable rock strength for engineering design and construction, sandstone in Anyang Section of South-to-North Water Diversion Project was used to carry out three kinds of rock strength assessment methods study. 1)Air drilling time was taken as an indicator to estimate the rock uniaxial compressive strength; 2)Collected available formulas were used to get the relationship between elastic wave speed and the uniaxial compressive strength; 3)Experimental data were fitted to get the empirical relationship between the point loading index and the uniaxial compressive strength. Through the above methods, three formulas for rock strength assessment were obtained. Taking AY33+600 as example, the sandstone rock strength was calculated. It was found that the three methods fitted each other well, and the error between assessment strengths and laboratory tests strength was 2%-9%. The application of these methods in Anyang section solved the problem caused by poor rock classification in the original designs.

Key words: strength assessment for sandstone, elastic wave, point loading index, air drilling time