Experimental study on the relationship between the strength of altered rocks and the short wave-length infrared spectral curve

AbstractAltered rocks widely exist in rock mass engineering. Alteration has an obvious deterioration effect on the physical and mechanical properties of rocks, which may cause engineering geological prob-lems or geological hazards. The main method to obtain the uniaxial compressive strength of altered rocks is indoor uniaxial compression test, which has the reality of long period, high cost, difficult sampling, and limited transportation. In this paper, the uniaxial compression test and short wavelength infrared spectral test analysis are performed on the altered rocks of a hydropower station in Southeast China to study the relationship between the strength and the short wavelength infrared spectral curve of altered rocks. The results show that, there is a correlation between the number of absorption peaks of short wavelength infrared spectral curve and the uniaxial compressive strength of altered rocks. In the wavelength ranges of 1880–1950 nm and 2170–2230 nm, the uniaxial compressive strength of altered rocks with two absorption peaks in the short wavelength infrared spectral curves are generally higher than 150 MPa. In the wavelength ranges of 1380–1430 nm, 1880–1950 nm, and 2170–2230 nm, the uniaxial compressive strength of altered rocks with three absorption peaks in the short wavelength infrared spectral curves are generally lower than 100 MPa. In the wavelength ranges of 1380–1430 nm, 1630–1660 nm, 1880–1950 nm, 2170–2230 nm, 2230–2380 nm, the uniaxial compressive strength of altered rocks with four absorption peaks in the short wavelength infrared spectral curves are generally between 100–150 MPa. This research will provide a new method for rapid evaluation of strength of altered rocks in the field.