Determination of deformation characteristics of natural rock using methods of close-range photogrammetry

Abstract

In the field of civil engineering, traditional deformation sensors are used (measurements of changes of length and widths in the stressed material), such as an electrical resistance strain gauge, deviation meters (mechanical dial gauge, electronic digital indicator, LVDT). These sensors work quite well, but the sample surface preparation and fixing the sensors on the sample surface can be timely and work skill demanding. On the other hand, conventional non-destructive testing methods, such as rebound hammers or ultrasonic pulse propagation have a disadvantage in large data scatterness and low reliability. This paper focuses on a practical, more reliable and cost-effective method for determining deformation characteristics, calculated from digital images using the principle of close-range photogrammetry. To verify the effectiveness of this method, a test was performed on a sample of natural stone from the tunnel Višňové. The data were obtained by these methods and correlated with the used load. After plotting the stress-strain curve, the static modulus of elasticity and the modulus of deformation were determined. These modules were compared with those determined from resistance strain gauge measurements.