Combined Effect of Loading Rate and Water Content on Mechanical Behavior of Natural Stones

Abstract

Uniaxial compressive strength (UCS) is considered to be the most widely used mechanical property to detect and classify rocks. However, tests are generally performed under dry conditions and standard loading rates. On the other hand, in the land environment neither the saturation degree of rocks is zero nor the loading rate is constant. In this study, three different sedimentary rocks in the Eastern Anatolia Region (Turkey) were used for determination of the effects of saturation degree on mechanical properties and combined effects of saturation degree and loading rates on UCS. For this purpose, point load strength, Schmidt and Shore hardness, ultrasonic wave velocity, and Brazilian tensile strength tests were carried out on oven-dried, 35, 70, 100% saturated specimens, and UCS tests were carried out in 0, 35, 70 and 100% saturation degrees and 0.50, 0.75 and 1.00 kN/s loading rates. Test results showed that increasing water content led to decreasing mechanical properties up to 40-50%, respectively, from dry to saturated conditions. Water absorption had an important effect on Brazilian and point load strength. Internal pressure caused by water effected tensile stress more. It was seen that saturation and loading rate increased with the UCS-increasing saturation rate and caused a buffer effect in low porosity rocks.