Determining the Geotechnical Characteristics of Some Sedimentary Rocks from Iran with an Emphasis on the Correlations between Physical, Index, and Mechanical Properties

Abstract

Geotechnical characteristics were assessed to correlate physical, index, and mechanical properties of twelve sedimentary rock samples of four rock types collected from northern and northwestern parts of Damghan, northern Iran. Mineralogical and physical properties of the rocks were determined from prepared specimens in the laboratory after the field investigations. Also, the selected rock samples were subjected to index and mechanical tests including P-wave velocity, Schmidt rebound hardness, slake durability, point load, Brazilian, block punch, and uniaxial compressive strength. Mineralogical studies by thin section and X-Ray diffraction methods indicated that the selected rock samples with different textures are mainly composed of quartz and calcite. The studied rocks had low to high dry unit weight, low to medium porosity and low to very high P-wave velocity. The rocks were classified as durable and very durable based on the slake durability index. They were very strong to extremely strong in point load index, weak to moderate in block punch index, and weak to strong in uniaxial compressive strength. So they were classified in different strength categories. The obtained correlations between different rock properties from regression analyses indicated that specific gravity and unit weights are affected by mineral content while the other characteristics including water absorption, primary wave velocity, Schmidt rebound hardness, slake durability index, point load index, Brazilian tensile strength, and block punch strength are controlled by the porosity of the rocks.