Laboratory testing of rocks and developing their interrelationships is a good way for assessment of rock behavior for mining and construction industries. A detailed testing program was envisaged to establish possible correlations between porosity and mechanical properties of sedimentary rocks from Salt range Punjab, Pakistan. Sandstone samples were collected from different formations of the salt range area. Sample preparation was carried out at the rock mechanics laboratory at UET Lahore as per suggested methods of ISRM. Samples with partings or defects were removed from the testing program. Acceptable samples were tested for porosity, density, UCS, BTS, and other properties. The test results obtained were used for statistical analysis to find possible correlations using MS Excel. The analysis showed that the rocks can be divided into two groups. The predictive relationships were determined between porosity and static mechanical properties of rocks, and between porosity and dynamic mechanical properties.
Determination of geotechnical data for any engineering project is a key aspect of design and research. Laboratory investigation of rock involves carefully testing of rock samples after preparation in accordance with the ISRM or ASTM standards. Some examples of useful rock properties include but are not limited to uniaxial compressive strength (UCS), Young's modulus, Poisson's ratio, tensile strength, and sonic wave velocities through rocks. Some non-destructive tests like sonic velocity (P and S waves), porosity (η), and density (ρ) can be performed on same sample before the destructive tests like Youngs modulus (E), Poisson's ratio (υ), compressive and tensile strength (σt). Non-destructive tests are very popular in rock engineering as these are cheaper than the destructive tests and require almost no sample preparation. Rock mechanical tests are also used for geotechnical investigation for a project in rocky areas. The most important factors that affect the sonic velocity in rocks are type of rock, mineral arrangement, density, porosity, anisotropy, pore-water, confining pressure, temperature, weathering, texture, structure, grain size, and grain shape. Generally, the rock behavior under stress is governed by the factors like interlocking between grains, grain size, texture, composition, pores, arrangement of minerals and pores, and external factors like weathering, groundwater, nature of applied stress, etc. Rock mechanic professionals and researchers have produced good literature to determine and explain rock behavior through correlations (D’Andrea. 1965; Chang et al. 2006; Chary et al., 2006; Hashemi et al., 2010; Kahraman and Yeken, 2008; Khandelwal and Singh, 2011; Norouzi et al., 2013; Sabatakakis et al., 2008; Shalabi et al., 2007).
