The present study reports the results of experiments conducted to under-stand the influence of saturation on dynamic elastic constants of sandstones. The intact rock specimens of sandstones have been tested using ultrasonic pulse technique to determine their compressional wave velocity () and shear wave velocity () at different degrees of water saturation (Sr). These rocks have also been tested to deter-mine their mineralogical constituents, chemical compositions, physical properties and strength & deformation characteristics. The values of dynamic modulus of elasticity (E), Poisson's ratio (ν), modulus of rigidity (G), bulk modulus (K) and compressibility (β) have been computed from the experimental results of, and unit weight (γ) of rock specimens using well known correlations. pvsvpvsv Significant to considerable reductions in both uniaxial compressive strength (σc) as well as tangent modulus at 50% of failure stress (Et50) have been observed for these rocks on full saturation from initial dry state. These sandstones in general, exhibit significant to moderate increase in E, ν and K with increase in saturation from dry to fully saturated state. Whereas, G marginally decreases or remains more or less unin-fluenced and β decreases significantly due to moisture variation. The sandstone com-prising of siliceous clay as grain cementing matrix exhibits maximum changes in all these elastic constants on full saturation as compared to other types of cementing ma-trix. Relevant recommendations for engineering design for projects in such field con-ditions have been given.
In rapidly developing country like India, the need for large scale structures is ever increasing. The sedimentary rocks such as sandstones, lime-stones, etc. are in common occurrence in India during tunneling, civil engineering constructions, mining operations, etc. In terms of area of exposure, sandstones alone account for 75% of sedimentary rocks. Thus the studies especially on sandstones cover large area of engineering interest.
