Influence of Chemical and Textural Characteristics on Geomechanical Properties of Sandstone

Abstract

To find out the influence of chemical and petrographic characteristics on geomechanical properties of sandstone, samples are collected from mines of Mungoli Opencast Mine (Western Coalfields Limited), Lakahnpur opencast mine (Mahanadi Coalfileds Limited) and Tamnar opencast mine (Jindal Power Limited). The samples from WCL are both coarse and fine grained but the samples from MCL are coarse grained. .However medium grained sandstone, shaly sandstone and ferruginous sandstones were collected from JPL. Specimens were prepared from the samples and tested for uniaxial compressive strength (U.C.S.), point load strength (P.L.S), Brazilian tensile strength (B.T.S), dry and saturated densities, porosity. Strength has found to be increased with decrease in porosity. Mineralogy and chemical composition were found out by XRD and XRF tests respectively. Quartz and kaolinite are the dominant minerals in this study. Siderite is dominant in fine grained sandstone of JPL.Strength has found to be increased with percentage of Ca, Mg and Fe concentration. Thin sections were prepared to study the texture of the sandstone, which were then analyzed by polarized optical microscope. Petrographic properties such as packing density and packing proximity were determined which were found to affecting the strength of the strength of the sandstone. They were found to be varied from 28.2% to 86.75% and 17.23% to 74.17% respectively. A strong relationship is observed for packing proximity with the strength of the sandstone. It was found that the U.C.S of the sandstone found to be varied from 13.82 MPa to 47.4 MPa. Similarly the point load strength and Brazilian tensile strength was found to be varied from 0.36 MPa to 5.38 MPa and 0.22 MPa to 7.2 MPa respectively. Besides these the dry density, saturated density and porosity have been found to be varied from 1.85 g/cc to 2.47 g/cc and 2.02 to 2.61 g/cc respectively.