A correlation between P-wave velocity and Schmidt hardness with mechanical properties of travertine building stones

As known, P-wave velocity and Schmidt hardness are non-destructive tests, which have been used for many years in geological, geotechnical, and civil engineering as an index tests for a quick assessment of rocks mechanical properties due to its rapidity and easiness, and non-destructiveness. The purpose of this study is to investigate the correlation between P-wave velocity and Schmidt hardness with some of mechanical properties of travertine building stones by empirical equations. Moreover, we have compared the accuracy of P-wave velocity and Schmidt hardness to estimate the mechanical properties of rocks. For this purpose, 15 types of travertine have been collected from various quarries of Iran and tested. The tests include the determination of P-wave velocity and Schmidt hardness, and mechanical properties include the unconfined compressive strength, Brazilian tensile strength, and point load strength. Using data analysis, empirical equations have been developed for estimating the mechanical properties from P-wave velocity and Schmidt hardness. To check the validity of the empirical equations, a t test was performed, which confirmed the validity of the proposed empirical equations. Moreover, the results show that P-wave velocity appears to be more reliable than the Schmidt hardness for estimating the mechanical properties. Consequently, we propose empirical equations avoiding from cumbersome and time consuming tests for determining the mechanical properties of rocks.     

Exploration of gold mineralization in a tropical region using Earth Observing-1 (EO1) and JERS-1 SAR data: a case study from Bau gold field,Sarawak, Malaysia

Bau gold mining district, located near Kuching, Sarawak, Malaysia, is a Carlin style gold deposits. Geological analyses coupled with remote sensing data were used to detect hydrothermal alteration rocks and structure elements associated with this type of gold mineralization. Image processing techniques, including principal components analysis, linear spectral unmixing, and Laplacian algorithms, were employed to carry out spectrolithological–structural mapping of mineralized zones, using Advanced Land Imager, Hyperion, and JERS-1 synthetic aperture radar scenes covering the study area and surrounding terrain. Hydrothermally alteration mineral zones were detected along the SSW to NNE structural trend of the Tai Parit fault that corresponds to the areas of occurrence of the gold mineralization in the Bau limestone. The results show that potentially interesting areas are observable by the methods used, despite limited bedrock exposure in this region and the constraints imposed by the tropical environment.     

Fuzzy logic application in compiling multi geohazards macro-zone maps; case study: Rahdar, 1:25,000 Quadrangle,Khuzestan, Iran

This paper is devoted to describe a new method of fuzzy logic applied to multi geohazards macro-zone maps. The basic steps are (1) compilation of macro-zone maps for each type of geohazard phenomenon. Each phenomenon is then assigned one of seven geohazard zones: very low, low, relatively low, moderate, relatively high, high, and very high; (2) definition of a membership function using a fuzzy logic algorithm to quantify the qualitative data, estimate a geohazard grade for each mesh point, and to convert qualitative maps to quantitative maps; (3) computation of the summed hazard grade for each mesh point and creation a cumulative geohazard map; and (4) compilation of a multi geohazards macro-zone map by defining a mathematical algorithm and again using fuzzy logic. The paper also describes a mechanism that takes subjective engineering judgments into account. Finally, a geohazard map with a scale of 1:25,000 (Rahdar district, Khuzestan, Iran) is compiled. This study divides the area into seven geohazard macro-zones. Zones of high and very high geohazard classification cover most of the area due to the large number of sinkholes and asymmetric subsidences, rock falls and other slop movements. Low and very low hazard zones only cover small localities.