Dhananjai Verma

Stability Analysis of an Open Cut Slope in Wardha Valley Coal Field

Open cast mines are the prime source of coal production in India. Due to an increase in coal demand, deeper surface mines are being planned to ensure better productivity with enhanced safety of these mines. The safe working environment and continuous production of the coal calls for the safe and stable design of cut slopes. The stability analysis of this slope requires in depth geotechnical investigation which are aided by result orientated stability assessment using empirical methods and numerical simulation. In the present study, a slope was examined to understand the mechanism and comparisons were made with field observations. The investigation has involved a 32m high cut slope from an open cast mine in Wardha valley coal field which has been analyzed using a two dimensional numerical simulation. The bench slope consisted of a low strength sandstones, shales and clay sequence. Hoek-Brown strength parameters established and used as input parameters in the model. The results indicate that the slope is critically stable and may lead to failure without warning and needs proper attention.

Characterization of hydrocarbon-bearing fluid inclusion in sandstones of Jaisalmer basin, Rajasthan: A preliminary approach

The quartz grains from the sandstone of Jaisalmer, Pariwar and Goru Formations of the Jaisalmer basin, Rajasthan, India, exhibits a variety of primary and secondary fluid inclusions. Most of them are hydrocarbon bearing fluid inclusions. Laser Raman studies indicate that the primary fluid inclusions were mostly having aliphatic hydrocarbons with lower degree of maturity, while the secondary fluid inclusions were generally with aliphatic as well as aromatic hydrocarbons with higher degree of maturity. This inference was consistent with their fluorescence characteristics. The homogenization temperatures of primary monophase CH4 rich fluid inclusions varied from −80°C to −100°C, whereas the primary biphase fluid inclusions (CH4-CO2) homogenized between +80°C and +150°C. The secondary petroleum rich monophase fluid inclusions were having homogenization temperature between −80°C to −90°C, whereas the secondary biphase fluid inclusions homogenized between +130°C and +180°C. Most of the secondary biphase fluid inclusions were having the mixtures of H2O-CO2-NaCl, and were identified on the basis clathrate formation and they got homogenized between +140°C and + 250 °C. The three past events of migration of petroleum inferred in the host rock which were marked by the presence of characteristic secondary fluid inclusions. They were identified on the basis of cross-cutting relationships of different trails of fluid inclusions in the quartz. The cement generation in the basin might have been occurred in two stages as per the fluid inclusion petrography.

Scale Effect on Strength and Failure Modes of Open Pit Cut Slope of Wardha Valley Coalfield in India

Stability of slopes is one of the basic problems in open cast mines. Economical and safe open pit slopes involve maximization of the angle of inclination of the slope with proper stability. Studies on stability require a complete knowledge of the local geology. Stability of rock slopes depends on the scale of the slope, type of rock, orientation and density of the discontinuities etc. With an increase in size of rock mass, the chances of presence of joints and fractures increases and hence the strength of the rock material reduces due to the inclusion of more discontinuities in the rock mass. In the present study, a mine slope at Wardha Valley Coalfield in India has been numerically analyzed to take into account the effect of number of joint sets on the stability. The results show a reduction in factor of safety with an increase in joint sets.