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The paper discusses the concept and methodologies for the development of longwall face stability index (LFSI). LFSI is used for estimation of chock-shield pressure and face convergence. The index comprises of engineering properties of main roof, depth of mining, different support capacities and mechanical properties of coal seam being mined and provides a numerical value in the range of -6.17 to 8.13. In this study, 324 finite element models of longwall panel are developed based on various combinations of geomining conditions of Indian coal measure strata. The LFSI is an outcome of the results from finite element models. This paper illustrates a real life example for the estimation of chock shield pressure and face convergence based on LFSI. Validation of the LFSI based calculation is carried out with the field monitored data and found that the LFSI based approach is sufficient to forecast face stability parameters at longwall face.

A parent benzothiazole nucleus was synthesized by para amino acetanilide, then it is subjected to treatment with various substituted aromatic aldehydes to get the corresponding Schiff’s bases followed by treatment with pthalic anhydride to form 2-(6- acetamidobenzo[d]thiazol-2-ylcarbamoyl)benzoic acid. The structures of synthesized compounds were confirmed by various spectroscopic methods such as IR, 1H NMR and mass spectroscopy. The products were evaluated for their anti-inflammatory and analgesic activities. Some of the compounds exhibited potent activities when compared with the standards.

The major causes of longwall failure in India are identified to be inadequate selection of powered support, incomplete investigation of geomining conditions, unavailability of spare parts and lack of knowledge for longwall operations. This study focuses on the first and second causes of failures which are to identify and understand the strata behaviour at longwall face. Based on geomining conditions of Indian longwall mines, 324 finite element models were developed to analyse the interaction of surrounding strata with four legged chock shield support, the popular powered support in India. Models thus developed were used to investigate the effect of parameters such as coal type, powered support capacity, elastic modulus, friction angle, thickness of main roof rock and depth of working on longwall face stability in terms of leg pressure, roof to floor convergence and peak abutment pressure. Statistical relations are also developed based on the data generated from finite element models. An index called face stability index (FSI) is also developed for easy estimation of front leg pressure for any longwall panel. Validation of the statistical models is carried out with the monitored shield pressure data collected from two longwall panels. List of symbolsA equivalent leg bore cross-section based on the stroke length weighted average c cohesion C coal type D depth DI depth index E modulus of elasticity E c modulus of elasticity of coal seam E m modulus of elasticity of main roof ECL Eastern Coalfields Limited FEA finite element analysis FEM finite element model FLP front leg pressure FSI face stability index L stroke length of powered support leg MI main roof index MVRA multivariate regression analysis P 0 load at U 0 P m yielding load PAP peak abutment pressure PS powered support (capacity) RFC roof to floor convergence RLP rear leg pressure SCCL Singareni Collieries Company Limited SI support index Sst sandstone p,q index T c thickness of coal seam T m thickness of main roof U 0 leg convergence corresponding to P 0 U m maximum leg convergence corresponding to P m Q friction angle n Poisson's ratio r density d dilation/flow angle a,f,k slopes b,g,c intercepts

Many conventional methods of soil/waste treatment are available that have a negative impact on the ecosystem. Natural polymers (biopolymers) are considered as eco-friendly and sustainable grouting additives that strongly react with water to produce a viscous suspension. This research study investigates the influence of biopolymer on the undrained shear strength and hydraulic characteristics of coal mine overburden dump, which is widely considered for the construction of embankments and water-retention structures around mines. Two biopolymers were employed, xanthan and guar gum, over a range of concentrations (0·25–1·5%). Experimental results indicate the significant enhancement of shear strength parameters with an increase in concentration and the curing period. Permeability tests, carried out for a long term, also showed a change in hydraulic conductivity values, which are dependent on biopolymer concentration and the ageing period. Thus, it can be concluded that the application of biopolymers as temporary seepage barriers for the protection of many geotechnical works (such as foundations) and underground structures is highly beneficial.

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