Analysis of chock shield pressure using finite element method and face stability index

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.