Development of a model to estimate strata behavior during bord and pillar extraction in underground coal mining

Abstract

Instrumentation and monitoring is undertaken aiming at evaluation of changing values of rock mechanic parameters, namely, dilation, load, convergence, and stress, during mining for a safe strata control. It enables the mining practitioners to anticipate roof fall–related dangers in advance and taking subsequent preventive measures while depillaring. The coal measure formations consist of relatively weaker stratified rock masses. Bed separation occurs in the overlying strata due to induced mining stresses, which cause the rock mass in its surrounding to displace. These occurrences can be monitored by installing geotechnical instruments at judicious locations to avoid occurrence of any dangerous condition due to roof fall. Improper anticipation of strata movement during extraction in coal mining is one of the principal causes of accidents due to roof and side collapses. Also, the installed instruments can help in prediction of any apprehensive condition during depillaring. Preventive measure can be taken if the strata movement is monitored and roof fall is predicted in advance. The study is aimed to develop a conceptual model roof fall warning index, based on critical strata movement during underground coal extractions. Numbers of mining aspects, such as analysis of instruments’ reading, geo-mining parameters, physico-mechanical properties roof formations, and induced stress, are taken into considerations for development of the model. This study is mainly focused to predict a critical strata movement value for safety of the bord and pillar method of mining, perticularly depillaring.