Analysis on types and interaction of stress fields in underground coal mines

The concept of supporting stress fields was put forward on the basis of in-situ and mining stress fields,which are the stress fields in surrounding rock caused by supports and the stress fields in the supports.The three types of stress fields consist of comprehensive stress field in underground coal mines.Based on the underground measurement data,the distribution characteristics of in-situ stresses,especially tectonic stresses were analyzed;the stress distribution features and laws,the magnitude of stress concentration around heading face and working face were analyzed by means of numerical simulation;the stress fields in surrounding rock caused by pretensioned bolting,individual hydraulic props and steel arches were computed.The stress magnitude and distribution features in bolt bar,plate and steel strap were computed in contrast to the magnitudes of in-situ stresses,mining stresses and supporting stresses.The affects of in-situ stresses to mining stresses,and the interaction and relation between mining and supporting stress fields were discussed.