Pillar stability evaluation based on load transfer distance and pillar effective width

Pillar stability evaluation is a major content and premise for room and pillar mining design. On the basis of analysis of pillar strength,pillar load and stability evaluation with tributary area method,the effective width is defined as the maximum diameter of inscribed circle in the coal pillar and is used to calculate the pillar strength. By leading into the load transfer distance ( LTD) ,the pillar stability evaluation method is established based on the LTD and effi- cient width. Compared with the results of stability evaluation for regular and irregular pillars,the new method can ef- fectively improve the limitation of traditional stability evaluation for tributary area method. In order to verify the relia- bility of new pillar stability evaluation method based on the load transfer distance and the effective width,the 3DEC numerical simulation is applied and analyzed. The distribution of numerical simulated pillar loads are consistent with theoretical calculations,almost all the relative errors are below 10% and the maximum relative error is 12. 68% . That is to say that the new evaluation method has a good universality not only suitable for regular pillars but also for irregular pillars.