Abstract: Surrounding rock looseness range and its variation is one of the important parameters in the stability evaluation and support of roadway surrounding rock.How to quickly and accurately detect the loosen range and provide better service for the project has become a hot current in deep mining research.Under the background of the support of deep extending roadway surrounding rock and failure characteristics in Chengjiao mine，based on summarizing the achievement on loose circle from the predecessor，two horizontal rock loose circles in Chengjiao mine are comparatively studied by adopting both tests and numerical simulation.The measurement was taken from 5 stations at two horizontal roadways by using ground penetrating radar test，getting that there are large differences in failure characteristic of surrounding rocks at the transverse sections of 5 stations.Some rocks are relatively intact，and some are seriously loose and broken.Difference of surrounding rock looseness range in vertical line of different section of roadway were large and ranged between 1.4~2.8 m.This difference are closely related with geological conditions and mining pressure.The looseness of surrounding rock of deep soft rock roadway in Chengjiao Mine ranged obtained by the numerical simulation between 2.0~3.0 m.The numerical simulation and the geological radar research results were comprehensively analyzed to determine the range of loose circle in deep soft rock roadway in Chengjiao Mine ranged between 1.4~3.0 m.The results have important reference value for selecting the deep extended roadway support in Chengjiao Mine.

Key words: Surrounding rock loose circle, Deep extension, Geological radar, Numerical simulation