Abstract：Developing features of fractured zones of roadway in isolated coal pillar area are theoretically studied by three dimensional distinct element code(3DEC). It is found in this paper that fractured zones of rock masses in high stress area are larger than those of others，but their horizontal displacement does not increase obviously. Small coal pillar in high stress area has pre-developed splits and large horizontal displacement，and its stress concentration degree is lower. For application in site，ground penetrating radar (GPR) is an effective method to determine the fractured zone and can be used to verify the theoretic results of 3DEC，which is important to locate roadways in site. GPR probing in field agrees with the result of numerical model of 3DEC. Therefore，the combined results of both stimulation and site probing present the reasonable position of roadway，which is 5～8 m to adjoining pits in the presented case.
