Abstract: Due to constraints from the geological conditions of goaf and the detection techniques,the traditional detection techniques for goaf cannot obtain accurate data from the area where the staff cannot enter in.The reliability based on these cavity data is so low for stability analysis of goaf.Therefore,3D laser scanning system(MDL-VS150) is used to make an accurate laser scanning.3D point cloud data,based on the 3D laser scanning,are adopted to build 3D entity model of the goaf by 3Dmine software.Based on FLAC3D software,the stability of goaf is analyzed.Then,the displacement and stress of the goaf in an Iron Mine are analyzed according to the simulation calculation results.The maximum vertical displacement is about 4.437 cm,and the maximum tensile and compressive stress in the surrounding rock are respectively 0.795 MPa and 3.221 MPa,which are lower than the tensile and compressive strength of rock.Therefore,goaf is presently in a stable state and collapse will not occur in a short term.However,the effective treatment measures should be taken timely for the long-term development of the mine.

Key words: Cavity detection, 3D laser scanning, Cavity stability, MDL-VS150