Abstract: Surface collapse induced by underground mining has become a major safety hazard in mining operations. The traditional concept of rock movement angle is still used to delineate the scope of surface collapse. The delimitation scope often deviates from the actual collapse scope. Based on the reliability index obtained by the response surface method， the calculation method of collapse area is established for improving the above problem. Firstly， the sensitivity analysis of rock mass mechanical parameters is carried out using the discrete element numerical calculation method. The parameters exhibiting strong sensitivity are selected as random variables to fit the response surface function. Then the reliability index of rock mass under different levels of degradation is calculated by MATLAB. Finally， the reliability index is used to categorize different risk levels. The proposed method is used to calculate and analyze the collapse area of Chaoyang xinhua molybdenum mine Co.，Ltd. in Liaoning Province. The numerical calculation results show that the elastic modulus， cohesion and internal friction angle of rock mass are the sensitive parameters influencing the calculation of surface collapse area. By comparing the results with the collapse area scanned by an unmanned aerial vehicle(UAV)， it has proved that the calculation method of collapse area proposed is reasonable and accurate， which can provide engineering guidance for the safety management of mining collapse areas.

Key words: surface collapse; reliability; response surface method; parameter sensitivity; numerical analysis