Abstract:Drilling and blasting method is widely used in the construction of tunnels or other underground projects. Collapse always occurs during the construction of tunnels due to the unfavorable geological conditions or other factors such as the excavation method, causing casualties, equipment damage, time delay or other adverse consequences. However, the current qualitative assessment method can not continue to satisfy the needs of project risk management. Hence, a quantitative assessment model of collapse risk is developed. Considering the variability of physical and mechanical parameters of surrounding rock, the probability of collapse is obtained by the Monte-Carlo method combined with the numerical method. The related scope of collapse is predicted by Protodyakonov"s theory. With the predicted probability and scope of collapse, the risk of casualties, time delay and economic loss is analyzed quantitatively through the introduction of spatiotemporal distribution index and vulnerability index. The quantitative assessment of collapse risk is realized by the quantifiable risk acceptance criterion based on the way of ALARP principle and F-N curve. Finally, with a specific engineering case, the operability and applicability of the developed risk quantitative assessment model is illustrated.