Numerical analysis of excavation damaged zone of underground caverns induced by excavation blasting

A numerical method to identify the range of excavation damaged zone (EDZ) induced by underground excavation and blasting is put forward. Firstly, the numerical approach for analyzing the underground excavation and blasting is presented based on three-dimensional elastoplastic FEM considering damage. This approach introduces how the blasting load, gravitational load and excavation load are calculated, applied and iterated. The influence of excavation blasting on surrounding rock stability and the effect of anchor support measures are both properly reflected. Based on the measurement method of EDZ in engineering practices, the threshold value of damage coefficient is obtained. Therefore, by employing the distribution of damage coefficients derived from numerical analysis, the range of EDZ of surrounding rock can be identified. A case study is conducted. It is discovered that the ranges of EDZ derived from numerical analysis and in-situ measurement agree well with each other; and the errors are within an acceptable range. It is therefore concluded that the proposed numerical method is effective to identify the range of EDZ of underground caverns induced by excavation and blasting.