Abstract: In the present stage of open-pit mine blasting,the residual rock powder is used to plug the hole. However,the method of rock powder plugging the hole is relatively primitive,and the plugging effect is poor. Especially,when the charge of the hole is large or the center of gravity is high,blasting punching is easy to occur,and the plugging body cannot intercept the explosion-generated gas well,leading to the leakage of a large amount of blasting energy and poor blasting effect. In order to improve the hole stemming effect,on the basis of previous experimental results,geopolymer was introduced to modify the rock powder stemming material. Based on the content and requirements of open-pit blasting stemming operation,six groups of different material ratios were designed for testing. The setting time and mechanical properties of the products of each scheme were tested,and the best ratio scheme was selected. In addition,the safety of blasting equipment caused by the heat release of geological polymerization reaction and the influence of geological polymerization products on the detonation of detonating tube are analyzed,and the safety of application of modified rock powder material is demonstrated. The numerical simulation of impact crushing of geopolymer modified rock powder stemming material is also carried out. It is considered that the material can form a massive structure similar to gravel under the impact of blasting,and can self-seal with mutual clamping under the shock wave,so as to improve the interception ability of hole stemming body to explosion energy,improve the utilization rate of energy, and thus improve the blasting effect. The parctice results show that the scheme is applied to the sectional charging structure of Pingshuo East Open-pit Mine,and good stemming effect is obtained,and the punching rate and bulk rate are reduced. 

Key words: open-pit mine,mine blasting,geopolymer,blasting-hole stemming,segmented charge